Interrogating the functions of PRDM9 domains in meiosis

Homologous recombination is required for proper segregation of homologous chromosomes during meiosis. It predominantly occurs at recombination hotspots that are defined by the DNA binding specificity of the PRDM9 protein. PRDM9 contains three domains which are typically different families of proteins involved in regulation of transcription in other proteins, yet, the role of PRDM9 in gene expression control has not been evaluated. Here we analyze the germline transcriptome of the  Prdm9-/- male mice in comparison to Prdm9+/+ males and find no apparent differences in the mRNA and miRNA profiles. We further explore the role of PRDM9 in meiosis by analyzing the activity of PRDM9 lacking effect of the KRAB, SSXRD and post-SET zinc finger domains deletion mutants in a cell expression system and the KRAB domain deletion in mice. We found that although the post-SET zinc finger and the KRAB domains are not essential for the methyltransferase activity of PRDM9 in a cell culture expression systemin vitro, mice lacking the KRAB domain mutant mice  domain show only residual PRDM9 methyltransferase activity and undergo meiotic arrest. In aggregate, our data indicate that these domains that are classically involved in gene regulation do not serve that role in PRDM9, but instead are involved in PRDM9 function has likely diverged from the typical function of a transcription factor and adapted the new role in setting the proper chromatin environment for initiation and completion of homologous recombination. Testes mRNA-seq, miRNA-seq, Chip-seq were generated using next generation sequencing. * The "GSE104850_RAW.tar" archive includes the processed data files for Samples GSM3053281-GSM3053299. *