Cytoskeletal networks and membrane architecture in heart

描述(由申请人提供)： 正常的心脏功能依赖于心脏的稳定和协调的组织和活动 肌膜、横管和肌浆网，但 人们对这些膜的组织和稳定知之甚少。这样做的长期目标是 研究建议是了解心肌细胞的膜系统是如何 以及它们如何相互作用以促进适当的心脏功能。为此，我们正在 研究心脏中的血影蛋白家族。幽灵蛋白是一个典型的 一大群丝状细胞骨架蛋白，称为幽灵蛋白超家族，它们是 负责支持和稳定肌膜和内膜系统。 心脏，它们的组织成不同的领域，以及肌膜的能力 传递收缩的力量。令人惊讶的是，人们只是粗略地研究了心脏中的幽灵蛋白，特别是因为它们的关键作用可能受到局部信号级联的调节。 包括磷酸化和去磷酸化。在这里，我们建议探索这一假设 幽灵蛋白超家族的细胞骨架结构 肌膜和T小管膜，并受蛋白激酶调节，负责 形成和稳定正常心脏功能所必需的膜区。 我们的研究表明，血影蛋白超家族的成员，包括dystrophin、bi-、AII-和BII-Spectrin，在心肌肌膜内表面形成一个高度交联的网络。 与横管相关的不同成分的血影蛋白网络(t- 小管)膜。这些幽灵蛋白的分子特征表明，它们的多样性， 这是由于选择性剪接以及使用不同的基因项目、靶点 它们与心肌中不同的膜结构域有关。磷酸化选择性地控制 这些领域的组织或稳定，部分是通过调节它们与 幽灵。我们建议通过四个具体目标来探讨您的初步观察结果： (1)进一步表征基于血影蛋白的膜骨架复合体，其组织和 支持心脏肌膜；(2)识别和表征专门的 缝隙连接处的血影蛋白网络；(3)确定血影蛋白的组织和功能 与T-管膜相关的网络；以及(4)确定磷酸化的效果 在T-Tubues的幽灵网络上。作为膜细胞骨架蛋白突变的基础 扩张型心肌病，我们的结果应该阐明一些基本的细胞生物学 心脏病的机制。

DESCRIPTION (provided by applicant): Proper cardiac function relies on the stability and coordinated organization and activity of the sarcolemma, the transverse tubules and the sarcoplasmic reticulum, yet the structures that organize and stabilize these membranes are barely understood. The long-range goal of this research proposal is to understand how the membrane systems of cardiac muscle cells are organized and how they interact to promote proper cardiac function. To this end, we are studying the spectrin family of proteins in the heart. Spectrin is the prototypical member of a large group of filamentous cytoskeletal proteins called the 'spectrin superfamily' that are responsible for supporting and stabilizing the sarcolemma and internal membrane systems in the heart, their organization into distinct domains, and the ability of the sarcolemma to transduce the force of contraction. Surprisingly, the spectrins have been studied only cursorily in the heart, especially as their key roles are likely to be regulated by local signaling cascades involving phosphorylation and dephosphorylation. Here we propose to explore the hypothesis that the cytoskeletal structures created by the spectrin superfamily of proteins at the sarcolemma and t-tubule membranes, and regulated by protein kinases, are responsible for the formation and stabilization of membrane domains necessary for proper cardiac function. Our studies show that members of the spectrin superfamily, including dystrophin, bI-, aII- and bII-spectrin, form a highly crosslinked network on the inner surface of the cardiac sarcolemma. Spectrin networks for a different composition associate with transverse tubule (t- tubule) membranes. Molecular characterization of the spectrins indicates that their diversity, which results from alternative splicing as well as from the use of different gene projects, targets them to different membrane domains in cardiac muscle. Phosphorylation selectively controls the organization or stability of these domains, in part by regulating their association with spectrin. We propose to pursue thee preliminary observations through four specific aims: (1) to characterize further the spectrin-based membrane skeletal complex that organizes and supports the cardiac sarcolemmal membrane;(2) to identify and characterize the specialized spectrin network at gap junctions; (3) to determine the organization and function of spectrin networks associated with t-tubule membranes; and (4) to define the effect of phosphorylation on the spectrin network at t-tubules. As mutations in membrane-cytoskeletal proteins underlie dilated cardiomyopathies, our results should elucidate some of the basic cell biological mechanisms of heart disease.