JCB
Journal of Cell Biology
Range of SHH signaling in adrenal gland is limited by membrane contact to cells with primary cilia
Ivona Mateska1,2[D, Kareena Nanda3, Natalie A. Dye1D, Vasileia Ismini Alexaki3(D, and Suzanne Eaton1,2
The signaling protein Sonic Hedgehog (SHH) is crucial for the development and function of many vertebrate tissues. It remains largely unclear, however, what defines the range and specificity of pathway activation. The adrenal gland represents a useful model to address this question, where the SHH pathway is activated in a very specific subset of cells lying near the SHH- producing cells, even though there is an abundance of lipoproteins that would allow SHH to travel and signal long-range. We determine that, whereas adrenal cells can secrete SHH on lipoproteins, this form of SHH is inactive due to the presence of cosecreted inhibitors, potentially explaining the absence of long-range signaling. Instead, we find that SHH-producing cells signal at short range via membrane-bound SHH, only to receiving cells with primary cilia. Finally, our data from NCI-H295R adrenocortical carcinoma cells suggest that adrenocortical tumors may evade these regulatory control mechanisms by acquiring the ability to activate SHH target genes in response to TGF-B.
Introduction
The Hedgehog (Hh) signaling cascade determines the fate and growth of many animal tissues during development, adult ho- meostasis, and disease (Ingham and McMahon, 2001). Hh is a secreted protein that can travel long distances (up to 300 um) through tissues to affect gene expression in a concentration- dependent manner during development (Briscoe and Thérond, 2013). Multiple mechanisms have been shown to facilitate long- range transport of the hydrophobic Hh ligand, including secre- tion on lipoproteins (Panáková et al., 2005; Palm et al., 2013) and exovesicles (Vyas et al., 2014). Nonetheless, in many adult ver- tebrate organs, where Hh is required for homeostatic mainte- nance, pathway activity is more restricted (Petrova and Joyner, 2014). The mechanisms defining where, when, and to what extent the Hh pathway becomes activated in these vertebrate tissues are largely unknown.
Sonic Hedgehog (SHH) is the most ubiquitous mammalian Hh homologue (Ingham et al., 2011). Once it travels to receiving cells, SHH signals by repressing the activity of its receptor, Patched1 (PTCH1), a transmembrane protein with a sterol- sensing domain (Kuwabara and Labouesse, 2002). PTCH1 reg- ulates the accessibility of small lipidic molecules that activate or inhibit another transmembrane protein, Smoothened (SMO; Taipale et al., 2002; Khaliullina et al., 2009). Once activated, SMO relocates to the tip of the primary cilium (Corbit et al.,
2005; Rohatgi et al., 2007; Milenkovic et al., 2009), a signaling organelle found in many mammalian cells (Christensen et al., 2007). In the primary cilium, SMO activates a signaling cascade that changes the posttranslational processing of glioma- associated oncogene (GLI) family transcription factors, pro- motes formation of their activator forms, and ultimately leads to transcription of Hh target genes (Haycraft et al., 2005; Tukachinsky et al., 2010; Humke et al., 2010; Hui and Angers, 2011).
Determining how SHH is produced and received is critical for understanding what limits the range of its activity. Lipoproteins are required for the release and long-range transport of the SHH ligand and its signaling output (Eaton, 2008). Additionally, lipoproteins carry Hh pathway inhibitors, such as endocanna- binoids (Khaliullina et al., 2009, 2015). Only sufficient amounts of lipid-modified SHH loaded in parallel on lipoproteins can overcome this inhibition (Palm et al., 2013). Alternatively, Hh can be secreted on exovesicles (Tanaka et al., 2005; Vyas et al., 2014) or can signal via direct cell-to-cell contacts (Rojas-Ríos et al., 2012; Bischoff et al., 2013; Sanders et al., 2013; Gradilla et al., 2014). Signaling by direct cell contact would presumably limit Hh signaling to short range, although there are examples of long cell protrusions carrying Hh in Drosophila melanogaster (Kornberg and Roy, 2014).
1Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; 2Biotechnologisches Zentrum, Technische Universität Dresden, Dresden, Germany; 3Institute of Clinical Chemistry and Laboratory Medicine, Technische Universität Dresden, Dresden, Germany.
Dr. Eaton died on July 2, 2019; Correspondence to Ivona Mateska: mateska@mpi-cbg.de; I. Mateska’s present address is Institute of Clinical Chemistry and Laboratory Medicine, Technische Universität Dresden, Dresden, Germany.
@ 2020 Mateska et al. This article is distributed under the terms of an Attribution-Noncommercial-Share Alike-No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution-Noncommercial-Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/).
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A
Capsule
SHH:GFP adrenal gland
GLI1:LacZ adrenal gland
Cortex
GFP DAPI
BGal SF1 DAPI
Medulla
Gli1+ Shh- Shh+ SF1- SF1+ SF1+
B
D
S16 Adrenal Supernatant
Adrenal glands + 0.5 M NaCl buffer dissociate with loose douncer
VLDL
LDL
HDL
Soluble Proteins
Pellet 1,000 x g (P1)
1,000 x g / 20 min
1.004
1.006
1.013
1.016
1.023
1.038
1.061
1.101
1.157
1.188
1.215
1.237
1.257
1.290
1.300
1.334
1.391
1.531
[g/ml]
Supernatant 1,000 x g
22 kD-
SHH
(S1)
36 kD-
Pellet 16,000 x g (P16)
16,000 x g / 20 min
Supernatant 16,000 x g
APOA1
(S16)
Pellet 150,000 x g (P150)
22 kD.
150,000 x g / 2 h
36 kD-
APOE
Supernatant 150,000 x g (S150)
E
S150 Adrenal Supernatant
C
VLDL
LDL
HDL
Soluble Proteins
S1
P16
S16
P150
S150
1.004
1.006
1.009
1.018
1.025
1.036
1.050
1.070
1.126
1.157
1.203
1.233
1.240
1.257
1.274
1.320
1.421
1.474
[g/ml]
22 kD-
SHH
22 kD-
SHH
36 kD-
36 kD-
APOA1
22 kD-
APOA1
36 kD-
22 kD 36 kD-
APOE
APOE
The adrenal gland represents an interesting model to address the question of how short- versus long-range SHH signaling is regulated. The adrenal gland is an endocrine organ with essen- tial functions in mammals that requires SHH for its develop- ment and adult homeostasis (Yates et al., 2013). It has an ample access to lipoproteins, as they are the major source of cholesterol for steroid hormones biosynthesis (Kraemer, 2007). Yet it is still unknown whether endogenously produced SHH can be secreted on lipoproteins, as it is in some cell lines (Palm et al., 2013), or whether it can signal in an alternative form. Although there is an abundance of lipoproteins, which would allow SHH to travel and signal long-range, SHH pathway activation is limited to short- range interactions between two adrenal compartments: the ad- renal cortex consisting of steroidogenic (SF1-positive) cells and the overlaying mesenchymal capsule (Fig. 1 A; Keegan and Hammer, 2002). Clusters of undifferentiated steroidogenic cells of the outer adrenal cortex produce SHH, which signals specifically to the adjacent nonsteroidogenic capsule cells (Ching and Vilain 2009; King et al., 2009; Guasti et al., 2011). These cells respond by expressing the SHH target genes, Gli1 and Ptch1, and
producing terminally differentiated lineages (King et al., 2009; Huang et al., 2010; Laufer et al., 2012; Freedman et al., 2013). Other cells of the cortex do not activate the SHH pathway- neither those in close proximity to the producing cells nor those far away (Wood and Hammer, 2011). How specific, short-range SHH signaling occurs even in the presence of lipoproteins is an important open question.
Importantly, ectopic overactivation of the SHH pathway in the adrenal gland has been implicated in disease, such as obesity and adrenal carcinoma. In both cases, no increase in the amount of the SHH ligand itself is seen (Gomes et al., 2014; Swierczynska et al., 2015; Werminghaus et al., 2014), making it unclear how the pathway is up-regulated. In the case of obesity, overactivated SHH pathway in capsule progenitors (SHH-receiving cells) re- sults in an expanded cortex and elevated levels of steroid hor- mones in mice (Swierczynska et al., 2015). In the case of adrenocortical tumors, SHH pathway components and target genes are overexpressed (Boulkroun et al., 2011; Gomes et al., 2014), and antagonizing the pathway reduces growth of the NCI- H295R adrenocortical carcinoma cell line (Werminghaus et al.,
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2014). How the pathway may be involved in adrenal cancer is unclear, however, as examples for both autocrine and paracrine SHH signaling promoting tumor growth can be found in other cancer types (Berman et al., 2003; Watkins et al., 2003; Yauch et al., 2008; Chan et al., 2012). Furthermore, it is unknown whether the SHH ligand itself is required, as a crosstalk between the SHH and TGF-B pathways exists in many tumors (Dennler et al., 2007; Javelaud et al., 2011).
Here, we address the mechanisms limiting the range and specificity of SHH signaling in normal and cancerous adreno- cortical cells. We find that SHH can be released on lipoproteins, but this pool is signaling inactive, possibly due to lipoprotein- associated pathway inhibitor(s). Instead, SHH signaling occurs via membrane contact, limiting the signaling range. We suggest that the specificity of SHH signaling is limited by the presence of primary cilia in receiving cells. Adrenocortical cells that produce SHH, both in vivo and in a carcinoma cell line, lack ARL13B- positive primary cilia and are unable to respond to the SHH ligand they produce. Importantly, the carcinoma cell line evades the requirement for SHH ligand by ectopically expressing SHH pathway target genes in response to TGF-B. These findings provide novel, fundamental, and potentially clinically relevant insight into mechanisms regulating SHH pathway signaling range and activity.
Results
Mouse adrenal glands secrete SHH on lipoproteins
To address how the specific range of SHH signaling is achieved in the adrenal gland, we first determined whether adrenocor- tical cells can secrete SHH associated with lipoproteins. To do so, we compared the distribution of SHH in a density gradient to that of apolipoprotein (APO) A1 and APOE, the major protein components of high-density lipoproteins (HDL; Hegele, 2009). We fractionated high-salt adrenal gland homogenates by differential centrifugation at 16,000 g and 150,000 g (Fig. 1, Band C) and subjected both supernatant fractions to isopycnic density centrifugation (Fig. 1, D and E; Palm et al., 2013). The majority of SHH in 16,000 g supernatants was found in lower- density fractions. Its distribution in the density gradient re- sembled that of APOA1 and, to a lesser extent, APOE (Fig. 1 D). The 150,000 g supernatants were additionally enriched in a higher-density pool of SHH (Fig. 1 E). We conclude that the adrenal glands can secrete SHH in fractions containing lipoproteins.
Given the importance of diet in regulating SHH pathway activity in the adrenal gland (Swierczynska et al., 2015), we investigated whether lipoproteins affect SHH secretion in the adrenal gland in mice with diet-induced obesity. We observed, however, no change in the fractionation of SHH or in the level or density of lipoproteins in the adrenals from mice fed with nor- mal and high-fat diets (HFDs; Fig. S1 A). Furthermore, the density of released SHH in adrenal supernatants was also not affected (Fig. S1, B and C). Thus, the elevated SHH signaling in the adrenals of mice fed a HFD does not appear to be caused by increased release of SHH or any obvious alterations in the released forms.
In culture, human adrenocortical carcinoma cells endogenously secrete SHH on lipoproteins
As an alternative model for probing SHH secretion and signaling in adrenal gland cells, we engaged the human adrenocortical carcinoma cell line NCI-H295R. These cells have been exten- sively used to study adrenal function and tumor biology (Gazdar et al., 1990; Rainey et al., 2004) and express SHH mRNA (Werminghaus et al., 2014). To confirm that this cell line accu- rately represents the SHH release mechanisms of adrenal glands, we asked whether and how NCI-H295R cells secrete SHH protein. Western blot analyses verified that NCI-H295R cells endogenously produce SHH (Fig. 2, A and B). Sera from different species (bovine, murine, and human) can act as a source of lipoproteins to enhance SHH release into the culture medium, but do not contain SHH (Fig. 2, B and C). Despite producing and secreting lipoproteins, NCI-H295R cells require extrinsically added serum supplement for SHH secretion (Fig. 2 D). Upon fractionating conditioned medium from NCI-H295R cells, we found that serum supports the release of a low-density SHH pool that is intermediate between low-density lipoproteins (LDLs) and HDL, cofractionating with APOA1 and APOE lipoproteins (Fig. 2, E-G). We also observed an additional higher-density pool of SHH in the supernatant of cells incubated with human serum (Fig. 2 G). The forms of SHH released from these cells closely resemble those isolated from the mouse adrenal gland in vivo (compare to Fig. 1, D and E), providing confidence that this cell line is an appropriate model for studying SHH release from adrenocortical cells.
To confirm that lipoproteins are sufficient for SHH release, we cultured NCI-H295R cells only with lipoproteins isolated from human serum and assayed the conditioned medium by density gradient centrifugation. We found that addition of hu- man lipoproteins promotes the release of SHH in a low-density form, consistent with LDL and HDL densities, but no SHH fractionates at higher densities (Fig. 3, A-C). Western blotting of gradient fractions with antibodies to apolipoproteins (APOA1 and APOE) showed that these proteins are present in the same low-density fractions as SHH (Fig. 3 C). Thus, SHH secreted from NCI-H295R cells can associate with lipoproteins. To con- firm this, we precipitated cell supernatants with antibodies to apolipoproteins and found that SHH immunoprecipitates with APOA1 and, less efficiently, APOE (Fig. 3 D). Based on the co- fractionation of SHH with LDL and HDL and its coimmunopre- cipitation with APOA1 and APOE, as well as previous reports (Palm et al., 2013), we conclude that adrenocortical carcinoma cells can release endogenously produced SHH on lipoproteins.
