Mechanisms of Gap Junction Regulation

 描述(由申请人提供)：缝隙连接是一种完整的膜蛋白，能够使相邻细胞之间的离子和低分子质量代谢物进行直接的细胞质交换。它们提供了一条传播和/或放大由细胞因子、生长因子和其他参与生长调节和发育的细胞信号分子触发的信号转导级联反应的途径。通过缝隙连接的细胞间通讯功能障碍与许多人类疾病的发生有关。该项目的目标是使用多学科方法来确定负责Cx43和Cx45功能的关键内在调控机制。中心假设是CXS发散CT结构域中独特的分子间相互作用影响缝隙连接调节。更具体地说，我们假设在衰竭的心脏中，Cx43CT的磷酸化改变了蛋白质伙伴的相互作用，导致Cx43从间盘重塑，Cx45 CTs的二聚化在一定程度上导致了Cx45的通道特性，使其有别于Cx43，并导致了Cx45在与Cx43的异构体通道中的显性-负向效应。众所周知，CXS的CT域是通道性质的关键调节因子，而胞浆结构域的二聚化是离子通道的关键调节因子。这一建议意义重大，因为发现如何调节CT结构域的相互作用将打开改善衰竭心脏Cx调节变化的病理效应的策略之门。研究这一概念的具体目的是：1)确定酪氨酸激酶如何下调Cx43缝隙连接的细胞间通讯；2)确定Cx43磷酸化如何改变蛋白质伴侣的相互作用；3)确定Cx45CT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.