FOXL2 transcriptionally represses Sf1 expression by antagonizing WT1 during ovarian development in mice.
Steroidogenic factor 1 (SF1; Ad4BP/NR5A1) plays key roles in gonadal development. Initially, the Sf1 gene is expressed in mouse fetal gonads of both sexes, but later is up-regulated in testes and down-regulated in ovaries. While Sf1 expression is activated and maintained by Wilms tumor 1 (WT1) and LIM homeobox 9 (LHX9), the mechanism of sex-specific regulation remains unclear. We hypothesized that Sf1 is repressed by the transcription factor Forkhead box L2 (FOXL2) during ovarian development. In an in vitro system (TM3 cells), up-regulation of Sf1 by the WT1 splice variant WT1-KTS was antagonized by FOXL2, as determined by quantitative RT-PCR. Using reporter assays, we localized the Sf1 proximal promoter region involved in this antagonism to a 674-bp interval. A conserved FOXL2 binding site was identified in this interval by in vitro chromatin immunoprecipitation. Introducing mutations into this site abolished negative regulation by FOXL2 in reporter assays. Finally, in Foxl2-null mice, Sf1 expression was increased 2-fold relative to wild-type XX fetal gonads. Our results support the hypothesis that FOXL2 negatively regulates Sf1 expression by antagonizing WT1-KTS during early ovarian development in mice.
1Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Bunkyo, Tokyo 113-8510, Japan. kkashimada.ped@tmd.ac.jp.
Kei
K
Takasawa
Kenichi
K
Kashimada
Emanuele
E
Pelosi
Masatoshi
M
Takagi
Tomohiro
T
Morio
Hiroshi
H
Asahara
David
D
Schlessinger
Shuki
S
Mizutani
Peter
P
Koopman
D000818:Animals; D001665:Binding Sites; D002454:Cell Differentiation; D005260:Female; D000074842:Forkhead Box Protein L2; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D060850:LIM-Homeodomain Proteins / Q000378:metabolism; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D016296:Mutagenesis; D009154:Mutation; D010053:Ovary / Q000196:embryology* / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054339:Steroidogenic Factor 1 / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D025721:WT1 Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000074842:Forkhead Box Protein L2; D051858:Forkhead Transcription Factors; C498893:Foxl2 protein, mouse; D060850:LIM-Homeodomain Proteins; C117058:Lhx9 protein, mouse; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; D025721:WT1 Proteins; C515058:steroidogenic factor 1, mouse
LHX9; reproduction; sex determination