The lipoprotein-associated SHH secreted from adrenocortical carcinoma cells is signaling-inactive
The above data indicate that both adrenal glands and adreno- cortical carcinoma cells produce and secrete SHH on lipo- proteins, which should facilitate long-range transport. Given the limited long-range signaling in the adrenal gland, we sought to determine whether this form of secreted SHH is actually signaling-active. Thus, we next analyzed the canonical (Gli1- dependent) signaling activity of lipoprotein-associated SHH using the Shh-LIGHT2 reporter expressed in NIH3T3 fibroblasts
JCB
A
E
NCI-H295R Cells + Bovine Serum
SHH
SHH
LDL
HDL
Soluble proteins
SHH
1.009
1.018
1.048
1.113
1.182
1.235
1.310
1.320
1.431
+ Serum
+
[g/ml]
22 kD
SHH
Cell-associated SHH
SHH secreted in the medium
1.011
1.018
1.033
1.070
1.160
1.187
1.237
1.297
1.417
SHH
36 kD-
[g/ml]
Palmitate
Cholesterol
NCI-H295R cell
APOA1
22 kD
B
1.009
1.018
1.048
1.113
1.182
1.235
1.310
1.320
1.431
Cell Lysate
Culture Medium
[g/ml]
Serum Bovine Human Mouse Serum Bovine Human Mouse
36 kD
APOE
free
serum serum
serum
free
serum serum serum
22 kD
SHH
F
50 kD-
NCI-H295R Cells + Mouse Serum
ACTIN
36 kD
LDL
HDL
1.009
1.016
1.033
1.071
1.140
1.218
Soluble proteins
1.267
1.354
1.481
[g/ml]
22 kD-
SHH
C
1.011
1.016
1.031
1.066
1.106
1.183
1.237
1.297
1.444
Culture Medium Without Cells
36 kD-
[g/ml]
Bovine Mouse Human serum serum serum
NCI-Shh -Lpp
APOA1
22 kD
22 kD
SHH
1.009
1.016
1.033
1.071
1.140
1.218
1.267
1.354
1.481
[g/ml]
36 kD-
APOE
D
NCI-H295R Cells - Serum-free
G
NCI-H295R Cells + Human Serum
LDL
HDL
Soluble proteins
1.008
1.016
1.033
1.073
1.115
1.210
1.279
1.300
1.424
LDL
HDL
Soluble proteins
[g/ml]
1.008
1.018
1.031
1.086
1.173
1.223
1.282
1.312
1.484
[g/ml]
22kD
SHH
22kD-
SHH
1.008
1.016
1.033
1.073
1.115
1.210
1.279
1.300
1.424
1.008
1.018
1.031
1.086
1.173
1.223
1.282
1.312
1.484
36kD-
[g/ml]
36kD-
[g/ml]
APOA1
APOA1
22kD
22kD
1.008
1.016
1.033
1.073
1.115
1.210
1.279
1.300
1.424
1.008
1.018
1.031
1.086
1.173
1.223
1.282
1.312
1.484
[g/ml]
[g/ml]
36kD-
APOE
36kD.
APOE
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A
C
NCI-H295R Cells + Human Serum Lipoproteins
SHH
SHH
SHH
+ Human Serum Lipoproteins (HSLpp)
LDL
HDL
Soluble proteins
1.006
1.016
1.036
1.086
1.187
1.250
1.280
1.337
1.511
+
HSLpp
[g/ml]
22 kD-
SHH
Cell-associated SHH
Lipoprotein-associated SHH secreted in the medium
1.006
1.014
1.030
1.053
1.123
1.200
1.264
1.317
1.474
36 kD-
[g/ml]
B
Cell Lysate
Culture Medium
Serum 0.625% 2.5% free
Serum 0.625% 2.5%
HSLpp HSLpp
APOA1
free
HSLpp HSLpp
22 kD
SHH
22 kD
1.006
1.014
1.030
1.053
1.123
1.200
1.264
1.317
1.474
50 kD-
[g/ml]
ACTIN
36 kD
APOE
36 kD
D
NCI-H295R Cells + Human Serum Lipoproteins
APOA1 IP
5%
100%
36 kD-
Input
Ft
Eluate
APOE IP
5%
100%
Input Ft
Eluate
APOA1
36 kD-
APOE
22 kD
22 kD-
SHH
22 kD-
SHH
(Fig. 4 A; Taipale et al., 2000). Compared with human embry- onic kidney (HEK)-293 cells stably transfected with SHH and Hela cells transiently engineered to produce SHH, NCI-H295R cells endogenously secrete low concentrations of SHH on lipo- proteins (Fig. S2 A). At this low concentration, none of the SHH preparations signal in the Shh-LIGHT2 assay, compared with the SMO agonist SAG, which strongly induces the LIGHT2 signal (Fig. 4 B and Fig. S2 B). Therefore, we concentrated the NCI- H295R-derived conditioned medium and assayed its SHH sig- naling activity. At higher concentrations, lipoprotein-associated ShhNc (cholesterol-modified SHH) derived from HEK-293 and Hela cells induces a potent signaling response; however, lipoprotein-associated SHH derived from NCI-H295R is still inactive (Fig. 4 C).
We wondered whether the reason for the inactive SHH was that NCI-H295R cells also secrete inhibitor(s) of the pathway, as was shown in other contexts (Khaliullina et al., 2015). To test this possibility, we added conditioned media from NCI-H295R cells to active concentrations of lipoprotein-associated ShhNc from HEK-293 cells. Indeed, we found that the NCI- H295R-conditioned media cause a dose-dependent inhibition of the signaling activity of HEK-derived ShhNc (Fig. 4 D and Fig. S2 C). This result is not due to an impact of the
NCI-H295R-conditioned medium on the viability or ciliation of the Shh-LIGHT2 cells (data not shown). Moreover, conditioned medium from Hela cells does not inhibit the SHH pathway (Fig. S2 D), indicating that the inhibition does not originate from the serum or the media themselves but is specific to media conditioned by NCI-H295R cells. While it is possible that NCI- H295R cells produce a signaling-inactive SHH isoform that can compete with HEK-derived ShhNc for its receptor PTCH1, the lowest amount of NCI-H295R-produced SHH that is inhibitory is 100x less than that of the added HEK-derived ShhNc (Fig. 4 D). Thus, it is highly unlikely that the inhibition is due to inhibition at the level of the ligand/receptor interaction but rather downstream. Confirming this hypothesis, we found that NCI-H295R-conditioned medium inhibits the activation of SMO by the SMO agonist SAG, which activates the pathway inde- pendently of the ligand (Fig. 4 E). To determine whether normal adrenocortical tissue also secretes this inhibitory molecule(s), we tested homogenates of mouse adrenal glands, as well as condi- tioned media from primary mouse adrenal cell cultures. Both cause a dose-dependent inhibition of the signaling activity of HEK-ShhNc (Fig. 4, F and G). The lowest volume of adrenal cell culture supernatant required for SHH pathway inhibition (1 ul; Fig. 4 G) corresponds to the secretome of ~500 adrenal cultured
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A
SHH source
SHH
SHH
8
SHH
B
HSLpp
HSLpp
HSLpp
Shh-LIGHT2 cells
Secreted
Lipoprotein-associated SHH
Shh-LIGHT2 cells
B
**
C
0.8
HEK-ShhNc
0.12-
**
0.7
HeLa-ShhNc
*
**
**
Luciferase activity
0.10-
Luciferase activity
0.6
NCI-Shh-Lpp
**
0.08-
0.5
0.06
0.4
*
**
0.04-
0.3
**
0.02
eeeeee
0.2
0.00
0.1
Background
SAG
NCI-Shh-Lpp
HeLa-ShhNc HEK-ShhNc
0.0
0,075ng Hela/HEK-ShhNc
0
10
Shh Conc [ng]
20
50
100
= amount of NCI-Shh-Lpp
D
0.5-
HEK-ShhNc +
NCI-Shh-Lpp
E
10ng
Lpp Control
0.8-
SAG +
NCI-Shh-Lpp
HeLa-ShhNc
0.7
Lpp Control
Luciferase activity
0.4-
F
Luciferase activity
0.6
0.3
0.5
0.4
0.2
*
0.3
0.1
**
0.2
**
0.1
*
*
0.0
0
0.001
0.01
0.1
1
10
100
0.0
0
0.01
0.1
1
10
+ NCI-Shh-Lpp [ng SHH]
+ NCI-Shh-Lpp [ng SHH]
F
0.30-
HEK-ShhNc +
Adrenal Gland Homogenate
G
0.30-
HEK-ShhNc +
Adrenal Cell Culture Supernatant
Luciferase activity
0.25-
10ng
PBS Control
Luciferase activity
0.25
10ng
Medium Control
0.20-
0.20-
0.15-
0.15
0.10-
0.10
0.05-
**
0.05
**
0.00
0 HL
0.01
uL
0.1 µL
1 μL
10 LL
0.00
0 μ.L.
0.1 µL
1 µL
10 µL
H
0.5-
HEK-ShhNc +
NCI-Shh-Lpp 10k
Lpp 10k Control
0.25-
HEK-ShhNc +
NCI-Shh-Lpp
Fraction 4 (43-150kD)
10ng
NCI-Shh-Lpp 30k
Lpp 30k Control
10ng
Fraction 2 (>600kD)
Fraction 5 (15-43kD)
Luciferase activity
0.4
NCI-Shh-Lpp 100k
Lpp 100k Control
Luciferase activity
0.20
Fraction 3 (150-600kD)
Fraction 6 (0.16-15kD)
0.3
0.15
0.2
0.10
0.1
**
0.05
0.0
0.00
0
0.01
0.1
1
10
0
1
5
25
+ NCI-Shh-Lpp [ng SHH]
+ NCI-Shh-Lpp [uL]
J
0.5.
HEK-ShhNc
NCI-Shh-Lpp - Ketoconazole
K
10ng
NCI-Shh-Lpp - Control
0.8-
HEK-ShhNc +
2AG 18:1
2AG 20:4
NADopa 18:1
NADopa 20:4
DMSO Control
Luciferase activity
0.4
0.7.
10ng
Luciferase activity
0.6.
0.3
I
0.5.
0.2
0.4.
0.3.
0.1
0.2.
0.0
0.1.
0
0.01
0.1
1
10
**
+ NCI-Shh-Lpp [ng SHH]
0.0
0 μ.Μ
1 µM
10 μ.Μ
100 µM
JCB
medium from NCI-H295R cells treated with 10 uM ketoconazole or vehicle control; (K) endocannabinoid lipids or vehicle control. The Lpp Control represents medium with added human serum lipoproteins, not cultured with NCI-H295R cells. Data are presented as mean + SD, n = 4-6 replicates, pooled from two or three experiments. * , P < 0.05; ** , P < 0.01; *** , P < 0.001. 2AG, 2-acylglycerol; NADopa, N-acyldopamine.
cells. In contrast, the lowest volume of NCI-H295R superna- tant showing SHH pathway inhibitory activity (Fig. 4, D, E, and H) corresponds to the secretome of ~55,000 NCI-H295R cells, implying that the primary adrenal cell culture super- natant has at least 100x more potent inhibitory effect than the NCI-H295R supernatant. Hence, our results indicate that al- though adrenocortical cells can secrete SHH on lipoproteins, this signaling form is inactive, due to an inhibitory mole- cule(s) that is cosecreted and blocks the SHH pathway at the level or downstream of SMO.
Next, we set out to characterize this inhibitor(s). We found that the inhibitory activity of the NCI-H295R supernatant is retained by filters up to a 100-kD cutoff (Fig. 4 H), and gel fil- tration chromatography identified inhibitory activity in frac- tions corresponding to estimated molecular weights of 43-600 kD (Fig. 4 I). These results suggest that the inhibitory activity is contained in large complexes that, consistent with their size, may be lipoproteins (German et al., 2006; Frazier-Wood et al., 2011). Considering the fact that the adrenal gland is the major producer of steroid hormones, we examined whether blocking steroidogenesis with ketoconazole (Nielsen et al., 2012) could affect the inhibitory activity of NCI-H295R supernatants. We found, however, that inhibiting steroidogenesis in NCI-H295R cells does not affect the inhibitory activity of the conditioned medium (Fig. 4 J). As alternative candidates, we considered endocannabinoids: anandamide, 2-arachidonoylglycerol, and endocannabinoid homologues containing various fatty acyl chain lengths including N-acyldopamines, which were shown to be lipoprotein-associated and repress the Hh/SHH pathway in Drosophila and mammalian cells (Khaliullina et al., 2015). Out of 18 tested endocannabinoid lipids, we found that N-acyldopamine 18:1 and 20:4 inhibit HEK-ShhNc activity, while others, such as 2-acylglycerol 18:1 and 20:4, were not inhibitory (Fig. 4 K). These results, together with the reported abundance of dopamine and arachidonic acid (C 20:4) in mouse adrenal glands (Igal et al., 1991; Campbell et al., 1991), suggest that N-acyldopamine 20:4 can act as an inhibitor of SHH signaling in the adrenal gland.
Membrane-associated SHH on adrenocortical carcinoma cells signals to adjacent fibroblasts
Since the secreted SHH pool from NCI-H295R cells appears to be unable to signal, we wondered whether these cells may be able to signal in a different way. In other systems, the Hh ligand can also signal by direct contact through membrane extensions (Kornberg and Roy, 2014). The existence of such a mechanism seems plausible in the adrenal gland, where SHH-producing cortical cells lie in close proximity to the SHH-responding cap- sular fibroblasts (Fig. 1 A; Guasti et al., 2011; Laufer et al., 2012).
Upon co-culturing Shh-LIGHT2 fibroblasts with NCI-H295R cells (Fig. 5 A), we found potent induction of Gli1-dependent reporter activity in the fibroblasts (Fig. 5 B). The increase in Gli1-dependent transcriptional activity is completely abolished
by treatment with the SHH-neutralizing antibody 5E1 and the pathway antagonist cyclopamine, verifying that it is specifically mediated by activation of the SHH pathway (Fig. 5 B). Two lines of evidence suggest that signaling occurs via the membrane- associated SHH. First, the addition of lipoproteins should in- duce lipoprotein-mediated SHH secretion from NCI-H295R cells, thereby decreasing the pool of membrane-associated SHH. In- deed, SHH pathway activity in Shh-LIGHT2 cells is higher under serum-free conditions, when SHH is mostly cell-associated, than in the presence of lipoproteins (Fig. 5, B and C). Second, Gli1- dependent transcription in Shh-LIGHT2 cells is induced only upon co-culture with NCI-H295R cells in direct physical contact and not when sharing the culture medium (Fig. 5 C). As an al- ternative readout of SHH pathway activity, we visualized SMO localization in responding NIH3T3 cells transfected with Smo- mEos2, a reporter of SMO localization. We co-cultured NIH3T3/ Smo-mEos2 cells with increasing numbers of NCI-H295R cells in serum-free media, with the prediction that more NCI-H295R cells would increase the number of cell-cell contacts and thereby cause increased SMO ciliary localization. Indeed, we observe a concentration-dependent enrichment of SMO in primary cilia (Fig. 5, D and E). Importantly, the ciliation rate of fibroblasts is not affected by the co-culture with carcinoma cells (data not shown). Thus, the membrane-associated SHH, rather than the lipoprotein-associated secreted SHH, is responsible for the SHH signaling activity of adrenocortical carcinoma cells, suggesting a contact-dependent activation of the SHH pathway in the re- sponding fibroblasts.
