Unlocking Trafficking Specificity for Cx43 Gap Junctions

离子通道功能紊乱是突发性心律失常的一个基本方面 心源性死亡。最近，人们越来越多地认识到心脏离子通道具有非常 半衰期短，疾病中离子通道功能紊乱的很大一部分是由改变的转运引起的 并将本地化更改为适当的子域。对细胞内贩运的监管仍然存在 对心脏离子通道知之甚少。 在以前的研究中，我们已经确定了连接蛋白43(Cx43)是如何通过缝隙连接半通道 以细胞骨架为基础的靶向输送至心脏间盘。最近，我们发现了一个 Cx43的内源截短异构体，交替翻译的GJA1-20k，是完整 Cx43正向转运和修复缺血所致的Cx43缝隙连接缺陷 本地化。我们的研究表明，GJA1-20k是通道和细胞器的关键分子 有动静。了解其在心肌细胞中作用的分子细节将揭示 通道定位的基本机制，并促进该分子的翻译使用 转化为新的和临床上重要的治疗策略。 本应用的目的是探索GJA1-20k的分子机制。 组织贩运公路。我们的中心假设是GJA1-20K，它在 发作的心肌应激，是一种强大的细胞骨架肌动蛋白核素构建的动力 运输公路对Cx43缝隙交汇处的运输至关重要。 我们在离子通道运输和识别GJA1-20k方面的专业知识，以及我们的细胞 生物工具和我们为这项提议生成的新小鼠模型，使我们能够成功地进行 通过追求两个具体目标来完成计划中的实验：1)GJA1-20K是形成GJA1-20K所必需的 Cx43在体内的缝隙连接？2)GJA1-20k是一种肌动蛋白核因子，能够构图细胞骨架吗？ 渠道传递的途径？ 一旦成功完成，预期结果将确定GJA1-20K是至关重要的 心肌细胞蛋白，其作用机制与肌动蛋白和微管有内在联系 细胞骨架，对基础健康的心脏很重要，在压力时期也是必不可少的。这样的结果 预计将产生积极影响，因为我们将引入一种新的治疗方法 (外源性GJA1-20K)，以限制致心律失常疾病的病理传播。同时，和 也许更长远的后果是，这些研究将有助于解决一个根本未解决的问题 蛋白质运输生物学中的谜团，即膜蛋白是如何直接输送到 它们各自的子域。

Disturbances in ion channel function is a fundamental aspect of the arrhythmias of sudden cardiac death. Recently, there has been is increased appreciation that cardiac ion channels have very short half lives, and much of disturbed ion channel function in disease results from altered trafficking and altered localization to the appropriate subdomain. Regulation of intracellular trafficking remains poorly understood for cardiac ion channels. In previous studies, we have identified how Connexin43 (Cx43) gap junction hemichannels undergo cytoskeleton based Targeted Delivery to cardiac intercalated discs. Recently, we found an endogenous truncated isoform of Cx43, the alternatively translated GJA1-20k, which is essential to full length Cx43 forward trafficking and can rescue ischemia induced defects in Cx43 gap junction localization. Our studies reveal that GJA1-20k is a critical molecule for channel and organelle movement. Understanding the molecular details of its role in cardiac muscle cells will reveal fundamental mechanisms of channel localization and also facilitate translational use of this molecule into novel and clinically important therapeutic strategies. The objective of this application is to explore the molecular mechanisms by which GJA1-20k organizes trafficking highways. Our central hypothesis is that GJA1-20k, which increases during episodes of myocardial stress, is a powerful cytoskeleton actin nucleator that builds the dynamic trafficking highways essential for Cx43 gap junction delivery. Our expertise in ion channel trafficking and identification of GJA1-20k, as well as our cell biological tools and the new mouse model we generated for this proposal, allow us to successfully carry out the planned experiments by pursuing two specific aims: 1) Is GJA1-20k essential to the formation of Cx43 gap junctions in vivo? 2) Is GJA1-20k an actin nucleator, capable of patterning cytoskeleton pathways for channel delivery? Once successfully completed, the expected outcomes are to identify that GJA1-20k is a vital cardiomyocyte protein whose mechanism of action is inherently linked to the actin and microtubule cytoskeleton, is important in baseline healthy heart, and essential during times of stress. Such results are expected to have a positive impact because we will have introduced a new therapeutic approach (exogenous GJA1-20k) to limit pathologic trafficking in arrhythmogenic disease. At the same time, and perhaps of even more long-term consequence, the studies will help resolve a fundamental unsolved mystery in the biology of protein trafficking which is how membrane proteins are delivered directly to their respective subdomain.