Similar Datasets
Project description:The cardiogenic transcription factors (TFs) Mef2c, Gata4, and Tbx5 can directly reprogram fibroblasts to induced cardiac-like myocytes (iCLMs), presenting a potential source of cells for cardiac repair. While activity of these TFs is enhanced by Hand2 and Akt1, their genomic targets and interactions during reprogramming are not well studied. We performed genome-wide analyses of cardiogenic TF binding and enhancer profiling during cardiac reprogramming. We found that these TFs synergistically activate enhancers highlighted by Mef2c binding sites and that Hand2 and Akt1 coordinately recruit other TFs to enhancer elements. Intriguingly, these enhancer landscapes collectively resemble patterns of enhancer activation during embryonic cardiogenesis. We further constructed a cardiac reprogramming gene regulatory network and found repression of EGFR signaling pathway genes. Consistently, chemical inhibition of EGFR signaling augmented reprogramming. Thus, by defining epigenetic landscapes these findings reveal synergistic transcriptional activation across a broad landscape of cardiac enhancers and key signaling pathways that govern iCLM reprogramming.
| S-EPMC6754266 | biostudies-literature
Project description:Fibroblasts can be directly reprogrammed toward a cardiac fate by introducing cardiogenic transcription factors (TFs), although the underlying mechanisms of the cardiac reprogramming process remain unclear. Three cardiac TFs, GATA4, MEF2C, and Tbx5 (referred to as GMT) can activate cardiac genes in fibroblasts and their cardiogenic activity is enhanced by the Hand2 TF and the Akt1 kinase. To understand the mechanistic basis of cardiac reprogramming, we performed a genome-wide analysis of cardiogenic TF binding sites and active enhancers, which were annotated by H3K27ac histone modification, during the reprogramming process. We found that cardiogenic TFs rapidly co-occupy core regulatory elements of cardiac genes and activate myriad cardiac enhancers that are enriched predominantly in Mef2 binding sites. Addition of Hand2 and Akt1 to the GMT reprogramming cocktail expands the spectrum of co-occupied active cardiac enhancers. As reprogramming proceeds over time, reprogramming TFs continue to activate additional cardiac enhancers, which are also enriched for Mef2 motifs, while fibroblast enhancers are silenced. This transition of the enhancer landscape strongly correlated with changes in the fibroblast and cardiac transcriptome. To test the relevance of cardiac reprogramming enhancers to the regulation of cardiogenesis in vivo, we assayed a collection of reprogramming enhancers in transgenic mouse embryos and found that they directed highly specific expression patterns in the developing heart. Our findings demonstrate that Hand2 and Akt1 enhance reprogramming by facilitating cardiac enhancer occupancy and identify Mef2 as a central effector of cardiac reprogramming, which coordinates the actions of accessory factors across a broad landscape of cardiac enhancers.
2019-04-15 | GSE112316 | GEO
Project description:Fibroblasts can be directly reprogrammed toward a cardiac fate by introducing cardiogenic transcription factors (TFs), although the underlying mechanisms of the cardiac reprogramming process remain unclear. Three cardiac TFs, GATA4, MEF2C, and Tbx5 (referred to as GMT) can activate cardiac genes in fibroblasts and their cardiogenic activity is enhanced by the Hand2 TF and the Akt1 kinase. To understand the mechanistic basis of cardiac reprogramming, we performed a genome-wide analysis of cardiogenic TF binding sites and active enhancers, which were annotated by H3K27ac histone modification, during the reprogramming process. We found that cardiogenic TFs rapidly co-occupy core regulatory elements of cardiac genes and activate myriad cardiac enhancers that are enriched predominantly in Mef2 binding sites. Addition of Hand2 and Akt1 to the GMT reprogramming cocktail expands the spectrum of co-occupied active cardiac enhancers. As reprogramming proceeds over time, reprogramming TFs continue to activate additional cardiac enhancers, which are also enriched for Mef2 motifs, while fibroblast enhancers are silenced. This transition of the enhancer landscape strongly correlated with changes in the fibroblast and cardiac transcriptome. To test the relevance of cardiac reprogramming enhancers to the regulation of cardiogenesis in vivo, we assayed a collection of reprogramming enhancers in transgenic mouse embryos and found that they directed highly specific expression patterns in the developing heart. Our findings demonstrate that Hand2 and Akt1 enhance reprogramming by facilitating cardiac enhancer occupancy and identify Mef2 as a central effector of cardiac reprogramming, which coordinates the actions of accessory factors across a broad landscape of cardiac enhancers.