Adrenocortical carcinoma cells do not respond to SHH ligand The inhibitory activity within the lipoprotein fraction of se- creted SHH, combined with the signaling-active membrane-bound SHH, partially explains the limited range of SHH signaling in the adrenal gland. However, it remains unclear why the SHH pathway is activated only in the overlaying capsule cells but not in the adrenocortical cells located in close proximity to the SHH- producing cells. Normal murine adrenal cortex and NCI-H295R cells express the key pathway transducers PTCH1 and SMO (Fig. 6, A-C), indicating that they could respond to the SHH they produce. However, normal adrenal cortex cells do not express the SHH targets GLI1-3 (Fig. 6, A and C), while NCI-H295R cells, which derive from adrenocortical carcinoma, do express these genes (Fig. 6, B and C), indicating that they may have acquired the ability to respond to the SHH they produce, as do many other tumors (Wetmore, 2003).
We investigated whether the carcinoma cell line had ac- quired the ability to respond to SHH, in order to determine whether pathway activation is differently regulated in these two contexts. We found, however, that repressing or activating SHH signaling does not affect the proliferation of NCI-H295R cells (Fig. 6 D). Furthermore, expression of the SHH target genes GLI1 and PTCH1 in NCI-H295R cells is unaffected by treatment with
JCB
A
SHH source
SHH
D
mEos2
SHH
SHH
NCI-H295R cells
Membrane-associated SHH
ARL13B
NIH3T3 reporter cells
NIH3T3 reporter + NCI-H295R cells
NIH3T3/Smo-mEos2
B
SAG Control No treatment
*
1.4-
mEos2
5E1
00
O
1.2-
lgG
Cyclopamine DMSO
o
Luciferase activity
1.0
ARL13B
C
0.8
0.6
NIH3T3/Smo-mEos2 + SAG
ARL13B mEos2 StAR
0.4.
8
6
0.2
0.0
Background SAG Shh-LIGHT2
Serum-free
+ Lipoproteins
Shh-LIGHT2 + NCI-H295R
NIH3T3/Smo-mEos2 + NCI-H295R
C
1.0
**
**
E
70-
**
**
Luciferase activity
0.8
% Smo-positive cilia
60
0.6
50
40
**
0.4
30
**
*
0.2
20
0.0
…
10.
00
-0.2
0
Background SAG Shh-LIGHT2
SF
+Lpp
SF
+Lpp
NIH3T3/ Smo-mEos2
+SAG
+ NCI-H295R
+ NCI-H295R
& NCI-H295R wall-separated
10,000
20,000
40,000
co-cultured
cells
2698
4667
656
2080
1938
in direct contact no direct contact
cilia
2000
3492
512
1514
1467
the SHH-blocking antibody 5E1, the SMO antagonist cyclop- amine (Fig. 6 E), the pathway agonist SAG, or ShhNc derived from HEK-293 cells (Fig. 6 F). In contrast, NIH3T3 cells robustly activate Gli1 and Ptch1 expression in response to SAG and ShhNc from HEK-293 cells, in a 5E1-dependent manner (Fig. 6 G). Thus, we conclude that the active membrane-associated SHH produced by adrenocortical carcinoma cells cannot activate the canonical SHH pathway in an autocrine manner. We also considered the possibility that adrenocortical carcinoma cells respond noncanonically to SHH (Teperino et al., 2014). SHH was shown to reprogram cell metab- olism toward the Warburg-like state (Teperino et al., 2012) and to reduce intracellular cAMP levels (Riobo et al., 2006; Shen et al., 2013). However, we do not observe similar effects of SHH path- way activation in NCI-H295R cells (Fig. S3, A-D).
We conclude that adrenocortical carcinoma NCI-H295R cells do not respond to the SHH they produce, nor to SHH from other sources, either in canonical or noncanonical ways. Furthermore, the inability of the SMO agonist SAG to activate the pathway in adrenocortical carcinoma cells suggests that these cells not only do not bind the ligand but also cannot respond to activated SMO.
Adrenocortical cells in vitro and in vivo lack ARL13B-positive primary cilia
Neither healthy nor cancerous adrenocortical cells appear to be able to respond to the SHH they produce, highlighting a key part of how the specific pattern of signaling activity is achieved in the adrenal gland. To investigate the underlying mechanism, we considered the critical role of primary cilia in SHH pathway
JCB
A
Gapdh
Shh
Smo
Ptch1
Gli1
Gli2
Gli3
Sufu
C
NCI-H295R
Adrenal Gland
D
No treatment
BrdU incorporation (Absorbance 450 - 550nm)
IgG Control Cyclopamine DMSO Control
2.00
SAG
5E1
500 bp
1.75
25 kD
1.50
200 bp
SHH
20 kD
1.25
205 kD
PTCH1
1.00
Mouse Adrenal cortex
120 kD
0.75
SMO
0.50
B
GAPDH
85 kD
Serum-free
+ Lipoproteins
SHH
SMO
PTCH1
GLI1
GLI2
GLI3
SUFU
205 kD
GLI1
120 kD
500 bp
GLI2
200 bp
238 kD
171 kD
GLI3
50 kD-
Adrenocortical carcinoma cells
37 kD
ACTIN
E
NCI-H295R
F
NCI-H295R
G
NIH3T3
No treatment
Cyclopamine
5E1
DMSO Control
1.75-
60-
3.0
GLI1 relative expression
OlgG Control
GLI1 relative expression
Gli1 relative expression
1.50
50-
2.5
2.0
1.25
40-
1.00
30-
1.5
0.75-
20-
1.0
10-
0.5
0.50
0
0.0
0.25
No
SAG
Shh
+5E1
+lgG
Serum-free
+ Lipoproteins
No
SAG HEK-ShhNc
treatment
treatment
HEK-ShhNc
1.50
PTCH1 relative expression
1.50-
PTCH1 relative expression
30-
Ptch1 relative expression
1.25
25.
1.25
20-
1.00
1.00
15
0.75
0.75
10.
5.
0.50
Serum-free
+ Lipoproteins
0.50
No
SAG HEK-ShhNc
0
treatment
No
SAG
Shh
+5E1
+lgG
treatment
HEK-ShhNc
JCB
A
B
AcTUB
ARL13B
AcTUB
100-
60-
ARL13B
% ciliated cells
20
10
8
6
NCI-H295R
4.
2.
AcTUB
ARL13B
D
AcTUB
ARL13B
100-
**
**
NIH3T3/Smo-mEos2
90-
80.
C
% ciliated cells
70-
AcTUB
60-
**
SF1
*
50
40-
30-
20-
*
10.
0
*
Cortex
Capsule
Capsule Cortex
Capsule : Cortex
E
Arl13b+
Arl13b+
Arl13bt
Capsule
ARL13B
Arl13b+
Arl13b+
SF10
I
*
0
Cortex
50.
Gli1+ SF1-
Shh- SF1+
Shh+ SF1+
Capsule Cortex
Capsule : Cortex
| 0 NCI-H295R | NIH3T3/ Smo-mEos2 | |
|---|---|---|
| AcTUB | 5338 | 1561 |
| ARL13B | 4527 | 1672 |
Figure 7. Adrenocortical cells in vitro and in vivo lack ARL13B-positive primary cilia. (A) Immunofluorescence of NCI-H295R cells (top) and NIH3T3/Smo- mEos2 cells (bottom) for acetylated tubulin (AcTUB; cyan), ARL13B (magenta), and nuclear DAPI (blue). The cyan arrowhead denotes an AcTUB-positive cilium, while the magenta arrowhead denotes a cilium where ARL13B colocalizes with AcTUB. Scale bar, 10 um. (B) Quantification of the percentage of ciliated NCI- H295R and NIH3T3/Smo-mEos2 cells, counted as cells positive for AcTUB or ARL13B. The number of counted cells is given under the graph. Data are presented as mean ± SD, n = 6-8 replicates, pooled from three experiments. *** , P < 0.001. (c) Mouse adrenal immunofluorescence of AcTUB (top) and ARL13B (bottom), costained with SF1, a nuclear steroidogenic marker (magenta), and nuclear DAPI (blue). The dashed line represents the approximate border between the adrenal capsule and cortex. Cilia are indicated by an asterisk. Scale bar, 10 um. (D) Quantification of the percentage of ciliated cells within the adrenal cortex and capsule, counted as cells positive for AcTUB or ARL13B. Each data point represents the quantification for one adrenal gland, presented as mean + SD. ** , P < 0.01. (E) Model representing the SHH-producing cortical and SHH-responding capsule cells in the adrenal gland. Subset of subcapsular cortical cells produce SHH (magenta) and signal to the overlying capsule cells (green), which possess ARL13B-positive primary cilia and respond by Gli1 expression. The cortical cells themselves (magenta and blue) do not respond to autocrine SHH signaling, possibly because of a lack of ARL13B-positive cilia.
activation (Huangfu and Anderson, 2005). It is known that many solid tumors lose their primary cilia (Seeger-Nukpezah et al., 2013). Similarly, we found that only 1-5% of NCI-H295R cells are ciliated, compared with >60% of NIH3T3 fibroblasts, which respond to SHH (Fig. 7, A and B; and Fig. S4). Further- more, only 0.5-2% of NCI-H295R cells are positive for ARL13B (Fig. 7 B and Fig. S4), a ciliary protein influencing the trafficking of SHH pathway components PTCH1, SMO, GLI2, and GLI3 (Caspary et al., 2007; Larkins et al., 2011).
This result made us wonder about the extent of ciliation in the normal adrenal gland. We found that cortical SF1-positive
steroidogenic cells, which produce but do not respond to SHH (King et al., 2009), have less cilia than the overlying capsule cells, which respond to SHH (Fig. 7, C and D). Furthermore, the ciliary protein ARL13B is significantly less abundant in the cortical cells than in the capsule cells (Fig. 7, C and D). These results indicate that the inability of the cells of the adrenal cortex to respond to the autocrine SHH signal correlates with the lack of ARL13B in these cells, thus limiting the SHH response to the overlying capsular cells (Fig. 7 E). The adrenal gland also has vascular endothelial cells lying in close proximity to SHH- producing cortical cells (Bassett and West, 1997). The almost
JCB
A
GLI2
GLI1
Control
TGF-ß
Control
TGF-ß
5.0-
**
*
*
4.0
Relative expression
4.0
Relative expression
3.0
3.0
2.0
2.0
1.0
TO
1.0
0.0
4h
8h
24h
0.0
4h
8h
24h
B
TGF- CHX
+
+
TGF-6
+
+
+
+
CHX
+
+
100 kD
75 kD
GLI2
250 kD
150 kD
GLI1
50 kD
Actin
50 kD
37 kD
37 kD
Actin
complete absence of ARL13B staining in the cortex of mouse adrenal gland (Fig. 7 C) suggests that endothelial cells of the adrenal cortex are also not ciliated. Similar to adrenocortical cells, we found that only 0.95% of human umbilical vein endo- thelial cells (HUVECs) are ciliated (Fig. S5 A), and treatment with SAG does not induce canonical SHH signaling (Fig. S5 B).
Collectively, our data are consistent with a model in which subcapsular SHH-producing cells signal by direct contact to the overlying capsule, while the inability to respond to SHH of steroidogenic cells themselves and endothelial cells within the adrenal cortex associates with lack of the ciliary protein ARL13B in these cells (Fig. 7 E). Thus, the limited range of SHH signaling in the adrenal gland can be explained both by the physical contact between producing and receiving cells and by the presence of ARL13B-positive primary cilia in the receiving cells.
Adrenocortical carcinoma cells express GLI2 and GLI1 in response to TGF-B
We have seen that the adrenocortical carcinoma cells express the SHH target gene GLI1 (Fig. 6, B and C) without responding to the SHH ligand or SMO activation (Fig. 6, E and F), highlighting a key difference between the normal and cancerous adreno- cortical tissue. How, then, is SHH target gene expression ec- topically produced in these cancer cells? Interestingly, another canonical target gene of the SHH pathway, GLI2, can be activated in normal and cancer cell types as an output of the TGF-B pathway, in a SHH-independent manner (Dennler et al., 2007). We tested whether the same crosstalk occurs in adrenocortical carcinoma cells and found that treatment of NCI-H295R cells with TGF-ß rapidly increases GLI2 expression, followed by de- layed increase of GLI1 expression (Fig. 8 A), while blocking translation abrogates the TGF-ß-induced increase in GLI2 and GLI1 protein levels (Fig. 8 B). This result suggests that the
expression of GLI1 and GLI2 is inducible in adrenocortical car- cinoma cells and might be sustained at high levels by autocrine TGF-ß signaling, as previously shown in pancreatic cancer cell lines (Dennler et al., 2007). Notably, in the normal murine ad- renal cortex, Shh, Smo, and Ptch1 are expressed, but Gli1 and Gli2 are not (Fig. 6 B), suggesting that this TGF-B-mediated pathway is not active in noncancerous adrenocortical tissue. Hence, de- spite the presence of SHH in both normal and cancer adreno- cortical cells, the Gli-dependent Hh pathway is activated in the cancer cells only by TGF-B and not by SHH.
Discussion
Here, we use the adrenal gland to probe mechanisms limiting SHH signaling to a specific subset of receiving cells in an adult, vertebrate organ. We verify that the adrenal gland and its de- rived adrenocortical carcinoma cell line, NCI-H295R, share the same mechanism of secreting SHH on lipoproteins. Our data extend the existing knowledge on short- and long-range sig- naling of an endogenously produced mammalian SHH and allow us to make novel predictions about how the SHH pathway can be mediated in a specific, short-range pattern in the healthy ad- renal gland, and how its regulation can be evaded in cancer.
