BNC1 is a master regulator of human epicardial cell heterogeneity and function
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ABSTRACT: Single cell RNAseq of a model of epicardium derived from human pluripotent stem cell (hPSC-epi) reveals that distinct epicardial sub-populations are defined by high levels of expression for the transcription factors BNC1 and TCF21. Cells positive for the transcription factor WT1 are included in the BNC1 population, which confirms the heterogeneity observed in the mouse with TCF21 and WT1. Analysis of genes differentially expressed between the two populations suggests differences in their biological activities. We identified THY1 as a membrane marker of the TCF21 population and we show that THY1+ cells can differentiate into cardiac fibroblast and smooth muscle cells while THY1- cells mostly produce the latter. Knocking-down BNC1 during the establishment of the populations led to an homogeneous epicardium containing mostly the TCF21high populations and differentiating mainly into cardiac fibroblasts. Using network inference methods and transcriptomic data from the different epicardial lineages derived from the hPSC-epi, we identified a core transcriptional network organized around WT1, TCF21 and BNC1 and orchestrated by BNC1.
Project description:Purpose: Studying the epicardium-myocardium crosstalk in the zebrafish larval heart. To do so, we aimed to identify, with RNA-seq, the genes dysregulated following the loss of the epicardial marker gene tcf21 in sorted epicardial cells and cardiomyocytes. Results: We first analyzed the transcriptome of epicardial and myocardial WT cells and identified cell-type specific/enriched genes. Then, we identified several differential expressed genes in tcf21 mutants, including several ligand-receptor couples known to mediate the epicardium-myocardium crosstalk.
Project description:The epicardium, an epithelium covering the heart, is essential for cardiac development. During embryogenesis, the epicardium provides instructive signals for the growth and maturation of cardiomyocytes and for coronary angiogenesis. We generated an in vitro model of human embryonic epicardium derived from human pluripotent stem cells (hPSC-epi). These cells were able to differentiate into cardiac fibroblasts (cf) and smooth muscle cells (smc) in vitro (hPSC-epi-cf and hPSC-epi-smc respectively). Furthermore, we showed that they improved maturation of hPSC-derived cardiomyocytes (hPSC-cardio) in vitro while neural crest cells derived from hPSC (hPSC-NC) could not. Furthermore, they improved survival of hPSC-cardio and stimulated angiogenesis when injected in a rat model of myocardium infarction. We performed mRNA sequencing of the hPSC-epi, hPSC-epi-cf, hPSC-smc and hPSC-NC in order to identify the secreted molecules specifically produced by the hPSC-epi and/or its derivatives in comparison with the hPSC-NC. Vascular smooth muscle cells have different embryonic origins and different properties depending on their location in the body. The coronary smooth muscle cells come from the epicardium while the aortic ones come from the mesoderm or the neural crest. We performed mRNA sequencing of human coronary artery smc and human aortic smc to identify a specific signature of the coronary smc. We also compared the genes expressed in the hPSC-epi-smc and the smc derived from hPSC-derived lateral plate mesoderm.
Project description:The aim of the approach was to use RNAseq analysis to identify genes expressed in Xenopus epicardium that were affected by embryonic depletion of the epicardial transcription factor Tcf21 compared to control-MO injected siblings. Both upregulated and downregulated genes were validated by RT-PCR and whole embryo in situ hybridization to validate gene expression and assess spatio-temporal distribution of genes of interest within the heart and epicardium. Approximately 70-100 stage 44-46 Xenopus laevis hearts were dissected to isolate total mRNA from which poly-adenylated RNA was extracted using the Illumina standard protocol. This experiment represents one replicate from pooled hearts. mRNA profiles of stage 44-45 Xenopus laevis sibling hearts from control or Tcf21-depleted embryos, were generated by deep sequencing using Illumina GAII.