2019-04-15 | GSE112315 | GEO
Project description:Cardiac Reprogramming Factors Synergistically Activate Genome-wide Cardiogenic Stage-Specific Enhancers
| PRJNA445646 | ENA
Project description:Cardiac Reprogramming Factors Synergistically Activate Genome-wide Cardiogenic Stage-Specific Enhancers (ChIP-seq data set)
| PRJNA445650 | ENA
Project description:Cardiac Reprogramming Factors Synergistically Activate Genome-wide Cardiogenic Stage-Specific Enhancers (RNA-seq data set)
| PRJNA445652 | ENA
Project description:Previous studies have shown that forced expression of core cardiogenic transcription factors can directly reprogram fibroblasts to induced cardiomyocyte-like cells (iCMs). This cardiac reprogramming approach suggests a potential strategy for cardiomyocyte regeneration. However, a major challenge of this approach remains the low conversion rate. Here, we showed that ensuring expression of four cardiogenic transcription factors (i.e. Gata4 (G), Hand2 (H), Mef2c (M), and Tbx5 (T)) in individual fibroblasts is an initial bottleneck for cardiac reprogramming. Following co-transduction of three or four retroviral vectors encoding individual cardiogenic transcription factors, only a minor subpopulation of cells indeed expressed all three (GMT) or four (GHMT) factors. By selectively analyzing subpopulations of cells expressing various combinations of reprogramming factors, we found that co-expression of GMT in individual fibroblasts is sufficient to induce sarcomeric proteins. However, only a small fraction of those cells expressing GMT were able to develop organized sarcomeric structures and contractility. In contrast, ensuring expression of GHMT markedly enhanced the development of contractile cardiac structures and functions in fibroblasts, although its incremental effect on sarcomeric protein induction was relatively small. Our findings provide new insights into the mechanistic basis of inefficient cardiac reprogramming and can help to devise efficient reprogramming strategies.
| S-EPMC6482135 | biostudies-literature
Project description:The modular DNA recognition code of the transcription-activator-like effectors (TALEs) from plant pathogenic bacterial genus Xanthomonas provides a powerful genetic tool to create designer transcription factors (dTFs) targeting specific DNA sequences for manipulating gene expression. Previous studies have suggested critical roles of enhancers in gene regulation and reprogramming. Here, we report dTF activator targeting the distal enhancer of the Pou5f1 (Oct4) locus induces epigenetic changes, reactivates its expression, and substitutes exogenous OCT4 in reprogramming mouse embryonic fibroblast cells (MEFs) to induced pluripotent stem cells (iPSCs). Similarly, dTF activator targeting a Nanog enhancer activates Nanog expression and reprograms epiblast stem cells (EpiSCs) to iPSCs. Conversely, dTF repressors targeting the same genetic elements inhibit expression of these loci, and effectively block reprogramming. This study indicates that dTFs targeting specific enhancers can be used to study other biological processes such as transdifferentiation or directed differentiation of stem cells.
| S-EPMC3757749 | biostudies-literature
Project description:Arabidopsis PR1 is a salicylic acid (SA) inducible marker gene for systemic acquired resistance (SAR). However, the regulation of PR1 in plants is poorly understood. In this study, we showed that AtWRKY50 transcription factor binds to two promoter elements of PR1 via its DNA binding domain. Interestingly, the DNA-binding sites for AtWRKY50 deviate significantly from the consensus WRKY binding W-box. The binding sites are located in close proximity to the binding sites for TGA transcription factors. Transactivation experiments in Arabidopsis protoplasts derived from wild type, npr1-1 and tga256 mutant plants indicated that AtWRKY50 alone was able to induce expression of a PR1::?-glucuronidase (GUS) reporter gene, independent of TGAs or NPR1. However, co-expression of TGA2 or TGA5 with AtWRKY50 synergistically enhanced expression to high levels. Yeast-2-hybrid assays and bimolecular fluorescence complementation (BiFC) experiments revealed that AtWRKY50 could interact with TGA2 and TGA5. Using electrophoretic mobility shift assays (EMSA) it was established that AtWRKY50 and TGA2 or TGA5 simultaneously bind to the PR1 promoter. Taken together, these results support a role of AtWRKY50 in SA-induced expression of PR1. Highlights: AtWRKY50 specifically binds to LS10 region of PR1 promoter and interacts with TGAs to synergistically activate PR1 expression.
| S-EPMC6053526 | biostudies-literature
Project description:Direct reprogramming of cardiac fibroblasts (CFs) to induced cardiomyocytes (iCMs) is a newly emerged promising approach for cardiac regeneration, disease modeling, and drug discovery. However, its potential has been drastically limited due to the low reprogramming efficiency and largely unknown underlying molecular mechanisms. We have previously screened and identified epigenetic factors related to histone modification during iCM reprogramming. Here, we used shRNAs targeting an additional battery of epigenetic factors involved in chromatin remodeling and RNA splicing factors to further identify inhibitors and facilitators of direct cardiac reprogramming. Knockdown of RNA splicing factors Sf3a1 or Sf3b1 significantly reduced the percentage and total number of cardiac marker positive iCMs accompanied with generally repressed gene expression. Removal of another RNA splicing factor Zrsr2 promoted the acquisition of CM molecular features in CFs and mouse embryonic fibroblasts (MEFs) at both protein and mRNA levels. Moreover, a consistent increase of reprogramming efficiency was observed in CFs and MEFs treated with shRNAs targeting Bcor (component of BCOR complex superfamily) or Stag2 (component of cohesin complex). Our work thus reveals several additional epigenetic and splicing factors that are either inhibitory to or required for iCM reprogramming and highlights the importance of epigenetic regulation and RNA splicing process during cell fate conversion.
| S-EPMC5878887 | biostudies-literature