While SHH signaling is predominantly short-range in the adrenal gland (Guasti et al., 2011; Laufer et al., 2012), we observe that adrenocortical cells can in fact secrete SHH on lipoproteins, which are well known to facilitate long-range morphogen transport in the Drosophila wing disc and developing mammalian neural tube (Eaton, 2008; Briscoe and Thérond, 2013). Specifi- cally, we present data suggesting that SHH can associate with APOA1- and APOE-positive lipoproteins. However, further ex- periments are required to verify a direct interaction between them. We cannot exclude the possibility of additional
JCB
mechanisms for SHH release and transport, including on other lipoproteins like APOB-positive LDL, as proposed in other systems (Thérond, 2012; Palm et al., 2013). In conjunction, the SHH-producing cells also secrete an inhibitor that prevents SMO activation and could thereby limit the signaling range of this SHH form. Endocannabinoid lipids are likely candidates, as they were identified in both human and Drosophila lipoproteins and found to repress the Hh pathway in the absence of ligand (Khaliullina et al., 2015). Along these lines, we show here that N-acyldopamine 18: 1 and 20:4 can inhibit the activity of HEK-ShhNc. Furthermore, we detected dopamine, the likely precursor of conjugated dop- amines, by liquid chromatography-multiple reaction monitoring (LC-MRM) analysis of supernatants from mouse adrenal glands. However, under these sample preparation and analytical con- ditions, we could only detect a trace amount of N-acyldopamine 20:4 (data not shown); therefore, an unambiguous determination of N-acyldopamines production by mouse adrenal glands requires further investigation. It is possible that other endocannabinoids or lipoprotein-associated molecules released from adrenal gland tissue might also contribute to the inhibition of the SHH pathway.
The inability of the lipoprotein-associated SHH to signal in culture is consistent with the observation that only short-range signaling is observed in the adrenal gland. Nonetheless, we cannot rule out the possibility that the secreted form is active in vivo. Heparan sulfate proteoglycans are components of the extracellular matrix that affect SHH signaling in the lung and other tissues (Häcker et al., 2005; Zhang et al., 2007; He et al., 2017). It remains an open question whether heparan sulfate proteoglycans can interact with SHH in the adrenal gland, and whether they can locally increase the concentration of lipoprotein-associated SHH to counteract inhibitors and induce pathway activation. We predict, however, that even if this is the case, pathway activation will only be at short range, at least in the healthy adult adrenal gland.
Our observation that membrane-bound SHH can generate a response in co-cultured fibroblasts is consistent with cell-to-cell contact-mediated short-range signaling in the adrenal gland. It was previously reported that Hh pathway components transit to responding cells via membrane protrusions extending for sev- eral cell diameters from producing cells (Bischoff et al., 2013; Sanders et al., 2013; Gradilla et al., 2014; Chen et al., 2017; González-Méndez et al., 2017). Whether similar protrusions exist in the adrenal gland is unknown. Filopodia have been ob- served in the rat adrenal cortex and in adrenocortical cancer cells, where they were thought to be involved in steroid hormone secretion (Pudney et al., 1981; Matsuo and Tsuchiyama, 1987). Given our data, the possibility that filopodia may connect the SHH-producing and -receiving cells should also be considered.
The way adrenocortical carcinoma cells signal to neighboring fibroblasts in our co-culture system resembles the ligand- dependent paracrine signaling in many tumors between the SHH-producing cancer cells and the surrounding stromal cells (Yauch et al., 2008). SHH pathway activation in the untrans- formed stromal tissue elicits changes that can both positively and negatively influence tumor growth (Shaw et al., 2009; Shin et al., 2014). For example, SHH produced by hepatocellular carcinoma cells induces glycolytic changes in the surrounding
stroma, thereby creating a microenvironment favoring tumor growth (Chan et al., 2012). Several groups have suggested contact-dependent SHH signal transduction in these cases (Zunich et al., 2009; Damhofer et al., 2015). In other organs, like the mouse notochord, long-range or membrane-to-membrane SHH signaling is determined by the localized expression of Disp1, a transmembrane protein required for secretion of cholesterol- modified SHH (Caspary et al., 2002).
While it has been suggested that activation of the Hh pathway in adrenocortical cells could be involved in tumorigenesis and that these tumors rely on SHH for growth (Boulkroun et al., 2011; Gomes et al., 2014; Werminghaus et al., 2014), we see that NCI-H295R cells are completely unresponsive to both the SHH signal itself and the SMO agonist. Thus, although adreno- cortical carcinoma cells can produce SHH, they cannot respond to it and do not require it for their growth. We find that these cells express the pathway transducers PTCH1 and SMO; however, they do not have cilia and lack the ciliary protein ARL13B. Pri- mary cilia are critically important for SHH signaling (Bangs and Anderson, 2017), and the atypical GTPase ARL13B is required for maintaining ciliary structure, proper levels of GLI2/3 activator forms, and ciliary trafficking of Hh pathway components (Caspary et al., 2007; Larkins et al., 2011; Mariani et al., 2016; Revenkova et al., 2018). Thus, the low level of ciliation of adrenocortical carcinoma cells provides an explanation for the complete lack of SHH response in these cells and is consistent with the fact that many solid tumors lose their primary cilia (Seeger-Nukpezah et al., 2013).
Our results in the cancer cell line led us to propose that the cell-specific presence of the ciliary protein ARL13B could also explain the pattern of SHH response in the adrenal gland. In- deed, our data show that cells of the adrenal cortex are less ciliated than the capsule cells and that few adrenocortical cells are positive for ARL13B. SHH produced by cortical cells would thereby affect proliferation, differentiation, and Gli1 and Ptch1 expression only in ARL13B-positive capsular progenitors and not in cortical steroidogenic lineages (King et al., 2009; Wood and Hammer, 2011; Laufer et al., 2012). In the developing mouse neural tube, loss of ARL13B results in low-level, ligand- independent, constitutive SHH pathway activation (Caspary et al., 2007). Furthermore, it is shown that ARL13B can func- tion outside of the cilium to regulate canonical and noncanonical SHH signaling (Mariani et al., 2016; Ferent et al., 2019; Gigante et al., 2020). In our data, the almost complete absence of GLI1-3 correlates with the absence of ciliary ARL13B in the mouse ad- renal cortex. However, we cannot rule out the possibility that, due to technical limitations, we do not detect low levels of nonciliary ARL13B in our assays. It is also possible that additional mechanisms and ciliary proteins other than ARL13B might contribute to the establishment of the specific pattern of SHH signaling observed in the adrenal gland.
Unlike the normal adrenal glands, the NCI-H295R carcinoma cells constitutively express the canonical SHH target genes GLI1 and GLI2. How do NCI-H295R cells express these targets if they cannot respond to SHH? We find that adrenocortical carcinoma cells behave as many other cancer cell types, by responding to TGF-ß (Dennler et al., 2007; Alexaki et al., 2010; Javelaud et al.,
JCB
2011), perhaps representing an adaptive strategy for adreno- cortical cancer cells to activate the mitogenic response down- stream of GLI2, even though they have lost their cilia. Our results suggest that therapeutic strategies to inhibit GLI-driven tumorigenesis in adrenocortical carcinoma may benefit from targeting TGF-ß rather than SHH signaling. TGF-6 expression is considerably higher in adrenocortical cancer cells than in the normal adrenal cortex (data not shown); thus, autocrine TGF-ß signaling might sustain high GLI1 and GLI2 expression levels. Interestingly, TGF-ß was reported to reduce the expression of the steroidogenic marker SF1 in a Y-1 mouse adrenocortical cell line (Lehmann et al., 2005), suggesting that TGF-ß might de- differentiate steroidogenic adrenocortical cells while enhanc- ing their GLI2-dependent tumorigenic potential.
Finally, in many other adult organs, the Hh pathway is a key regulator of tissue homeostatic maintenance that becomes up- regulated upon injury and repair (Petrova and Joyner, 2014). Therefore, we expect that the mechanisms regulating the range of SHH pathway activity described here for the adrenal gland may also be relevant for these tissues, as SHH-producing cells are often located in distinct subregions at a short distance from the SHH-responding cells (Petrova and Joyner, 2014). Thus, this work should advance our understanding of SHH-mediated reg- ulation of adult tissue homeostasis.
Materials and methods
Animal experiments
Wild-type C57BL/6J mice were from Harlan Laboratories or in- house husbandry of the Biomedical Services Facility (Max Planck Institute of Molecular Cell Biology and Genetics [MPI- CBG], Dresden, Germany). Heterozygous GliLacz (Gliltm2Alj/J) and ShhGFP (Shhtm6Amc/J) mice were obtained from the Jack- son Laboratory and were backcrossed to a C57BL/6J background at the Biomedical Services facility for three generations. For the HFD-induced obesity experiment, 8-wk-old mice were fed a HFD or a normal diet (60% kcal from fat or 10% kcal from fat, respectively; Research Diets Inc.) for 18 wk. After euthanasia, adrenal glands were excised in ice-cold PBS and cleaned from the surrounding fat tissue. Animal work was approved by the Ethical Committee of the Landesdirektion Dresden.
Laser microdissection of adrenal cortex
Adrenal glands from C57BL/6 mice were embedded in O.C.T. Compound (Tissue-Tek), and 25-um-thick slices were cut with a cryotome (Cryostat NX50; Thermo Fisher Scientific) and transferred onto MembraneSlide 1.0 PEN (Zeiss). The adrenal cortex, without inclusion or disruption of the adrenal capsule, was then microdissected using a WF Laser Microdissection system (Zeiss) and the Axiovision software.
Lipoprotein isolation from plasma and serum
Human serum from human male AB plasma was purchased from Sigma-Aldrich. Mouse serum was obtained by letting mouse blood coagulate at RT, followed by centrifugation at 1,500 g for 20 min at 4℃. The total lipoprotein fraction was separated according to Rudel et al. (1974). A serum aliquot was adjusted to
d = 1.225 g/ml with solid KBr (Sigma-Aldrich) in PBS (0.385 g KBr/ml serum solution) and centrifuged at 39,800 rpm for 24 h at 8℃ in a Sw40Ti rotor (Beckman Coulter). The upper lipo- protein layer (~1 ml) was collected and desalted three times with 10 ml PBS and concentrated using an Amicon Ultra 10K (Merck Millipore).
Isolation of nonmembrane-associated SHH from adrenal glands
Adrenal glands from 30 wild-type mice were pooled together to obtain enough SHH protein to be detected by Western blotting. The glands were incubated in hyperosmotic NaCl buffer (0.5 M NaCl, 20 mM Tris-HCl, pH 8.0 [Sigma Life Science], 0.05% NP- 40 [Fluka], and cOmplete Protease Inhibitor Cocktail [Roche]) for 20 min on ice, and the tissue was gently dissociated in a Dounce tissue grinder with a loose pestle on ice. The dissociated adrenals were first centrifuged at 1,000 g for 20 min at 4℃ to obtain S1 supernatant and P1 pellet (nuclei, cell debris, and large membrane fragments were pelleted). An S1 aliquot was further centrifuged at 16,000 g for 20 min at 4℃ to obtain S16 super- natant and P16 pellet. Last, an S16 aliquot was centrifuged at 50,000 rpm (~150,000 g) for 2 h at 4℃ in a TLA-55 rotor (Beckman Coulter) to obtain S150 supernatant and P150 pellet (small vesicles, exosomes, and some lipoproteins were pelleted). Equal volumes of the supernatants were centrifuged at each speed, and the resulting pellets were completely dissolved in radioimmunoprecipitation assay buffer (150 mM NaCl, 0.1% Triton X-100 [Serva], 0.5% sodium deoxycholate [Sigma- Aldrich], 0.1% SDS [Serva], 50 mM Tris-HCl, pH 8.0, and cOmplete Protease Inhibitor Cocktail) in volumes equal to the volume of the corresponding supernatant. The resulting super- natants (S1, S16, and S150) were fractionated by OptiPrep den- sity gradient centrifugation or analyzed by Western blotting.
Cell culture
NCI-H295R cells were maintained in DMEM/F-12 with L-glutamine and 15 mM Hepes (Gibco), with 2.5% Nu-Serum type 1 (BD Biosciences), 1% insulin-transferrin-selenium (ITS; Gibco), and 50 U/ml penicillin and 50 µg/ml streptomycin (Gibco), at 37°C in 5% CO2. Nu-Serum type 1 is a serum sup- plement that contains 25% FBS.
HeLa and HEK-293 cells were maintained in DMEM high- glucose (Gibco) with 10% FBS (Gibco) and 50 U/ml penicillin and 50 µg/ml streptomycin, at 37°℃ in 5% CO2.
Shh-LIGHT2 cells were maintained in DMEM high-glucose supplemented with 10% FBS, 150 µg/ml zeocin (Invitrogen), and 400 µg/ml geneticin (G418; Invitrogen), at 37°℃ in 5% CO2. The Shh-LIGHT2 cells are NIH3T3 mouse fibroblasts, expressing a firefly luciferase under the control of a promoter consisting of eight consecutive Gli1-binding sites and a Renilla luciferase as an internal control (Sasaki et al., 1997; Taipale et al., 2000).
NIH3T3/Smo-mEos2 cells were maintained in DMEM high- glucose supplemented with 10% FCS (Gibco), 1% MEM Non- Essential Amino Acids Solution (Gibco), and 50 U/ml penicillin and 50 µg/ml streptomycin, at 37℃ in 5% CO2. The NIH3T3/ Smo-mEos2 cells are NIH3T3 cells stably transfected with a construct containing the fluorescent protein mEos2 (with peak
Mechanisms limiting SHH signaling in adrenal glands
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excitation at 506 nm and peak emission at 519 nm) fused to the C terminus of SMO (Kim et al., 2014).
HUVECs (Lonza) were cultured on 0.2% gelatin-coated plates in Endothelial Cell Growth Basal Medium-2 (Lonza) supple- mented with Endothelial Cell Growth Medium-2 (Lonza) at 37℃ in 5% CO2. For stimulations and ciliation, HUVECs were treated in serum-free Endothelial Cell Growth Basal Medium-2 for 24 h.
For primary adrenal cell culture, both adrenal glands from one mouse were collected in ice-cold PBS and 0.5% BSA (Sigma-Aldrich) and cleaned from the surrounding fat tissue. The adrenals were digested in a solution of 1.6 mg/ml Collagenase I (Sigma-Aldrich) and 1.6 mg/ml BSA dissolved in PBS for 1 h at 37℃ in thermomixer at 900 rpm. After digestion, cells were dissociated by passing through a 22-gauge needle and 100-um cell strainer; centrifuged at 300 g for 5 min at 4℃; resuspended in DMEM/F12 supplemented with 1% FBS, 50 U/ml penicillin, and 50 µg/ml streptomycin; and plated in a 96- well plate coated with 0.2% gelatin (resulting in cells from one ad- renal gland per well). After 24 h, the culture supernatant was col- lected and centrifuged at 1,000 g for 20 min at 4℃.
