ChIP-seq analysis of H3K4me1, H3K4me3 and H3K27me3 modification in testes of chromosome substitution strains.. Mus musculus

The importance of proper gene regulation to the evolution of reproductive isolation is not well understood. Here we investigated the influence of different subspecies-derived X chromosome on the transcriptional regulation of recipient subspecies genome by using the X-chromosome substitution strain, which shows male-specific sterility. Transcription profiling by microarray experiments showed that large-scale aberrations in gene expression were occurred on the introgressed X chromosome. This improper transcriptional profile was restored by introducing chromosome 1 from the same donor strain as the X chromosome. The restoration implies that some trans-acting regulatory factors, which regulate transcription of downstream X-linked genes, locate on chromosome 1 and this regulatory incompatibility is one of the causes for reproductive isolation between the two subspecies. Our data likely reflect the evolutionary divergence of transcriptional regulation between the subspecies. To investigate the histone modification associating with transcriptional activity on the genome of X-chromosome substitution strains, we perform ChIP-seq analysis by using antibodies against H3K4me1, H3K4me3 and H3K27me3. The misregulated expression was observed in testes of X-chromosome substitution strain, B6-ChrXTMSM, at 5- and 7-day-aged. The B6-ChrXTMSM strain has distal half of the X chromosome from MSM strain in the genetic background of C57BL/6J (B6) strain. The misregulation of B6-ChrXTMSM was restored in testes of F1 male progeny from the crosses between B6-ChrXTMSM females and B6-Chr1MSM males, (XT x 1)F1. Thus we performed ChIP-seq analysis on testis genome from B6, MSM, B6-ChrXTMSM and (XT x 1)F1 males at 5- and 7-day-aged.