Transcriptional activation of human CYP17 in H295R adrenocortical cells depends on complex formation among p54(nrb)/NonO, protein-associated splicing factor, and SF-1, a complex that also participates in repression of transcription.

Sewer MB, Nguyen VQ, Huang CJ, Tucker PW, Kagawa N, Waterman MR
Endocrinology. 2002 143 (4): 1280-90

PMID: 11897684 · DOI:10.1210/endo.143.4.8748

The first 57 bp upstream of the transcription initiation site of the human CYP17 (hCYP17) gene are essential for both basal and cAMP-dependent transcription. EMSA carried out by incubating H295R adrenocortical cell nuclear extracts with radiolabeled -57/-38 probe from the hCYP17 promoter showed the formation of three DNA-protein complexes. The fastest complex contained steroidogenic factor (SF-1) and p54(nrb)/NonO, the intermediate complex contained p54(nrb)/NonO and polypyrimidine tract-binding protein-associated splicing factor (PSF), and the slowest complex contained an SF-1/PSF/p54(nrb)/NonO complex. (Bu)(2)cAMP treatment resulted in a cAMP-inducible increase in the binding intensity of only the upper complex and also activated hCYP17 gene transcription. SF-1 coimmunoprecipitated with p54(nrb)/NonO, indicating direct interaction between these proteins. Functional assays revealed that PSF represses basal transcription. Further, the repression of hCYP17 promoter-reporter construct luciferase activity resulted from PSF interacting with the corepressor mSin3A. Trichostatin A attenuated the inhibition of basal transcription, suggesting that a histone deacetylase interacts with the SF-1/PSF/p54(nrb)/NonO/mSin3A complex. Our studies lend support to the idea that the balance between transcriptional activation and repression is essential in the control of adrenocortical steroid hormone biosynthesis.

MeSH Terms (25)

Adrenal Cortex Amino Acid Sequence Blotting, Western Cell Nucleus Cells, Cultured Cycloheximide DNA-Binding Proteins Fushi Tarazu Transcription Factors Gene Expression Regulation, Enzymologic Histone Deacetylases Homeodomain Proteins Humans Immunoenzyme Techniques Molecular Sequence Data Nuclear Proteins Plasmids Promoter Regions, Genetic Protein Synthesis Inhibitors Receptors, Cytoplasmic and Nuclear Serine-Arginine Splicing Factors Steroid 17-alpha-Hydroxylase Steroidogenic Factor 1 Transcription, Genetic Transcriptional Activation Transcription Factors

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