TGF-ß treatment
NCI-H295R cells were plated at 500,000 cells/well in a six-well plate. At ~80% confluence they were stimulated with 10 ng/ml human recombinant TGF-ß1 or vehicle control. After the ap- propriate time of culture, cells were lysed for mRNA isolation or for Western blotting. Where indicated, 50 µg/ml cycloheximide was added 30 min before TGF-ß and was present throughout the whole treatment period.
Preparation of SHH-containing conditioned media
To study SHH secretion from NCI-H295R cells, cells were switched overnight to serum-free medium (DMEM/F-12 and 1% ITS), and then to serum-free medium with the appropriate se- rum supplement added. The resulting conditioned media were collected after 72 h, centrifuged at 1,000 g for 20 min at 4℃, and concentrated using an Amicon Ultra 10K for density gradient centrifugation, immunoprecipitation, or Western blotting. To prepare secreted SHH for signaling assays, the conditioned media from NCI-H295R cells grown in the appropriate experi- mental condition were concentrated 100x through Amicon Ultra 10K, 30K, or 100K. Controls were identically processed supple- mented media without cultured cells.
To prepare lipoprotein-associated ShhNc, we used HEK-293 cells stably transfected with SHH or Hela cells. Hela cells were transfected with pCMV-XL5 plasmid encoding full-length hu- man SHH (SC300021; OriGene) using polyethylenimine (Poly- sciences) in serum-free DMEM medium, switched to DMEM and 10% FBS at 6 h after transfection, and cultured for an ad- ditional 72 h. The resulting conditioned media were centrifuged at 1,000 g for 20 min at 4℃, and the lipoprotein-associated SHH was isolated by KBr density centrifugation (Rudel et al., 1974) and concentrated using an Amicon Ultra 10K. The controls were identically processed media from nontransfected cells.
OptiPrep density gradient centrifugation
OptiPrep density gradient centrifugation was performed ac- cording to Eugster et al. (2007). Samples were mixed with 60%
OptiPrep stock solution (Sigma-Aldrich) to a final concentration of 50% OptiPrep and 45%, 35%, 25%, and 10% OptiPrep solutions were subsequently layered on top of the sample. The samples were centrifuged at 50,000 rpm for 20 h at 4℃ in a TLS-55 rotor (Beckman Coulter). Fractions of 100 ul (for gradients from ad- renal glands supernatants) or 200 ul (for gradients from NCI- H295R-conditioned media) were collected, and their densities were calculated based on the measured refractive index. Frac- tions for Western blotting were precipitated with methanol (VWR Chemicals)/chloroform (Sigma-Aldrich) and resuspended in 1× Reducing Laemmli buffer.
SDS-PAGE and Western blotting
Total protein concentration was measured using the Pierce BCA Protein Assay Kit (Thermo Fisher Scientific), according to the manufacturer’s protocol. For Western blotting of cell lysates, cells were lysed either with 50 mM Tris-HCl, pH 7.4, 0.5 M NaCl, and 1% Triton X-100 (for blotting proteins with a molecular weight below 80 kD) or with 10 mM Tris-HCl, pH 7.4, 1% SDS, and 1 mM sodium vanadate (for blotting proteins with a molecular weight above 80 kD). The cell lysates were centrifuged at 16,000 g for 5 min at 4℃. The cell supernatants were collected and pre- pared for Western blotting with 5x Reducing Laemmli buffer (63 mM Tris-HCl, pH 6.8, 0.0005% bromophenol blue [Serva], 10% glycerol [Merck], 2% SDS, and 0.1% 2-mercaptoethanol [Sigma-Aldrich]). 50 µg protein were loaded in each lane.
Gel electrophoresis was performed according to standard protocols (Laemmli, 1970). Protein samples were denatured at 95℃ for 5 min and loaded on a 15% acrylamide gel (Severn Biotech Ltd.) or a gradient 4-20% polyacrylamide gel (Anamed GmbH) for SDS-PAGE. SeeBlue Plus2 Pre-Stained Standard (Life Technologies) or PageRuler Prestained Protein Ladder (Thermo Fisher Scientific) was used as a protein size ladder. The sepa- rated proteins were transferred onto Amersham Protran nitro- cellulose membrane (GE Healthcare Lifescience), and the transfer efficiency was estimated by staining the proteins with 0.2% Ponceau S solution (Serva). After washing in distilled water, the membranes were blocked with 5% skimmed milk in 0.1% Tween-20 (Sigma-Aldrich) in 1× TBS (TBS-T) for 1 h at RT, and washed subsequently in TBS-T. The primary antibodies were di- luted in 5% BSA in TBS-T and incubated overnight at 4°℃ on a shaking platform, while the secondary antibodies were diluted in 5% skimmed milk in TBS-T and incubated for 1-2 h at RT. All antibodies are listed in Table 1 (primary antibodies) and Table 2 (secondary antibodies). After washing the membranes in TBS-T, the signal was detected using the SuperSignal West Pico Chem- iluminiscent Substrate (Thermo Fisher Scientific) and a chem- iluminiscence film (Amersham Hyperfilm ECL; GE Healthcare).
For reprobing the same membrane for multiple proteins, the membranes were stripped for 20 min at RT in stripping buffer (25 mM glycine and 1% SDS in distilled water, pH 2.2), extensively washed in TBS-T, and blocked with 5% skimmed milk in TBS-T for 30 min at RT before incubating with the next primary antibody.
Co-immunoprecipitation
The immunoprecipitation of apolipoproteins was performed using Protein-G agarose (Roche) according to the manufacturer’s
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| Antibody | Source | Dilution | Manufacturer | Use |
|---|---|---|---|---|
| Actin | Mouse | 1:1,000 | Sigma-Aldrich | WB |
| Acetylated tubulin | Mouse | 1:1,000 | Sigma-Aldrich | ICC |
| Acetylated tubulin | Rabbit | 1:1,000 | Abcam | IHC |
| ApoA1 | Goat | 1:1,000 | Abcam | WB, IP |
| ApoA1 | Rabbit | 1:1,000 | Calbiochem | WB |
| ApoE | Goat | 1:500 | Santa Cruz | WB, IP |
| ApoE | Mouse | 1:500 | Calbiochem | WB |
| Arl13b | Mouse | 1:1,000 | Abcam | ICC |
| Arl13b | Rabbit | 1:500 | Abcam | ICC, IHC |
| B-Galactosidase | Chicken | 1:1,000 | Abcam | IHC |
| GFP | Rabbit | 1:500 | Life Technologies | IHC |
| Gli1 | Rabbit | 1:500 | Abcam | WB |
| Gli2 | Rabbit | 1:1,000 | Proteintech | WB |
| Gli3 | Goat | 1:100 | R&D Systems | WB |
| Glutamylated tubulin | Mouse | 1:1,000 | Adipogen | ICC |
| IFT88 | Rabbit | 1:500 | Merck Millipore | ICC |
| PTCH1 | Rat | 1:500 | R&D Systems | WB |
| SF1 | Rat | 1:500 | TransGenic Inc. | IHC |
| Smoothened | Rabbit | 1:500 | Abcam | WB |
| Shh | Mouse | 1:500 | Invitrogen | WB |
| Shh | Rabbit | 1:500 | Cell Signaling | WB |
| StAR | Rabbit | 1:500 | Santa Cruz | ICC |
ICC, immunocytochemistry; IHC, immunohistochemistry; IP, immunoprecipitation; WB, Western blotting.
protocol. The NCI-H295R-conditioned medium was adjusted with 1 M Tris-HCl, pH 7.4, to a final concentration of 50 mM Tris-HCl. To reduce the nonspecific binding to the agarose beads, the medium was first incubated with Protein-G agarose for 3 h at 4℃ on rotating wheel. Beads were pelleted at 12,000 g and dis- carded. An aliquot of the supernatant was left as an input sample, and the rest was incubated with Protein-G agarose and 5 µg/ml antibody overnight at 4℃ on a rotating wheel. The antibodies used are listed in Table 1. The beads were pelleted at 12,000 g, and the supernatant was kept as the flow-through. The beads were then washed with 50 mM Tris-HCl, pH 7.4, with increasing concen- trations of NaCl-two washes with 150 mM NaCl, two washes with 0.5 M NaCl, and the last wash without NaCl-and the bound proteins were eluted by boiling the beads for 5 min in 5x non- reducing Laemmli buffer. The input and flow-through samples were precipitated with methanol/chloroform and resuspended in 1× reducing Laemmli buffer, and all samples were analyzed by Western blotting. The resulting blots were probed for SHH and the respective immunoprecipitated protein.
Shh-LIGHT2 activity assay
For the Shh-LIGHT2 activity assay, Shh-LIGHT2 cells were plated at 70,000 cells/well in 96-well plates, and after 24 h they were switched to DMEM and 1% ITS with the appropriate SHH-
conditioned medium. Luciferase activity was measured in cell lysates after 24 h using the Dual Glo Luciferase Assay (Promega) according to the manufacturers’ protocol.
For measuring Shh-LIGHT2 activity in co-culture experiments, 20,000 Shh-LIGHT2 cells were plated with 20,000 NCI-H295R cells either in direct physical contact in 96-well plates or separated in four-well culture inserts (Ibidi). After 24 h, the cultures were switched to DMEM and 1% ITS with or without human lipo- proteins and stimulated as described. The luciferase activity was measured after 48 h using the Dual Glo Luciferase Assay.
Treatments were as follows: 10 µg/ml 5E1 monoclonal mouse antibody (produced by Protein Expression Facility, MPI-CBG), 10 µg/ml mouse IgG] Isotype Control (R&D Systems), 200 nM SMO agonist SAG (Calbiochem), 10 uM cyclopamine (Cayman Chem- icals), and 10 uM ketoconazole (Sigma-Aldrich) or appropriate controls. The endocannabinoid lipids used are listed in Table 3.
For preparing adrenal homogenate, single adrenal glands were homogenized in 50 ul PBS with BioVortexer (BioSpec Products) on ice and centrifuged at 1,000 g for 20 min at 4°℃, and the cleared homogenate was collected.
Gel filtration chromatography
NCI-H295R-conditioned medium was fractionated according to size by gel filtration chromatography on a Superdex 200 PC 3.2/
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| Antibody | Source | Dilution | Manufacturer | Use |
|---|---|---|---|---|
| Anti-mouse IgG, HRP | Goat | 1:5,000 | Merck Millipore | WB |
| Anti-rabbit IgG, HRP | Donkey | 1:5,000 | Merck Millipore | WB |
| Anti-goat IgG, HRP | Donkey | 1:3,000 | Merck Millipore | WB |
| Anti-rat IgG, HRP | Goat | 1:5,000 | Merck Millipore | WB |
| Anti-rabbit IgG, HRP | Goat | 1:5,000 | Jackson ImmunoResearch | WB |
| Anti-mouse IgG, Alexa 488 | Goat | 1:1,000 | Life Technologies | ICC |
| Anti-mouse IgG, Alexa 647 | Goat | 1:1,000 | Life Technologies | ICC |
| Anti-rabbit IgG, Alexa 555 | Goat | 1:1,000 | Life Technologies | ICC |
| Anti-rabbit IgG, Alexa 647 | Goat | 1:1,000 | Life Technologies | ICC, IHC |
| Anti-rat IgG, Alexa 555 | Goat | 1:1,000 | Life Technologies | IHC |
| Anti-chicken IgG, Alexa 555 | Goat | 1:1,000 | Life Technologies | IHC |
| Anti-rabbit IgG, light chain-specific, HRP conjugate | Mouse | 1:5,000 | Jackson ImmunoResearch | WB (co-IP control) |
| Protein G, HRP conjugate | 1:5,000 | Thermo Fisher Scientific | WB (co-IP control) |
ICC, immunocytochemistry; IHC, immunohistochemistry; IP, immunoprecipitation; WB, Western blotting.
30 column (GE Healthcare). The running buffer used was PBS, 20 mM Hepes, and 150 mM NaCl, the fraction volume was 500 ul, and size standards were thyroglobulin (600 kD), immunoglobulin G (150 kD), ovalbumin (43 kD), myoglobin (15 kD), and vitamin B (0.16 kD). The fractions around each size peak were pooled to- gether, concentrated to the initial volume loaded on the column, and probed for their activity on the Shh-LIGHT2 assay.
LC-MRM lipid analysis
Extraction and analysis of endocannabinoids, endocannabinoid homologues, dopamine, and dopamine conjugates was carried out using a previously described protocol with the slight modification of using dopamine-d4 as an internal standard and commercially available dopamine as a calibrant. The transitions for dopamines and dopamine conjugates included in the MRM assay were in- ferred from literature: N-acyl dopamine 18:1 (m/z 418.3 to m/z 154.1 and m/z 137.1), N-acyl dopamine 18:0 (m/z 420.3 to m/z 154.1 and m/z 137.1), N-acyl dopamine 20:4 (440.200 to m/z 154.1 and m/z 137.1), dopamine (m/z 154.00 to m/z 137.00 and to m/z 119 and 91, respectively) and dopamine d4 (m/z 158.0 to m/z 141.0 and 123.0, respectively). MRM transitions for endocannabinoid ho- mologues were inferred from Bilgin and Shevchenko (2017).
Seahorse assay
A Seahorse XF96 Analyzer (Agilent Technologies) was used to measure extracellular acidification rate and oxygen consumption
| Compound name | Manufacturer | Catalog no. |
|---|---|---|
| 2-Oleoyl glycerol (2AG 18:1) | Cayman Chemicals | 16537 |
| 2-Arachidonoyl glycerol (2-AG 20:4) | Cayman Chemicals | 62160 |
| N-oleoyl dopamine (18:1) | Cayman Chemicals | 10115 |
| N-arachidonoyl dopamine (20:4) | Cayman Chemicals | 90057 |
rate of NCI-H295R cells. NCI-H295R cells were plated at 80,000/ well in a Seahorse 96-well plate coated with 0.2% gelatin (Sigma- Aldrich) and after 24 h starved in DMEM/F12 and 1% BSA for 5 h. Stimulations and measurements were performed in XF Base Medium according to the manufacturer’s protocol.
cAMP assay
The intracellular cAMP was measured using the Direct cAMP ELISA kit (Enzo Life Sciences) according to manufacturer’s protocol. NCI-H295R cells were plated at 500,000 cells/well in a six-well plate, and at ~80% confluence they were stimulated as described for the respective time periods. As a positive control for inducing cAMP production, we used 20 uM forskolin (Sigma-Aldrich).
