Elucidation of the Role for PHF7 in Direct Reprogramming of Fibroblasts to Cardiomyocytes

项目摘要 缺血性心脏病是全球发病率、死亡率和医疗保健支出的主要原因 心脏在受伤后不能再生。心肌梗塞(MI)后，心肌细胞 经历大量的细胞死亡并通过激活驻留的心脏成纤维细胞(CFs)，被非 可收缩的纤维性疤痕，最终导致心力衰竭。旨在促进心力衰竭的新疗法 心肌细胞的再生是迫切需要的。近年来，驻地中心直接重新编制方案，以 诱导的心肌样细胞(ICLM)已成为一种有希望的治疗策略，以改变纤维化的目的 受损心脏对功能心肌的反应。心脏直接重编程最初是 通过转录因子(TF)Gata4、MeF2C和Tbx5(GMT)的过表达实现；后来， Hand2(GHMT)和Akt1(AGHMT)被发现在胚胎和新生儿细胞类型中促进这一过程。 然而，这些鸡尾酒在重新编程成人人类和老鼠方面取得的成功有限 成纤维细胞，限制了这种疗法的临床翻译。我们实验室对哺乳动物进行了筛查。 发现成人成纤维细胞心脏重编程新调控因子的基因调控因子 组蛋白阅读器PHF7是最有效的激活因子。在目前正在修订的工作中，我们有 证明PHF7能够显著激活成人人和小鼠成纤维细胞的重编程 在加入五因素重编程时增加心脏超级增强剂的染色质可及性 鸡尾酒。然而，目前还不知道PHF7需要哪些转录因子才能以最佳方式促进 成人心脏重编程。我们的初步数据支持PHF7是一个关键调节因子的总体假设 体外培养的成体成纤维细胞转化成有功能的心肌细胞 体内存在较少的心脏转录因子。为了探索这一假设，我将讨论 以下目标：(1)确定使用PHF7实现成人心脏重编程所必需的因素，以及(2) 目的：明确PHF7在体内改善心肌梗死后心功能的能力。完成 这些研究将加强我们对成人心脏重编程所必需的因素的理解。 细胞类型，并阐明这种转化所必需的机制。此外，这些研究可能会 为开发一种新的心脏重编程治疗因子提供基础 缺血性心脏病。拟议的研究将在大型、高生产率的 埃里克·N·奥尔森博士，德克萨斯大学西南医学中心博士。所有学习和职业发展 将在奥尔森博士的指导下进行，奥尔森博士是心脏直接重新编程领域的先驱。

Project Summary Ischemic heart disease is the leading cause of morbidity, mortality, and healthcare expenditure worldwide due to an inability of the heart to regenerate following injury. Following myocardial infarction (MI), cardiomyocytes undergo massive cell death and through activation of resident cardiac fibroblasts (CFs), are replaced by non- contractile fibrotic scar, ultimately leading to heart failure. Novel heart failure therapies aimed at promoting cardiomyocyte regeneration are desperately needed. In recent years, direct reprogramming of resident CFs to induced cardiac-like myocytes (iCLMs) has emerged as a promising therapeutic strategy to repurpose the fibrotic response of the injured heart toward a functional myocardium. Direct cardiac reprogramming was initially achieved through the overexpression of the transcription factors (TFs) Gata4, Mef2c, and Tbx5 (GMT); later, Hand2 (GHMT) and Akt1 (AGHMT) were found to enhance this process in embryonic and neonatal cell types. However, these cocktails have demonstrated limited success in reprogramming adult human and mouse fibroblasts, constraining the clinical translation of this therapy. Our laboratory undertook a screen of mammalian gene regulatory factors to discover novel regulators of cardiac reprogramming in adult fibroblasts and identified the histone reader PHF7 as the most potent activating factor. In work currently under revision, we have demonstrated the ability of PHF7 to markedly activate reprogramming in adult human and mouse fibroblasts by increasing chromatin accessibility at cardiac super enhancers when added to a five-factor reprogramming cocktail. However, it is not yet known which transcription factors are necessary for PHF7 to optimally facilitate adult cardiac reprogramming. Our preliminary data support the overall hypothesis that PHF7 is a critical regulator of cardiac cell fate conversion and potently reprograms adult fibroblasts to functional cardiomyocytes in vitro and in vivo in the presence of fewer cardiac transcription factors. To explore this hypothesis, I will address the following aims: (1) to define the factors necessary to achieve adult cardiac reprogramming with PHF7, and (2) to define the ability of PHF7 to improve cardiac function following myocardial infarction in vivo. Completion of these studies will enhance our understanding of the factors necessary to achieve cardiac reprogramming in adult cell types and elucidate the mechanisms necessary for this conversion. Further, these studies will potentially provide the basis for development of a novel therapeutic factor in cardiac reprogramming for the treatment of ischemic heart disease. The proposed studies will be performed in the large and highly productive laboratory of Dr. Eric N. Olson, PhD at University of Texas Southwestern Medical Center. All studies and career development will be carried out under the guidance of Dr. Olson, a pioneer in the field of direct cardiac reprogramming.