Project description:In the adult heart, the epicardium becomes activated after injury, contributing to cardiac healing by secretion of paracrine factors. Here we analyzed by single-cell RNA sequencing combined with RNA in situ hybridization and lineage tracing of WT1+ cells the cellular composition, location, and hierarchy of epicardial stromal cells (EpiSC) in comparison to activated myocardial fibroblasts/stromal cells in infarcted mouse hearts. We identified 11 transcriptionally distinct EpiSC populations, that can be classified in three groups each containing a cluster of proliferating cells. Two groups expressed cardiac specification makers and sarcomeric proteins suggestive of cardiomyogenic potential. Transcripts of HIF-1α and HIF-responsive genes were enriched in EpiSC consistent with the epicardium being a hypoxic niche. Expression of paracrine factors was not limited to WT1+ cells but was a general feature of activated cardiac stromal cells. Our findings provide the cellular framework by which myocardial ischemia may trigger in EpiSC the formation of cardioprotective/regenerative responses.
Project description:Next-generation sequencing (NGS) has significantly advanced the elucidation of developmental signaling mechanisms that are important for different cell lineage formation from human pluripotent stem cells (hPSCs). We report here the application of RNA-sequencing technology for transcriptome profile of human primary and hPSC-derived epicardial cell, and compare to those of other cell lineages including hPSCs, mesoderm, cardiomcyotyes. Eight epicaridal cell samples from four different hPSC lines and four different donors were performed in IIIumina HiSeq2500. The resulting sequence reads (about 20 million reads per sample) were mapped to human genome (hg19) using HISAT, and the RefSeq transcript levels (RPKMs) were quantified using the python script rpkmforgenes.py. Our RNA-seq data confirmed the stable expression of key epicardial cell markers including WT1, TBX18, TCF21, ALDH1A2 and ZO1, and the gene set enrichment analysis (GSEA) showed enrichment in extracellular matrix related pathways and keratinocyte (epithelial) differentiation. Hierarchical clustering of differentially expressed genes uncovered several as yet uncharacterized genes that may contribute to epicardial function. This study represents the first detailed analysis of epicardial transcriptomes generated by RNA-seq technology, providing insight into the mechanisms underlying the differentiation of hPSCs into epicardial cells.
Project description:The goal of this study was to perform transcriptional profiling of single epicardium-derived cells during early cardiac development. Epicardium enriched Wilms Tumor Gene 1 (Wt1) genetic lineage tracing mouse line (Wt1CreERT2/+; R26mTmG) was utilized to collect fluorescently labeled epicardial cells at embryonic day (E) 12.5 and following epicardial-to-mesenchymal transition at E16.5. Additionally, single cell transcriptional profiling was performed in endothelial cells that were collected from Wt1CreERT2/+ mice and Wt1CreERT2/+;MRTF-A-/-;MRTF-Bflox/flox to generate myocardin-related transcription factor A and B gene deletions in the epicardium and evaluate the impact of deleting a mechanosensitive gene program on coronary vasculature development at E14.5. This transcriptional data provides a resource to determine relative mRNA changes in epicardium-derived cells and endothelial cells during significant stages of cardiac development.