Proliferation assay
Proliferation of NCI-H295R was measured using the BrdU Cell Proliferation ELISA Kit (Abcam), according to the manu- facturer’s protocol. NCI-H295R cells were cultured at 40,000 cells/well in a 96-well plate for 24 h and stimulated as described for 48 h, and BrdU was added in the last 24 h.
Quantitative real-time and semi-quantitative RT-PCR
For RT-PCR experiments, NCI-H295R cells were plated at 500,000 cells/well in a 24-well plate, and NIH3T3 cells were plated at 100,000 cells/well in a 24-well plate, stimulated as described after 24 h, and cultured for another 48 h. mRNA was extracted with the RNeasy Mini Kit (Qiagen), and cDNA was synthesized with M-MLV Reverse Transcription (Promega GMBH) according to the manufacturer’s instructions. Gene ex- pression was determined using the FastStart Essential DNA Green Master and the LightCycler96 System from Roche. The sequences of the used primers are listed in Table 4 (semi- quantitative RT-PCR) and Table 5 (quantitative RT-PCR). The relative expression of the genes was calculated using the ACt
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| Gene name | Sequence Fw (5'->3') | Sequence Rev (5'->3') | Amplicon length |
|---|---|---|---|
| Human GAPDH | CGACCACTTTGTCAAGCTCA | AGGGGTCTACATGGCAACTG | 200 bp |
| Human SHH | TGATGAACCAGTGGCCAGG | GTGGCCATCTTCGTCCCA | 62 bp |
| Human SMO | CAGTTTCAGCGGTGCCAAC | GGTGAGTGTGTGCAGCAGCT | 74 bp |
| Human PTCH1 | TGTTCGGCATGATGGGC | AGCGATCAGGATGACCACG | 65 bp |
| Human GLI1 | GGCACCATCCATTTCTACAGTG | TGCTTTCCTCCCTGATGGG | 68 bp |
| Human GLI2 | AGTTTGTTCTCGGGTGCTCTG | ACATCTGTCATCTGAAGCGGC | 339 bp |
| Human GLI3 | CACCCTCCTCATCTTTTCCC | GGTGTGGGGAGATCCTAATG | 172 bp |
| Human SUFU | TTTACCCTGACCAGCCGAAC | TGGAACACGTATCGTGCCAA | 319 bp |
| Mouse Gapdh | TCCACCACCCTGTTGCTGTA | GACTTCAACAGCAACTCCCAC | 118 bp |
| Mouse Shh | CAGCGGCAGATATGAAGGGA | GGTGATGTCCACTGCTCGAC | 274 bp |
| Mouse Smo | GTGTGAGAATGACCGAGTGGA | GAACAGCGGGTTCTGACACT | 268 bp |
| Mouse Ptch1 | TGTGGCTGAGAGCGAAGTTT | AGTGCTGAGTCCAGGTGTTG | 319 bp |
| Mouse Gli1 | TTCCTACGGCCATCTCTCCA | AATCGAACTCCTGGCTGCAA | 386 bp |
| Mouse Gli2 | AGACACCAGGAGGGAAGGTA | CGAGGCTAAAGAGTCCCCTC | 301 bp |
| Mouse Gli3 | GCCCTCGACGTCTAGTGATG | GTTGATGTAGGGGTGTGGGG | 373 bp |
| Mouse Sufu | ACAGGAACATGGGGAGTCCT | CAATGGGCACTGTCCGTAGT | 465 bp |
Fw, forward; Rev, reverse.
method, and the values were normalized to those for the ref- erence gene B-actin or 18S.
Immunohistochemistry
The adrenal glands were fixed in 4% PFA in PBS, extensively washed in PBS, cryopreserved in 30% sucrose (AppliChem GmbH) in PBS overnight at 4℃, embedded in Tissue Freezing Medium (Triangle Biomedical Sciences), and frozen at -80℃. Each adrenal was cut into 8-um-thick serial sections. Before staining, adrenal sections were prewarmed at RT for 30 min, washed with PBS, permeabilized with 0.1% Triton X-100 and 5% normal goat serum (Biowest) in PBS for 20 min, treated with 0.25% glycine in PBS for 15 min to reduce the autofluorescence, and blocked for nonspecific binding in 10% BSA in PBS for 1 h at RT. Then sections were incubated overnight at 4℃ with the appropriate primary antibodies, washed with PBS, and incu- bated for 1 h at RT with the respective secondary antibody to- gether with DAPI (1:5,000; Roche). All antibodies and dyes were diluted in 1% BSA in PBS and are listed in Table 1 (primary an- tibodies) and Table 2 (secondary antibodies). After washing with PBS, cryosections were mounted in VectaShield mounting me- dium (Vector Labs), covered with a 0.17-mm coverglass, fixed with nail polish, and kept at 4℃ until imaging.
Immunocytochemistry
For immunocytochemistry, cells were plated on 13-mm cover- slips in 24-well plates, grown until confluence, and serum-starved (DMEM or DMEM/F12 and 1% ITS) for 48 h to induce ciliation. The appropriate treatments were also performed in the starvation me- dium. After removal of the culture medium and washes in PBS, cells were fixed in 4% PFA for 20 min, permeabilized with 0.1% Triton
X-100 and 1% BSA in PBS for 20 min, and blocked with 10% BSA in PBS for 30 min at RT. Then they were incubated with primary antibody for 2 h at RT and with secondary antibody together with DAPI for 1 h at RT. All antibodies and dyes were diluted in 1% BSA in PBS and are listed in Table 1 (primary antibodies) and Table 2 (secondary antibodies). After a series of washes, coverslips were mounted on slides with VectaShield mounting medium, fixed with nail polish, and kept at 4℃ until imaging.
Image acquisition and analysis
Z-optical series microscopic images were acquired at RT on the Zeiss LSM 700 inverted confocal microscope (Zeiss); illuminated with laser lines at 405 nm, 488 nm, 555 nm, and 639 nm; and de- tected by two photomultiplier tube detectors. A Plan-Apochromat objective with 63x magnification, 1.40 NA, and M27 thread, work- ing with the oil immersion medium Immersol 518 F, was used. Laser power, photomultiplier gain, and pinhole size were set for each antibody individually and kept constant for all subsequent image acquisitions. For each condition, at least six view fields were imaged per coverslip or tissue section. Images were acquired with the ZEN 2012 (SP5 FP3 Black, 64-bit) software, and processed and quantified with the Fiji/ImageJ software. The quantification of cell and cilia number in cell cultures was done on maximum intensity Z-projection images with the Cell Counter plugin in Fiji. The quantification of cell and cilia number in adrenal glands sections was done with a Fiji script written by the Scientific Computing facility (MPI-CBG and Center for Systems Biology Dresden).
Statistical analysis
The statistical analysis and plotting of the results were per- formed with Graphpad Prism version 6.0c (GraphPad Software
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| Gene name | Sequence Fw (5'->3') | Sequence Rev (5'->3') |
|---|---|---|
| Human 18S | TGCCCTATCAACTTTCGATG | GATGTGGTAGCCGTTTCTCA |
| Human B-ACTIN | GCCGTCTTCCCCTCCATCGTG | GGAGCCACACGCAGCTCATTGTAGA |
| Human PTCH1 | CCACAGAAGCGCTCCTACAA | TGTTCCAATTTCCACTGCCTG |
| Human GLI1 | AGAGAGACCAACAGCTGCAC | GAGGTGAGATGGACAGTGCC |
| Human GLI2 | CCCACGCTCTCCATGATCTC | AGCAGGAAGGCCAAACAGTC |
| Mouse b-Actin | GAGCACAGCTTCTTTGCAGCTCCTT | TGCCATGTTCAATGGGGTACTTCAG |
| Mouse Ptch1 | TGCTGTGCCTGTGGTCATCCTGATT | CAGAGCGAGCATAGCCCTGTGGTTC |
| Mouse Gli1 | CAGCAGCTGCACTGAAGGATCTC | GCTGGCATCAGAAAGGGGCG |
Fw, forward; Rev, reverse.
Inc.). Data were analyzed with the Mann-Whitney U test and are graphically represented as mean + SD.
Online supplemental material
Fig. S1 shows that HFD-induced obesity in mice does not change the fractionation of SHH or lipoproteins in the adrenal gland. Fig. S2 provides additional data on the inhibitory activity of NCI- H295R-derived conditioned medium on the SHH signaling activity in Shh-LIGHT2 cells. Fig. S3 shows that human adre- nocortical carcinoma NCI-H295R cells do not respond to auto- crine noncanonical SHH signaling. Fig. S4 provides additional data showing that NCI-H295R cells are poorly ciliated. Fig. S5 shows that HUVECs do not respond to canonical SHH signaling.
Author contributions: Conceptualization: I. Mateska, V.I. Alexaki, and S. Eaton; Investigation: I. Mateska, K. Nanda, and V.I. Alexaki; Formal Analysis: I. Mateska, K. Nanda, V.I. Alexaki, and S. Eaton; Methodology: I. Mateska, V.I. Alexaki, and S. Ea- ton; Visualization: I. Mateska; Writing/Original Draft Prepara- tion: I. Mateska, N.A. Dye, V.I. Alexaki, and S. Eaton; Writing/ Review and Editing: I. Mateska, N.A. Dye, and V.I. Alexaki; Su- pervision: N.A. Dye, V.I. Alexaki, and S. Eaton; Funding Acqui- sition: V.I. Alexaki and S. Eaton.
Submitted: 22 October 2019
Revised: 27 July 2020
Accepted: 15 September 2020
Acknowledgments
We dedicate this manuscript to our endlessly inspiring colleague and mentor, Suzanne Eaton, who sadly passed away during the last stages of its preparation.
We are grateful to Valentina Greco, Marino Zerial, Jacqueline M. Tabler, Triantafyllos Chavakis, Stefan R. Bornstein, Marta M. Swierczynska, Petra Born, Stephanie Spannl, and Suhrid Ghosh for helpful discussions and critical comments on the manuscript. We acknowledge Canelif Yilmaz for performing laser micro- dissection of the adrenal cortex, Christine Mund for technical assistance, and Philip Beachy (Stanford University School of Medicine, Standford, CA) for providing Shh-LIGHT2 and NIH3T3/Smo-mEos2 cells. We thank Laura Bindila (Lipidomics Unit, University Medical Center Mainz of the Johannes Guten- berg University Mainz) for performing the LC-MRM lipid analysis, Barbara Borgonovo (MPI-CBG) for assisting with gel filtration chromatography, the Biomedical Services Facility (MPI-CBG) for help with animal husbandry, the Light Micros- copy Facility (MPI-CBG) for help with imaging, and the Scien- tific Computing Facility (MPI-CBG and Center for Systems Biology Dresden) for providing the Fiji script for cell and cilia quantification in adrenal glands.
This work was supported by grants from the Deutsche For- schungsgemeinschaft (KFO 252 to S. Eaton, and SFB-TRR 205 to S. Eaton and V.I. Alexaki), and by the Max Planck Gesellschaft. The authors declare no competing financial interests.
