Epigenetics & Chromatin最新文献

Morphogenesis and development of hair follicle fundamentally depend on the interaction between the epidermis and dermis, with dermal papilla cells (DPCs) playing a critical role in these processes. H3K4me3, one of the key histone modifications, is essential for coordinating gene expression. However, the epigenetic modification profile of H3K4me3 in cashmere goat DPCs and its mechanism of action in hair follicle development remain unexplored. In this study, the apparent regulation map of H3K4me3 was drawn by CUT&Tag technology. DPCs were exogenously treated with the H3K4me3 inhibitor BCL-121 and the agonist PBIT. Functional experiment results showed that increasing H3K4me3 levels significantly enhanced the proliferation capacity of DPCs and promoted the expression of Wnt signaling pathway-related genes. Subsequently, the regulatory mechanism of H3K4me3 was explored, and the differentially expressed gene RSPO3 in the embryonic stage regulated by H3K4me3 was screened through CUT&Tag and RNA-seq correlation analysis. Functional studies demonstrated that RSPO3 could promote DPCs proliferation, inhibit apoptosis, and increase the expression of genes related to the Wnt signaling pathway. In summary, our findings indicated that H3K4me3 regulates the transcription of RSPO3 in DPCs, which would lay the foundation for the molecular mechanism of hair follicle development.

Background: INO80 and SWR1 are evolutionarily related ATP-dependent chromatin remodeling complexes that regulate the chromatin occupancy of the histone variant H2A.Z, playing critical roles in transcriptional regulation, genome replication, and DNA repair. While the H2A.Z-related functions of INO80 and SWR1 are well characterized in budding yeast and metazoans, much less is known about their composition and chromatin-targeting mechanisms outside of the Opisthokonts. We previously found that a distinct bromodomain-containing protein, IBD1, is involved in multiple chromatin-related complexes, including the SWR1-complex, in the ciliate protozoan Tetrahymena thermophila.

Results: Here, we report that a closely related bromodomain-containing protein, IBD2, functions as an acetyl lysine reader module within a putative INO80 complex. Through iterative proteomic analyses, we show that the Tetrahymena INO80 complex retains several conserved subunits found in its yeast and metazoan counterparts. In vitro binding assays reveal that recombinant IBD2 preferentially recognizes acetylated histone H3 tails. Chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) demonstrates that IBD2 is enriched near transcription start sites and promoter regions. Notably, the IBD1 and IBD2 genomic binding profiles strongly correlate with that of H2A.Z (Hv1), supporting their functional association with the SWRI- and INO80-complexes.

Conclusions: Together, our findings support a model in which H2A.Z chromatin dynamics are modulated by SWR1- and INO80-complexes that are differentially recruited to chromatin via distinct bromodomain proteins that recognize specific histone acetylation marks.

Background: The Pacific white shrimp (Litopenaeus vannamei) is the most widely farmed shrimp species globally, yet the epigenetic regulation underlying its embryonic development remains largely unexplored. Histone modifications are known to orchestrate gene expression during early development in model organisms, but their role in crustaceans is poorly understood.

Results: In this study, we present the first comprehensive histone modification landscape during L. vannamei embryogenesis using CUT&Tag (Cleavage Under Targets and Tagmentation). We profiled high-resolution landscapes of four histone marks (H3K4me1, H3K4me3, H3K27ac, H3K27me3) across seven developmental stages from blastula to nauplius, revealing dynamic chromatin state transitions associated with developmental progression. Integration with transcriptomic data uncovered a strong temporal correlation between chromatin states and gene expression, particularly during zygotic genome activation (ZGA). Furthermore, our analysis uncovered key developmental genes associated with critical biological processes such as molting, body segmentation, and neurogenesis, providing novel insights into the epigenetic regulation of these events. Functional annotation of cis-regulatory elements based on histone marks identified candidate enhancers and regulatory loci linked to these key genes.

Conclusions: Our study provides the first epigenomic framework of shrimp embryogenesis, uncovering chromatin-based regulatory mechanisms during early development. The identification of stage-specific enhancers and active chromatin regions offers valuable resources for functional genomics in crustaceans and sheds light on conserved and divergent aspects of ZGA regulation beyond model systems.

Background: Insulators are the multifunctional DNA binding proteins that perform architectural functions and regulate gene transcription. Although insulators have a well-established role in genome organization, it is still unclear how insulator proteins affect the control of tissue-specific processes. The Drosophila insulator BEAF32 (Boundary Element-Associated Factor of 32 kD) is a component of chromatin complexes found in open chromatin regions containing promoters of housekeeping genes. BEAF32 knockout impairs oogenesis and female fertility suggesting its specific functions during oogenesis.

