Project description:Acetylation of the histone variant H2A.Z (H2A.Zac) occurs at active promoters and is associated with oncogene activation in prostate cancer, but its role in enhancer function is still poorly understood. Here we show that H2A.Zac containing nucleosomes are commonly redistributed to neo-enhancers in cancer resulting in a concomitant gain of chromatin accessibility and ectopic gene expression. Notably incorporation of acetylated H2A.Z nucleosomes is a pre-requisite for activation of Androgen receptor (AR) associated enhancers. H2A.Zac nucleosome occupancy is rapidly remodelled to flank the AR sites to initiate the formation of nucleosome-free regions and the production of AR-enhancer RNAs upon androgen treatment. Remarkably higher levels of global H2A.Zac correlate with poorer prognosis. Together these data demonstrate the novel contribution of H2A.Zac in activation of newly formed enhancers in prostate cancer.
Project description:Acetylation of the histone variant H2A.Z (H2A.Zac) occurs at active promoters and is associated with oncogene activation in prostate cancer, but its role in enhancer function is still poorly understood. Here we show that H2A.Zac containing nucleosomes are commonly redistributed to neo-enhancers in cancer resulting in a concomitant gain of chromatin accessibility and ectopic gene expression. Notably incorporation of acetylated H2A.Z nucleosomes is a pre-requisite for activation of Androgen receptor (AR) associated enhancers. H2A.Zac nucleosome occupancy is rapidly remodelled to flank the AR sites to initiate the formation of nucleosome-free regions and the production of AR-enhancer RNAs upon androgen treatment. Remarkably higher levels of global H2A.Zac correlate with poorer prognosis. Together these data demonstrate the novel contribution of H2A.Zac in activation of newly formed enhancers in prostate cancer.
Project description:Acetylation of the histone variant H2A.Z (H2A.Zac) occurs at active promoters and is associated with oncogene activation in prostate cancer, but its role in enhancer function is still poorly understood. Here we show that H2A.Zac containing nucleosomes are commonly redistributed to neo-enhancers in cancer resulting in a concomitant gain of chromatin accessibility and ectopic gene expression. Notably incorporation of acetylated H2A.Z nucleosomes is a pre-requisite for activation of Androgen receptor (AR) associated enhancers. H2A.Zac nucleosome occupancy is rapidly remodelled to flank the AR sites to initiate the formation of nucleosome-free regions and the production of AR-enhancer RNAs upon androgen treatment. Remarkably higher levels of global H2A.Zac correlate with poorer prognosis. Together these data demonstrate the novel contribution of H2A.Zac in activation of newly formed enhancers in prostate cancer.
Project description:The histone variant H2A.Z has been implicated in nucleosome exchange, transcriptional activation and Polycomb repression. However, the relationships among these seemingly disparate functions remain obscure. We mapped H2A.Z genome-wide in mammalian ES cells and neural progenitors. H2A.Z is deposited promiscuously at promoters and enhancers, and correlates strongly with H3K4 methylation. Accordingly, H2A.Z is present at poised promoters with bivalent chromatin and at active promoters with H3K4 methylation, but is absent from stably repressed promoters that are specifically enriched for H3K27 trimethylation. We also characterized post-translational modification states of H2A.Z, including a novel species dually-modified by ubiquitination and acetylation that is enriched at bivalent chromatin. Our findings associate H2A.Z with functionally distinct genomic elements, and suggest that post-translational modifications may reconcile its contrasting locations and roles. Examination of histone variant, histone modifications and transcription machinery in 3 cell types
Project description:Chromatin modifications have been implicated in the self-renewal and differentiation of embryonic stem cells (ESCs). However, the function of histone variant H2A.Z in ESCs remains unclear. We show that H2A.Z is highly enriched at promoters and enhancers and is required for both efficient self-renewal and differentiation of murine ESCs. H2A.Z deposition leads to an abnormal nucleosome structure, decreased nucleosome occupancy and increased chromatin accessibility. In self-renewing ESCs, knockdown of H2A.Z compromises OCT4 binding to its target genes and leads to decreased binding of MLL complexes to active genes and of PRC2 complex to repressed genes in self-renewal of ESCs. During differentiation of ESCs, inhibition of H2A.Z also compromises RA-induced RARα binding, activation of differentiation markers and the repression of pluripotency genes. We propose that H2A.Z mediates such contrasting activities by acting as a 'general facilitator' that generates access for a variety of complexes both activating and repressive. ChIP-Seq in murine embryonic stem (mES) cells for H2A.Z and acetylated H2A.Z. ChIP-Seq of H3K4me3, H3K27me3, RbBP5, SUZ12 and OCT4 for mES cells of both H2A.Z RNAi knockdown and shLuc control. ChIP-Seq of RARalpha in H2A.Z knockdown (withdraw of LIF and exposure to RA for 3h) and control cells. MNase-Seq and chromatin accessibility assay using Benzonase digestion followed by next-generation sequencing for mES cells of both H2A.Z RNAi knockdown and shLuc control. ChIP-Seq of H2A.Z and H3K4me3 for mES cells of both MLL4 RNAi knockdown and shLuc control. RNA-Seq for mES cells of H2A.Z knockdown and shluc control. RNA-Seq for embryonic bodies derived from mES cells (H2A.Z knockdown and shLuc control) at day 3 and day 7.
Project description:H2A.Z is an evolutionarily conserved H2A variant implicated in the regulation of gene expression, however its role in transcriptional deregulation in cancer remains poorly understood. Using genome-wide studies, we investigated the role of promoter-associated H2A.Z and acetylated H2A.Z (acH2A.Z) in gene deregulation and its relationship with DNA methylation and H3K27me3 in prostate cancer. Our results reconcile the conflicting reports of positive and negative roles for histone H2A.Z and gene expression states. We find that H2A.Z is enriched in a bimodal distribution at nucleosomes surrounding the transcription start sites (TSSs) of both active and poised gene promoters, whereas acH2A.Z is only localized at the TSSs of actively expressed genes. Interestingly, H2A.Z spreads across the entire promoter of inactive genes in a de-acetylated state. Gene deregulation in cancer is also associated with a reorganization of acH2A.Z and H2A.Z nucleosome occupancy across the promoter region and TSS of genes. Notably, in cancer cells we find that a gain of acH2A.Z at the TSS occurs with an overall decrease of H2A.Z levels in concert with oncogene activation. Furthermore, underacetylated H2A.Z at TSSs is increased with silencing of tumour suppressor genes. We also demonstrate that acH2A.Z anti-correlates with promoter H3K27me3 and DNA methylation. For the first time, we show that acetylation of H2A.Z is a key modification involved in gene activity in normal cells and in epigenetic gene deregulation in tumourigenesis.