References
Alexaki, V.I., D. Javelaud, L.C.L. Van Kempen, K.S. Mohammad, S. Dennler, F. Luciani, K.S. Hoek, P. Juarez, J.S. Goydos, P.J. Fournier, et al. 2010. GLI2- mediated melanoma invasion and metastasis. J. Natl. Cancer Inst. 102: 1148-1159. https://doi.org/10.1093/jnci/djq257
Bangs, F., and K.V. Anderson. 2017. Primary cilia and Mammalian Hedgehog signaling. Cold Spring Harb. Perspect. Biol. 9:a028175. https://doi.org/10 .1101/cshperspect.a028175
Bassett, J.R., and S.H. West. 1997. Vascularization of the adrenal cortex: its possible involvement in the regulation of steroid hormone release. Microsc. Res. Tech. 36:546-557. https://doi.org/10.1002/(SICI)1097 -0029(19970315)36:6<546:AID-JEMT11>3.0.CO;2-O
Berman, D.M., S.S. Karhadkar, A. Maitra, R. Montes De Oca, M.R. Gersten- blith, K. Briggs, A.R. Parker, Y. Shimada, J.R. Eshleman, D.N. Watkins, and P.A. Beachy. 2003. Widespread requirement for Hedgehog ligand stimulation in growth of digestive tract tumours. Nature. 425:846-851. https://doi.org/10.1038/nature01972
Bilgin, M., and A. Shevchenko. 2017. Quantification of Endogenous Endo- cannabinoids by LC-MS/MS. Lipidomics. 125:99-107. https://doi.org/10 .1007/978-1-4939-6946-3_7
Bischoff, M., A .- C. Gradilla, I. Seijo, G. Andrés, C. Rodríguez-Navas, L. González-Méndez, and I. Guerrero. 2013. Cytonemes are required for the establishment of a normal Hedgehog morphogen gradient in Dro- sophila epithelia. Nat. Cell Biol. 15:1269-1281. https://doi.org/10.1038/ ncb2856
Boulkroun, S., B. Samson-Couterie, J.F. Golib-Dzib, L. Amar, P.F. Plouin, M. Sibony, H. Lefebvre, E. Louiset, X. Jeunemaitre, T. Meatchi, et al. 2011. Aldosterone-producing adenoma formation in the adrenal cortex in- volves expression of stem/progenitor cell markers. Endocrinology. 152: 4753-4763. https://doi.org/10.1210/en.2011-1205
Briscoe, J., and P.P. Thérond. 2013. The mechanisms of Hedgehog signalling and its roles in development and disease. Nat. Rev. Mol. Cell Biol. 14: 416-429. https://doi.org/10.1038/nrm3598
JCB
Campbell, W.B., M.T. Brady, L.J. Rosolowsky, and J.R. Falck. 1991. Metabolism of arachidonic acid by rat adrenal glomerulosa cells: synthesis of hy- droxyeicosatetraenoic acids and epoxyeicosatrienoic acids. Endocrinol- ogy. 128:2183-2194. https://doi.org/10.1210/endo-128-4-2183
Caspary, T., M.J. García-García, D. Huangfu, J.T. Eggenschwiler, M.R. Wyler, A.S. Rakeman, H.L. Alcorn, and K.V. Anderson. 2002. Mouse Dispatched homolog1 is required for long-range, but not juxtacrine, Hh signaling. Curr. Biol. 12:1628-1632. https://doi.org/10.1016/S0960-9822(02)01147-8
Caspary, T., C.E. Larkins, and K.V. Anderson. 2007. The graded response to Sonic Hedgehog depends on cilia architecture. Dev. Cell. 12:767-778. https://doi.org/10.1016/j.devcel.2007.03.004
Chan, I.S., C.D. Guy, Y. Chen, J. Lu, M. Swiderska-Syn, G.A. Michelotti, G. Karaca, G. Xie, L. Krüger, W.K. Syn, et al. 2012. Paracrine Hedgehog signaling drives metabolic changes in hepatocellular carcinoma. Cancer Res. 72:6344-6350. https://doi.org/10.1158/0008-5472.CAN-12-1068
Chen, W., H. Huang, R. Hatori, and T.B. Kornberg. 2017. Essential basal cy- tonemes take up Hedgehog in the Drosophila wing imaginal disc. De- velopment. 144:3134-3144. https://doi.org/10.1242/dev.149856
Ching, S., and E. Vilain. 2009. Targeted disruption of Sonic Hedgehog in the mouse adrenal leads to adrenocortical hypoplasia. Genesis. 47:628-637. https://doi.org/10.1002/dvg.20532
Christensen, S.T., L.B. Pedersen, L. Schneider, and P. Satir. 2007. Sensory cilia and integration of signal transduction in human health and disease. Traffic. 8:97-109. https://doi.org/10.1111/j.1600-0854.2006.00516.x
Corbit, K.C., P. Aanstad, V. Singla, A.R. Norman, D.Y.R. Stainier, and J.F. Reiter. 2005. Vertebrate Smoothened functions at the primary cilium. Nature. 437:1018-1021. https://doi.org/10.1038/nature04117
Damhofer, H., V.L. Veenstra, J.A.M.G. Tol, H.W.M. van Laarhoven, J.P. Me- dema, and M.F. Bijlsma. 2015. Blocking Hedgehog release from pan- creatic cancer cells increases paracrine signaling potency. J. Cell Sci. 128: 129-139. https://doi.org/10.1242/jcs.157966
Dennler, S., J. André, I. Alexaki, A. Li, T. Magnaldo, P. ten Dijke, X.J. Wang, F. Verrecchia, and A. Mauviel. 2007. Induction of sonic hedgehog medi- ators by transforming growth factor-B: Smad3-dependent activation of Gli2 and Glil expression in vitro and in vivo. Cancer Res. 67:6981-6986. https://doi.org/10.1158/0008-5472.CAN-07-0491
Eaton, S. 2008. Multiple roles for lipids in the Hedgehog signalling pathway. Nat. Rev. Mol. Cell Biol. 9:437-445. https://doi.org/10.1038/nrm2414
Eugster, C., D. Panáková, A. Mahmoud, and S. Eaton. 2007. Lipoprotein- heparan sulfate interactions in the Hh pathway. Dev. Cell. 13:57-71. https://doi.org/10.1016/j.devcel.2007.04.019
Ferent, J., S. Constable, E.D. Gigante, P.T. Yam, L.E. Mariani, E. Legué, K.F. Liem Jr., T. Caspary, and F. Charron. 2019. The Ciliary Protein Arl13b Functions Outside of the Primary Cilium in Shh-Mediated Axon Guidance. Cell Rep. 29:3356-3366.e3. https://doi.org/10.1016/j.celrep .2019.11.015
Frazier-Wood, A.C., S. Glasser, W.T. Garvey, E.K. Kabagambe, I.B. Borecki, H.K. Tiwari, M.Y. Tsai, P.N. Hopkins, J.M. Ordovas, and D.K. Arnett. 2011. A clustering analysis of lipoprotein diameters in the metabolic syndrome. Lipids Health Dis. 10:237. https://doi.org/10.1186/1476-511X -10-237
Freedman, B.D., P.B. Kempna, D.L. Carlone, M. Shah, N.A. Guagliardo, P.Q. Barrett, C.E. Gomez-Sanchez, J.A. Majzoub, and D.T. Breault. 2013. Adrenocortical zonation results from lineage conversion of differenti- ated zona glomerulosa cells. Dev. Cell. 26:666-673. https://doi.org/10 .1016/j.devcel.2013.07.016
Gazdar, A.F., H.K. Oie, C.H. Shackleton, T.R. Chen, T.J. Triche, C.E. Myers, G.P. Chrousos, M.F. Brennan, C.A. Stein, and R.V. La Rocca. 1990. Es- tablishment and characterization of a human adrenocortical carcinoma cell line that expresses multiple pathways of steroid biosynthesis. Cancer Res. 50:5488-5496.
German, J.B., J.T. Smilowitz, and A.M. Zivkovic. 2006. Lipoproteins: When size really matters. Curr. Opin. Colloid Interface Sci. 11:171-183. https://doi .org/10.1016/j.cocis.2005.11.006
Gigante, E.D., M.R. Taylor, A.A. Ivanova, R.A. Kahn, and T. Caspary. 2020. ARL13B regulates Sonic hedgehog signaling from outside primary cilia. eLife. 9:e50434. https://doi.org/10.7554/eLife.50434
Gomes, D.C., L.F. Leal, L.M. Mermejo, C.A. Scrideli, C.E. Martinelli Jr., M.C.B.V. Fragoso, A.C. Latronico, L.G. Tone, S. Tucci, J.A. Yunes, et al. 2014. Sonic hedgehog signaling is active in human adrenal cortex de- velopment and deregulated in adrenocortical tumors. J. Clin. Endocrinol. Metab. 99:E1209-E1216. https://doi.org/10.1210/jc.2013-4098
González-Méndez, L., I. Seijo-Barandiarán, and I. Guerrero. 2017. Cytoneme- mediated cell-cell contacts for Hedgehog reception. eLife. 6:e24045. https://doi.org/10.7554/eLife.24045
Gradilla, A .- C., E. González, I. Seijo, G. Andrés, M. Bischoff, L. González-Mendez, V. Sánchez, A. Callejo, C. Ibáñez, M. Guerra, et al. 2014. Exosomes as Hedgehog carriers in cytoneme-mediated transport and secretion. Nat. Commun. 5:5649. https://doi.org/10.1038/ncomms6649
Guasti, L., A. Paul, E. Laufer, and P. King. 2011. Localization of Sonic hedgehog secreting and receiving cells in the developing and adult rat adrenal cortex. Mol. Cell. Endocrinol. 336:117-122. https://doi.org/10.1016/j.mce .2010.11.010
Häcker, U., K. Nybakken, and N. Perrimon. 2005. Heparan sulphate prote- oglycans: the sweet side of development. Nat. Rev. Mol. Cell Biol. 6: 530-541. https://doi.org/10.1038/nrm1681
Haycraft, C.J., B. Banizs, Y. Aydin-Son, Q. Zhang, E.J. Michaud, and B.K. Yoder. 2005. Gli2 and Gli3 localize to cilia and require the intraflagellar transport protein polaris for processing and function. PLOS Genet. 1:e53. https://doi.org/10.1371/journal.pgen.0010053
He, H., M. Huang, S. Sun, Y. Wu, and X. Lin. 2017. Epithelial heparan sulfate regulates Sonic Hedgehog signaling in lung development. PLOS Genet. 13: e1006992. https://doi.org/10.1371/journal.pgen.1006992
Hegele, R.A. 2009. Plasma lipoproteins: genetic influences and clinical im- plications. Nat. Rev. Genet. 10:109-121. https://doi.org/10.1038/nrg2481
Huang, C.C.J., S. Miyagawa, D. Matsumaru, K.L. Parker, and H.H.C. Yao. 2010. Progenitor cell expansion and organ size of mouse adrenal is regulated by sonic hedgehog. Endocrinology. 151:1119-1128. https://doi .org/10.1210/en.2009-0814
Huangfu, D., and K.V. Anderson. 2005. Cilia and Hedgehog responsiveness in the mouse. Proc. Natl. Acad. Sci. USA. 102:11325-11330. https://doi.org/10 .1073/pnas.0505328102
Hui, C.C., and S. Angers. 2011. Gli proteins in development and disease. Annu. Rev. Cell Dev. Biol. 27:513-537. https://doi.org/10.1146/annurev-cellbio -092910-154048
Humke, E.W., K.V. Dorn, L. Milenkovic, M.P. Scott, and R. Rohatgi. 2010. The output of Hedgehog signaling is controlled by the dynamic association between Suppressor of Fused and the Gli proteins. Genes Dev. 24: 670-682. https://doi.org/10.1101/gad.1902910
Igal, R.A., E.C. Mandon, and I.N. de Gómez Dumm. 1991. Abnormal metabolism of polyunsaturated fatty acids in adrenal glands of diabetic rats. Mol. Cell. Endocrinol. 77:217-227. https://doi.org/10.1016/0303-7207(91)90077-6
Ingham, P.W., and A.P. McMahon. 2001. Hedgehog signaling in animal de- velopment: paradigms and principles. Genes Dev. 15:3059-3087. https:// doi.org/10.1101/gad.938601
Ingham, P.W., Y. Nakano, and C. Seger. 2011. Mechanisms and functions of Hedgehog signalling across the metazoa. Nat. Rev. Genet. 12:393-406. https://doi.org/10.1038/nrg2984
Javelaud, D., V.I. Alexaki, S. Dennler, K.S. Mohammad, T.A. Guise, and A. Mauviel. 2011. TGF-B/SMAD/GLI2 signaling axis in cancer progression and metastasis. Cancer Res. 71:5606-5610. https://doi.org/10.1158/0008 -5472.CAN-11-1194
Jonas, A., and M.C. Phillips. 2008. Lipoprotein Structure. In Biochemistry of Lipids, Lipoproteins and Membranes. D.E. Vance, and J.E. Vance, edi- tors. Fifth edition. Elsevier B.V. pp. 485-506.
Keegan, C.E., and G.D. Hammer. 2002. Recent insights into organogenesis of the adrenal cortex. Trends Endocrinol. Metab. 13:200-208. https://doi .org/10.1016/S1043-2760(02)00602-1
Khaliullina, H., D. Panáková, C. Eugster, F. Riedel, M. Carvalho, and S. Eaton. 2009. Patched regulates Smoothened trafficking using lipoprotein- derived lipids. Development. 136:4111-4121. https://doi.org/10.1242/dev .041392
Khaliullina, H., M. Bilgin, J.L. Sampaio, A. Shevchenko, and S. Eaton. 2015. Endocannabinoids are conserved inhibitors of the Hedgehog pathway. Proc. Natl. Acad. Sci. USA. 112:3415-3420. https://doi.org/10.1073/pnas .1416463112
Kim, J., E.Y.C. Hsia, J. Kim, N. Sever, P.A. Beachy, and X. Zheng. 2014. Simulta- neous measurement of smoothened entry into and exit from the primary cilium. PLOS One. 9:e104070. https://doi.org/10.1371/journal.pone.0104070
King, P., A. Paul, and E. Laufer. 2009. Shh signaling regulates adrenocortical development and identifies progenitors of steroidogenic lineages. Proc. Natl. Acad. Sci. USA. 106:21185-21190. https://doi.org/10.1073/pnas .0909471106
Kornberg, T.B., and S. Roy. 2014. Cytonemes as specialized signaling filopo- dia. Development. 141:729-736. https://doi.org/10.1242/dev.086223
Kraemer, F.B. 2007. Adrenal cholesterol utilization. Mol. Cell. Endocrinol. 265- 266:42-45. https://doi.org/10.1016/j.mce.2006.12.001
Kuwabara, P.E., and M. Labouesse. 2002. The sterol-sensing domain: mul- tiple families, a unique role? Trends Genet. 18:193-201. https://doi.org/10 .1016/S0168-9525(02)02640-9
JCB
Laemmli, U.K. 1970. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 227:680-685. https://doi.org/10 .1038/227680a0
Larkins, C.E., G.D.G. Aviles, M.P. East, R.A. Kahn, and T. Caspary. 2011. Arl13b regulates ciliogenesis and the dynamic localization of Shh signaling proteins. Mol. Biol. Cell. 22:4694-4703. https://doi.org/10.1091/mbc.e10-12-0994
Laufer, E., D. Kesper, A. Vortkamp, and P. King. 2012. Sonic hedgehog sig- naling during adrenal development. Mol. Cell. Endocrinol. 351:19-27. https://doi.org/10.1016/j.mce.2011.10.002
Lehmann, T.P., J.M. Biernacka-Lukanty, W.H. Trzeciak, J.Y. Li, and J.Y. Li. 2005. Steroidogenic factor 1 gene transcription is inhibited by trans- forming growth factor . Endocr. Res. 31:71-79. https://doi.org/10.1080/ 07435800500229110
