| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
INTRACELLULAR SIGNAL SYSTEMS |
Department of Biochemistry and Center in Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
Address all correspondence to: Dr. Marion B. Sewer, Department of Biochemistry, Vanderbilt University School of Medicine, 606 Light Hall, Nashville, Tennessee 37232-0146. E-mail: . waterman{at}toxicology.mc.vanderbilt.edu
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Transcriptional regulation of the bovine CYP17 (bCYP17; 17
-hydroxylase/17,20-lyase) gene has been extensively studied, and ACTH/cAMP-dependent transcription has been found to occur via two cAMP regulatory sequences (CRS1 and CRS2) in the 5'-flanking region of the gene. CRS1, which lies approximately -243/-225 upstream of the transcriptional initiation site, binds the homeodomain proteins Pbx1, Meis1, and Pknox (7). CRS2 (-80/-40 of bCYP17), on the other hand, binds the orphan nuclear receptors chicken ovalbumin promoter-transcription factor and steroidogenic factor-1 (SF-1) in a mutually exclusive manner, where chicken ovalbumin promoter-transcription factor acts to suppress transcription and SF-1 stimulates gene expression (8).
We (8A ) and others (9) have recently found that cAMP-dependent transcription of the human CYP17 gene occurs via a single CRS located from -57/-38 upstream of the transcriptional initiation site. Further, we have identified the transcription factors interacting with this region showing that SF-1, p54nrb/NonO and poly-pyrimidine tract-binding protein-associated splicing factor (PSF) bind both each other and the human CYP17 (hCYP17) promoter, thereby conferring cAMP responsiveness to the hCYP17 gene. p54nrb is the human homolog of murine NonO, a ubiquitously expressed non-POU domain-containing, octamer-binding protein that contains both DNA- and RNA-binding domains (10). PSF is an essential mammalian splicing factor (11) that has also been shown to repress porcine CYP11A (cholesterol side-chain cleavage cytochrome P450) (12). Using EMSA we demonstrated that cAMP stimulates increased binding intensity of a SF-1-p54nrb/NonO-PSF complex to the -57/-38 region of the hCYP17 promoter (8A ). This cAMP-inducible binding was found to be cell line selective, cycloheximide sensitive, and observable within 2 h after cAMP stimulation.
The transcription of steroid hydroxylase genes has been extensively studied in various species (1, 2, 13). Each gene contains unique CRS that interact with specific transcription factors, and this interaction acts to confer basal and cAMP-dependent transcriptional activity. We have recently found that the cAMP-dependent transcription of the hCYP17 gene is regulated by the concerted action of SF-1, PSF, and p54nrb/NonO binding to the -57/-38 region of the gene’s promoter (8A ). This work also detected for the first time in the study of steroid hormone biosynthesis that cAMP can induce the cycloheximide-sensitive binding of transcription factors to a responsive sequence in the promoter. The aim of the present study was to determine the mechanism by which cAMP evokes an increase in the binding intensity of SF-1, PSF, and p54nrb/NonO to the -57/-38 region of the hCYP17 5' flank.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Preparation of plasmid constructs
A plasmid containing a 57-bp fragment of the hCYP17 promoter fused to the luciferase gene in the pGL3 vector (Promega Corp., Madison, WI) was generated by ligating double-stranded oligonucleotides that corresponded to -57/-2 of the hCYP17 promoter upstream of the luciferase gene in the pGL3 vector. Data obtained from luciferase assays (relative luciferase light units, RLU) were normalized to the protein content of each sample.
Cell culture, transient transfection, and luciferase assay
H295R adrenocortical cells (14) were cultured in DMEM/F-12 medium (Life Technologies, Inc., Gaithersburg, MD) supplemented with 10% Nu-Serum I (Collaborative Biomedical Products, Bedford, MA), 0.5% ITS Plus (Collaborative Biomedical Products), and antibiotics. Twenty-four hours before transfection, cells were subcultured onto six-well culture dishes. Plasmids were transfected into H295R cells using the Effectene nonliposomal lipid transfection reagent (QIAGEN, Valencia, CA) for 24 h, followed by an additional 2- to 12-h incubation in the presence or absence of 1 mM (Bu)2cAMP, OA (5–50 nM), PV (5–50 µM), 10 µM protein kinase inhibitor [PKI-(6–22) peptide], or 25 µM PD98059. Cells were harvested, and cellular extracts were prepared for luciferase assays (Promega Corp.) and protein concentration determination (Pierce Chemical Co., Rockford, IL).
