Left-right asymmetry and PITX2 in atrial fibrillation

项目摘要 房颤（AF）是美国最常见的持续性心律失常，终生风险为25%， 占所有心血管疾病的三分之一。与AF相关的治疗和护理费用约为26美元 仅在美国，每年就有10亿美元，占所有医疗保险支出的10%。使人衰弱的并发症 与房颤相关的疾病包括心力衰竭和中风。遗传学和房颤疾病风险之间的分子联系不是 这是一个很好理解的问题，并对治疗性疗法和病人护理造成了重大的知识差距。共同编码 配对样同源结构域转录因子（TF）PITX 2的调节变异已经被 与房颤风险密切相关。PITX 2最为人所知的是在发育过程中调节左右不对称。在 在心脏中，PITX 2在左心房（LA）和肺静脉（PV）心肌中表达，这是最常见的 AF的触发点。Pitx 2减少的小鼠模型容易受到AF的影响，我最近的工作描述了如何 Pitx 2的减少扰乱了TF网络，并暗示了AF风险的发育起源;然而， 不明这项研究的中心假设是PITX 2驱动左侧命运决定 通过表观遗传重塑，这赋予了持久的转录后果， 成人疾病为了解决这个假设，第一个目标是研究Pitx 2依赖的DNA 甲基化组左右决定。原肠胚形成中建立的左右不对称导致Pitx 2表达 左心房没有右心房我发现左右DNA甲基化模式的差异发生在 PITX 2位点，表明PITX 2调节DNA甲基化。在第二个目标中，我将研究PITX 2的作用 氧化应激反应和体内平衡中的左右模式。肺静脉输送富氧血液， 静脉这样做，从肺到LA，在左和右之间的氧合中产生生理差异。 富氧环境容易产生氧化应激，导致房颤风险。确定的初步工作a PITX 2和氧化反应因子OXR 1在LA中的新相互作用，以及先前的工作 提示PITX 2通过应激反应TF、NRF 2参与缺血后的氧化应激反应。这一目标 旨在阐明PITX 2在介导氧化应激和AF发展中的作用， 早期干预的途径。最后，我们将探讨PITX 2的分子机制 转录抑制主要地，PITX 2在LA中充当阻遏物。我发现了一种新的互动 PITX 2和能够与组蛋白H4 R3结合的COPRS-PRMT 5精氨酸甲基转移酶复合物之间的相互作用 甲基化，一种压抑的标记。此外，PRMT 5依赖性H4 R3甲基化可以逆转，表明 通过PITX 2调节基因表达的机制。总而言之，拟议项目旨在了解 PITX 2在AF背景下LA表观遗传模式中的作用。该研究采用了一种新的方法， 询问PITX 2基因调控网络，并为该领域开发了几种新的试剂和数据集。 此外，通过这项工作，我希望获得更有针对性的方法在房颤患者护理的见解。

PROJECT SUMMARY Atrial fibrillation (AF) is the most common sustained arrhythmia in the United States with a 25% lifetime risk, and accounts for one-third of all cardiovascular diseases. Treatment and care associated with AF costs roughly $26 billion/year in the United States alone and accounts for 10% of all Medicare spending. Debilitating complications linked to AF include heart failure and stroke. The molecular links between genetics and AF disease risk are not well understood and pose a significant knowledge gap for curative therapies and patient care. Common coding and regulatory variations of the paired-like homeodomain transcription factor (TF), PITX2, have been resoundingly linked to AF risk. PITX2 is best known for regulating left-right asymmetry during development. In the heart, PITX2 is expressed in the left atrial (LA) and pulmonary vein (PV) myocardium, the most common trigger sites for AF. Mouse models of reduced Pitx2 are susceptible to AF, and my recent work describes how decreased Pitx2 perturbs TF networks and hints at a developmental origin of AF risk; however, the mechanism is unknown. The central hypothesis for this study is that PITX2 drives left-sided fate determination through epigenetic remodeling, which imparts long-lasting transcriptional consequences underlying adult disease. To address this hypothesis, the first aim proposes to investigate the Pitx2-dependent DNA methylome in left-right determination. Left-right asymmetry established in gastrulation leads to Pitx2 expression in the left but not right atria. I have uncovered that the left-right DNA methylation patterning differences occur at PITX2 sites, suggesting PITX2 regulates DNA methylation. In the second aim, I will investigate the role of PITX2 left-right patterning in oxidative stress response and homeostasis. The PV delivers oxygen-rich blood, the only vein to do so, to the LA from the lungs, creating a physiological distinction in oxygenation between left and right. Oxygen-rich environments are prone to oxidative stress, contributing to AF risk. Preliminary work identified a novel interaction between PITX2 and the oxidative response factor, OXR1, in the LA, and previous work implicates PITX2 in oxidative stress response following ischemia through stress-response TF, NRF2. This aim is designed to illuminate the role of PITX2 in mediating oxidative stress and the development of AF, a tractable pathway for early intervention. In the final aim, I will investigate the molecular mechanisms of PITX2 transcriptional repression. Predominantly, PITX2 acts as a repressor in the LA. I identified a novel interaction between PITX2 and the COPRS-PRMT5 arginine methyltransferase complex capable of histone H4R3 methylation, a repressive mark. Furthermore, PRMT5-dependent H4R3 methylation can be reversed, suggesting a mechanism of tunable gene expression by PITX2. Altogether, the proposed project aims to understand the role of PITX2 in epigenetic patterning of the LA in context of AF. The proposed study takes a novel approach to interrogating the PITX2 gene regulatory network and develops several new reagents and datasets for the field. Furthermore, through this work, I hope to gain insights for more targeted approaches in AF patient care.