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

在正常心脏中，横小管（t-小管）集中L-型钙通道 （LTCCs）启动心跳到心跳的细胞内钙瞬变，这有助于调节 心脏收缩和舒张。钙瞬变的改变是一个关键的病理生理学标志， 心脏衰竭然而，LTCC在t-小管微区表达的维持机制， 最佳钙诱导钙释放（CICR）仍然知之甚少。了解动态 调节t-小管处的钙处理微区，特别是 微区，是需要了解的病理生理学衰竭的心脏，并确定新的 可以用于心力衰竭治疗开发的靶向途径和分子。 这个MPI应用程序的总体目标是进一步加深我们对如何 LTCC在t-小管cBIN 1-微结构域的表达得以维持，以及为什么LTCC定位在 心衰我们将探讨中心假设，即稳态LTCC表达在t-小管， 高度动态化，由内部交付和外部交付共同维护。我们预计 内部递送由LTCC的细胞内肌动蛋白库决定，所述细胞内肌动蛋白库由 新鉴定的肌动蛋白成核剂GJA 1 - 20 k（Aim 1，RMS）。我们还希望有一个当地的 cBIN 1囊泡的细胞外储库（Aim 2，TTH），其从 心脏的其他区域来调节T-小管表面的LTCC表达。在心力衰竭中， 资源枯竭，但可以从外部恢复。 一个膜生物学实验室（TTH）和一个专注于心力衰竭的贩运实验室的资源 研究进展（RMS）在本申请中结合了拟议的研究计划。的基本原理 这项研究的基础是，t-小管微区的LTCC是动态调节的， 从内到外，在心力衰竭中减少，并且可以恢复，这是一种新的治疗方法 治疗心力衰竭 拟议的研究是创新的，因为它将确定新的监管机制， 心力衰竭进展期间心肌重塑，并导致分子的建立 以及可以用于治疗开发的途径。这个提议有一个很强的前提 因为它是基于大量已发表的和初步的数据， 完整细胞系和原代心肌细胞研究，以及成功的遗传和体内动物研究 心力衰竭模型其意义是高的，因为它将导致新的治疗方法的开发 策略，将允许保存和恢复有效的兴奋-收缩耦合， 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.