EMSA
For nuclear extract isolation, cells were subcultured onto 100-mm dishes for 24 h, followed by incubation with (Bu)2cAMP, OA, PV, PKI, or PD98059 for 2–12 h. Nuclear extracts were prepared according to the method of Dignam et al. (15). Double-stranded oligonucleotides were labeled with [-32P]dCTP (3000 Ci/mmol; NEN Life Science Products, Boston, MA) by a fill-in reaction using DNA polymerase I, Klenow fragment (Stratagene). Five micrograms of nuclear protein, 0.5 µg poly(dI-dC), 50 µg BSA, and 32P-labeled probe (10,000 cpm) were mixed in 25 µl binding buffer [20 mM HEPES (pH 7.9), 80 mM KCl, 5 mM MgCl2, 2% Ficoll, 5% glycerol, 0.1 mM EDTA, and 0.2 mM dithiothreitol] on ice.
RNA isolation, Northern blotting, and hybridization conditions
H295R cells were subcultured onto six-well plates and treated with (Bu)2cAMP in the presence or absence of kinase (PKI and PD98059) and phosphatase (OA and PV) inhibitors for periods ranging from 4–24 h. Total RNA was prepared from treated cells by acid-phenol extraction (16). RNA concentrations were determined by absorbance at 260 nm. For Northern blot assays (17), RNA (10 µg) was fractionated by agarose (1%) gel electrophoresis in the presence of 5% formaldehyde and transferred to nylon transfer membrane filters (Hybond-N+, Amersham Pharmacia Biotech, Piscataway, NJ). A 1.2-kb cDNA fragment of hCYP17 was used to detect hCYP17 mRNA expression. Results were normalized to the content of glyceraldehyde-3-phosphate dehydrogenase (GAP) mRNA. cDNA probes were labeled with [-32P]dCTP by random primer labeling (Prime It II, Stratagene). Blots were hybridized overnight at 42 C in a 2x SSC solution containing 50% formamide, 5x Denhardt’s solution, 2% SDS, 100 µg/ml denatured single-stranded salmon sperm DNA, and 32P-labeled cDNA probes. The hybridized membranes were sequentially washed twice for 10 min each time in 2x SSC/0.2% SDS and twice for 5 min each time in 0.2x SSC/0.2% SDS at 42 C. The amount of probe bound to the filter was quantitated using PhosphorImager and ImageQuant software (Molecular Dynamics, Inc., Sunnyvale, CA).
In vitro dephosphorylation of nuclear proteins
Nuclear extracts (5 µg) isolated from unstimulated H295R cells were incubated with recombinant protein phosphatase 
, (-PPase; Calbiochem, La Jolla, CA). The reaction was carried out for 20 min at 30 C in buffer comprised of 50 mM Tris-Cl (pH 7.8), 5 mM dithiothreitol, 2 mM MnCl2, and 100 µg/ml BSA. A range of concentrations of -PPase from 1–200 U was used.
In vivo labeling and immunoprecipitation
For in vivo labeling, H295R cells were cultured in 100-mm dishes. The medium was changed to phosphate-free DMEM containing 1.5 mCi [32P]orthophosphate (NEN Life Science Products). Cells were grown for 16 h before harvesting for immunoprecipitation. Some cells were stimulated with 1 mM (Bu)2cAMP for 12 h before harvest. Radiolabeled cells were harvested, and nuclear extracts were isolated as described above. For immunoprecipitation assays nuclear proteins were incubated with anti-SF-1 antiserum or anti-NonO antiserum and protein A-Sepharose beads overnight at 4 C with rotation. The mixture was then centrifuged, and the supernatant was removed. Beads were washed three times and resuspended in SDS-PAGE gel loading buffer for SDS-PAGE (8% gel) and Western blotting. Western blots were subjected to audioradiography to detect 32P-labeled proteins. For detection of SF-1 and p54nrb/NonO, membranes were blocked overnight in TBS-Tween 20 containing 5% BSA, followed by incubation with anti-SF-1 (a gift from Dr. K. Morohashi, National Institute for Basic Biology, Okazaki, Japan) or anti-NonO (donated by Dr. P. W. Tucker, University of Texas, Austin, TX) antisera. Membranes were washed in TBS-Tween 20 and incubated with protein G-horseradish peroxidase conjugate (Bio-Rad Laboratories, Inc., Hercules, CA). Protein expression was detected using the ECL Plus Western blot detection kit (Amersham Pharmacia Biotech).
