TET-mediated epigenetic regulation in cardiac development.

项目概要/摘要 基因表达的表观遗传调控途径密切参与了早期免疫缺陷的调控。 病理性应激下心脏发育和心脏重塑。扰乱心脏转录 在心脏早期发育和心脏再生过程中的网络可能导致心脏疾病。在所有的 作为已知的表观基因组修饰物，10 - 11易位（泰特）蛋白家族是相对较新的成员 在哺乳动物基因组中，它被发现介导DNA甲基化的逆转。泰特双加氧酶（TET 1 -3） 能够将5-甲基胞嘧啶（5 mC）转化为5-羟甲基胞嘧啶（5 hmC）并进一步氧化 物种，从而促进活性DNA去甲基化。5 mC/5 hmC分布的动态变化， 转录重编程在早期CM发展中起着至关重要的作用，这是一个关键时期，也提供了 研究心脏基因的基本表观遗传调控机制的最佳时间窗口 转录。我们自己的初步研究表明，小鼠体内泰特蛋白的遗传缺失， 心肌细胞（CM）发育。在细胞水平上，Tet-deficient CM进一步表现出降低的 增殖和代谢功能障碍。在分子水平上，在泰特缺失后，我们观察到大量的 DNA甲基化的改变和染色质结构的紊乱，这可能是导致DNA甲基化的破坏的原因。 心脏转录网络和参与增殖的关键代谢基因的异常表达， 糖酵解和线粒体呼吸。我们假设Tet-mediated DNA去甲基化 信号通路对于维持适当的染色质可及性和染色质成环至关重要，从而调节 转录编程来指导CM开发。心脏特异性泰特的即时可用性 三重基因敲除小鼠模型，以及一套创新的工具，开发用于精确映射和编辑 DNA修饰，使我们处于一个极具竞争力的地位，以解开新的表观遗传调控 控制CM发展的机制。在目的1中，我们将定义泰特/5 hmC如何调节染色质 可及性和关键转录因子与其靶标的结合， 输出并保持适当的CM开发。在目标2中，我们将研究泰特/5 hmC如何调节染色质 通过与关键基因组位点上的增强子和绝缘子元件相互作用形成环以控制代谢基因 在CM发展过程中。在完成建议的研究后，我们预期会设立一个 新的范式，通过引入一个以前未被充分认识的层面，在表观遗传调控的 心血管系统我们提出的研究结果也将提供新的见解， 负责心脏基因转录和心脏发育的机制，从而形成坚实的基础 用于开发潜在的表观遗传疗法，以预防和治疗先天性心脏病。

Project Summary/Abstract Epigenetic regulatory pathways governing gene expression are intimately involved in the regulation of early heart development and cardiac remodeling under pathological stress. Disrupting the cardiac transcriptional networks during early heart development and cardiac regeneration may lead to heart diseases. Among all the known epigenomic modifiers, the Ten-Eleven Translocation (TET) protein family is a relatively new member found to mediate the reversal of DNA methylation in the mammalian genome. The TET dioxygenases (TET1-3) are capable of converting 5-methylcytosine (5mC) to 5-hydroxymethyl-cytosine (5hmC) and further oxidized species, thereby promoting active DNA demethylation. The dynamic changes in 5mC/ 5hmC distributions and transcriptional reprogramming play vital roles during early CM development, a critical period that also provides an optimal time window to study fundamental epigenetic regulatory mechanisms that govern cardiac gene transcription. Our own preliminary studies revealed that genetic depletion of Tet proteins in mice impaired early cardiomyocyte (CM) development. At the cellular level, Tet-deficient CMs further exhibited reduced proliferation and metabolic dysfunction. At the molecular level, upon Tet deletion, we observed massive changes in DNA methylation and a disorganized chromatin architecture that might account for disrupted cardiac transcriptional networks and abnormal expression of key metabolic genes involved in proliferation, glycolysis and mitochondrial respiration in CMs. We hypothesize that the Tet-mediated DNA demethylation pathway is critical for maintaining proper chromatin accessibility and chromatin looping, thereby regulating transcriptional programming to instruct CM development. The immediate availability of a cardiac-specific Tet triple knockout mouse model, as well as a set of innovative tools developed for precise mapping and editing of DNA modifications, has placed us in an extremely competitive position to unravel novel epigenetic regulatory mechanisms controlling CM development. In Aim 1, we will define how Tet/5hmC regulate chromatin accessibility and the binding of key transcriptional factors to their targets to program essential transcriptional outputs and maintain proper CM development. In Aim 2, we will examine how Tet/5hmC regulate chromatin looping by interplaying with enhancer and insulator elements at critical genomic loci to control metabolic gene expression during CM development. Upon completion of our proposed studies, we anticipate to establish a new paradigm by introducing a previously underappreciated dimension in the epigenetic regulation of the cardiovascular system. Findings from our proposed studies will also provide novel insights into the molecular mechanisms responsible for cardiac gene transcription and heart development, thereby forming a solid basis for developing potential epigenetic therapies to prevent and treat congenital heart diseases.