Mariani, L.E., M.F. Bijlsma, A.A. Ivanova, S.K. Suciu, R.A. Kahn, and T. Caspary. 2016. Arl13b regulates Shh signaling from both inside and outside the cilium. Mol. Biol. Cell. 27:3780-3790. https://doi.org/10.1091/ mbc.e16-03-0189
Matsuo, K., and H. Tsuchiyama. 1987. Human normal and neoplastic adre- nocortical cells in tissue culture observed by scanning electron mi- croscopy. Acta Pathol. Jpn. 37:65-76. https://doi.org/10.1111/j.1440-1827 .1987.tb03134.x
Milenkovic, L., M.P. Scott, and R. Rohatgi. 2009. Lateral transport of Smoothened from the plasma membrane to the membrane of the cil- ium. J. Cell Biol. 187:365-374. https://doi.org/10.1083/jcb.200907126
Nielsen, F.K., C.H. Hansen, J.A. Fey, M. Hansen, N.W. Jacobsen, B. Halling- Sørensen, E. Björklund, and B. Styrishave. 2012. H295R cells as a model for steroidogenic disruption: a broader perspective using simultaneous chemical analysis of 7 key steroid hormones. Toxicol. In Vitro. 26: 343-350. https://doi.org/10.1016/j.tiv.2011.12.008
Palm, W., M.M. Swierczynska, V. Kumari, M. Ehrhart-Bornstein, S.R. Bornstein, and S. Eaton. 2013. Secretion and signaling activities of lipoprotein-associated hedgehog and non-sterol-modified hedgehog in flies and mammals. PLOS Biol. 11:e1001505. https://doi.org/10.1371/ journal.pbio.1001505
Panáková, D., H. Sprong, E. Marois, C. Thiele, and S. Eaton. 2005. Lipoprotein particles are required for Hedgehog and Wingless signalling. Nature. 435:58-65. https://doi.org/10.1038/nature03504
Petrova, R., and A.L. Joyner. 2014. Roles for Hedgehog signaling in adult organ homeostasis and repair. Development. 141:3445-3457. https://doi.org/10 .1242/dev.083691
Pudney, J., P.R. Sweet, G.P. Vinson, and B.J. Whitehouse. 1981. Morphological correlates of hormone secretion in the rat adrenal cortex and the role of filopodia. Anat. Rec. 201:537-551. https://doi.org/10.1002/ar.1092010310
Rainey, W.E., K. Saner, and B.P. Schimmer. 2004. Adrenocortical cell lines. Mol. Cell. Endocrinol. 228:23-38. https://doi.org/10.1016/j.mce.2003.12.020
Revenkova, E., Q. Liu, G.L. Gusella, and C. Iomini. 2018. The Joubert syn- drome protein ARL13B binds tubulin to maintain uniform distribution of proteins along the ciliary membrane. J. Cell Sci. 131:jcs212324. https:// doi.org/10.1242/jcs.212324
Riobo, N.A., B. Saucy, C. Dilizio, and D.R. Manning. 2006. Activation of heterotrimeric G proteins by Smoothened. Proc. Natl. Acad. Sci. USA. 103:12607-12612. https://doi.org/10.1073/pnas.0600880103
Rohatgi, R., L. Milenkovic, and M.P. Scott. 2007. Patched1 regulates hedgehog signaling at the primary cilium. Science. 317:372-376. https://doi.org/10 .1126/science.1139740
Rojas-Ríos, P., I. Guerrero, and A. González-Reyes. 2012. Cytoneme-mediated delivery of hedgehog regulates the expression of bone morphogenetic proteins to maintain germline stem cells in Drosophila. PLOS Biol. 10: e1001298. https://doi.org/10.1371/journal.pbio.1001298
Rudel, L.L., J.A. Lee, M.D. Morris, and J.M. Felts. 1974. Characterization of plasma lipoproteins separated and purified by agarose-column chro- matography. Biochem. J. 139:89-95. https://doi.org/10.1042/bj1390089
Sanders, T.A., E. Llagostera, and M. Barna. 2013. Specialized filopodia direct long-range transport of SHH during vertebrate tissue patterning. Na- ture. 497:628-632. https://doi.org/10.1038/nature12157
Sasaki, H., C. Hui, M. Nakafuku, and H. Kondoh. 1997. A binding site for Gli proteins is essential for HNF-3ß floor plate enhancer activity in transgenics and can respond to Shh in vitro. Development. 124:1313-1322. Seeger-Nukpezah, T., J.L. Little, V. Serzhanova, and E.A. Golemis. 2013. Cilia and cilia-associated proteins in cancer. Drug Discov. Today Dis. Mech. 10: e135-e142. https://doi.org/10.1016/j.ddmec.2013.03.004
Shaw, A., J. Gipp, and W. Bushman. 2009. The Sonic Hedgehog pathway stimulates prostate tumor growth by paracrine signaling and re- capitulates embryonic gene expression in tumor myofibroblasts. On- cogene. 28:4480-4490. https://doi.org/10.1038/onc.2009.294
Shen, F., L. Cheng, A.E. Douglas, N.A. Riobo, and D.R. Manning. 2013. Smoothened is a fully competent activator of the heterotrimeric G protein G(i). Mol. Pharmacol. 83:691-697. https://doi.org/10.1124/mol .112.082511
Shin, K., A. Lim, C. Zhao, D. Sahoo, Y. Pan, E. Spiekerkoetter, J.C. Liao, and P.A. Beachy. 2014. Hedgehog signaling restrains bladder cancer pro- gression by eliciting stromal production of urothelial differentiation factors. Cancer Cell. 26:521-533. https://doi.org/10.1016/j.ccell.2014.09 .001
Swierczynska, M.M., I. Mateska, M. Peitzsch, S.R. Bornstein, T. Chavakis, G. Eisenhofer, V. Lamounier-Zepter, and S. Eaton. 2015. Changes in morphology and function of adrenal cortex in mice fed a high-fat diet. Int. J. Obes. 39:321-330. https://doi.org/10.1038/ijo.2014.102
Taipale, J., J.K. Chen, M.K. Cooper, B. Wang, R.K. Mann, L. Milenkovic, M.P. Scott, and P.A. Beachy. 2000. Effects of oncogenic mutations in Smoothened and Patched can be reversed by cyclopamine. Nature. 406: 1005-1009. https://doi.org/10.1038/35023008
Taipale, J., M.K. Cooper, T. Maiti, and P.A. Beachy. 2002. Patched acts cata- lytically to suppress the activity of Smoothened. Nature. 418:892-897. https://doi.org/10.1038/nature00989
Tanaka, Y., Y. Okada, and N. Hirokawa. 2005. FGF-induced vesicular release of Sonic hedgehog and retinoic acid in leftward nodal flow is critical for left-right determination. Nature. 435:172-177. https://doi.org/10.1038/ nature03494
Teperino, R., S. Amann, M. Bayer, S.L. McGee, A. Loipetzberger, T. Connor, C. Jaeger, B. Kammerer, L. Winter, G. Wiche, et al. 2012. Hedgehog partial agonism drives Warburg-like metabolism in muscle and brown fat. Cell. 151:414-426. https://doi.org/10.1016/j.cell.2012.09.021
Teperino, R., F. Aberger, H. Esterbauer, N. Riobo, and J.A. Pospisilik. 2014. Canonical and non-canonical Hedgehog signalling and the control of metabolism. Semin. Cell Dev. Biol. 33:81-92. https://doi.org/10.1016/j .semcdb.2014.05.007
Thérond, P.P. 2012. Release and transportation of Hedgehog molecules. Curr. Opin. Cell Biol. 24:173-180. https://doi.org/10.1016/j.ceb.2012.02.001
Tukachinsky, H., L.V. Lopez, and A. Salic. 2010. A mechanism for vertebrate Hedgehog signaling: recruitment to cilia and dissociation of SuFu-Gli protein complexes. J. Cell Biol. 191:415-428. https://doi.org/10.1083/jcb .201004108
Vyas, N., A. Walvekar, D. Tate, V. Lakshmanan, D. Bansal, A. Lo Cicero, G. Raposo, D. Palakodeti, and J. Dhawan. 2014. Vertebrate Hedgehog is secreted on two types of extracellular vesicles with different signaling properties. Sci. Rep. 4:7357. https://doi.org/10.1038/srep07357
Watkins, D.N., D.M. Berman, S.G. Burkholder, B. Wang, P.A. Beachy, and S.B. Baylin. 2003. Hedgehog signalling within airway epithelial progenitors and in small-cell lung cancer. Nature. 422:313-317. https://doi.org/10 .1038/nature 01493
Werminghaus, P., M. Haase, P.J. Hornsby, S. Schinner, M. Schott, L.K. Mal- endowicz, B.J. Lammers, P.E. Goretzki, V. Müller-Mattheis, Markus Giessing, and H.S. Willenberg. 2014. Hedgehog-signaling is upregulated in non-producing human adrenal adenomas and antagonism of hedgehog-signaling inhibits proliferation of NCI-H295R cells and an immortalized primary human adrenal cell line. J. Steroid Biochem. Mol. Biol. 139:7-15. https://doi.org/10.1016/j.jsbmb.2013.09.007
Wetmore, C. 2003. Sonic hedgehog in normal and neoplastic proliferation: insight gained from human tumors and animal models. Curr. Opin. Genet. Dev. 13:34-42. https://doi.org/10.1016/S0959-437X(03)00002-9
Wood, M.A., and G.D. Hammer. 2011. Adrenocortical stem and progenitor cells: unifying model of two proposed origins. Mol. Cell. Endocrinol. 336: 206-212. https://doi.org/10.1016/j.mce.2010.11.012
Yates, R., H. Katugampola, D. Cavlan, K. Cogger, E. Meimaridou, C. Hughes, L. Metherell, L. Guasti, and P. King. 2013. Adrenocortical Development, Maintenance, and Disease. In Curr. Top Dev. Biol. Vol. Vol. 106. P. Thomas, editor. Elsevier Inc. pp. 239-312.
Yauch, R.L., S.E. Gould, S.J. Scales, T. Tang, H. Tian, C.P. Ahn, D. Marshall, L. Fu, T. Januario, D. Kallop, et al. 2008. A paracrine requirement for hedgehog signalling in cancer. Nature. 455:406-410. https://doi.org/10 .1038/nature07275
Zhang, F., J.S. McLellan, A.M. Ayala, D.J. Leahy, and R.J. Linhardt. 2007. Ki- netic and structural studies on interactions between heparin or heparan sulfate and proteins of the hedgehog signaling pathway. Biochemistry. 46:3933-3941. https://doi.org/10.1021/bi6025424
Zunich, S.M., T. Douglas, M. Valdovinos, T. Chang, W. Bushman, D. Wal- terhouse, P. Iannaccone, and M.L.G. Lamm. 2009. Paracrine sonic hedgehog signalling by prostate cancer cells induces osteoblast differ- entiation. Mol. Cancer. 8:12. https://doi.org/10.1186/1476-4598-8-12
JCB
Supplemental material
A
Normal Diet
High-Fat Diet
Normal Diet
High-Fat Diet
S1
P16
S16
P150
S150
S1
P16
$16
P150
$150
S1
P16
$16
P150
$150
P16
$16
P150
$150
$1
22 kD-
SHH
36 kD-
APOA1
22 kD-
36 kD-
APOE
B
S16 Adrenal Supernatant
NORMAL DIET
HIGH-FAT DIET
VLDL
LDL
HDL
Soluble Proteins
VLDL
LDL
HDL
Soluble Proteins
1.003
1.006
1.009
1.018
1.030
1.043
1.068
1.098
1.162
1.198
1.228
1.260
1.267
1.282
1.312
1.340
1.407
1.521
1.004
1.009
1.013
1.018
1.030
1.043
1.061
1.101
1.165
1.202
1.233
1.248
1.275
1.324
1.347
1.367
1.441
1.551
[g/ml]
[g/ml]
22kD
SHH
22kD
SHH
36kD
36kD
APOA1
APOA1
22kD
22kD
36kD
APOE
36kD
APOE
C
S150 Adrenal Supernatant
NORMAL DIET
HIGH-FAT DIET
VLDL
LDL
HDL
Soluble Proteins
VLDL
LDL
HDL
Soluble Proteins
1.006
1.009
1.014
1.023
1.033
1.050
1.075
1.125
1.177
1.212
1.227
1.257
1.287
1.304
1.320
1.380
1.397
1.514
1.004
1.009
1.013
1.018
1.030
1.043
1.061
1.101
1.165
1.202
1.233
1.248
1.275
1.324
1.347
1.367
1.441
1.551
[g/ml]
[g/ml]
22kD
SHH
22kD
SHH
36kD
36kD
APOA1
APOA1
22kD
22kD
36kD
APOE
36kD
APOE
JCB
A
NCI-Shh-Lpp HEK-ShhNc HeLa-ShhNc ShhNc St
B
0.16
**
1:5
1:50
1:100
1.4 ng/p.L
2uL
5uL
2uL
5uL
15uL 20uL 7
7uL
Luciferase activity
0.14
0.12
36 kD
0.10
SHH St
0.08
0.06
22 kD
SHH
0.04
0.02
0.00
Background SAG
NCI-Shh-Lpp
HEK-ShhNc +5E1
+NCI-Shh-Lpp
Unconc. Conc.
Unconc. Conc.
C
D
2.00
Gli1 Relative expression
**
0.30-
HEK-ShhNc +
HeLa (no SHH)
1.75
Luciferase activity
0.25
10 ng
NCI-Shh-Lpp
1.50
1.25
0.20
1.00
0.15
0.75
0.10
0.50
0.25
0.05
0.00
0.00
Back ground
SAG
HEK
+5E1
0.05
0.5
5
50
0.05
0.5
5
50
0
0.05
0.5
5
ShhNc
+ NCI-Shh-Lpp [uL]
+ Lpp Control [uL]
+ concentrated medium [ul]
JCB
A
200-
Control
Lpp
5E1
lgG
200
Control
SAG
Cyclopamine
DMSO
Glucose Treatment
Oligomycin
2-DG
Glucose Treatment
Oligomycin
2-DG
ECAR (mpH/min)
150-
ECAR (mpH/min)
150
100-
100
50
50
0
0
20
40
60
80
100
120
140
160
180
200
220
240
260
0
Time (minutes)
0
20
40
60
80
100
Time (minutes)
120
140
160
180
200
220
240
260
B
Control
Lpp
5E1
lgG
Control
SAG
Cyclopamine
DMSO
600-
600
Treatment
Oligomycin
FCCP.
Rot/Ant
Treatment
Oligomycin
FCCP
Rot/Ant
500-
500
OCR (pmol/min)
OCR (pmol/min)
400-
400
300
300
200-
200
100-
100
99000
0
0
20
40
60
80
100
120
140
160
180
200
0
0
20
40
60
80
100
120
140
160
180
200
Time (minutes)
Time (minutes)
C
5 min treatment
30-
24 h treatment
6
25
20
CAMP [pmol/ml]
5
CAMP [pmol/ml]
12
10.
4
8
3
6
2
4
1
2
0
0
Serum-free
+ Lipoproteins
Forskolin
Serum-free
+ Lipoproteins
Forskolin
No treatment
5E1
lgG Control
Cyclopamine
DMSO Control
JCB
**
100
Acetylated Tubulin
60
ARL13B
Glutamylated Tubulin
20
IFT88
% ciliated cells
10
8
**
6
*
4
2
0
NCI-H295R
NIH3T3/Smo-mEos2
| AcTUB | 2597 | 1728 |
| ARL13B | 2377 | 2093 |
| GlutTUB | 3004 | 2060 |
| IFT88 | 1970 | 1761 |
A
ARL13B
AcTUB
B
GLI1
PTCH1
GLI2
2.5
3.0-
3.0
Relative expression
Relative expression
Relative expression
2.0-
2.0-
2.0-
1.5-
1.0-
1.0-
1.0-
0.5
0.0-
0.0
0.0
-1.0
DMSO
SAG
DMSO
SAG
DMSO
SAG
Figure S5. HUVECs do not respond to canonical SHH signaling. (A) Immunofluorescence of HUVECs stained for acetylated tubulin (AcTUB; cyan), ARL13B (magenta), and nuclear DAPI (blue). Magenta arrowhead denotes an ARL13B-positive cilium. From 419 cells counted, 0.95% were positive for ARL13B. Scale bar, 10 um. n = 3 replicates. (B) Quantitative RT-PCR for GLI1, PTCH1, and GLI2 expression in HUVECs treated with SAG (200 nM) for 24 h, using 18S rRNA as an internal control. Data are presented as mean + SD, n = 9 replicates, pooled from three experiments.