Statistical analysis
Data from Northern blots were expressed as a percentage of the mean of the control group in each experiment. Data obtained from transfection assays were expressed as relative light units per microgram of protein. One-way ANOVA and the Newman-Keuls test were used to determine differences among treatment groups.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Studies by Hammer et al. (18) demonstrated that SF-1 can be phosphorylated on serine 203 by MAPK in a PKA-independent manner and enhance basal transcriptional activity. Thus, in the present study our goal was to determine whether cross-talk between the PKA and MAPK pathways conveys the cAMP-inducible binding to the -57/-38 region of the hCYP17 5' flank. Specifically, of numerous MAPK family members (19, 20, 21) we postulated that the p42/p44MAPK pathway (ERK1 and ERK2) (22, 23) may play a role in ACTH/cAMP-dependent transcriptional regulation of hCYP17. The effects of the PKA inhibitor PKI (10 µM) and the MAPK inhibitor PD98059 (25 µM) on cAMP-inducible binding of nuclear proteins to a -57/-38 radiolabeled double-stranded oligonucleotide were examined by EMSA. As shown in Fig. 1A
, three DNA-protein complexes are formed. Our previous studies have shown (8A ) that SF-1 or p54nrb/NonO comprise the lower, fastest migrating band, p54nrb/NonO and PSF comprise the middle complex, and SF-1, p54nrb/NonO, and PSF bind to each other to comprise the upper DNA-protein complex. Transcription is repressed when PSF in the upper complex binds to the corepressor mSin3A. When nuclear extracts isolated from H295R cells treated with 1 mM (Bu)2cAMP for 2 or 12 h were used, increased binding intensity of the upper DNA-protein complex was observed (Fig. 1A, lanes 2 and 8). Unexpectedly, treatment of cells for 12 h with 25 µM PD98059 alone also increased the binding of the upper complex (Fig. 1A, lanes 6 and 12). When using nuclear extracts isolated from cells that were treated with both (Bu)2cAMP and PD98059 for 12 h, the cAMP-inducible binding of the upper complex was further increased (Fig. 1A, lane 10). No effect of PD98059 was seen on the formation of the lower bands, nor was coadministration of 10 µM PKI able to alter the formation of any of the bands. Therefore, we conclude that PKA does not phosphorylate SF-1, p54nrb/NonO, or PSF directly, but plays some other role in the pathway, perhaps by phosphorylating an intermediary protein.
|
shows that transfection of 57-pGL3 increases luciferase activity by approximately 4-fold over pGL3 alone. Treating the cells with 1 mM (Bu)2cAMP for 12 h further increased transcriptional activity, as did 25 µM PD98059 (Fig. 1B). However, the effect of coadministration of (Bu)2cAMP and PD98059 was not additive. In addition to inducing the transcriptional activity of transiently transfected hCYP17 promoter-reporter constructs, 25 µM PD98059 increased the expression of endogenous hCYP17 mRNA (Fig. 1, C and D). A representative Northern (n = 3/group) is shown in Fig. 1C, and densitometric analysis (Fig. 1D) demonstrates a 25-fold increase in hCYP17 mRNA accumulation after exposure to (Bu)2cAMP and a 10-fold induction with PD98059 treatment alone. PKI significantly suppressed the cAMP-dependent increase in hCYP17 mRNA expression, emphasizing that PKA is essential for induced hCYP17 transcription, but not via the direct phosphorylation of SF-1, p54nrb/NonO, or PSF (see below).
Inhibition of phosphatase activity attenuates the cAMP-inducible binding to -57/-38 of the hCYP17 promoter
As we were unable to inhibit the cAMP-inducible formation of the upper DNA-protein complex by inactivating the MAPK pathway, we hypothesized that dephosphorylation could be the key event that conveys cAMP-evoked increased binding intensity. To test this idea we performed EMSA on nuclear extracts that were isolated from cells that were treated with (Bu)2cAMP in the presence and absence of the phosphatase inhibitors OA (10 nM) and PV (50 µM).
