MOLECULAR STUDIES OF GAP JUNCTION REMODELING

描述（改编自申请人的摘要）几条研究线索表明，间隙连接细胞间通讯的失调或间隙连接重塑有助于室性心律失常的底物。 使用犬梗死模型，本计划的研究表明，间隙连接的结构位置和间隙连接的电生理特性的变化与折返回路中阻滞的功能线相关。在人类缺血性心肌病和我们对室性心动过速和心脏性猝死的转基因小鼠的研究中也观察到了类似的缝隙连接重构。然而，肌病性心脏表现出多种结构和功能的紊乱，因此，独特的心律失常一直难以研究孤立的其他贡献因素。本提案中描述的研究的目标是了解间隙连接重塑的分子机制，并确定失调的细胞间偶联对促炎底物形成的具体贡献。因此，申请人已经开始阐明控制间隙连接表达和重塑的机制，并发现Wnt信号级联通过双重转录和翻译后机制通过β-连环蛋白起作用，是控制连接蛋白43表达的重要调节途径。此外，他们还制备了几种条件下的基因靶向小鼠模型，以阐明重塑在致炎底物形成中的作用。他们的目标是使用基因靶向和嵌合小鼠在连接重构、传导异常和心肌发生中的作用; 2）确定β-连环蛋白介导的信号传导的作用及其与正常和重构的心肌细胞和心脏中的Cx43表达的调节中的其他信号传导途径的关系; 3）确定缝隙连接折返激发的机制。阐明调节缝隙连接重构的机制及其在致心律失常底物中的作用对致死性心律失常的新药物治疗具有重要意义。

Description (Adapted from Applicant's Abstract) Several lines of investigation suggest that dysregulation of gap junction intercellular communication, or gap junctional remodeling, contributes to the substrate for ventricular arrhythmias. Using the canine infarct model, investigations in this Program have shown that changes in the structural location of gap junctions and the electrophysiological properties of gap junctions are associated with functional lines of block in reentrant circuits. Similar gap junctional remodeling has also been observed in human ischemic cardiomyopathy and in our studies of genetically modified mice with ventricular tachycardia and sudden cardiac death. Myopathic hearts, however, show a multitude of structural and functional perturbations, thus, the unique arrhythmias has been difficult to study in isolation from other contributory factors. The goal of the studies described in this proposal is to understand the molecular mechanisms of gap junctional remodeling and to determine the specific contribution of dysregulated intercellular coupling to the formation of the arrhythmogenic substrate. The applicant has, therefore, begun to elucidate mechanisms controlling gap junctional expression and remodeling and discovered that the Wnt signaling cascade, acting through beta-catenin via duel transcriptional and post-translational mechanisms, is an important regulatory pathway controlling connexin43 expression. Furthermore, they have prepared several conditions gene-targeted murine models to elucidate the role of remodeling in formation of the arrhythmogenic substrate. Their goals in junctional remodeling, conduction abnormalities and arrhythmogenesis, using gene-targeted and chimeric mice; 2) to determine the role of beta-catenin mediated signaling and its relationship with other signaling pathways in the regulation of Cx43 expression in normal and remodeled cardiomyocytes and hearts; 3) to determine the mechanisms responsible for gap junctional reentrant excitation appears to be related to changes in gap junction distribution. Elucidation of the mechanisms regulating gap junctional remodeling and its role in the arrhythmogenic substrate have significant implications for novel pharmacotherapy of lethal cardiac arrhythmias.