Project description:In this article, we first obtained HP1 triple-knockout embryonic stem cells using Crispr-Cas9 and Cre-loxP systems. At the same time, we also obtained single-knock and double-knock cell lines respectively. On this basis, we studied The function of HP1 in embryonic stem cells was found to have a very important role in the regulation of differentiation and reproduction-related genes.In our follow-up study, we found that the deletion of HP1 leads to the differentiation tendency of embryonic stem cells into endoderm. Considering that HP1 has an important function of H3K9me3 recognition and binding, we examined the effect of HP1 deletion on histone modifications, we found that H3K9me2 and H3K9me3 modifications were significantly reduced, and then through rescue experiments, we thought that HP1 may be through OCT4 and NANOG and then further functional.
Project description:The family of Heterochromatin Protein 1 (HP1) consists of highly conserved proteins, which have important functions in the nucleus of eukaryotic cells. In mammals there are three HP1 paralogs: HP1(alpha), Hp1(beta), and Hp1(gamma)They are encoded by the Cbx5, Cbx1, and Cbx3 genes, respectively. Hp1 and Hp1 stably interact with Chd4 and Adnp to form the ChAHP complex. In this project, Chd4, Adnp, and the three Cbx genes were endogenously tagged with a FLAG-Avi tag in mouse embryonic stem cells. The tagged proteins were subjected to tandem-affinity purification and analysis by mass spectrometry.
Project description:H3K9 methylation (H3K9me) marks transcriptionally silent genomic regions called heterochromatin. A conserved class of HP1 proteins are critically required to establish and maintain heterochromatin. HP1 proteins bind to H3K9me, recruit factors that promote heterochromatin formation, and oligomerize to form phase-separated condensates. We do not understand how HP1 protein binding to heterochromatin establishes and maintains transcriptional silencing. Here, we demonstrate that the S.pombe HP1 homolog, Swi6, can be completely bypassed to establish silencing at ectopic and endogenous loci when an H3K4 methyltransferase, Set1 and an H3K14 acetyltransferase, Mst2 are deleted. Deleting Set1 and Mst2 enhances Clr4 enzymatic activity, leading to higher H3K9me levels and increased spreading. In contrast, Swi6 and its capacity to oligomerize were indispensable during epigenetic maintenance. Our results demonstrate the role of HP1 proteins in regulating histone modification crosstalk during establishment and identifies a genetically separable function in maintaining epigenetic memory.
Project description:H3K9 methylation (H3K9me) marks transcriptionally silent genomic regions called heterochromatin. A conserved class of HP1 proteins are critically required to establish and maintain heterochromatin. HP1 proteins bind to H3K9me, recruit factors that promote heterochromatin formation, and oligomerize to form phase-separated condensates. We do not understand how HP1 protein binding to heterochromatin establishes and maintains transcriptional silencing. Here, we demonstrate that the S.pombe HP1 homolog, Swi6, can be completely bypassed to establish silencing at ectopic and endogenous loci when an H3K4 methyltransferase, Set1 and an H3K14 acetyltransferase, Mst2 are deleted. Deleting Set1 and Mst2 enhances Clr4 enzymatic activity, leading to higher H3K9me levels and increased spreading. In contrast, Swi6 and its capacity to oligomerize were indispensable during epigenetic maintenance. Our results demonstrate the role of HP1 proteins in regulating histone modification crosstalk during establishment and identifies a genetically separable function in maintaining epigenetic memory.
Project description:Drosophila heterochromatin protein 1- HP11 is believed to be involved in active transcription, transcriptional gene silencing, and the formation of heterochromatin2-7. However, little is known about the function of HP1 during development. Using a Gal4-induced RNA interference system, we show that conditional depletion of HP1 in transgenic flies results in preferential lethality in male flies. Cytological analysis of mitotic chromosomes reveals that HP1 depletion causes sex-biased chromosomal defects, including telomere fusions. The global levels of specific histone modifications, particularly the hallmarks of active chromatin, are preferentially increased in males as well. Expression analysis revealed that approximately twice as many genes are specifically regulated by HP1 in males compared to females. Furthermore, HP1-regulated genes showed greater enrichment for HP1 binding in males. Taken together, these results reveal that HP1 modulates chromosomal integrity, histone modifications, and transcription in a sex-specific manner. Keywords: sex-specific, HP1, gender comparison
Project description:Activity-dependent neuroprotective protein (ADNP) is one of the most frequent autism spectrum disorder-associated gene products known to date. Here we show that Adnp interacts with the chromatin remodeler Chd4 and the heterochromatin protein HP1 to form a stable complex, which we refer to as ChAHP. Genetic ablation of ChAHP components or DNA binding sites in embryonic stem cells prematurely activates lineage-specific genes, revealing an important role for Adnp in restraining the differentiation capacity of pluripotent cells. Adnp targets the ChAHP complex to specific sequence motifs at euchromatic loci, representing an H3K9 methylation-independent mechanism of HP1 recruitment and gene silencing.
Project description:Embryonic stem cells (ESCs) have a hyperdynamic chromatin structure characterized by fewer discrete foci of heterochromatin protein 1 family of proteins (HP1) compared to somatic cells. During reprogramming of somatic cells, depletion of HP1γ early, reduced, while depletion later, enhanced the generation of induced pluripotent stem cells (iPSCs); concomitant with a change from a centromeric to nucleoplasmic localization. To identify the interactome of HP1γ in different biochemical environment in ESCs, we compared protein complexes of HP1γ at 0.42M salt (Dignam et al, 1983), with micrococcal nuclease (MCN) digestion with 0.3M NaCl, and MCN with 0.5M NaCl. To understand the effectors of the change in localization, we isolated protein complexes containing HP1γ in ESCs and compared the profile to that in partially reprogrammed intermediates called pre-iPSCs. Given the differential distribution of the HP1 family in ESCs, we also compared the protein interactome of HP1γ in ESCs with that of HP1α and HP1β. In addition, we probed histone associations of HP1γ in ESCs further by querying the histone post-translational modifications that were detectable. The HP1 proteins themselves are decorated with multiple PTMs, several of which we have found to be novel. Taken together our results reveal the complex contribution of the HP1 proteins to pluripotency.