Epigenetic regulation of sex determination by the histone demethylase Jmjd1a

Developmental gene expression is defined through cross-talk between the function of transcription factors and epigenetic status including histone modification. Although several known transcription factors play crucial roles in mammalian sex determination, how chromatin regulation contributes to this process is unknown. We observed male-to-female sex reversal in mice lacking the H3K9 demethylase Jmjd1a, and found that Jmjd1a directly regulates expression of the mammalian Y chromosome sex-determining gene Sry, by regulating H3K9me2 marks. These studies reveal a pivotal role for epigenetic regulation in mammalian sex determination, and provide new impetus for identifying additional causes of disorders of sex determination by environmental factors. Gene expression patterns were measured in gonadal somatic cells of Jmjd1a mutant and control embryos at E11.5. Three biological replicates were performed in each group.