Project description:we identify Scml2, a subunit of a germ cell-specific polycomb repressive complex 1 (PRC1), as a critical epigenetic modifier that establishes the germline-specific epigenome through two distinct functions. One of these functions is in the stem cell phase of spermatogonia and the other is on meiotic sex chromosomes. During the stem cell phase of spermatogonia, Scml2 establishes Rnf2- dependent ubiquitination of H2A (Rnf2-ubH2A) as an epigenetic memory that subsequently ensures programmed repression of somatic genes during the late stages of spermatogenesis. Additionally, during meiosis, Scml2 interacts with M-NM-3H2AX and works downstream of the DNA damage response factor Mdc1 on the sex chromosomes and, contrary to autosomes, suppresses Rnf2-ubH2A for proper epigenetic programming of the sex chromosomes. Taken together, Scml2 positively regulates Rnf2-ubH2A on autosomes and negatively regulates Rnf2-ubH2A on the sex chromosomes to establish the germline-specific epigenome in spermatogenesis. Our study reveals a novel layer of epigenetic regulation in the male germline and adds further insight into the functionality of the polycomb proteins. RNA-seq and ChIP-seq analyses using wild-type and Scml2 KO spermatogenic cells
Project description:Gametogenesis is dependent on the expression of germline-specific genes. However, it remains unknown how the germline epigenome is distinctly established from that of somatic lineages. Here we show that genes commonly expressed in somatic lineages and spermatogenesis-progenitor cells undergo repression in a genome-wide manner in late stages of the male germline and identify underlying mechanisms. SCML2, a germline-specific subunit of a Polycomb repressive complex 1 (PRC1), establishes the unique epigenome of the male germline through two distinct antithetical mechanisms. SCML2 works with PRC1 and promotes RNF2-dependent ubiquitination of H2A, thereby marking somatic/progenitor genes on autosomes for repression. Paradoxically, SCML2 also prevents RNF2-dependent ubiquitination of H2A on sex chromosomes during meiosis, thereby enabling unique epigenetic programming of sex chromosomes for male reproduction. Our results reveal divergent mechanisms involving a shared regulator by which the male germline epigenome is distinguished from that of the soma and progenitor cells.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility.
Project description:Sperm chromatin retains small amounts of histones, and the chromatin states of sperm mirror gene expression programs of the next generation. It remains largely unknown how paternal epigenetic information is transmitted through sperm chromatin. Here we developed a novel mouse model of paternal epigenetic inheritance in which deposition of Polycomb repressive complex 2 (PRC2) mediated-repressive H3K27me3 is attenuated in the paternal germline. By applying modified methods of assisted reproductive technology, we rescued infertility of mice absent of Polycomb protein SCML2, which is the regulator of germline gene expression through the establishment of H3K27me3 on bivalent promoters with other active marks H3K4me2/3. In F1 males of Scml2-knockout mice, which has wild-type genotype, gene expression is dysregulated in the male germline during spermiogenesis. These dysregulated genes are targets of SCML2-mediated H3K27me3 in mature sperm. Thus, SCML2 mediates intergenerational inheritance of paternal epigenetic information through the regulation of sperm chromatin.
Project description:To characterize the genetic basis of hybrid male sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven ‘hotspots,’ seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL - but not cis eQTL - were substantially lower when mapping was restricted to a ‘fertile’ subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility. Gene expression was measured in whole testis from males aged 62-86 days. Samples include 190 first generation lab-bred male offspring of wild-caught mice from the Mus musculus musculus - M. m. domesticus hybrid zone.