Project description:<p>Non-coding regions comprise most of the human genome and harbor a significant fraction of risk alleles for neuropsychiatric diseases, yet their functions remain poorly defined. We created a high-resolution map of non-coding elements involved in human cortical neurogenesis by contrasting chromatin accessibility and gene expression in the germinal zone and cortical plate of the developing cerebral cortex. To obtain a high resolution depiction of chromatin structure and gene expression in developing human fetal cortex, we dissected the post-conception week (PCW) 15-17 human neocortex into two major anatomical divisions to distinguish between proliferating neural progenitors and post mitotic neurons: (1) GZ: the neural progenitor-enriched region encompassing the ventricular zone (VZ), subventricular zone (SVZ), and intermediate zone (IZ) and (2) CP: the neuron-enriched region containing the subplate (SP), cortical plate (CP), and marginal zone (MZ). Tissues were obtained from three independent donors and three to four technical replicates from each tissue were processed for ATAC-seq to define the landscape of accessible chromatin and RNA-seq for genome-wide gene expression profiling.</p>
Project description:We performed profiling of allele-specific chromatin accessibility profiling in mouse spermatocytes. To this end, we isolated tetraploid spermatocytes using FACS-sorting from F1 crosses of the C57B6J and CAST/EiJ strains. We then performed ATAC-Seq (Corces et al. 2017) and analyzed allele-specific chromatin accessibility.
Project description:Regulation of gene expression is linked to the organization of the genome. With age, chromatin alterations occur on all levels of genome organization, accompanied by changes in the gene expression profile. However, little is known about the changes on the level of transcriptional regulation. Here, we used a multi-omics approach and integrated ATAC-, RNA- and NET-seq to identify age-related changes in the chromatin landscape of murine liver and to investigate how these are linked to transcriptional regulation. We provide the first systematic inventory of the connection between aging, chromatin accessibility and transcriptional regulation in a whole tissue. Aging in murine liver is characterized by an increase in chromatin accessibility at promoter regions, but not in an increase of transcriptional output. Instead, aging is accompanied by a decrease of promoter-proximal pausing of RNA polymerase II (Pol II). We propose that these changes in transcriptional regulation are due to a reduced stability of the pausing complex and may represent a mechanism to compensate for the age-related increase in chromatin accessibility in order to prevent aberrant transcription.
Project description:Melanomas are heterogeneous and adopt multiple transcriptional states that can confer an invasive phenotype and resistance to therapy. Little is known about the epigenetic drivers of these cell states, limiting our ability to regulate melanoma heterogeneity and tumor progression. Here we identify stress-induced HDAC8 activity as the driver of a transcriptional state that increased the formation of melanoma brain metastases (MBM). Exposure of melanocytes and melanoma cells to multiple different stresses led to HDAC8 activation, a switch to a gene expression signature associated with a neural crest-stem cell like state (NCSC) and the adoption of an amoeboid, invasive phenotype. This cell state enhanced the survival of melanoma cells under shear stress conditions and increased the formation of metastases in the brain. ATAC-Seq and ChIP-Seq analysis showed HDAC8 to alter chromatin structure by increasing H3K27ac and accessibility at c-Jun binding sites without changing global histone acetylation. The increased accessibility of Jun binding sites was paralleled by decreased H3K27ac and accessibility at MITF binding sites and loss of melanoma-lineage gene expression. Mass spectrometry-based acetylomics demonstrated that HDAC8 deacetylated the histone acetyltransferase (HAT) EP300 leading to its enzymatic inactivation. This, in turn, led to an increased binding of EP300 to Jun-transcriptional sites and decreased binding to MITF-transcriptional sites. Increased expression of EP300 decreased invasion and increased the sensitivity of melanoma cells to multiple stresses while inhibition of EP300 function increased invasion, resistance to stress and the development of MBM. We identified HDAC8 as a novel mediator of transcriptional co-factor inactivation and chromatin accessibility that increases MBM development.
Project description:SARS-CoV-2 induces widespread transcriptomic changes in host cells upon infection, in part through activation and modulation of innate immunity pathways and downstream gene regulation. However, the mechanisms by which SARS-CoV-2 and its evolutionary variants differentially affect host cell transcriptomic states remain largely unclear. Through chromatin proteomic (iDAPT-MS) analysis, we found that although SARS-CoV-2 and other pathogenic coronaviruses exhibit similar proteomic shifts on chromatin, SARS-CoV-2 uniquely promotes TP53 nuclear accumulation and activation. Parallel assessment of SARS-CoV-2 viral protein expression on host chromatin states (ATAC-seq) identifies intracellular spike protein as a key determinant of virus-mediated chromatin accessibility changes. Multilevel chromatin profiling reveals increased TP53 nuclear accumulation, TP53-associated chromatin accessibility changes, and TP53 target gene activation upon expression of SARS-CoV-2 alpha (B.1.1.7) and delta (B.1.617.2) spike variants relative to the ancestral spike sequence. TP53, ACE2, and furin cleavage are required for these changes, driving decreased cellular proliferation, increased cellular senescence, and increased cytokine release. Finally, BA.1 but not BA.2, BA.2.12.1, nor BA.4/BA.5 spike expression leads to attenuated TP53 activity and fusogenicity relative to ancestral spike. Our findings implicate spike-mediated host TP53 activation as a “rheostat” of COVID-19 pathogenicity.