Phosphorylation of steroidogenic factor 1 is mediated by cyclin-dependent kinase 7.
The nuclear receptor steroidogenic factor-1 (SF1) is critical for development and function of steroidogenic tissues. Posttranslational modifications are known to influence the transcriptional capacity of SF1, and it was previously demonstrated that serine 203 is phosphorylated. In this paper we report that serine 203 is phosphorylated by a cyclin-dependent kinase 7 (CDK7)-mediated process. As part of the CDK-activating kinase complex, CDK7 is a component of the basal transcription factor TFIIH, and phosphorylation of SF1 as well as SF1-dependent transcription was clearly reduced in cells carrying a mutation that renders the CDK-activating kinase complex unable to interact with the TFIIH core. Coimmunoprecipitation analyses revealed that SF1 and CDK7 reside in the same complex, and kinase assays demonstrated that immunoprecipitated CDK7 and purified TFIIH phosphorylate SF1 in vitro. The CDK inhibitor roscovitine blocked phosphorylation of SF1, and an inactive form of CDK7 repressed the phosphorylation level and the transactivation capacity of SF1. Structural studies have identified phosphoinositides as potential ligands for SF1. Interestingly, we found that mutations designed to block phospholipid binding dramatically decreased the level of SF1 phosphorylation. Together our results suggest a connection between ligand occupation and phosphorylation and association with the basic transcriptional machinery, indicating an intricate regulation of SF1 transactivation.
Lewis
Aurélia E
AE
Department of Biomedicine, University of Bergen, 5009 Bergen, Norway.
Rusten
Marte
M
Hoivik
Erling A
EA
Vikse
Elisabeth L
EL
Hansson
Magnus L
ML
Wallberg
Annika E
AE
Bakke
Marit
M
D000209:Acute-Phase Proteins / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins; D002460:Cell Line; D002522:Chlorocebus aethiops; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010743:Phospholipids / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D011687:Purines / Q000494:pharmacology; D000077546:Roscovitine; D012694:Serine / Q000378:metabolism; D054339:Steroidogenic Factor 1 / Q000235:genetics / Q000378:metabolism*; D051758:Transcription Factor TFIIH / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors; D014162:Transfection; D000099231:Lipopolysaccharide-Binding Protein; D000095043:Cyclin-Dependent Kinase-Activating Kinase
D000209:Acute-Phase Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D018844:Cyclin-Dependent Kinases; D008562:Membrane Glycoproteins; D010743:Phospholipids; D011687:Purines; D000077546:Roscovitine; D012694:Serine; D054339:Steroidogenic Factor 1; D051758:Transcription Factor TFIIH; D014157:Transcription Factors; D000099231:Lipopolysaccharide-Binding Protein; C514215:MNAT1 protein, human; D000095043:Cyclin-Dependent Kinase-Activating Kinase; C515057:NR5A1 protein, human