Results: To get a better understanding of BEAF32 roles in oogenesis, we first examined its ovarian binding targets and discovered an enrichment of its localization sites in the promoters of both housekeeping and tissue-specific genes. Differential expression gene analysis revealed that BEAF32 knockout resulted in abnormal activation of non-ovarian tissue-specific genes in the ovaries, implying that BEAF32 regulates tissue-specific patterns of gene expression. We discovered that BEAF32 occupied many ovary-specific gene promoters and acted as a positive regulator of expression for the cell-cycle regulatory kinase, Polo. To investigate the possible role of BEAF32 in the Piwi-interacting RNAs (piRNAs) pathway we analyzed ovarian small RNAs in BEAF32 null mutants and found a strong decrease in the production of piRNAs from the 3R subtelomeric region. Our data suggest that the BEAF32-containing chromatin complex located upstream of the subtelomeric repeats preserves transcriptional and chromatin integrity of this domain in the germline. BEAF32 was also found to localize upstream of flamenco, a major piRNA source locus in follicular cells, and to be required for cell-specific transcription of the flamenco locus.

Conclusions: Our findings suggest that BEAF32 coordinates multiple transcriptional regulatory functions important for Drosophila oogenesis. BEAF32 represses the ectopic expression of developmental and tissue-specific genes in the ovaries. BEAF32 regulates polo kinase and other oogenesis-related genes. We demonstrate here that BEAF32 play a specific ovarian role in the maintenance of piRNA-producing loci. Our results support an important role for the BEAF32 insulator protein in determining the proper landscape of tissue-specific gene expression.

Background: Methylation of H4K20 has been implicated in the regulation of gene expression but also plays essential roles in numerous cellular functions, making studies of its effects on transcription challenging. To gain insights into the role of H4K20 methylation in regulating gene expression, we studied H4K20me1 and H4K20me3 in the context of the well-characterized erythroid differentiation of human hematopoietic stem and progenitor cells.

Results: H4K20me1 enrichment over the gene body was strongly correlated with expression changes. During erythroid differentiation, there was a dramatic decline in the level of RNA Polymerase II (Pol II); H4K20me1 was lost where Pol II was lost, and gained at genes where Pol II occupancy was maintained and transcripts were upregulated. We did identify a small subset of highly expressed genes, including beta-globin, that had a dramatic loss of H4K20me1 during erythroid differentiation, despite a substantial gain of Pol II. The histone demethylase PHF8 was present at these genes, as well as at the transcription start site of many active genes. In contrast to H4K20me1 over gene bodies correlating with transcription, enrichment at the transcription start site occurred at genes with low levels of Pol II occupancy and RNA expression throughout erythroid differentiation. The majority of H4K20me3 was present over intergenic regions, consistent with its well-established role as a repressor of repetitive elements. Intriguingly, H4K20me3 was also present at the transcription start site of genes with H4K20me1 over the gene body. At these genes, H4K20me3 levels were highly correlated with chromatin accessibility at the transcription start site, and an elevated Pol II pausing index. There was a dramatic loss of H4K20me3 occupancy in genic, but not intergenic, regions during erythroid differentiation.

Conclusions: There are dynamic changes in H4K20 methylation during cellular differentiation that correlate strongly with Pol II occupancy and activity. These changes occurred in genic regions, with H4K20me3 at the transcription start site correlated with Pol II pausing, and H4K20me1 gene body levels tightly linked with transcriptional changes. Together, these data provide important insights into the role of H4K20 methylation in the regulation of gene expression during cellular differentiation.

Background: Genomic imprinting is required for normal development, and abnormal methylation of differentially methylated regions (iDMRs) controlling the parent of origin-dependent expression of the imprinted genes has been found in congenital disorders affecting growth, metabolism, neurobehavior, and in cancer. In most of these cases the cause of the imprinting abnormalities is unknown. Also, these studies have generally been performed on a limited number of CpGs, and a systematic investigation of iDMR methylation in the general population is lacking.

