title: Essential but differential role of FOXL2wt and FOXL2C134W in GDF-9 stimulation of follistatin transcription in co-operation with Smad3 in the human granulosa cell line COV434.
abstract: The FOXL2(C134W) mutation has been identified in virtually all adult granulosa cell tumors (GCTs). Here we show that the exogenous FOXL2 expression is necessary for GDF-9 stimulation of follistatin transcription in the human GCT cell line, COV434 that lacks endogenous FOXL2 expression. Interestingly, in the presence of Smad3 co-expression, FOXL2(C134W) negated GDF-9 stimulation of follistatin transcription. However, mutation of the Smad binding element (SBE) located in the intronic enhancer elements in the follistatin gene restored normal FOXL2 activity to FOXL2(C134W), thus the altered activity of FOXL2(C134W) is dependent on the ability of Smad3 to directly bind the SBE. Mutation of the FOXL2 binding element (FBE) or the FBE and SBE completely prevented GDF-9 activity, suggesting that the FBE is essential for GDF-9 stimulation in COV434. Overall, our study supports the view that altered interaction of FOXL2(C134W) with co-factors may underlie the pathogenesis of this mutation in GCTs.
authors.affiliation: Department of Reproductive Medicine, University of California San Diego, School of Medicine, La Jolla, CA 92093-0633, USA.
authors.forename: David
authors.initials: D
authors.lastname: Nonis
authors.forename: Kirsten J
authors.initials: KJ
authors.lastname: McTavish
authors.forename: Shunichi
authors.initials: S
authors.lastname: Shimasaki
mesh_terms: D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D005260:Female; D038681:Follistatin / Q000235:genetics* / Q000378:metabolism; D000074842:Forkhead Box Protein L2; D051858:Forkhead Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006106:Granulosa Cell Tumor; D006107:Granulosa Cells / Q000378:metabolism*; D055429:Growth Differentiation Factor 9 / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010053:Ovary / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic; D051381:Rats; D051900:Smad3 Protein / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: C421604:FOXL2 protein, human; C503233:FST protein, human; D038681:Follistatin; D000074842:Forkhead Box Protein L2; D051858:Forkhead Transcription Factors; C525897:GDF9 protein, human; D055429:Growth Differentiation Factor 9; C497790:SMAD3 protein, human; D051900:Smad3 Protein