Regulation of Cav1.2 Trafficking by GJA1-20k and cBIN1

正常心脏横管(T管)浓缩L型钙通道 (LTCCs)启动搏动至搏动的细胞内钙瞬变，这有助于调节 心脏收缩和松弛。改变的钙瞬变是一个关键的病理生理学标志 心脏衰竭。然而，在T-小管微区维持LTCC表达的机制 最佳的钙诱导钙释放(CICR)仍然知之甚少。了解动态 T-管钙处理微区的调节，特别是LTCC在 微域，是理解心力衰竭的病理生理学和识别新的 可作为心力衰竭治疗发展靶点的途径和分子。 这个MPI应用程序的总体目标是进一步机械地理解 T-微管cBIN1微区LTCC的表达及LTCC定位改变的原因 心力衰竭。我们将探索这样一个中心假设，即T小管上的动态平衡LTCC表达是 高度动态，并通过内部交付和外部交付进行维护。我们预计， 内部递送由Z盘中组织的LTCC的细胞内肌动蛋白库决定，由 新发现的肌动蛋白核转录因子GJA1-20k(Aim 1，RMS)。我们还预计会有一个当地的 CBIN1囊泡的胞外储存库(Aim 2，TTH)，它从 心脏的其他区域来调节T管表面的LTCC表达。在心力衰竭方面，两者 能源正在枯竭，但可能会通过外源恢复。 膜生物实验室(TTH)和人口贩运实验室的资源集中在心力衰竭上 进展(RMS)在本申请中被结合到拟议的研究计划中。其基本原理是 这项研究的基础是t-微管微区的LTCC是动态调节的 从内到外，心力衰竭的发生率都有所降低，并且可以恢复，这是一种新的治疗方法 治疗心力衰竭。 拟议的研究具有创新性，因为它将确定新的监管机制 在心力衰竭进展过程中重塑心肌，并导致分子的建立 以及可用于治疗开发的靶向途径。这项提议有很强的前提 因为它是基于大量发表的和成功的体外无细胞培养的初步数据 研究，完整细胞系和原代心肌细胞研究，以及成功的遗传和活体动物 心力衰竭模型。它的意义很高，因为它将导致新的治疗方法的发展 将允许保存和恢复有效的兴奋-收缩偶联的策略 病态的心脏。

In normal hearts, the transverse tubules (t-tubules) concentrate L-type calcium channels (LTCCs) to initiate the beat-to-beat intracellular calcium transients which contribute to the regulation of cardiac contraction and relaxation. An altered calcium transient is a key pathophysiological sign of failing heart. However, mechanisms of maintenance of LTCC expression at t-tubule microdomains for optimal calcium-induced-calcium-release (CICR) remain poorly understood. Understanding the dynamic regulation of calcium handling microdomains at t-tubules, and in particular LTCC regulation at the microdomains, is needed to understand the pathophysiology of failing hearts and to identify new pathways and molecules that can be targeted for heart failure therapy development. The overall objective of this MPI application is to further our mechanistic understanding of how LTCC expression at t-tubule cBIN1-microdomains is maintained and why LTCC localization is altered in heart failure. We will explore the central hypothesis that homeostatic LTCC expression at t-tubules is highly dynamic and maintained by both internal delivery and external delivery. We expect that the internal delivery is determined by intracellular actin reservoirs of LTCCs organized at Z-disks by a newly identified actin nucleator GJA1-20k (Aim 1, RMS). We also expect that there is a local extracellular reservoir of cBIN1 vesicles (Aim 2, TTH), which feed t-tubule cBIN1-microdomains from other regions of the heart to modulate LTCC expression at t-tubule surfaces. In heart failure, both sources are depleted yet could be exogenously restored. The resources of a membrane biology lab (TTH) and a trafficking lab focused on heart failure progression (RMS) are combined in this application for the proposed research plan. The rationale that underlies the proposed research is that LTCCs at t-tubule microdomains are dynamically regulated from both inside and out, are reduced in heart failure, and can be restored presenting a novel therapy for heart failure. The proposed research is innovative because it will identify new regulatory mechanisms of remodeled myocardium during heart failure progression, and lead to the establishment of molecules and pathways that can be targeted for therapy development. The proposal has a strong premise because it is based on extensive published and preliminary data from successful in vitro cell-free studies, intact cell line and primary cardiomyocyte studies, and successful genetic and in vivo animal heart failure models. The significance is high because it will lead to development of new therapeutic strategies that will allow preservation and restoration of efficient excitation-contraction coupling in diseased hearts.