The stimulatory adrenocorticotropin (ACTH) on steroidogenic gene action of transcription in the adrenal cortex is mediated through a cAMP/PKA-dependent pathway. We have demonstrated that the ACTH/cAMP-stimulated transcription of the human CYP17 gene (hCYP17) requires mitogen-activated protein kinase phosphatase 1 (MKP-1), an inactivator of extracellular-signal-related kinases 1/2 (ERK1/2). In human adrenocortical H295R cells, MKP-1 is rapidly induced by ACTH/cAMP and PKA can phosphorylate MKP-1 in vitro. We have also shown that inhibition of ERK1/2 activation mimics the stimulatory effect of ACTH/cAMP on hCYP17 gene expression. We postulate that ERK1/2 constitutively phosphorylates steroidogenic factor 1 (SF-1) and that in response to ACTH/cAMP, MKP-1 acts to dephosphorylate ERK1/2, thereby increasing hCYP17 transcription. Our previous studies have also demonstrated that SF-1, p54nrb and polypyrimidine tract binding protein-associated splicing factor (PSF) form a complex that is essential for cAMP-dependent transcription of hCYP17. Further, we have demonstrated that the corepressor mSin3A and a histone deacetylase (HDAC) interact with this complex and repress hCYP17 transcription. We hypothesize that dephosphorylation of SF-1 results in dissociation of mSin3A and the HDAC from the complex and recruitment of coactivators. This proposal aims to characterize the functional significance of MKP-1 activation and SF-1 dephosphorylation in ACTH/cAMP-stimulated hCYP17 gene transcription. Further, we will determine the mechanism by which SF-1 is constitutively phosphorylated and examine how phosphorylation of SF-1 represses hCYP17 expression. Finally, we will determine how the SF-1/p54nrb/PSF complex interacts with each other and how this complex interacts with corepressors/coactivators to allow for repression/activation of hCYP17. Using both biochemical and molecular techniques, including reporter gene transfection assays, chromatin immunoprecipitation, phosphatase/kinase activity assays, and mass spectrometry, our findings will provide insight into the mechanism by which the ACTH/cAMP pathway and the MAPK signaling cascade interact to ensure biosynthesis of adrenal hormones to meet physiological needs in humans. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM073241-02
Application #
6901080
Study Section
Endocrinology Study Section (END)
Program Officer
Okita, Richard T
Project Start
2004-06-07
Project End
2009-05-31
Budget Start
2005-06-01
Budget End
2006-05-31
Support Year
2
Fiscal Year
2005
Total Cost
$221,956
Indirect Cost
Name
Georgia Institute of Technology
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
097394084
City
Atlanta
State
GA
Country
United States
Zip Code
30332
Lu, Jia Yang; Sewer, Marion B (2015) p54nrb/NONO regulates cyclic AMP-dependent glucocorticoid production by modulating phosphodiesterase mRNA splicing and degradation. Mol Cell Biol 35:1223-37
Li, Donghui; Dammer, Eric B; Sewer, Marion B (2012) Resveratrol stimulates cortisol biosynthesis by activating SIRT-dependent deacetylation of P450scc. Endocrinology 153:3258-68
Lucki, Natasha C; Sewer, Marion B (2010) The interplay between bioactive sphingolipids and steroid hormones. Steroids 75:390-9
Li, Donghui; Sewer, Marion B (2010) RhoA and DIAPH1 mediate adrenocorticotropin-stimulated cortisol biosynthesis by regulating mitochondrial trafficking. Endocrinology 151:4313-23
Sewer, Marion B; Jagarlapudi, Srinath (2009) Complex assembly on the human CYP17 promoter. Mol Cell Endocrinol 300:109-14
Sewer, Marion B; Li, Donghui; Dammer, Eric B et al. (2008) Multiple Signaling Pathways Coordinate CYP17 Gene Expression in the Human Adrenal Cortex. Acta Chim Slov 55:53-57
Dammer, Eric B; Sewer, Marion B (2008) Phosphorylation of CtBP1 by cAMP-dependent protein kinase modulates induction of CYP17 by stimulating partnering of CtBP1 and 2. J Biol Chem 283:6925-34
Urs, Aarti N; Dammer, Eric; Kelly, Samuel et al. (2007) Steroidogenic factor-1 is a sphingolipid binding protein. Mol Cell Endocrinol 265-266:174-8
Sewer, Marion B; Dammer, Eric B; Jagarlapudi, Srinath (2007) Transcriptional regulation of adrenocortical steroidogenic gene expression. Drug Metab Rev 39:371-88
Ozbay, Tuba; Rowan, Anne; Leon, Adam et al. (2006) 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 147:1427-37