Foxl3, a Sexual Switch in Germ Cells, Initiates Two Independent Molecular Pathways for Commitment to Oogenesis in Medaka
foxl3, a sexual switch in germ cells, initiates two independent molecular pathways for commitment to oogenesis in medaka Mariko Kikuchia, Toshiya Nishimuraa,1, Satoshi Ishishitab, Yoichi Matsudab,c, and Minoru Tanakaa,2 aDivision of Biological Science, Graduate School of Science, Nagoya University, 464-8602 Nagoya, Japan; bAvian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, 464-8601 Nagoya, Japan; and cDepartment of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, 464-8601 Nagoya, Japan Edited by John J. Eppig, The Jackson Laboratory, Bar Harbor, ME, and approved April 8, 2020 (received for review October 23, 2019) Germ cells have the ability to differentiate into eggs and sperm and elegans (8–10). To date, however, neither protein has been im- must determine their sexual fate. In vertebrates, the mechanism of plicated in germline feminization. commitment to oogenesis following the sexual fate decision in During oogenesis in mice, several transcription factors facili- germ cells remains unknown. Forkhead-box protein L3 (foxl3)isa tate folliculogenesis: lhx8 (LIM homeobox 8) and figla (factor in switch gene involved in the germline sexual fate decision in the the germline alpha) regulate differentiation of primordial follicles teleost fish medaka (Oryzias latipes). Here, we show that foxl3 or- (11–14), and nobox (newborn ovary homeobox), which acts ganizes two independent pathways of oogenesis regulated by REC8 downstream of Lhx8, is indispensable for the formation of sec- meiotic recombination protein a (rec8a), a cohesin component, and ondary follicles (12, 15). It remains unknown how these tran- F-box protein (FBP)47(fbxo47), a subunit of E3 ubiquitin ligase.
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