Two hours after treating cells with both 1 mM (Bu)2cAMP and 10 nM OA, significantly less cAMP-inducible binding of the upper complex was observed (Fig. 2, lane 3). PV also significantly attenuated the increase in binding intensity of the upper complex that was evoked by (Bu)2cAMP treatment (lane 4). At the 12-h point, OA was still effective in inhibiting cAMP-inducible binding (lane 9). Neither agent had a significant effect on the formation of the upper complex when administered in the absence of (Bu)2cAMP. These findings show that removal of a phosphate group from SF-1, p54nrb/NonO, and/or PSF probably mediates the cAMP-dependent increase in binding of the SF-1/p54nrb/NonO/PSF complex to the -57/-38 region of the hCYP17 promoter.
|
). As shown in Fig. 3A, transfection of cells with 57-pGL3 increased luciferase activity compared with the pGL3 empty vector by 5-fold, and (Bu)2cAMP treatment further stimulated transcriptional activity 2.5-fold. Treatment of the transfected cells with concentrations of OA ranging from 5–50 nM produced a dose-dependent decrease in the cAMP-dependent increase in transcription.
|
). Like OA, peroxyvanadate (5–50 µM) was also effective in producing a dose-dependent attenuation of the cAMP-dependent luciferase activity of the 57-pGL3 construct. No significant effect of treating the cells with PV alone was detected (Fig. 3B).
Phosphatase inhibitors attenuate cAMP-mediated transcription of endogenous hCYP17 in H295R cells
The effect of OA on the cAMP-mediated increase in endogenous hCYP17 mRNA expression was also examined. Cells were treated for 12 h with 1 mM (Bu)2cAMP with or without OA (5, 10, and 50 nM), and total RNA was isolated for analysis by Northern blotting. Figure 4A shows representative samples from experiments performed to determine whether OA affected the cAMP-dependent mRNA expression of endogenous hCYP17. As depicted, (Bu)2cAMP significantly increased mRNA expression of hCYP17, and OA acts to inhibit this cAMP-evoked increase (Fig. 4B). PV (5, 10, and 50 µM) was found to have similar effects on cAMP-stimulated hCYP17 mRNA expression (Fig. 4, C and D).
|
-PPase is a dual specificity phosphatase that dephosphorylates proteins that are phosphorylated on serine, threonine, or tyrosine residues. Nuclear extracts were isolated from unstimulated cells and incubated in vitro with increasing units (1–200) of -PPase for 20 min at 30 C. As shown in Fig. 5A, removal of a phosphate group(s) from SF-1, p54nrb/NonO, and/or PSF promotes increased binding to the region -57/-38 of the hCYP17 promoter.
|
), indicating cAMP-mediated dephosphorylation of SF-1. No significant difference was seen in the amount of SF-1 immunoprecipitated, as measured by Western blotting (Fig. 5B, lower panel). Further, 32P-labeled nuclear extracts isolated from cells that were in situ labeled were exposed to -PPase, followed by immunoprecipitation with anti-SF-1 or anti-NonO antiserum. As shown in Fig. 5, B and C, incubation of 32P-labeled nuclear extracts with -PPase before immunoprecipitation resulted in a decrease in the intensity of the immunoprecipitated SF-1, further confirming the removal of a phosphate group(s) from the protein. Little effect of p54nrb/NonO phosphorylation or dephosphorylation was observed. |
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
SF-1 is expressed in all major steroid-producing tissues and is required for their development and differentiation. SF-1 binds as a monomer to its responsive elements located in the promoter of steroidogenic genes and is thus thought to be a key regulator of steroid hormone biosynthesis. Overexpression of SF-1 has been shown to greatly increase both basal and cAMP-dependent reporter gene expression for constructs prepared from the bovine CYP17, 3ßHSD, CYP11A, and CYP19 genes (8, 24, 25, 26, 27). The mechanism by which SF-1 conveys ACTH/cAMP-increased transcription is unclear; especially as SF-1 mRNA expression remains constant after elevation of ACTH/cAMP levels (28, 29). Studies have found that the MAPK pathway alters the expression of genes that are transcriptionally regulated by SF-1. Transcription of the glycoprotein hormone -subunit is regulated by the release of GnRH via a MAPK-dependent pathway. The promoter of the glycoprotein hormone -subunit is also regulated by SF-1 (30). One can speculate that the activation of SF-1 may involve ligand binding to the receptor. However, the existence of a ligand for SF-1 has not been confirmed. Thus, a model in which posttranslational modification of SF-1 or other proteins that interact with SF-1 to confer transcriptional activation of the steroid hydroxylase genes seems plausible.
