Gap junctions mediate direct cell-to-cell communication by forming channels that physically couple cells, thereby linking their cytoplasm, permitting the exchange of molecules, ions, and electrical impulses. Gap junctions are assembled from connexin (Cx) proteins, with connexin 43 (Cx43) being the most ubiquitously expressed and best studied. While the molecular events that dictate the Cx43 life cycle have largely been characterized, the unusually short half-life of connexins of only 1-5 hours, resulting in constant endocytosis and biosynthetic replacement of gap junction channels has remained puzzling. The Cx43 C-terminal (CT) domain serves as the regulatory hub of the protein affecting all aspects of gap junction function. Here, deletion within the Cx43 CT (amino acids 256-289), a region known to encode key residues regulating gap junction turnover is employed to examine the effects of dysregulated Cx43 gap junction endocytosis using cultured cells (Cx43^∆256-289) and a zebrafish model (cx43^lh10). We report that this CT deletion causes defective gap junction endocytosis as well as increased gap junction intercellular communication (GJIC). Increased Cx43 protein content in cx43^lh10 zebrafish, specifically in the cardiac tissue, larger gap junction plaques and longer Cx43 protein half-lives coincide with severely impaired development. Our findings demonstrate for the first time that Cx43 gap junction endocytosis is an essential aspect of gap junction function and when impaired, gives rise to significant physiological problems as revealed here for cardiovascular development and function.

间隙连接通过形成物理耦合细胞的通道来介导细胞间的直接通讯，从而连接细胞质，允许分子、离子和电脉冲的交换。间隙连接由连接蛋白 (Cx) 蛋白组装而成，其中连接蛋白 43 (Cx43) 是最普遍表达和研究得最好的。虽然决定 Cx43 生命周期的分子事件在很大程度上已被表征，但连接蛋白异常短的半衰期仅为 1-5 小时，导致持续的内吞作用和间隙连接通道的生物合成替代仍然令人费解。Cx43 C 末端 (CT) 结构域作为蛋白质的调节中心，影响间隙连接功能的各个方面。在这里，Cx43 CT 内的缺失（氨基酸 256-289），^Δ256-289）和斑马鱼模型（cx43 ^lh10）。我们报告这种 CT 缺失会导致间隙连接内吞作用缺陷以及间隙连接细胞间通讯 (GJIC) 增加。cx 43 ^lh10斑马鱼中 Cx43 蛋白含量增加，特别是在心脏组织中，更大的间隙连接斑块和更长的 Cx43 蛋白半衰期与严重受损的发育相吻合。我们的研究结果首次表明，Cx43 间隙连接内吞作用是间隙连接功能的一个重要方面，当受损时，会引起显着的生理问题，如本文所揭示的心血管发育和功能。