Connexin-based Signaling in the Heart: Cellular and Exosomal

心脏中基于连接蛋白的信号传导：细胞和外泌体

• 批准号: 10553255
• 负责人: ROBERT G GOURDIE
• 金额: $ 84.53万
• 依托单位: VIRGINIA POLYTECHNIC INST AND ST UNIV
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-20 至 2028-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10553255
• 关键词: Actins; Action Potentials; Acute; Animal Model; Anti-Arrhythmia Agents; Area; Arrhythmia; Biomedical Engineering; Brain; Cardiac; Cardiology; Clinical; Collaborations; Complex; Connexin 43; Connexins; Coupling; Data; Drug Design; Drug Targeting; Gap Junctions; Goals; Heart; Hour; Human; Knockout Mice; Mammals; Medicine; Mutation; Myocardial; Myocardial Infarction; Myocardium; Phase; Phase III Clinical Trials; Production; Protein Isoforms; Proteins; Reporting; Role; Severities; Signal Transduction; Skin; Sodium Channel; Sudden Death; Testing; Therapeutic; Tissues; Translating; Ventricular; Virus; exosome; heart preservation; human female; in silico; induced pluripotent stem cell; invention; ischemic injury; novel; novel therapeutic intervention; peptidomimetics; pharmacologic; porcine model; response; superresolution imaging; voltage

PROJECT ABSTRACT/SUMMARY The gap junction (GJ) protein Connexin 43 (Cx43) has long been held to be obligate for conduction of action potential (AP) in the ventricular myocardium. However, accumulating evidence during the last two decades from non-mammals, Cx43 knockout mice and human Cx43 mutations suggests that Cx43 GJs do not provide a sufficient explanation for how AP propagates in the heart – and indeed, that Cx43 GJs may be dispensable for cardiac conduction. Based on its short half (~1.5 hours), we recently estimated that on average the human female heart produces more than 80 grams of Cx43 per year – a rate more than 30-times that of actin, the most abundant myocardial protein in steady state. My lab is focused on two questions that are raised by these data. First, what is the mechanism of AP propagation in the ventricle, if Cx43 GJ-based coupling alone cannot account for this phenomenon? Second, if not absolutely required for cardiac conduction, for what purpose does the heart produce Cx43 at such high rates? In recently reported studies, we have determined that: A) Trans- interacting complexes of voltage-gated sodium channels (trans-VGSCs) located at the GJ edge (the perinexus) contribute to cardiac conduction; and B) That the Cx43 carboxyl terminus (CT) has key roles in modulating the heart's response to ischemic injury. Building on these findings, the goals of this project are to: 1) Determine the contribution of trans-VGSCs to cardiac AP propagation and the extent to which this mechanism operates independent of Cx43 GJ-based coupling; 2) Develop a pharmacologic approach to targeting trans-VGSCs as a novel anti-arrhythmic strategy; 3) Determine the extent to which the high levels of Cx43 production by the heart may be accounted for by recent findings that Cx43 is exported in exosomes; 4) Determine whether circulating exosomal Cx43, including Cx43 CT isoforms, are part of a natural signaling mechanism that modulates ischemic injury severity; and 5) Develop a novel therapeutic approach to treat myocardial infarction based on exosomes carrying Cx43 CT mimetic peptides, including translational testing in a large animal model – the pig. The project will involve cross-disciplinary collaboration between biologists, medicinal chemists, biomedical engineers and clinicians – both human and veterinary. The PI has genuine translational bona-fides, with a drug targeting the Cx43 CT invented in his lab currently in multiple Phase III clinical trials. State-of-the-art approaches will be used including super resolution imaging, in silico drug design, genetically modified viruses, iPSCs and testing of exosome-based therapeutics on large animal models. We posit that the primary assignment of myocardial Cx43 may not be in AP propagation. Rather, it is our hypothesis that the high energetic commitment to Cx43 production made by the heart, and other tissues (e.g., skin, vasculature and brain), relates mainly to functions of Cx43 in an exosome-based signaling mechanism that modulates response to ischemic injury in humans and other mammals. This R35 project seeks to challenge prevailing views on the role of the GJ protein Cx43 and translate the new perspectives gained for clinical benefit in treatment of arrhythmia and myocardial infarction.

项目摘要/总结 间隙连接 (GJ) 蛋白 Connexin 43 (Cx43) 长期以来一直被认为负责传导作用 心室肌电位（AP）。然而，过去二十年里不断积累的证据 非哺乳动物、Cx43 敲除小鼠和人类 Cx43 突变表明 Cx43 GJ 不提供 充分解释 AP 如何在心脏中传播——事实上，Cx43 GJ 对于心脏的传播可能是可有可无的 心脏传导。根据其较短的一半（约 1.5 小时），我们最近估计，平均而言，人类女性 心脏每年产生超过 80 克 Cx43，这一速度是最丰富的肌动蛋白的 30 倍多 心肌蛋白处于稳态。我的实验室专注于这些数据提出的两个问题。第一的， 如果仅基于 Cx43 GJ 的耦合无法解释 AP 在心室中传播的机制是什么 这种现象？其次，如果心脏传导不是绝对需要的，那么心脏传导的目的是什么？ CX43的生产率这么高？在最近报道的研究中，我们确定：A）反式 位于 GJ 边缘（perinexus）的电压门控钠通道（trans-VGSC）的相互作用复合物 有助于心脏传导； B) Cx43 羧基末端 (CT) 在调节 心脏对缺血性损伤的反应。基于这些发现，该项目的目标是： 1) 确定 跨 VGSC 对心脏 AP 传播的贡献以及该机制运作的程度 独立于基于 Cx43 GJ 的耦合； 2) 开发一种针对跨 VGSC 的药理学方法 新颖的抗心律失常策略； 3) 确定心脏产生高水平 Cx43 的程度 可能是由于最近发现 Cx43 在外泌体中输出； 4）判断是否循环 外泌体 Cx43，包括 Cx43 CT 亚型，是调节缺血的天然信号传导机制的一部分 伤害严重程度； 5）开发一种基于外泌体治疗心肌梗塞的新方法 携带 Cx43 CT 模拟肽，包括在大型动物模型（猪）中进行转化测试。项目 将涉及生物学家、药物化学家、生物医学工程师和 临床医生——包括人类和兽医。 PI 具有真正的转化诚意，其药物针对的是 他的实验室发明的 Cx43 CT 目前正在进行多项 III 期临床试验。将使用最先进的方法 包括超分辨率成像、计算机药物设计、转基因病毒、iPSC 和测试 基于外泌体的大型动物模型疗法。我们假设心肌 Cx43 的主要分配 可能不在 AP 传播中。相反，我们的假设是对 Cx43 的高能量承诺 由心脏和其他组织（例如皮肤、脉管系统和大脑）产生的物质主要与 Cx43 在基于外泌体的信号传导机制中调节人类和其他组织对缺血性损伤的反应 哺乳动物。该 R35 项目旨在挑战关于 GJ 蛋白 Cx43 作用的普遍观点，并将其转化为 心律失常和心肌梗塞治疗的临床益处获得了新的视角。