Description:
<jats:title>Abstract</jats:title><jats:p>Gonad‐specific transcription factor spermatogenesis‐ and oogenesis‐specific helix‐loop‐helix transcription factor 1 (SOHLH1) plays a key role in the transcriptional regulation of the expression of differentiating spermatogonial genes. However, its role in spermatocytes (meiotic male germ cells) remains largely unknown. In this study, <jats:italic>Sohlh1</jats:italic> knockout (KO) male mice displayed meiotic defects at the zygotene stage during spermatogenesis. Microarray analyses identified 66 upregulated genes and 139 downregulated genes in <jats:italic>Sohlh1</jats:italic> KO testes compared with those in wild‐type testes at postnatal Day 7.5. Among many of the downregulated genes, <jats:italic>Sycp1</jats:italic> and <jats:italic>Sycp3</jats:italic>, which encode synaptonemal complex proteins 1 and 3 (SYCP1 and SYCP3), respectively, were significantly reduced in <jats:italic>Sohlh1</jats:italic> knockout mice. Transmission electron microscopy revealed no formation of the synaptonemal complex in <jats:italic>Sohlh1</jats:italic> KO spermatocytes. Luciferase reporter and chromatin‐immunoprecipitation assays demonstrated that SOHLH1 enhanced the expression of the <jats:italic>Sycp1</jats:italic> and <jats:italic>Sycp3</jats:italic> genes by binding the −1276, −708, and −94 basepairs (bp) E‐boxes upstream of the <jats:italic>Sycp1</jats:italic> promoter and the −64 and −43 bp E‐boxes upstream of the <jats:italic>Sycp3</jats:italic> promoter. Our data suggest that SOHLH1 transcriptionally regulates the expression of many target genes critical for the meiotic phase of spermatogenesis.</jats:p>