Dynamic changes of the Nav1.5 interactome and contributions to heart failure

由SCN5A编码的NaV1.5电压门控钠通道是 启动心脏动作电位的大分子蛋白质复合体。NaV1.5功能异常是 遗传性和获得性心律失常的显著基础，反映在令人震惊的 已识别的NaV1.5突变的阵列。其中一小部分与扩张型心肌病有关 但其潜在的机制尚不清楚。一个主要的假说是，心律失常导致了 心肌病，不能解释为什么大多数致心律失常的NaV1.5突变不会导致 也不知道为什么敲除NaV1.5相互作用蛋白FGF13会导致心律失常 保护压力超负荷导致的心力衰竭(HF)，尽管相关的NaV1.5功能障碍。 此外，其他原因引起的心衰导致病理性重构，从而破坏VGSC的调节。 大分子复杂，并通过鲜为人知的机制增加心律失常的风险。 复杂的机制洞察是，不同的亚细胞定义了不同的NaV1.5池 与心肌细胞的定位，每个假设都有蛋白质伙伴唯一地定义 不同的池，并授予特定的通道属性和功能。然而，关键的合作伙伴仍然 由于低吞吐量“最受欢迎的”候选方法的挑战，人们对此知之甚少。 我们提出了一种无偏见的多级发现策略，采用了新开发的第二级发现策略 新一代邻近标记工具，新颖的鼠标模型，再加上经过精心校准的十字 旨在增加我们发现的特异性的比较。利用两个实验室的专业知识 个人和协作记录应用大型工具集来剖析复杂的生理 机制和定义病理状态下的扰动，我们提出了适应性的候选验证 建立生理状态和生理状态下NAV1.5相互作用的全面图像的方法 当受到疾病的困扰时。通过这些创新方法，我们建议：1)定义静态和 不同亚细胞池中的动态NaV1.5通道相互作用和“邻域”；2)阐明 高频如何改变NaV1.5微环境；以及3)确定高频对消融的保护作用 NaV1.5交互角色，FGF13。 有了这些目标，我们的目标是定义NaV1.5大分子对 心力衰竭及其相关心律失常的发展和进展以及心力衰竭是如何扰乱心脏的 NaV1.5复合体会增加心律失常的风险，并在恶性循环中加剧心衰。

The NaV1.5 voltage-gated Na+ channel encoded by SCN5A is the fundamental component of macromolecular protein complexes that initiate the cardiac action potential. Abnormal NaV1.5 function is a prominent substrate for inherited and acquired forms of cardiac arrhythmias, reflected by a staggering array of identified NaV1.5 mutations. A small subset of these are associated with dilated cardiomyopathy but the underlying mechanisms are not known. A leading hypothesis, that the arrhythmias drive the cardiomyopathy, cannot explain why most arrhythmogenic NaV1.5 mutations do not cause cardiomyopathy nor why knockout of the NaV1.5 interacting protein FGF13 leads to arrhythmias yet is protective for pressure overload-induced heart failure (HF) despite associated NaV1.5 dysfunction. Moreover, HF from other causes leads to pathological remodeling that disrupts regulation of the VGSC macromolecular complex and increases arrhythmia risk through mechanisms that are poorly understood. Complicating mechanistic insight is that there are different NaV1.5 pools defined by distinct subcellular localizations with the cardiomyocyte, each hypothesized to have protein partners that uniquely define the distinct pools and confer specific channel properties and functions. However, the critical partners remain poorly understood because of challenges of low throughput “favorite” candidate approaches. We propose an unbiased multilevel discovery strategy, employing newly developed second generation proximity labeling tools, novel mouse models, coupled with carefully calibrated cross comparisons designed to increase the specificity of our findings. Exploiting the expertise from two labs with individual and collaborative track records applying a large tool set to dissect complex physiologic mechanisms and define perturbations in pathological states, we propose adaptable candidate validation approaches to establish a comprehensive picture of NaV1.5 interactomes under physiological states and when perturbed by disease. With these innovative approaches we propose to: 1) Define the static and dynamic NaV1.5 channel interactomes and “neighborhoods” within distinct subcellular pools; 2) Elucidate how HF alters the NaV1.5 microenvironment; and 3) Determine the HF-protective effects for ablation of the NaV1.5 interactor, FGF13. With these aims, our goals are to define the contributions of the NaV1.5 macromolecular to development and progression of HF and its associated arrhythmias and to unravel how HF perturbs the NaV1.5 complex to increase arrhythmia risk and exacerbate HF in a vicious cycle.