Project description:BackgroundChromatin state provides a clear decipherable blueprint for maintenance of transcriptional patterns, exemplifying a mitotically stable form of cellular programming in dividing cells. In this regard, genomic studies of chromatin states within cancerous tissues have the potential to uncover novel aspects of tumor biology and unique mechanisms associated with disease phenotypes and outcomes. The degree to which chromatin state differences occur in accordance with breast cancer features has not been established.MethodsWe applied a series of unsupervised computational methods to identify chromatin and molecular differences associated with discrete physiologies across human breast cancer tumors.ResultsChromatin patterns alone are capable of stratifying tumors in association with cancer subtype and disease progression. Major differences occur at DNA motifs for the transcription factor FOXA1, in hormone receptor-positive tumors, and motifs for SOX9 in Basal-like tumors. We find that one potential driver of this effect, the histone chaperone ANP32E, is inversely correlated with tumor progression and relaxation of chromatin at FOXA1 binding sites. Tumors with high levels of ANP32E exhibit an immune response and proliferative gene expression signature, whereas tumors with low ANP32E levels appear programmed for differentiation.ConclusionsOur results indicate that ANP32E may function through chromatin state regulation to control breast cancer differentiation and tumor plasticity. This study sets a precedent for future computational studies of chromatin changes in carcinogenesis.
Project description:We report a genome wide enrichment, redistribution and accumulation of H2A.Z at specific chromatin control regions, in particular at enhancers and insulators, in mouse embryonic fibroblasts depleted for Anp32e (MEFs Anp32e-/-). H2A.Z ChIP-seq in MEFs WT (+/+) or KO (-/-) for Anp32e.
Project description:Rapid removal of the histone variant H2A.Z from neural chromatin is a key step in learning-induced gene expression and memory formation, but the molecular mechanisms underlying learning-induced H2A.Z removal are unknown. Anp32e was recently identified an H2A.Z-specific histone chaperone that removes H2A.Z from nucleosomes in dividing cells, but whether it plays a similar role in non-dividing neurons is unknown. Moreover, prior studies only investigated effects of Anp32e on H2A.Z binding under steady state-conditions, such that its effect on H2A.Z removal under stimulus-induced conditions is unknown. Here, we show that Anp32e regulates H2A.Z binding in neurons under steady-state conditions, but that stimulus-induced H2A.Z removal is largely independent of Anp32e. In assessing the functional consequences of Anp32e, we showed that its depletion leads to H2A.Z-dependent impairment in dendritic arborization in cultured hippocampal neurons, as well as impaired recall of contextual fear memory and transcriptional regulation. Together, these data indicate the Anp32E regulates behavioral and morphological outcomes by preventing H2A.Z accumulation in chromatin rather than by regulating activity-mediated H2A.Z dynamics.
Project description:We report a genome wide enrichment, redistribution and accumulation of H2A.Z at specific chromatin control regions, in particular at enhancers and insulators, in mouse embryonic fibroblasts depleted for Anp32e (MEFs Anp32e-/-).
Project description:ANP32e, a chaperone of H2A.Z, is receiving increasing attention because of its link to cancer growth and progression. An unanswered question is whether ANP32e regulates H2A.Z dynamics during the cell cycle; if so, this could have clear implications for the proliferation of cancer cells. Using the human U2OS cancer cell line model system, we have confirmed that ANP32e regulates the growth of these cells. ANP32e preferentially interacts with H2A.Z during G1 phase of the cell cycle. Unexpectedly, however, ANP32e does not mediate the removal of H2A.Z from chromatin, is not a stable component of the p400 remodeling complex, and is not strongly associated with chromatin. Instead, most ANP32e is in the cytoplasm. Here, ANP32e preferentially interacts with H2A.Z in G1 phase in response to an increase in H2A.Z protein abundance and regulates its protein stability. This G1-specific interaction between ANP32e and H2A.Z is also observed in the nucleoplasm but is unrelated to any change in H2A.Z abundance. Collectively, these results challenge the idea that ANP32e is involved in regulating the abundance of H2A.Z in chromatin as part of a chromatin remodeling complex. Rather, we propose that ANP32e acts as a molecular chaperone that maintains the soluble pool of H2A.Z by regulating its protein stability and acting as a buffer in response to cell cycle-dependent changes in H2A.Z abundance.
