Mechanisms by which phosphorylation and protein partners regulate Cx45

连接蛋白是整合的膜蛋白，其寡聚化以形成间隙连接通道。间隙 连接组成的Cx43介导的电耦合和脉冲传播的正常 工作心肌在衰竭的心脏中，Cx43重构（表达减少， 闰盘、侧膜处存在增加）导致室性心律失常。 然而，衰竭的心脏也异常上调心室中Cx45的表达， 通常在很低的水平。这大大增强了心律失常的倾向，逻辑上是由于 Cx45通道相对于Cx43具有低电导和高电压敏感性。关键是， Cx45在闰盘上的有害作用可能被Cx45的倾向放大， 与Cx43形成异聚体通道，其中Cx43对Cx43的功能具有主导作用。 产生的频道。不幸的是，人们对驱动Cx45存在的机制知之甚少。 闰盘或Cx45的功能特性的决定因素，使其 存在于心室闰盘危险。具体目标1和2中提议的研究 探讨Cx45羧基端磷酸化（Cx45 CT）的新机制 结构域调节Cx45蛋白伴侣相互作用以增加或减少间隙连接 体外和体内的细胞间通讯（以及与对Cx43影响的差异）。具体 目的3的重点是确定如何最近发现的高亲和力蛋白质-蛋白质相互作用， Cx45 CT二聚化影响通道功能特性。这一提议的意义 发现了CT结构域磷酸化和相互作用是如何被调节的 将使策略，以改善病理改变的连接蛋白衰竭的心脏， 其他地方

Connexins are integral membrane proteins that oligomerize to form gap junction channels. Gap junctions composed of Cx43 mediate electrical coupling and impulse propagation in the normal working myocardium. In the failing heart, Cx43 remodeling (decreased expression, loss at intercalated discs, increased presence at lateral membranes) contributes to ventricular arrhythmias. However, the failing heart also aberrantly upregulates expression of Cx45 in ventricles, where it is normally at very low levels. This greatly enhances the propensity for arrhythmias, logically due to the low conductance and high voltage-sensitivity of Cx45 channels relative to Cx43. Crucially, the deleterious effect of Cx45 at the intercalated discs is likely amplified by the propensity of Cx45 to form heteromeric channels with Cx43, in which it has a dominant effect on the function of the resulting channels. Unfortunately, little is known about the mechanisms that drive Cx45 presence at intercalated discs or about the determinants of the functional properties of Cx45 that make its presence at ventricular intercalated discs dangerous. Studies proposed in Specific Aims 1 and 2 address novel mechanisms by which phosphorylation of the Cx45 carboxyl terminal (Cx45CT) domain modulates Cx45 protein partner interactions to increase or decrease gap junction intercellular communication in vitro and in vivo (and the differences from effects on Cx43). Specific Aim 3 focuses on determining how a recently discovered high-affinity protein-protein interaction of the Cx45CT, dimerization, affects the channel functional properties. The significance of this proposal is that discovery of how phosphorylations and interactions of the CT domain can be modulated would enable strategies to ameliorate pathological alterations of connexins the failing heart and elsewhere.