title: Transcriptional complexes at the CYP17 CRS.
abstract: Steroid hormone biosynthesis in the adrenal cortex is controlled by the peptide hormone adrenocorticotropin (ACTH), which acts to increase intracellular cAMP, resulting in the activation of cAMP-dependent protein kinase (PKA) and subsequent increase in steroidogenic gene transcription. We have identified three proteins interacting with the human CYP17 cAMP responsive sequence (CRS): steroidogenic factor 1 (SF-1), p54nrb, and polypyrimidine tract-binding protein-associated splicing factor (PSF). Nuclear extracts isolated from cAMP stimulated of H295R cells showed cAMP-inducible binding to the human CYP17 (hCYP17) CRS. This cAMP-inducible binding was dependent on a dual-specificity phosphatase (DSP). DSP activity was subsequently shown to be is essential for conveying ACTH/cAMP-stimulated transcription of several steroidogenic genes in the human adrenal cortex. We report here that the transactivation potential of SF-1 is also dependent on phosphatase activity; suggesting that SF-1 is dephosphorylated in response to ACTH/cAMP stimulation. Finally, we demonstrate a role for mitogen-activated protein kinase phosphatase 1 (MKP-1), a nuclear DSP, in conveying SF-1-dependent transcription of an hCYP17 promoter-reporter construct in the H295R human adrenocortical cell line. We conclude that a DSP, possibly MKP-1, is essential for enhancing hCYP17 transcription in the adrenal cortex by desphosphorylating of SF-1, thereby increasing the binding affinity of SF-1, p54nrb, and PSF for the hCYP17 promoter.
authors.affiliation: School of Biology, Georgia Institute of Technology, Atlanta, GA 30332-0230, USA. marion@toxicology.mc.vanderbilt.edu
authors.forename: M B
authors.initials: MB
authors.lastname: Sewer
authors.forename: M R
authors.initials: MR
authors.lastname: Waterman
mesh_terms: D018797:Cell Cycle Proteins; D000242:Cyclic AMP / Q000235:genetics*; D054638:Dual Specificity Phosphatase 1; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D017874:Immediate-Early Proteins / Q000502:physiology; D008565:Membrane Proteins; D010749:Phosphoprotein Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000502:physiology; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D020218:Response Elements / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology; D014407:Tumor Cells, Cultured
chemical_list: C464455:CYYR1 protein, human; D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D017874:Immediate-Early Proteins; D008565:Membrane Proteins; D011506:Proteins; D000242:Cyclic AMP; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D010744:Phosphoric Monoester Hydrolases; C517019:DUSP1 protein, human; D054638:Dual Specificity Phosphatase 1; D017027:Protein Tyrosine Phosphatases