Results: By analysing a vast number of either in-house generated or online available whole-genome methylation array datasets of unaffected individuals, and patients with complex and rare disorders, we determined the most common iDMR methylation profiles in a large population and identified many genetic and non-genetic factors contributing to their variability in blood DNA. We found that methylation variability was not homogeneous within the iDMRs and that the CpGs closer to the ZFP57 binding sites are less susceptible to methylation changes. We demonstrated the methylation polymorphism of three iDMRs and the atypical behaviour of several others, and reported the association of 25 disease- and 47 non-disease-complex traits as well as 15 Mendelian and chromosomal disorders with iDMR methylation changes. The most significantly associated complex traits included ageing, intracytoplasmic sperm injection, African versus European ancestry, female sex, pre- and postnatal exposure to pollutants and blood cell type compositions, while the associated genetic diseases included Down syndrome and the developmental disorders with molecular defects in the DNA methyltransferases DNMT1 and DNMT3B, H3K36 methyltransferase SETD2, chromatin remodelers SRCAP and SMARCA4 and transcription factor ADNP.

Conclusions: These findings identify several genetic and non-genetic factors including new genes associated with genomic imprinting maintenance in humans, which may have a role in the aetiology of the diseases with imprinting abnormalities and have clear implications in molecular diagnostics.

Background: N-terminal acetylation (Nt-Ac), mediated by N-terminal acetyltransferases (NATs) is one of the most abundant protein modifications occurring approximately in 80% of all eukaryotic proteins. In contrast to the broad spectrum NATs, the human N-alpha-acetyltransferase 40 (NAA40) is highly specific, currently known to Nt-acetylate only the two histone proteins H4 and H2A, which share an Ser(1)-Gly(2)-Arg(3)-Gly(4) N-terminal sequence. Previous work from our lab and others has highlighted the biological and clinical relevance of this NAA40-mediated modification.

Results: In this study, by performing in silico analysis of protein sequences combined with biochemical assays we identify the histone variants H2A.X and H2A.J and the chromatin remodeler SMARCD2 as new potential substrates of human NAA40. Subsequently, focusing on H2A.X, we show for the first time by mass spectrometry analysis that H2A.X is N-terminally acetylated (Nt-acH2A.X) within human cells. Next, we demonstrate that NAA40 specifically interacts and N-terminally acetylates histone H2A.X, in vitro and within cells. Finally, we provide evidence that H2A.X N-terminal acetylation is responsive to Ultraviolet B (UVB)-induced DNA damage and its associated enzyme NAA40 affects the survival of cells exposed to UVB irradiation.

Conclusion: Our findings identify H2A.X as a novel bona fide substrate of NAA40. Moreover, the responsiveness of H2A.X N-terminal acetylation to UV-induced DNA damage indicates that this is a dynamic modification with potential biological functions.

Background: MED12 is a key regulator of transcription and chromatin architecture, essential for normal hematopoiesis. While its dysregulation has been implicated in hematological malignancies, the mechanisms driving its upregulation in acute myeloid leukemia (AML) remain poorly understood. We investigated MED12 expression across AML subgroups by integrating chromatin accessibility profiling, histone modification landscapes, and DNA methylation (DNAm) patterns. Functional assays using DNMT inhibition were performed to dissect the underlying regulatory mechanisms.

Results: MED12 shows subtype-specific upregulation in AML compared to hematopoietic stem and progenitor cells, independent of somatic mutations. Chromatin accessibility profiling reveals that the MED12 locus is epigenetically primed in AML blasts, with increased DNase hypersensitivity at regulatory elements. Histone modification analysis demonstrates strong H3K4me3 and H3K27ac enrichment around the transcription start site (TSS), consistent with promoter activation, while upstream and intragenic regions exhibit enhancer-associated marks (H3K4me1, H3K27ac). Notably, hypermethylation within TSS-proximal regulatory regions (TPRRs)-including promoter-overlapping and adjacent CpG islands-correlates with ectopic MED12 overexpression, challenging the canonical view of DNAm as strictly repressive. Functional studies show that DNMT inhibition via 5-azacytidine reduces MED12 expression despite promoter demethylation in cells with hypermethylated TPRRs, suggesting a noncanonical role for DNA methylation in maintaining active transcription. Furthermore, MED12 expression positively correlates with DNMT3A and DNMT3B expression, implicating these methyltransferases in sustaining its epigenetic activation.

Conclusion: This study identifies a novel regulatory axis in which aberrant DNA methylation, rather than genetic mutation, drives MED12 upregulation in AML. Our findings suggest that TPRR hypermethylation may function noncanonically to support transcriptional activation, likely in cooperation with enhancer elements. These results underscore the importance of epigenetic mechanisms in AML and highlight enhancer-linked methylation as a potential contributor to oncogene dysregulation. Future studies should further explore the role of noncanonical methylation-mediated gene activation in AML pathogenesis and therapeutic targeting.