SF-1 is phosphorylated on serine 203 by MAPK (18). It is thought that this phosphorylation leads to increased cofactor recruitment, which then modulates the coordinate regulation of multiple SF-1 target genes (steroid hydroxylases) in response to hormone stimulation (18). However, SF-1 was not found to be a cAMP-dependent phosphoprotein. We show here that both cAMP and the inhibition of the MAPK pathway can independently result in increased binding of SF-1, PSF, and p54nrb/NonO to the hCYP17 promoter and also increase hCYP17 reporter gene activity. The cross-talk between the cAMP and MAPK pathways has been demonstrated in models of neuronal differentiation (31, 32, 33). It is unclear whether cross-talk occurs between the two pathways; however, our results suggest that the cAMP-mediated transcription may be independent of the MAPK pathway. However, based on our findings that PD98059 partially antagonized the stimulatory effect of (Bu)2cAMP, it is possible that the MAPK pathway and the ACTH/cAMP pathways may overlap.
Our present findings have demonstrated a role for phosphatase activity in the cAMP-dependent expression of hCYP17. We propose a mechanism for cAMP-dependent transcription of the hCYP17 gene where, after the release of ACTH from the anterior pituitary and the activation of adenylyl cyclase, the increase in intracellular cAMP causes the activation of PKA and the subsequent phosphorylation of a phosphatase, with both serine/threonine and tyrosine activity [plausibly an MAPK phosphatase (MKP)], that is involved in maintaining optimal steroidogenic capacity. Once activated, this phosphatase removes a phosphate from SF-1, thereby activating this nuclear receptor and alleviating the repression evoked by the binding of the corepressor mSin3A to PSF. Inactivation of the mSin3A/histone deacetylase corepressor system then results in increased affinity of the interaction of SF-1, p54nrb/NonO, and PSF with the hCYP17 promoter, subsequently increasing hCYP17 gene transcription. Alternatively, the phosphatase (MKP) could be involved in the inactivation of the MAPK that maintains SF-1 constitutively phosphorylated (18).
Recently, cAMP-induced increases in steroidogenic acute regulatory protein (StAR) mRNA has been found to be dependent upon phosphoprotein phosphatase activities (34). Using competitive RT-PCR, it was found that inhibition of phosphoprotein phosphatase-1 and -2A activities attenuated the forskolin-induced expression of StAR mRNA (34). We believe that hCYP17 regulation in H295R cells in response to cAMP has similar features.
In bovine adrenocortical cells, the prototypical morphological cell rounding observed upon treatment with ACTH or cAMP is blocked by the tyrosine phosphatase inhibitor sodium orthovanadate (35). It was hypothesized that the mechanism for cell detachment and disassembly of focal adhesions was mediated by PKA phosphorylation and activation of a phosphatase(s) in response to increased intracellular cAMP (35). Our model for the activation of phosphatase activity by PKA (Fig. 6) is very similar. However, one clear difference between bovine adrenocortical cells and human H295R cells is that ACTH/cAMP has never been shown in bovine cells to enhance transcription factor binding to bCYP17 or any other steroidogenic gene.
|
The regulation of MAPKs (specifically p42 and p44) has been studied in Y1 mouse adrenocortical cells (40). It was found that ACTH and basic fibroblast growth factor each increased MAPK kinase (MEK) activity (40). Furthermore, PD98059 blocked the activation of MEK and thus the phosphorylation of p42 and p44 by ACTH (40). These findings showing evidence for a negative influence of PKA on MEK activation are in contrast to our current work, where MAPK inhibition mimicked the stimulatory effects of cAMP on hCYP17 gene transcription. Time-course and dose-response studies are currently underway to further examine the effects of PD98059 on hCYP17 gene expression. It is possible that the discrepancy may be due to the difference in cell lines (murine Y1 vs. human H295R). We have also recently found that the cAMP-inducible binding of SF-1, PSF, and p54/NonO to the hCYP17 promoter only occurs when using nuclear extracts isolated from H295R cells and not Y1 cells (8A ).
