Project description:As approximately 70% of human breast tumors are estrogen receptor α (ERα)-positive, estrogen and ERα play essential roles in breast cancer development. By interrupting the ERα signaling pathway, endocrine therapy has been proven to be an effective therapeutic strategy. In the present study, we identified a novel mechanism by which Transcription Start Site (TSS)-associated histone H3K27 acetylation signals the Super Elongation Complex (SEC) to regulate transcriptional elongation of the ERα gene. The SEC interacts with H3K27ac on ERα TSS through its scaffold protein AFF4. Depletion of AFF4 by siRNA or CRISPR/Cas9 dramatically reduces expression of ERα and its target genes, consequently inhibiting breast cancer cell growth. More importantly, AFF4 mutant which lacks H3K27ac interaction failed to rescue ERα gene expression, suggesting H3K27 acetylation at TSS region is a key mark bridging the transition from transcriptional initiation to elongation, and perturbing SEC function can be an alternative strategy for targeting ERα signaling pathway at the level of chromatin.
Project description:As approximately 70% of human breast tumors are estrogen receptor α (ERα)-positive, estrogen and ERα play essential roles in breast cancer development. By interrupting the ERα signaling pathway, endocrine therapy has been proven to be an effective therapeutic strategy. In this study, we identified a mechanism by which Transcription Start Site (TSS)-associated histone H3K27 acetylation signals the Super Elongation Complex (SEC) to regulate transcriptional elongation of the ESR1 (ERα) gene. SEC interacts with H3K27ac on ESR1 TSS through its scaffold protein AFF4. Depletion of AFF4 by siRNA or CRISPR/Cas9 dramatically reduces expression of ESR1 and its target genes, consequently inhibiting breast cancer cell growth. More importantly, a AFF4 mutant which lacks H3K27ac interaction failed to rescue ESR1 gene expression, suggesting H3K27 acetylation at TSS region is a key mark bridging the transition from transcriptional initiation to elongation, and perturbing SEC function can be an alternative strategy for targeting ERα signaling pathway at chromatin level.
Project description:ChIP-seq for H3K27 acetylation and RNA-seq were performed during spermatogenesis. We analyzed two representative stages of spermatogenesis: purified pachytene spermatocytes (PS) undergoing meiosis; and postmeiotic round spermatids (RS) from adult testes.
Project description:We ablated the expression of the Nuclear Receptor Corepressor 1 specifically in mice livers and rendered them hypothyroid. Then we performed H3K27 acetylation CHIP-Seq. We found decreased H3K27ac in the livers of hypothyroid wild type and NCoR1KO mice. Therefore, we concluded that the thyroid hormone receptor may recruit histone deacetilases independently of NCoR1.
Project description:Acetyl-Coenzyme A (acetyl-CoA) is a central metabolite and the acetyl source for protein acetylation, particularly histone acetylation that promotes gene expression. However, the effect of acetyl-CoA levels on histone acetylation status in plants remains unknown. Here, we show that malfunctioned cytosolic acetyl-CoA carboxylase1 (ACC1) in Arabidopsis leads to elevated levels of acetyl-CoA and promotes histone hyperacetylation predominantly at lysine 27 of histone H3 (H3K27). The increase of H3K27 acetylation (H3K27ac) is dependent on ATP-citrate lyase which cleaves citrate to acetyl-CoA in the cytoplasm, and requires histone acetyltransferase GCN5. A comprehensive analysis of the transcriptome and metabolome in combination with the genome-wide H3K27ac profiles of acc1 mutants, demonstrate the dynamic changes of H3K27ac, gene transcripts and metabolites occurring in the cell by the increased levels of acetyl-CoA. This study suggests that H3K27ac is an important link between cytosolic acetyl-CoA level and gene expression in response to the dynamic metabolic environments in plants.
Project description:Genome-wide profiling of H3K9/K14 Acetylation and H3K27 trimethylation at promoters in the human lung embryonic fibroblast cell line MRC5
Project description:In serum-starved and re-fed mouse fibroblast, nascent RNA-seq analysis showed that the BET inhibitor JQ1 antagonized a process regulating PIC formation and a downstream process involved in progressive elongation. To specifically address the role of BRD4 and its interactions with acetylated histones and P-TEFb, YFP-tagged BRD4 proteins (wild type and mutant BRD4) were stably expressed in cells, endogenous BRD4 of which was knocked down by shRNA (shBRD4). Nascent RNA-seq analysis showed that BRD4 facilitated transcript elongation in a manner dependent on acetylated histone interaction but not P-TEFb. Furthermore, the role of BRD4 in enhancer activity was evaluated by mapping the intergenic distributions of Pol II, CDK9, H3K27 acetylation (Ac) and H4 Ac as well as BRD4 by ChIP-seq analysis. The results suggest that the role of intergenic BRD4 on nearby gene expression is mediated through enhanced synthesis of eRNA.