Transcriptional regulation of the cholesterol side chain cleavage cytochrome P450 gene (CYP11A1) revisited: binding of GATA, cyclic adenosine 3',5'-monophosphate response element-binding protein and activating protein (AP)-1 proteins to a distal novel cluster of cis-regulatory elements potentiates AP-2 and steroidogenic factor-1-dependent gene expression in the rodent placenta and ovary.
The first and key enzyme controlling the synthesis of steroid hormones is cholesterol side chain cleavage cytochrome P450 (P450scc, CYP11A1). This study sought to elucidate overlooked modes of regulation of P450scc transcription in the rodent placenta and ovary. Transcription of P450scc requires two clusters of cis-regulatory elements: a proximal element (-40) known to bind either activating protein 2 (AP-2) in the placenta, or steroidogenic factor 1 in the ovary, and a distal region of the promoter (-475/-447) necessary for potentiation of the AP-2/steroidogenic factor 1-dependent activity up to 7-fold. In primary cultures of mouse trophoblast giant cells and rat ovarian granulosa cells, binding of trans-factors to the distal regulatory sequences generated transcriptional activity in a tissue-specific pattern: in the placenta, cAMP response element (CRE)-binding protein 1 (CREB-1) and GATA-2 binding generates promoter activity in a cAMP-independent manner, whereas in ovarian cells, CREB-1 and GATA-4 are required for FSH responsiveness. However, as ovarian follicles advance toward ovulation, elevated Fra-2 expression replaces CREB-1 function by binding the same CRE(1/2) motif. Our findings suggest that upon onset of follicular recruitment, CREB-1 mediates FSH/cAMP signaling, which switches to cAMP-independent expression of P450scc in luteinizing granulosa cells expressing Fra-2. In the placenta, the indispensable role of CREB-1 was demonstrated by use of dominant-negative CREB-1 mutant, but neither cAMP nor Ser133 phosphorylation of CREB-1 is required for P450scc transcription. These observations suggest that placental regulation of P450scc expression is subjected to alternative signaling pathway(s) yet to be found.
Sher
Noa
N
Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Yivgi-Ohana
Natalie
N
Orly
Joseph
J
D051697:Activating Transcription Factor 1 / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002784:Cholesterol / Q000378:metabolism*; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics*; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D051921:Fos-Related Antigen-2 / Q000378:metabolism; D050980:GATA Transcription Factors / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009154:Mutation; D010053:Ovary / Q000187:drug effects / Q000201:enzymology*; D010920:Placenta / Q000187:drug effects / Q000201:enzymology*; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000235:genetics / Q000378:metabolism; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D051697:Activating Transcription Factor 1; C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D051921:Fos-Related Antigen-2; C497873:Fosl2 protein, mouse; D050980:GATA Transcription Factors; D018398:Homeodomain Proteins; D020033:Protein Isoforms; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C515058:steroidogenic factor 1, mouse; C515060:steroidogenic factor 1, rat; D012694:Serine; D005640:Follicle Stimulating Hormone; D002784:Cholesterol; D002786:Cholesterol Side-Chain Cleavage Enzyme