Project description:By contrast with mammals, adult zebrafish have a high capacity to regenerate damaged or lost myocardium through proliferation of spared cardiomyocytes. The epicardial sheet covering the heart is activated by injury and aids muscle regeneration through paracrine effects and as a multipotent cell source, and has received recent attention as a target in cardiac repair strategies. While it is recognized that epicardium is required for muscle regeneration and itself has high regenerative potential, the extent of cellular heterogeneity within epicardial tissue is largely unexplored. In this study, we performed transcriptome analysis on dozens of epicardial lineage cells purified from zebrafish harboring a transgenic reporter for the pan-epicardial gene tcf21. Hierarchical clustering analysis suggested the presence of at least three epicardial cell subsets defined by expression signatures. We validated many new pan-epicardial and epicardial markers by alternative expression assays. Additionally, we explored the function of the scaffolding protein and main component of caveolae, caveolin-1 (cav1), which was present in each epicardial subset. In BAC transgenic zebrafish, cav1 regulatory sequences drove strong expression in ostensibly all epicardial cells and in coronary vascular endothelial cells. Moreover, cav1 mutant zebrafish generated by genome editing showed grossly normal heart development and adult cardiac anatomy, but displayed profound defects in injury-induced cardiomyocyte proliferation and heart regeneration. Our study defines a new platform for the discovery of epicardial lineage markers, genetic tools, and mechanisms of heart regeneration. Deep sequencing of isolated single epicardial cells
Project description:Identification of epicardium-enriched genes in the embryonic heart. The epicardium encapsulates the heart and functions as a source of multipotent progenitor cells and paracrine factors essential for cardiac development and repair. Injury of the adult heart results in re-activation of a developmental gene program in the epicardium, but the transcriptional basis of epicardial gene expression has not been delineated. We established a mouse embryonic heart organ culture and gene expression system that facilitated the identification of epicardial enhancers activated during heart development and injury. Epicardial activation of these enhancers depends on a combinatorial transcriptional code centered on CCAAT/enhancer binding protein (C/EBP) transcription factors. Disruption of C/EBP signaling in the adult epicardium reduced injury-induced neutrophil infiltration and improved cardiac function. These findings reveal a transcriptional basis for epicardial activation and heart injury, providing a platform for enhancing cardiac regeneration. Total RNA obtained from lacZ-positive epicardial cells isolated from the E11.5 Tcf21lacZ hearts compared to total dissociated heart cells
Project description:Epicardium-derived cells (EPDCs) contribute cardiac cell types during development and in adulthood respond to Thymosin β4 (Tβ4) and myocardial infarction (MI) by reactivating a fetal gene program to promote neovascularization and cardiomyogenesis. The mechanism for epicardial gene activation remains elusive. Here we reveal that SWI/SNF chromatin-remodeling complexes restored embryonic potential upon MI. BRG1, the essential ATPase subunit of SWI/SNF, physically interacted with Tβ4 and was recruited by CCAAT/enhancer-binding protein β (C/EBPβ) to discrete regulatory elements in the Wilm’s tumor 1 (Wt1) locus. BRG1-Tβ4 co-operative binding promoted transcription of Wt1 as the master regulator of embryonic EPDCs and Wt1as, an antisense lncRNA produced from within intron 1, which increased Wt1 mRNA stability through heteroduplex formation. ChIP-seq revealed global BRG1 binding which was enhanced by Tβ4 at key embryonic epicardial loci downstream of Wt1. These findings reveal novel essential functions for chromatin-remodeling and antisense RNA in the embryonic programming of EPDCs during cardiac development and repair.
Project description:To delineate the role of the epicardium, the initial site of presentation of the ACM phenotype, the Dsp gene, encoding desmosome protein desmoplakin (DSP) was conditionally deleted in the mouse epicardial cells under the transcriptional regulation of Wilms tumor 1 (Wt1) locus. Single cell RNA sequencing (scRNA-Seq) of ~ 40,000 tagged epicardial-derived cells (EDCs), isolated using the dual reporter R26mT/mG mice, showed an increased number of EDCs expressing unique molecular identifiers of fibroblasts as well as a unique subset of epicardial-derived fibroblasts expressing pro-fibrotic genes in the Wt1-Cre: R26mT/mG: Dsp mice. Analysis of pseudo-bulk RNA-Seq data identified ~ 800 differentially expressed genes (DEGs), which were predominantly involved in epithelial-mesenchymal transition (EMT). The DEGs were the targets of TGFB1 among other trophic/mitotic factors, whose activation was verified by immunohistochemistry and quantification of transcript levels of selected TGBF1 pathway genes. Retro-mapping of the DEGs to the cell clusters, identified by scRNA-Seq, denoted epicardial-derived fibroblasts and to a lesser extent the epithelial cells as the main sources of paracrine factors in the myocardium of Wt1-Cre: R26mT/mG: Dsp mice.