Molecular Mechanisms for Atrial Fibrillation in Aging

衰老过程中心房颤动的分子机制

基本信息

批准号：
9098782
负责人：
Sami Fouad Noujaim
金额：
$ 37.41万
依托单位：
UNIVERSITY OF SOUTH FLORIDA
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-07-01 至 2020-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9098782
关键词：
Acetylcholine Action Potentials Address Age Aging Arrhythmia Atrial Fibrillation Biochemical Cardiac Cells Chimeric Proteins Crystallization Data Development Disease Elderly Electric Stimulation Electrophysiology (science)Genetically Engineered Mouse Goals Heart Heart Atrium Heat shock proteins Hydrogen Peroxide Incidence Ion Channel Ions Knock-out Knockout Mice Lead Link Mediating Molecular Molecular Biology Molecular Conformation Molecular Models Morbidity - disease rate Mus Muscarinics Muscle Cells Optics Organ Oxidative Stress Pathway interactions Pharmacology Phosphatidylinositol 4,5-Diphosphate Phosphatidylinositols Phosphorylation Population Potassium Prevalence Resolution Roentgen Rays Role Signal Pathway Structure Techniques Testing X-Ray Crystallography aged biophysical analysis catalase clinical practice heart rhythm in vivo innovation insight models and simulation molecular dynamics molecular modeling mortality novel overexpression patch clamp protein kinase C epsilon protein structure public health relevance targeted agent

项目摘要

DESCRIPTION (provided by applicant): In clinical practice, atrial fibrillation (AF) is the most common heart rhythm disturbance, and a major cause of morbidity and mortality. The incidence of AF increases greatly with age, and given the aging of our overall population, its prevalence is rising at alarming rates. Yet the treatment of AF remains inadequate due in part to our relatively poor understanding of AF pathoelectrophysiology. In this application, we propose to focus on aging mediated AF. The goal is to investigate previously unexplored direct mechanistic links between aging, oxidative stress, the acetylcholine sensitive inward rectifier potassium current IKACh, and AF. We will test the hypothesis that the increased oxidative stress in aged atria activates PKCepsilon, which in turn phosphorylates Kir3.1- a molecular correlate of IKACh, leading to muscarinic stimulation independent constitutively active IKACh, shortening of action potential duration, and AF perpetuation. Our preliminary data support our hypothesis and show that: 1-) aging promotes the phosphorylation of Kir3.1 and leads to the constitutive activation of IKACh, 2-) oxidative stress activates PKCepsilon, phosphorylates Kir3.1, and shortens the atrial action potential due to a constitutively active IKACh, and facilitates the development of rotors responsible for AF, and 3)- phosphorylation of Kir3.1 initiates conformational changes which could increase the channel's interaction with its activator PIP2, and result in the opening of the channel's intracellular ion permeation pathway. We will test our hypothesis in 3 specific aims: 1-) To investigate the molecular and signaling pathways leading to constitutively active IKACh in aging, through oxidative stress and PKCepsilon mediated Kir3.1 phosphorylation; 2-) To determine the structural changes that occur in Kir3.1 phosphorylated by PKCepsilon, with X-ray crystallography and molecular dynamics simulations; and 3-) To study the role of aging, PKCepsilon and constitutively active IKACh in the inducibility and dynamics of atrial fibrillation. We will make simultaneous use of several complementary and powerful techniques (X-ray crystallography, molecular modeling, molecular biology, single cell, and whole organ electrophysiology) to test our aims and to investigate from the protein structure, to the multicellular level, the details of how aging modifies the structure and function of an ion channel leading to proarrhythmic electrical changes in the atria. We postulate that the studies proposed will increase our understanding of AF pathoelectrophysiology, and could direct the identification of antifibrillatory pathway targets, and the development of novel, specific, and effective anti-atral fibrillation agents.

描述（由申请人提供）：在临床实践中，心房颤动（AF）是最常见的心律失常，也是发病率和死亡率的主要原因。房颤的发病率随着年龄的增长而大大增加，并且考虑到我们总体人口的老龄化。其患病率正在以惊人的速度上升，但部分由于我们对 AF 病理电生理学的了解相对不足，我们建议重点关注衰老介导的 AF。研究先前未探索过的衰老、氧化应激、乙酰胆碱敏感内向整流钾电流 IKACh 和 AF 之间的直接机制联系。我们将检验以下假设：老年心房氧化应激增加会激活 PKCepsilon，进而磷酸化 Kir3.1-一种分子。 IKACh 相关，导致独立于毒蕈碱刺激的组成型活性 IKACh、动作电位持续时间缩短和 AF我们的初步数据支持我们的假设并表明：1-) 衰老促进 Kir3.1 磷酸化并导致 IKACh 的组成性激活，2-) 氧化应激激活 PKCepsilon，磷酸化 Kir3.1，并缩短心房作用。由于 IKACh 具有组成型活性，因此具有潜力，并促进负责 AF 的转子的发育，以及 3)- 磷酸化Kir3.1 引发构象变化，这可能会增加通道与其激活剂 PIP2 的相互作用，并导致通道的细胞内离子渗透途径打开。我们将在 3 个具体目标中检验我们的假设：1-) 研究通过氧化应激和 PKCepsilon 介导的 Kir3.1 磷酸化导致衰老过程中 IKACh 持续活跃的分子和信号传导途径；2-) 通过 X 射线晶体学和分析确定 PKCepsilon 磷酸化的 Kir3.1 中发生的结构变化；分子动力学模拟；和 3-) 研究衰老、PKCepsilon 和组成型活性 IKACh 在诱导性和心房颤动的动力学。我们将同时使用多种互补且强大的技术（X射线晶体学、分子建模、分子生物学、单细胞和全器官电生理学）来测试我们的目标，并从蛋白质结构到多细胞水平、细节进行研究我们假设所提出的研究将增加我们对房颤病理电生理学的理解，并可以指导抗纤颤通路的识别。目标，以及开发新型、特异性和有效的抗心房颤动药物。