Effect of Brwd1 mutation on the mouse oocyte transcriptome

The Brwd1 mutation, though having dramatic effects on the spermatocyte transcriptome, had little effect on the oocyte transcriptome. Postmeiotic gene expression is essential for development and maturation of sperm and eggs. In B6/C3H females, Brwd1 ablation causes severe chromosome condensation and structural defects associated with abnormal telomere structure. In contrast to males, transcriptome analysis at the germinal vesicle stage revealed only minor changes in gene expression including a >2 fold overexpression of the histone methyltransferase MLL5 and LINE-1 elements transposons. Thus, loss of BRWD1 function interferes with the completion of oogenesis and spermatogenesis through sexually dimorphic mechanisms. Our results demonstrate that BRWD1 is essential for the epigenetic control of chromosome stability during female meiosis while playing a critical role in haploid gene transcription during the post-meiotic differentiation events of spermiogenesis. Oocytes isolated from B6/C3H wild type (WT) and homozygous Brwd1 mutants were subjected to transcriptome analysis by microarrays. Three replicates of 100 oocytes each were prepared from WT and mutant oocytes.