Project description:Temporal data on gene expression and context-specific open chromatin states can improve identification of key transcription factors (TFs) and the gene regulatory networks (GRNs) controlling cellular differentiation. However, their integration remains challenging. Here, we delineate a general approach for data-driven and unbiased identification of key TFs and dynamic GRNs, called EPIC-DREM. We generated time-series transcriptomic and epigenomic profiles during differentiation of mouse multipotent bone marrow stromal cells (MSCs) towards adipocytes and osteoblasts. Using our novel approach we constructed time-resolved GRNs for both lineages and identifed the shared TFs involved in both differentiation processes. To take an alternative approach to prioritize the identified shared regulators, we mapped dynamic super-enhancers in both lineages and associated them to target genes with correlated expression profiles. The combination of the two approaches identified aryl hydrocarbon receptor (AHR) and Glis family zinc finger 1 (GLIS1) as mesenchymal key TFs controlled by dynamic MSC-specific super-enhancers that become repressed in both lineages. AHR and GLIS1 control differentiation-induced genes and we propose they function as guardians of mesenchymal multipotency.
Project description:We employed Assay for Transposase-Accessible Chromatin with high throughput sequencing (ATAC-seq) to map the accessible chromatin landscape in articular knee cartilage of OA patients. We identified 109,215 accessible chromatin regions for cartilages, of which 71% were annotated as enhancers. By overlaying them with genetic and DNA methylation data, we have determined potential OA-relevant enhancers and their putative target genes. Furthermore, through integration with RNA-seq data, we characterized genes that are altered both at epigenomic and transcriptomic levels in OA. These genes are enriched in pathways regulating ossification and mesenchymal stem cell (MSC) differentiation. Consistently, the differentially accessible regions in OA are enriched for MSC-specific enhancers and motifs of transcription factor families involved in osteoblast differentiation. In conclusion, we demonstrate how direct chromatin profiling of clinical tissues can provide comprehensive epigenetic information for a disease and suggest candidate genes and enhancers of translational potential.
Project description:Single-cell multi-omic datasets, in which multiple molecular modalities are profiled within the same cell, provide a unique opportunity to discover the interplay between cellular epigenomic and transcriptomic changes. To realize this potential, we developed MultiVelo, a mechanistic model of gene expression that extends the popular RNA velocity framework by incorporating epigenomic data. MultiVelo uses a probabilistic latent variable model to estimate the switch time and rate parameters of gene regulation, providing a quantitative summary of the temporal relationship between epigenomic and transcriptomic changes. Fitting MultiVelo on single-cell multi-omic datasets revealed two distinct mechanisms of regulation by chromatin accessibility, quantified the degree of concordance or discordance between transcriptomic and epigenomic states within each cell, and inferred the lengths of time lags between transcriptomic and epigenomic changes.
Project description:Here we apply integrated epigenomic and transcriptomic profiling to uncover super-enhancer heterogeneity between breast cancer subtypes, and provide clinically relevant biological insights towards TNBC. Using CRISPR/Cas9-mediated gene editing, we identify genes that are specifically regulated by TNBC-specific super-enhancers, including FOXC1 and MET, thereby unveiling a mechanism for specific overexpression of the key oncogenes in TNBC. We also identify ANLN as a novel TNBC-specific gene regulated by super-enhancer. Our studies reveal a TNBC-specific epigenomic landscape, contributing to the dysregulated oncogene expression in breast tumorigenesis.
Project description:Temporal profiling of chromatin accessibility during metastasis revealed dynamic changes in chromatin accessibility during osteosarcoma lung colonization. We sought to determine whether these changes were due to epigenomic reprogramming, or shifts in subclonal frequency. To do this we performed scATAC-seq on MG63.3-GFP cells grown in vitro.
Project description:Metastatic melanoma is either intrinsically resistant or rapidly acquires resistance to targeted drugs such as MAPK inhibitors (MAPKi). Here, using a drug screen targeting chromatin regulators in patient-derived 3D melanoma cell cultures, we discovered that PARP inhibitors are capable of restoring MAPKi sensitivity. This synergy was found to be independent of DNA damage repair pathways and was effective both in vitro and in vivo in patients-derived xenografts. Strikingly, through integrated transcriptomic, proteomic and epigenomic analysis, we discovered that PARPi induces lysosomal autophagy which was accompanied by enhanced mitochondrial lipid metabolism that, ultimately, increased antigen presentation and sensitivity to T-cell cytotoxicity. Moreover, we also found that PARP inhibitors regulated EMT-like phenotype switching by dampening the mesenchymal phenotype via transcriptomic and epigenetic rearrangements. This, in turn, redirected melanoma cells towards a proliferative and, thus, MAPKi-sensitive state. Our study provides a scientific rational for treating patients with PARPi in combination with MAPKi to annihilate acquired therapy resistance.
Project description:Fresh-frozen meningioma tissues of varying WHO grades were analyzed by shotgun DDA proteomics. The proteomic profiles were compared and reflected a set of new clinical subtypes derived from genomic, epigenomic and transcriptomic data which improved risk stratification.
