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:H3K9 tri-methylation (H3K9me3) plays emerging roles in gene regulation, beyond its accumulation on pericentric constitutive heterochromatin. It remains a mystery why and how H3K9me3 undergoes dynamic regulation in male meiosis. Here, we identify a novel, critical regulator of H3K9 methylation and spermatogenic heterochromatin organization: the germline-specific protein ATF7IP2 (MCAF2). We show that, in male meiosis, ATF7IP2 amasses on autosomal and X pericentric heterochromatin, spreads through the entirety of the sex chromosomes, and accumulates on thousands of autosomal promoters and retrotransposon loci. On the sex chromosomes, which undergo meiotic sex chromosome inactivation (MSCI), the DNA damage response pathway recruits ATF7IP2 to X pericentric heterochromatin, where it facilitates the recruitment of SETDB1, a histone methyltransferase that catalyzes H3K9me3. In the absence of ATF7IP2, male germ cells are arrested in meiotic prophase. Analyses of ATF7IP2-deficient meiosis reveal the protein’s essential roles in the maintenance of MSCI, suppression of retrotransposons, and global activation of autosomal genes. We propose that ATF7IP2 is a downstream effector of the DDR pathway in meiosis that coordinates the organization of heterochromatin and gene regulation through the spatial regulation of SETDB1-mediated H3K9me3 deposition. We performed gene expression analysis using data obtained from RNA-seq of Atf7ip2+/+ and Atf7ip2-/- pachytene spermatocytes.
Project description:H3K9 tri-methylation (H3K9me3) plays emerging roles in gene regulation, beyond its accumulation on pericentric constitutive heterochromatin. It remains a mystery why and how H3K9me3 undergoes dynamic regulation in male meiosis. Here, we identify a novel, critical regulator of H3K9 methylation and spermatogenic heterochromatin organization: the germline-specific protein ATF7IP2 (MCAF2). We show that, in male meiosis, ATF7IP2 amasses on autosomal and X pericentric heterochromatin, spreads through the entirety of the sex chromosomes, and accumulates on thousands of autosomal promoters and retrotransposon loci. On the sex chromosomes, which undergo meiotic sex chromosome inactivation (MSCI), the DNA damage response pathway recruits ATF7IP2 to X pericentric heterochromatin, where it facilitates the recruitment of SETDB1, a histone methyltransferase that catalyzes H3K9me3. In the absence of ATF7IP2, male germ cells are arrested in meiotic prophase. Analyses of ATF7IP2-deficient meiosis reveal the protein’s essential roles in the maintenance of MSCI, suppression of retrotransposons, and global activation of autosomal genes. We propose that ATF7IP2 is a downstream effector of the DDR pathway in meiosis that coordinates the organization of heterochromatin and gene regulation through the spatial regulation of SETDB1-mediated H3K9me3 deposition. CUT&RUN of H3K9me3 in Atf7ip2+/+ and Atf7ip2-/- pachytene spermatocytes and CUT&Tag of ATF7IP2 in C57/B6 WT pachytene spermatocytes.
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:We identified genes expressed in mouse liver that are regulated by Cux2, a highly female-specific liver transcription factor whose expression is regulated by sex-dependent plasma GH patterns. Using adenovirus to overexpress Cux2 (Adeno-Cux2) in male liver, we show that Cux2 represses ~35% of male-biased genes and induces/de-represses ~35% of female-biased genes. Adeno-CMV was used as a control for adenoviral infection. (Published in: TL Conforto et al 2012, Mol Cell Biol. 2012, 32:4611-4627. PubMed PMID: 22966202; PMCID: PMC3486175)
Project description:Spermatogenesis is a unidirectional differentiation process that generates haploid sperm, but how the gene expression program that directs this process is established is largely unknown. Here we determine the high-resolution 3D chromatin architecture of male germ cells during spermatogenesis and show that CTCF-mediated 3D chromatin predetermines the gene expression program required for spermatogenesis. In undifferentiated spermatogonia, CTCF-mediated chromatin interactions between meiosis-specific super-enhancers (SE) loci and target genes precede activation of meiosis-specific SEs on autosomes. These meiotic SE recruit the master transcription factor A-MYB in meiotic spermatocytes, which strengthens their 3D contacts and instructs a burst of meiotic gene expression. We also find that at the mitosis-to-meiosis transition, the germline-specific Polycomb protein SCML2 resolves chromatin loops that are specific to mitotic spermatogonia. Moreover, SCML2 and A-MYB establish the unique 3D chromatin organization of sex chromosomes during meiotic sex chromosome inactivation. We propose that CTCF-mediated 3D chromatin organization enforces epigenetic priming that directs unidirectional differentiation, thereby determining the cellular identity of the male germline.
Project description:Spermatogenesis is a unidirectional differentiation process to produce haploid sperm. However, it remains largely unknown how the gene expression program is determined to direct a unidirectional differentiation. Here we unveil the high-resolution 3D chromatin architecture of male germ cells and show that CTCF-mediated 3D chromatin predetermines the gene expression program required for spermatogenesis. At the mitosis-to-meiosis transition, the germline-specific Polycomb protein SCML2 resolves chromatin loops specific to mitotic spermatogonia. On autosomes, CTCF-mediated 3D chromatin manifests the structural feature of meiosis-specific super-enhancer (meiotic SE) loci already in undifferentiated spermatogonia. In meiotic spermatocytes, the master transcription factor A-MYB is recruited to these meiotic SE loci to strengthen their 3D contacts to instruct the burst of meiotic gene expression. Further, SCML2 and A-MYB establish unique 3D chromatin of the sex chromosomes in meiotic sex chromosome inactivation. We propose that CTCF-mediated 3D chromatin underlines epigenetic priming to direct unidirectional differentiation, thereby determining the cellular identity of the male germline.
Project description:Spermatogenesis is a unidirectional differentiation process to produce haploid sperm. However, it remains largely unknown how the gene expression program is determined to direct a unidirectional differentiation. Here we unveil the high-resolution 3D chromatin architecture of male germ cells and show that CTCF-mediated 3D chromatin predetermines the gene expression program required for spermatogenesis. At the mitosis-to-meiosis transition, the germline-specific Polycomb protein SCML2 resolves chromatin loops specific to mitotic spermatogonia. On autosomes, CTCF-mediated 3D chromatin manifests the structural feature of meiosis-specific super-enhancer (meiotic SE) loci already in undifferentiated spermatogonia. In meiotic spermatocytes, the master transcription factor A-MYB is recruited to these meiotic SE loci to strengthen their 3D contacts to instruct the burst of meiotic gene expression. Further, SCML2 and A-MYB establish unique 3D chromatin of the sex chromosomes in meiotic sex chromosome inactivation. We propose that CTCF-mediated 3D chromatin underlines epigenetic priming to direct unidirectional differentiation, thereby determining the cellular identity of the male germline.