The direct activation of phosphatases by tyrosine phosphorylation has been well documented (41, 42), whereas regulation of phosphatases by serine/threonine phosphorylation has been documented only indirectly (43, 44). Bouchard et al. (41) used peptide mapping and microsequencing to demonstrate the phosphorylation of protein tyrosine phosphatase 1C on tyrosine 538 after incubation with tyrosine kinase. The fact that both PV and OA act to attenuate cAMP-inducible transcription factor binding, reporter activity, and endogenous hCYP17 mRNA expression suggests that PKA phosphorylates and activates both serine/threonine and tyrosine phosphatase activities (dual function phosphatase). Dual function phosphatases (known as MKPs) are a subclass of the protein tyrosine phosphatase gene superfamily that are selective for dephosphorylating phosphothreonine and phosphotyrosine residues within MEKs (20).
In summary, we have demonstrated that the cAMP-stimulated increased binding intensity of the SF-1/p54nrb/NonO/PSF complex to the -57/-38 region of the hCYP17 promoter is mediated by activation of serine/threonine and tyrosine phosphatase activity. Phosphatase activity mediates both the cAMP-dependent increases in reporter construct transcriptional activity and endogenous hCYP17 mRNA expression. Moreover, we have demonstrated that cAMP stimulation of H295R cells results in the dephosphorylation of SF-1, as measured by immunoprecipitation of SF-1 after in vivo labeling with [32P]orthophosphate. We conclude that the cAMP-dependent transcriptional regulation of steroid hormone biosynthesis requires phosphatase activity.
|
Footnotes |
|---|
This work was supported by NIH Grants DK-28350 and ES-00267 (to M.R.W.), a UNCF/Merck Science Initiative Postdoctoral Fellowship (to M.B.S.), and NIH Postdoctoral Training Grant T32-CA-09582 (to M.B.S.).
Abbreviations: bCYP17, Bovine CYP17; CRS, cAMP-responsive sequence; hCYP17, human CYP17; GAP, glyceraldehyde-3-phosphate dehydrogenase; MEK, MAPK kinase; MKP, MAPK phosphatase; OA, okadaic acid; -PPase, -protein phosphatase; PSF, poly-pyrimidine tract-binding protein-associated splicing factor; PV, peroxyvanadate; RLU, relative luciferase light units; SF-1, steroidogenic factor; SHP, short heterodimer protein; StAR, steroidogenic acute regulatory protein.
Received November 15, 2001.
Accepted for publication February 1, 2002.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
on Tyr789, a binding site for the SH3-SH2-SH3 adaptor protein GRB-2 in vivo. EMBO J 13:3020–3032[Medline]
subunits mediate specific phosphorylation of the protein-tyrosine phosphatase SH-PTP1 induced by lysophosphatidic acid. J Biol Chem 271:20151–20155This article has been cited by other articles:
 |
|
 |
|
  A. E. Lewis, M. Rusten, E. A. Hoivik, E. L. Vikse, M. L. Hansson, A. E. Wallberg, and M. Bakke Phosphorylation of Steroidogenic Factor 1 Is Mediated by Cyclin-Dependent Kinase 7 Mol. Endocrinol., January 1, 2008; 22(1): 91 - 104. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Li, A. N. Urs, J. Allegood, A. Leon, A. H. Merrill Jr., and M. B. Sewer Cyclic AMP-Stimulated Interaction between Steroidogenic Factor 1 and Diacylglycerol Kinase {theta} Facilitates Induction of CYP17 Mol. Cell. Biol., October 1, 2007; 27(19): 6669 - 6685. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Zhang, M.-X. Zhang, Y. H. Shen, J. K. Burks, Y. Zhang, J. Wang, S. A. LeMaire, K. Yoshimura, H. Aoki, J. S. Coselli, et al. TNF-{alpha} Suppresses Prolyl-4-Hydroxylase {alpha}1 Expression via the ASK1-JNK-NonO Pathway Arterioscler. Thromb. Vasc. Biol., August 1, 2007; 27(8): 1760 - 1767. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. B. Dammer, A. Leon, and M. B. Sewer Coregulator Exchange and Sphingosine-Sensitive Cooperativity of Steroidogenic Factor-1, General Control Nonderepressed 5, p54, and p160 Coactivators Regulate Cyclic Adenosine 3',5'-Monophosphate-Dependent Cytochrome P450c17 Transcription Rate Mol. Endocrinol., February 1, 2007; 21(2): 415 - 438. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. H. Mellon, S. R. Bair, C. Depoix, J.