Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada.
Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada.
J Cell Sci. 2024 Apr 1;137(7). doi: 10.1242/jcs.261631. Epub 2024 Apr 17.
Connexins are channel-forming proteins that function to facilitate gap junctional intercellular communication. Here, we use dual cell voltage clamp and dye transfer studies to corroborate past findings showing that Cx31.1 (encoded by GJB5) is defective in gap junction channel formation, illustrating that Cx31.1 alone does not form functional gap junction channels in connexin-deficient mammalian cells. Rather Cx31.1 transiently localizes to the secretory pathway with a subpopulation reaching the cell surface, which is rarely seen in puncta reminiscent of gap junctions. Intracellular retained Cx31.1 was subject to degradation as Cx31.1 accumulated in the presence of proteasomal inhibition, had a faster turnover when Cx43 was present and ultimately reached lysosomes. Although intracellularly retained Cx31.1 was found to interact with Cx43, this interaction did not rescue its delivery to the cell surface. Conversely, the co-expression of Cx31 dramatically rescued the assembly of Cx31.1 into gap junctions where gap junction-mediated dye transfer was enhanced. Collectively, our results indicate that the localization and functional status of Cx31.1 is altered through selective interplay with co-expressed connexins, perhaps suggesting Cx31.1 is a key regulator of intercellular signaling in keratinocytes.
连接蛋白是形成通道的蛋白，其功能是促进缝隙连接细胞间通讯。在这里，我们使用双细胞电压钳和染料转移研究来证实过去的发现，即 Cx31.1（由 GJB5 编码）在缝隙连接通道形成中存在缺陷，表明 Cx31.1 单独在缝隙连接缺陷型哺乳动物细胞中不能形成功能性缝隙连接通道。相反，Cx31.1 瞬时定位于分泌途径，亚群到达细胞表面，这在类似于缝隙连接的斑点中很少见。细胞内保留的 Cx31.1 被降解，因为 Cx31.1 在蛋白酶体抑制存在的情况下积累，当 Cx43 存在时其周转率更快，最终到达溶酶体。尽管细胞内保留的 Cx31.1 被发现与 Cx43 相互作用，但这种相互作用并不能挽救其向细胞表面的转运。相反，Cx31 的共表达显著挽救了 Cx31.1 组装到缝隙连接中的情况，其中缝隙连接介导的染料转移增强。总的来说，我们的结果表明，Cx31.1 的定位和功能状态通过与共表达的连接蛋白的选择性相互作用而改变，这可能表明 Cx31.1 是角质形成细胞细胞间信号传递的关键调节剂。
