Epigenetic reprogramming of cardiac myofibroblasts for cardiac repair

项目总结 心力衰竭与心脏成纤维细胞(Fib)的激活有关，后者促进心脏纤维化和 病理性心脏重塑。利用成年小鼠心脏的单细胞RNA测序(scRNA-seq)，我们 发现Zust同源物增强子2(EZH2)是已知催化转录的主要酶 抑制标记H3K27me3在特定的POSTN+Fib亚群(肌成纤维细胞，MFib)中高表达。 值得注意的是，对EZH2在调节心脏MFib中的功能作用知之甚少，这是一种关键知识 GAP由于其表观遗传变异性和病理作用。我们证明，尽管这些MFib Express GATA4是一个早期的心脏转录因子，它们不表达心血管祖细胞(CPC)基因 程序，如NKX2.5。重要的是，EZH2的缺失抑制了MFib的增殖并开启了 心血管祖细胞(CPC)基因计划。此外，EZH2基因的缺失增加了促血管生成 MFib的旁分泌作用和改善心肌梗死后的心功能 在给予新型rAAV-flex-DTA载体的小鼠中，心功能丧失，该载体可消融MFib缺乏 EZH2，证实了该细胞群的重要功能。这些发现表明，EZH2是一种 抑制MFib向有益表型的转变以及对EZH2的抑制提供了一种独特的 抑制MFib增殖同时激活修复机制的治疗方法。的总目标是 这个项目是为了验证一个中心假设，即抑制肌成纤维细胞中的EZH2可以改变细胞的命运 从促纤维化的肌成纤维细胞转化为促血管生成的CPC，从而减轻纤维化，改善心脏 血管生成，并促进缺血心肌的心脏修复。这个提议的项目是创新的。 因为它将从心脏再生的新方法中产生独特的机械洞察力 将心肌成纤维细胞从增殖和促纤维化表型转变为促血管生成和促纤维化表型 再生表型。我们的重点是EZH2介导的染色质重塑在表观遗传抑制中的作用 GATA4介导的CPC计划具有翻译意义，因为EZH2抑制剂已在临床上使用 最近被批准用于治疗滤泡性淋巴瘤。我们的初步发现突出了这种可能性 使这一途径成为减轻心脏纤维化和促进心脏疾病的新策略的重点 缺血损伤后的血管生成。

PROJECT SUMMARY Heart failure is associated with activation of cardiac fibroblasts (Fib), which promotes cardiac fibrosis and pathological cardiac remodeling. Employing single-cell RNA-sequencing (scRNA-seq) in adult mouse hearts, we discovered that Enhancer of Zeste homolog 2 (EZH2), the major enzyme known to catalyze the transcriptional repression mark H3K27me3, is highly expressed in a specific POSTN+ Fib subpopulation (myofibroblasts, MFib). Of note, little is known about the functional role of EZH2 in regulating cardiac MFib, which is a critical knowledge gap given their epigenetic variability and pathological role. We demonstrate that although these MFib express GATA4, an early cardiac transcription factor, they fail to express the cardiovascular progenitor (CPC) gene programs, such as NKX2.5. Importantly, deletion of EZH2 inhibited MFib proliferation and switched on cardiovascular progenitor cell (CPC) gene programs. Moreover, deletion of EZH2 increased the pro-angiogenic paracrine effects of MFib and improved cardiac function post myocardial infarction (MI) These beneficial effects on cardiac function were lost in mice administered a novel rAAV-FLEX-DTA vector, which ablates MFib lacking EZH2, confirming the important functional role of this cell population. These findings suggest that EZH2 is a restraint on the transition of MFib to beneficial phenotypes and that inhibition of EZH2 provides a unique therapeutic approach to diminishing MFib proliferation while activating repair mechanisms. The overall goal of this project is to test the central hypothesis that EZH2 inhibition in myofibroblasts can transform the cell fate from pro-fibrotic myofibroblasts into pro-angiogenic CPC, thus attenuating fibrosis, improving cardiac angiogenesis, and boosting cardiac repair in the ischemic myocardium. This proposed project is innovative because it will generate unique mechanistic insights from novel approaches to cardiac regeneration by transforming cardiac myofibroblasts from a proliferative and pro-fibrotic phenotype to a pro-angiogenic and pro- regenerative phenotype. Our focus on EZH2-mediated chromatin remodeling in epigenetic repression of GATA4-mediated CPC program is translationally significant, as EZH2 inhibitors are available clinically and have recently been approved for the treatment of follicular lymphoma. Our preliminary findings highlight the potential for this pathway to be the focus of novel strategies for mitigating cardiac fibrosis and promoting cardiac angiogenesis after ischemic injury.