-L. Vigne, N. B. Hecht, and P. B. Brake Translin Coactivates Steroidogenic Factor-1-Stimulated Transcription Mol. Endocrinol., January 1, 2007; 21(1): 89 - 105. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. A. Ferris and M. A. Shupnik Mechanisms for Pulsatile Regulation of the Gonadotropin Subunit Genes by GNRH1 Biol Reprod, June 1, 2006; 74(6): 993 - 998. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Ozbay, A. Rowan, A. Leon, P. Patel, and M. B. Sewer Cyclic Adenosine 5'-Monophosphate-Dependent Sphingosine-1-Phosphate Biosynthesis Induces Human CYP17 Gene Transcription by Activating Cleavage of Sterol Regulatory Element Binding Protein 1 Endocrinology, March 1, 2006; 147(3): 1427 - 1437. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. N. Winnay and G. D. Hammer Adrenocorticotropic Hormone-Mediated Signaling Cascades Coordinate a Cyclic Pattern of Steroidogenic Factor 1-Dependent Transcriptional Activation Mol. Endocrinol., January 1, 2006; 20(1): 147 - 166. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. A. Myers, K. Hyatt, M. Mlynarczyk, I. M. Bird, and C. A. Ducsay Long-term hypoxia represses the expression of key genes regulating cortisol biosynthesis in the near-term ovine fetus Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2005; 289(6): R1707 - R1714. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. L. Nelson-Degrave, J. K. Wickenheisser, K. L. Hendricks, T. Asano, M. Fujishiro, R. S. Legro, S. R. Kimball, J. F. Strauss III, and J. M. McAllister Alterations in Mitogen-Activated Protein Kinase Kinase and Extracellular Regulated Kinase Signaling in Theca Cells Contribute to Excessive Androgen Production in Polycystic Ovary Syndrome Mol. Endocrinol., February 1, 2005; 19(2): 379 - 390. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. E. Fluck and W. L. Miller GATA-4 and GATA-6 Modulate Tissue-Specific Transcription of the Human Gene for P450c17 by Direct Interaction with Sp1 Mol. Endocrinol., May 1, 2004; 18(5): 1144 - 1157. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. L. Bland, R. C. Fowkes, and H. A. Ingraham Differential Requirement for Steroidogenic Factor-1 Gene Dosage in Adrenal Development Versus Endocrine Function Mol. Endocrinol., April 1, 2004; 18(4): 941 - 952. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Val, C. Aigueperse, B. Ragazzon, G. Veyssiere, A.-M. Lefrancois-Martinez, and A. Martinez Adrenocorticotropin/3',5'-Cyclic AMP-Mediated Transcription of the Scavenger akr1-b7 Gene in Adrenocortical Cells Is Dependent on Three Functionally Distinct Steroidogenic Factor-1-Responsive Elements Endocrinology, February 1, 2004; 145(2): 508 - 518. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. Fan, T. Yanase, Y. Wu, H. Kawate, M. Saitoh, K. Oba, M. Nomura, T. Okabe, K. Goto, J. Yanagisawa, et al. Protein Kinase A Potentiates Adrenal 4 Binding Protein/Steroidogenic Factor 1 Transactivation by Reintegrating the Subcellular Dynamic Interactions of the Nuclear Receptor with Its Cofactors, General Control Nonderepressed-5/Transformation/ Transcription Domain-Associated Protein, and Suppressor, Dosage-Sensitive Sex Reversal-1: a Laser Confocal Imaging Study in Living KGN Cells Mol. Endocrinol., January 1, 2004; 18(1): 127 - 141. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Li, R. E. Feltzer, K. L. Dawson, E. A. Hudson, and B. J. Clark Janus Kinase 2 and Calcium Are Required for Angiotensin II-dependent Activation of Steroidogenic Acute Regulatory Protein Transcription in H295R Human Adrenocortical Cells J. Biol. Chem., December 26, 2003; 278(52): 52355 - 52362. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. C. Fowkes, M. Desclozeaux, M. V. Patel, S. J. B. Aylwin, P. King, H. A. Ingraham, and J. M. Burrin Steroidogenic Factor-1 and The Gonadotrope-Specific Element Enhance Basal and Pituitary Adenylate Cyclase-Activating Polypeptide-Stimulated Transcription of the Human Glycoprotein Hormone {alpha}-Subunit Gene in Gonadotropes Mol. Endocrinol., November 1, 2003; 17(11): 2177 - 2188. [Abstract] [Full Text] [PDF]
|
|
|
|
