Mechanisms of Gap Junction Regulation

 描述（由申请人提供）：间隙连接是一种整合的膜蛋白，能够在相邻细胞之间进行离子和低分子量代谢物的直接细胞质交换。它们提供了一种传播和/或放大由细胞因子、生长因子和参与生长调节和发育的其他细胞信号分子触发的信号转导级联的途径。通过间隙连接的细胞间通讯功能障碍与许多人类疾病有关。本项目的目标是使用多学科的方法来确定负责Cx43和Cx45功能的关键内在调节机制。中心假设是，独特的分子间相互作用内的不同的CT域的Cx影响间隙连接调节。更具体地说，我们假设，在衰竭的心脏，Cx43 CT磷酸化改变蛋白伴侣的相互作用，导致Cx43从闰盘重塑，Cx45 CT的二聚化，部分负责Cx45的通道特性，使其与Cx43和Cx45在异聚体通道与Cx43的显性负效应。众所周知，Cx的CT结构域是通道特性的关键调节剂，并且胞质结构域的二聚化是离子通道的关键调节剂。这一建议是重要的，因为发现如何通过CT域介导的相互作用可以调制将打开大门的战略，以改善改变Cx调节的病理影响，在衰竭的心脏。本文拟从以下几个方面探讨这一概念：1）确定酪氨酸激酶如何下调Cx43间隙连接细胞间通讯，2）确定Cx43磷酸化如何改变蛋白质伴侣相互作用，3）确定Cx45 CT二聚化的重要性和机制。

 DESCRIPTION (provided by applicant): Gap junctions are integral membrane proteins that enable the direct cytoplasmic exchange of ions and low-molecular-mass metabolites between adjacent cells. They provide a pathway for propagating and/or amplifying the signal transduction cascades triggered by cytokines, growth factors, and other cell signaling molecules involved in growth regulation and development. Dysfunctional intercellular communication via gap junctions has been implicated in causing many human diseases. The objective of this project is to use a multi-disciplinary approach to identify the key intrinsic regulatory mechanisms that are responsible for Cx43 and Cx45 function. The central hypothesis is that unique intermolecular interactions within the divergent CT domain of Cxs affect gap junction regulation. More specifically, we hypothesize that in the failing heart, Cx43CT phosphorylation alters protein partner interactions leading to remodeling of Cx43 from the intercalated disc, and that dimerization of Cx45 CTs is, in part, responsible for the channel properties of Cx45 that distinguish it from Cx43 and for the dominant-negative effect of Cx45 in heteromeric channels with Cx43. It is well-known that the CT domains of Cxs are key regulators of channel properties, and that dimerization of cytosolic domains are key regulators of ion channels. This proposal is significant because discovery of how interactions mediated by the CT domain can be modulated would open the door to strategies to ameliorate the pathological effects of altered Cx regulation in the failing heart. The following Specific Aims are proposed to investigate this concept: 1) Define how tyrosine kinases down regulate Cx43 gap junction intercellular communication, 2) Determine how Cx43 phosphorylation alters protein partner interactions, and 3) Identify the importance and mechanism of Cx45CT dimerization.