Left-right asymmetry and PITX2 in atrial fibrillation

项目总结 房颤是美国最常见的持续性心律失常，其终生风险为25%。 占所有心血管疾病的三分之一。与房颤相关的治疗和护理费用约为26美元 仅在美国就达到10亿/年，占所有医疗保险支出的10%。令人衰弱的并发症 与房颤有关的疾病包括心力衰竭和中风。遗传学和房颤风险之间的分子联系不是 很好地理解并在治疗和病人护理方面造成了巨大的知识鸿沟。通用编码 而成对的类同源域转录因子(Tf)PITX2的调节变体已经被 与房颤风险密切相关。PITX2最出名的是在发育过程中调节左右不对称。在……里面 在心脏中，PITX2在左房(LA)和肺静脉(PV)心肌中表达最常见 房颤触发点。Pitx2减少的小鼠模型容易患房颤，我最近的工作描述了 降低的Pitx2干扰了TF网络，并暗示了房颤风险的发育起源；然而，机制 是未知的。这项研究的中心假设是PITX2驱动左侧命运决定 通过表观遗传重塑，这将带来长期的转录后果 成人疾病。为了解决这一假设，第一个目的是研究依赖Pitx2的DNA 左右决定中的甲基组。原肠胚形成的左右不对称导致Pitx2的表达 在左心房，但不在右心房。我发现左右DNA甲基化模式的差异发生在 PITX2位点，提示PITX2调控DNA甲基化。在第二个目标中，我将调查PITX2的作用 氧化应激反应和动态平衡中的左右模式。PV提供富含氧气的血液，是唯一的 静脉这样做，从肺到LA，在左和右之间创造了生理上的氧合差异。 富氧环境容易产生氧化应激，从而增加房颤的风险。初步工作确定了一个 PITX2和氧化反应因子OXR1在LA中的新相互作用及以前的工作 PITX2通过应激反应因子Tf、NRF2参与缺血后的氧化应激反应。这一目标 旨在阐明PITX2在介导氧化应激和房颤的发展中的作用，房颤是一种易驯服的 早期干预途径。最后，我将对PITX2的分子机制进行研究 转录抑制。在LA中，PITX2主要起抑制因子的作用。我发现了一种新的相互作用 PITX2与组蛋白H4R3的COPRS-PRMT5精氨酸甲基转移酶复合体之间的相互作用 甲基化，一种压抑的标记。此外，依赖PRMT5的H4R3甲基化可以逆转，这表明 PITX2调控基因表达的机制。总而言之，拟议的项目旨在了解 PITX2在房颤患者左房表观遗传模式形成中的作用这项拟议的研究采用了一种新的方法来 询问PITX2基因调控网络，并为该领域开发几种新的试剂和数据集。 此外，通过这项工作，我希望为房颤患者的治疗提供更有针对性的方法。

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.