Regulation of epicardial cell differentiation during development and disease

发育和疾病过程中心外膜细胞分化的调节

• 批准号: 8975800
• 负责人: Eric M Small
• 金额: $ 38.38万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-12-15 至 2018-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8975800
• 关键词: Address; Adult; Affect; Agonist; Apoptosis; Cardiac; Cardiac Myocytes; Cardiovascular Physiology; Cell Differentiation process; Cell Line; Cell physiology; Cells; Cicatrix; Complement Factor B; Complex; Contractile Proteins; Coronary; Coronary Vessels; Cues; Cytoplasm; Data; Development; Diffusion; Disease; Embryo; Embryonic Development; Epicardium; Fetal Heart; Fibroblasts; Fibrosis; Gene Activation; Gene Expression; Gene Expression Profile; Gene Targeting; Genes; Grant; Healed; Health; Heart; Histocompatibility Testing; Hypoxia; Injury; Invaded; Ischemia; Lead; Light; Mechanics; Mediating; Mesenchymal; Molecular; Mus; Myocardial Infarction; Myocardial Ischemia; Myocardium; Myofibroblast; Natural regeneration; Nuclear; Oxygen; Phenotype; Physiological; Population; Process; Production; Publishing; Regulation; Regulator Genes; Rho-associated kinase; Role; Serum Response Factor; Signal Transduction; Smooth Muscle Myocytes; Stem cells; Testing; Tissues; Transcriptional Regulation; WT1 gene; Work; angiogenesis; base; cardiac repair; cardiogenesis; cell motility; cell type; design; factor A; fetal; healing; heart cell; heart metabolism; myocardin; new therapeutic target; novel therapeutic intervention; precursor cell; programs; research study; response; rho; transcription factor

DESCRIPTION (provided by applicant): The epicardium is a single cell-layer mesothelial sheet that surrounds the heart and harbors a multi-potent progenitor cell population. Amazingly, epicardial-to-mesenchymal transition (EMT) leads to cardiac fibroblast and coronary vessel formation at the precise moment that diffusion fails to fuel the heart. The epicardial fetal gene program is re-awakened in ischemic heart disease and contributes to coronary neoangiogenesis and fibrosis. Surprisingly, none of the currently known regulatory mechanisms explain how EMT occurs in perfect synchrony with physiological demand. Serum response factor (SRF) is a widely expressed transcription factor that controls gene expression programs through interactions with tissue specific or signal responsive co- factors. Embryonic and adult cardiovascular function depends upon interactions between SRF and myocardin, which is specifically expressed in cardiomyocytes and smooth muscle cells, constitutively nuclear, and required for activation of genes encoding contractile proteins. Conversely, myocardin-related transcription factor (MRTF)-A and MRTF-B are broadly expressed, but held dormant in the cytoplasm until physiological signals lead to their nuclear accumulation. MRTF-A and -B promote differentiation of a mesenchymal / myofibroblast cell type in response to a growing list of agonists, including Rho-Rho kinase, TGF-¿1, and mechanical tension. Our recently published data reveal a critical role for MRTF-A in myofibroblast differentiation and scar formation following myocardial infarction. Our preliminary studies reveal SRF, MRTF-A and MRTF-B are enriched in the embryonic and adult epicardium and are required for EMT. Further, MRTF/SRF activity is induced by hypoxia and promotes a mesenchymal phenotype in cooperation with Wilms tumor 1 (WT1), including the coordinated regulation of guidance cues (Wnt signaling) and cytoskeletal components. Based on our preliminary data and the work of others, we hypothesize that physiological hypoxia in the epicardium promotes the synergistic interaction between MRTFs, SRF, and WT1 that drives EMT, coronary vessel formation and cardiac fibroblast production during development and disease. We will test this hypothesis with three Specific Aims that will define the molecular mechanisms underlying transcriptional regulation in the epicardium. Aim 1 will determine how MRTFs and SRF control epicardial cell function during development using conditional deletion of these factors and lineage tracing experiments in mice. Aim 2 will determine the transcriptional mechanism governing epicardial cell fate and function by defining the expression signature cooperatively regulated by SRF, MRTFs, and WT1 in the epicardium, and identify the physiological cues that modulate this gene regulatory axis. Aim 3 will define the role of MRTF-SRF in epicardial derived cell differentiation and cardiac function following myocardial infarction. These studies will test a paradigm-shifting hypothesis that explains the coordinated regulation of epicardial cell migration and differentiation by physiological cues and reveal novel therapeutic targets for the treatment of ischemic heart disease.

描述（由申请人提供）：心外膜是包围心脏的单细胞层间皮层，并含有多能祖细胞群。令人惊奇的是，心外膜间质转化（EMT）导致心脏成纤维细胞和冠状血管形成。在缺血性心脏病中，当扩散无法为心脏提供燃料时，心外膜冠状动脉胎儿基因程序被重新唤醒，并有助于新血管生成和令人惊讶的是，目前已知的调节机制都没有解释 EMT 如何与生理需求完美同步地发生。血清反应因子 (SRF) 是一种广泛表达的转录因子，通过与组织特异性或信号响应辅助因子相互作用来控制基因表达程序。胚胎和成人心血管功能取决于 SRF 和心肌素之间的相互作用，心肌素在心肌细胞和平滑肌细胞中特异性表达，是组成性核细胞，是激活编码离线收缩蛋白的基因所必需的。心肌素相关转录因子 (MRTF)-A 和 MRTF-B 广泛表达，但在细胞质中保持休眠状态，直到生理信号导致它们的核积累，从而促进间充质/肌成纤维细胞类型的分化。越来越多的激动剂，包括 Rho-Rho 激酶、TGF-¿我们最近发表的数据揭示了 MRTF-A 在心肌梗死后肌成纤维细胞分化和疤痕形成中的关键作用，我们的初步研究表明 SRF、MRTF-A 和 MRTF-B 在胚胎和成人心外膜和心外膜中丰富。此外，MRTF/SRF 活性是由缺氧诱导的，并与 Wilms 肿瘤 1 (WT1) 协同促进间充质表型，包括协调一致。根据我们的初步数据和其他人的工作，我们发现心外膜的生理性缺氧促进了 MRTF、SRF 和 WT1 之间的协同相互作用，从而驱动 EMT、冠状血管形成和我们将用三个具体目标来检验这一假设，这三个目标将定义心外膜转录调控的分子机制，目标 1 将如何确定。 MRTF 和 SRF 通过条件性删除这些因子来控制发育过程中的心外膜细胞功能，目标 2 将通过定义 SRF、MRTF 和 WT1 协同调节的表达特征来确定控制心外膜细胞命运和功能的转录机制。目标 3 将确定 MRTF-SRF 在心外膜衍生细胞分化和心脏功能中的作用。这些研究将检验一种范式转变的假设，该假设解释了生理信号对心外膜细胞迁移和分化的协调调节，并揭示了治疗缺血性心脏病的新治疗靶点。