Project description:Bivalent domains marked with repressive H3K27me3 and activating H3K4me2/3 are a molecular signature of totipotency in stem cells and development. While bivalent domains are retained throughout the germline to recover totipotency in the next generation, the mechanisms establishing bivalent domains remains unknown. Here we demonstrate that a germline-specific Polycomb protein, SCML2, binds to chromatin containing hypomethylated DNA to induce H3K27me3, thereby initiating the establishment of germline-specific bivalent domains in mice. SCML2 regulates two distinct classes of autosomal bivalent domains, the first are maintained constitutively through spermatogenesis (Class I), and the second are specifically established during meiosis (Class II). In postmeiotic spermatids, the loss of H3K27me3 leads to an increase of H3K4me2/3 on bivalent domains and disorganization of pericentromic heterochromatin. We propose that SCML2 regulates dynamic bivalent domains in the germline as a molecular imprint to recover totipotency after fertilization. Overall design: ChIP-seq, ATAC-seq and RNA-seq analyses using wild-type and Scml2-KO spermatogenic cells
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 γH2AX 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:Polycomb repressive complex-1 (PRC1) is essential for the epigenetic regulation of gene expression. SCML2 is a mammalian homolog of Drosophila SCM, a Polycomb-group protein that associates with PRC1. Here, we show that SCML2A, an SCML2 isoform tightly associated to chromatin, contributes to PRC1 localization and also directly enforces repression of certain Polycomb target genes. SCML2A binds to PRC1 via its SPM domain and interacts with ncRNAs through a novel RNA-binding region (RBR). Targeting of SCML2A to chromatin involves the coordinated action of the MBT domains, RNA binding, and interaction with PRC1 through the SPM domain. Deletion of the RBR reduces the occupancy of SCML2A at target genes and overexpression of a mutant SCML2A lacking the RBR causes defects in PRC1 recruitment. These observations point to a role for ncRNAs in regulating SCML2 function and suggest that SCML2 participates in the epigenetic control of transcription directly and in cooperation with PRC1. This is the ChIP-seq part of the study
Project description:The male germline transcriptome changes dramatically during the mitosis-to-meiosis transition to activate late spermatogenesis genes and to transiently suppress genes commonly expressed in somatic lineages and spermatogenesis progenitor cells, termed somatic/progenitor genes. These changes reflect epigenetic regulation. Induction of late spermatogenesis genes during spermatogenesis is facilitated by poised chromatin established in the stem cell phases of spermatogonia, whereas silencing of somatic/progenitor genes during meiosis and postmeiosis is associated with formation of bivalent domains which also allows the recovery of the somatic/progenitor program after fertilization. Importantly, during spermatogenesis mechanisms of epigenetic regulation on sex chromosomes are different from autosomes: X-linked somatic/progenitor genes are suppressed by meiotic sex chromosome inactivation without deposition of H3K27me3. Our results suggest that bivalent H3K27me3 and H3K4me2/3 domains are not limited to developmental promoters (which maintain bivalent domains that are silent throughout the reproductive cycle), but also underlie reversible silencing of somatic/progenitor genes during the mitosis-to-meiosis transition in late spermatogenesis. 29 samples analyzed by ChIP-Seq
Project description:The aim of the study was to investigate whether the trefoil peptide genes, in concerted action with a miRNA regulatory network, were contributing to nutritional maintrenance. Using a Tff2 knock-out mouse model, 48 specific miRNAs were noted to be significantly deregulated when compared to the wild type strain. Overall design: n = 6 mus musculus wild type samples and n = 6 knock-down experiments have been screened for a currently known mus musculus miRNAs and validated by TaqMan
Project description:The aim of the study was to investigate whether the trefoil peptide genes, in concerted action with a miRNA regulatory network, were contributing to nutritional maintrenance. Using a Tff3 knock-out mouse model, 21 specific miRNAs were noted to be significantly deregulated when compared to the wild type strain. Overall design: n = 6 mus musculus wild type samples and n = 6 knock-down experiments have been screened for a currently known mus musculus miRNAs and validated by TaqMan
Project description:The histone variant H2A.Z is essential for maintaining the identity of embryonic stem cell (ESC) by keeping bivalent developmental genes at a poised state. However, how H2A.Z is deposited into the bivalent domains remains unknown. In mammals, two chromatin-remodeling complexes, Tip60/p400 and SRCAP, exchange the canonical histone H2A for H2A.Z in the chromatin. Here we show that Glioma Amplified Sequence 41 (Gas41), a shared subunit of the two H2A.Z-depositing complexes, functions as a reader of histone acetylation and recruits Tip60/p400 and SRCAP to deposit H2A.Z into specific chromatin regions including bivalent domains. The YEATS domain of Gas41 bound to acetylation on histone H3K27 and H3K14 both in vitro and in cells. Crystal structure of the Gas41 YEATS domain in complex with the H3K27ac peptide revealed that, similar to the AF9 and ENL YEATS domains, Gas41 YEATS forms a serine-lined aromatic cage for Kac recognition; mutations of either the aromatic residues of YEATS domain or the nearby residue of H3K27 abrogated the interaction. In mESCs, knockdown of Gas41 led to cell differentiation as the result of derepression of differentiation genes. Importantly, the differentiated morphology was rescued by expressing wild type Gas41, but not the YEATS domain mutated counterparts that do not recognize histone acetylation. Mechanically, we found that Gas41 depletion led to reduction of H2A.Z levels and a concomitant reduction of H3K27me3 levels at the promoters of a subset of bivalent genes. Together, our study identifies the Gas41 YEATS domain as a reader of histone acetylation and establishes a link between histone acetylation and H2A.Z deposition in the maintenance of ESC identity. Overall design: ChIP-seq of H2AZ, H3K27Ac, H3K27me3, H3K4me3, H3K14ac, were applied in J1 mouse ES cells; mRNA-seq of shNT and shGas41 in J1 mouse ES cells.