Project description:The impairment of left ventricular (LV) diastolic function with inadequate increase in myocardial relaxation velocity directly results in lower LV compliance, increased LV filling pressures and heart failure symptoms. The development of agents facilitating the relaxation of human cardiomyocytes requires a better understanding of the underlying regulatory mechanisms. We performed a high-content microscopy-based screening in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) using a library of 2565 human miRNA mimics and measured relaxation kinetics via high-computing analyses of motion movies. We identified hsa-miR-548v, a primate specific miRNA, as the miRNA producing the largest increase in relaxation velocities. This positive lusitropic effect was reproduced in engineered cardiac tissues generated with healthy and BRAF T599R mutant hiPSC-CMs, and was independent of changes in calcium transients. Consistent with improvements in viscoelastic responses to mechanical stretch, RNA-sequencing showed that hsa-miR-548v down-regulated multiple targets, especially components of the mechano-sensing machinery. The exogenous administration of hsa-miR-548v in hiPSC-CMs notably resulted in a significant reduction of ANKRD1/CARP1 expression and localization at the sarcomeric I-band. This study suggests that the sarcomere I-band is a critical control center of the ability of cardiomyocytes to relax and a target for improving relaxation and diastolic dysfunction.
Project description:Genome-wide chromatin state underlies gene expression potential and cellular function. Epigenetic features and nucleosome positioning contribute to the accessibility of DNA, but widespread regulators of chromatin state are largely unknown. Our study investigates how coordination of ANP32E and H2A.Z contributes to genome-wide chromatin state in mouse fibroblasts. We define H2A.Z as a universal chromatin accessibility factor, and demonstrate that ANP32E antagonizes H2A.Z accumulation to restrict chromatin accessibility genome-wide. In the absence of ANP32E, H2A.Z accumulates at promoters in a hierarchical manner. H2A.Z initially localizes downstream of the transcription start site, and if H2A.Z is already present downstream, additional H2A.Z accumulates upstream. This hierarchical H2A.Z accumulation coincides with improved nucleosome positioning, heightened transcription factor binding, and increased expression of neighboring genes. Thus, ANP32E dramatically influences genome-wide chromatin accessibility through subtle refinement of H2A.Z patterns, providing a means to reprogram chromatin state and to hone gene expression levels.
Project description:Genome-wide chromatin state underlies gene expression potential and cellular function. Epigenetic features and nucleosome positioning contribute to the accessibility of DNA, but widespread regulators of chromatin state are largely unknown. Our study investigates how coordination of ANP32E and H2A.Z contributes to genome-wide chromatin state in mouse fibroblasts. We define H2A.Z as a universal chromatin accessibility factor, and demonstrate that ANP32E antagonizes H2A.Z accumulation to restrict chromatin accessibility genome-wide. In the absence of ANP32E, H2A.Z accumulates at promoters in a hierarchical manner. H2A.Z initially localizes downstream of the transcription start site, and if H2A.Z is already present downstream, additional H2A.Z accumulates upstream. This hierarchical H2A.Z accumulation coincides with improved nucleosome positioning, heightened transcription factor binding, and increased expression of neighboring genes. Thus, ANP32E dramatically influences genome-wide chromatin accessibility through subtle refinement of H2A.Z patterns, providing a means to reprogram chromatin state and to hone gene expression levels.
Project description:The mechanisms that regulate H2A.Z and its requirement for transcription in differentiated mammalian cells remains ambiguous. In this study, we identified the interaction between the C-terminus of ANP32e and N-terminus of H2A.Z in a yeast two-hybrid screen. Knockdown of ANP32e resulted in proteasomal degradation and nuclear depletion of H2A.Z or of a chimeric green florescence protein fused to its N-terminus. This effect was reversed by inhibition of protein phosphatase 2A (PP2A) and, conversely, reproduced by overexpression of its catalytic subunit. Accordingly, knockdown of ANP32e inhibited phosphorylation of H2A.Z, whereas a mutation of serine-9 proved its requirement for both the protein’s stability and nuclear localization, as did knockdown of the nuclear mitogen and stress-induced kinase 1. Moreover, ANP32e’s knockdown also revealed its differential requirement for cell signaling and gene expression, whereas, genome-wide binding analysis confirmed its co-localization with H2A.Z at transcription start sites, as well as, gene bodies of inducible genes. The data also suggest that H2A.Z restricts transcription, which is moderated by ANP32e after induction of transcriptional activity of inducible and housekeeping genes vs. constitutively-expressed tissue-specific genes during cellular growth. Thus, ANP32e, through inhibition of PP2A, is required for nucleosomal inclusion of H2A.Z and the regulation of gene expression.