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

由SCN 5A编码的NaV 1.5电压门控Na+通道是 启动心脏动作电位的大分子蛋白质复合物。NaV1.5功能异常 遗传性和获得性心律失常的主要基质，反映在惊人的 一系列已鉴定的NaV1.5突变。其中一小部分与扩张型心肌病有关 但其潜在机制尚不清楚。一个主要的假设，即心律失常驱动 心肌病，不能解释为什么大多数致瘤性NaV1.5突变不会引起 心肌病，也不知道为什么敲除NaV1.5相互作用蛋白FGF 13会导致心律失常， 尽管存在相关的NaV1.5功能障碍，但仍能保护压力超负荷诱导的心力衰竭（HF）。 此外，其他原因引起的HF导致病理性重塑，破坏VGSC的调节 大分子复合物和增加心律失常的风险，通过机制知之甚少。 复杂的机制见解是，不同的亚细胞定义了不同的NaV1.5池， 定位与心肌细胞，每一个假设有蛋白质的合作伙伴，独特地定义了 不同的池，并赋予特定的通道特性和功能。然而，关键的合作伙伴仍然是 由于低吞吐量的“最喜欢的”候选方法的挑战，人们对其了解甚少。 我们提出了一个公正的多级发现策略，采用新开发的第二 一代邻近标记工具，新颖的小鼠模型，加上精心校准的交叉 比较旨在增加我们发现的特异性。利用两个实验室的专业知识 个人和合作的跟踪记录应用大型工具集来解剖复杂的生理 机制和定义扰动的病理状态，我们提出了适应性候选验证 建立生理状态下NaV1.5相互作用组的全面图片的方法， 当被疾病困扰时。通过这些创新的方法，我们建议：1）定义静态和 不同亚细胞池内的动态NaV1.5通道相互作用组和“邻域”; 2）阐明 HF如何改变NaV1.5微环境;以及3）确定消融的HF保护作用。 NaV1.5相互作用因子FGF 13。 有了这些目标，我们的目标是确定NaV1.5大分子对 HF及其相关心律失常的发展和进展，并阐明HF如何干扰 NaV1.5复合物增加心律失常风险并加剧HF的恶性循环。

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.