Function of the Medaka Male Sex-Determining Gene
Substantial genetic and experimental evidence has accumulated that the medaka male sex-determining gene on the Y chromosome is dmrt1bY/dmY. The gene emerged approximately 5–10 million years ago from a duplication of the autosomal dmrt1a gene. The dmrt1bY gene encodes a nuclear protein of 36 kDa that binds to specific DNA sequences via the conserved DM domain containing two so-called intertwined zinc fingers. Transcriptional regulation by a Dmrt1a and Dmrt1bY binding site in the dmrt1bY promoter and posttranscriptional regulation through a highly conserved element in the 3′-UTR contribute to a specific expression in the somatic cells of the developing male gonad anlage during the sex determination stage and a massive downregulation in the Sertoli cells of the adult testes. The initiating process of sexual development of the undifferentiated gonad toward either ovary or testes, namely the inhibition of proliferation of the primordial germ cells in males, is mediated by Dmrt1bY. The molecular mechanisms by which Dmrt1bY brings about this effect are unknown so far.
KeywordsSertoli Cell Adult Testis Dmrt1 Gene Embryonic Gonad Undifferentiated Gonad
I gratefully acknowledge the contribution of present and former members of my laboratory and many colleagues worldwide. Their research is the basis of this manuscript. I also apologize to those whose work unintentionally might not have been mentioned adequately. I thank Amaury Herpin for critical discussions and comments and Monika Niklaus Ruiz for help in preparing the manuscript. I also thank Susanne Schories and Ingo Braasch for help with Fig. 16.2.
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