Department of Biological Sciences, Lehigh University, 111 Research Drive, Iacocca Hall, Bethlehem, PA 18015, USA.
Department of Biological Sciences, Lehigh University, 111 Research Drive, Iacocca Hall, Bethlehem, PA 18015, USA.
FEBS Lett. 2014 Mar 3;588(5):836-44. doi: 10.1016/j.febslet.2014.01.048. Epub 2014 Jan 31.
Gap junctions (GJs) traverse apposing membranes of neighboring cells to mediate intercellular communication by passive diffusion of signaling molecules. We have shown previously that cells endocytose GJs utilizing the clathrin machinery. Endocytosis generates cytoplasmic double-membrane vesicles termed annular gap junctions or connexosomes. However, the signaling pathways and protein modifications that trigger GJ endocytosis are largely unknown. Treating mouse embryonic stem cell colonies - endogenously expressing the GJ protein connexin43 (Cx43) - with epidermal growth factor (EGF) inhibited intercellular communication by 64% and activated both, MAPK and PKC signaling cascades to phosphorylate Cx43 on serines 262, 279/282, and 368. Upon EGF treatment Cx43 phosphorylation transiently increased up to 4-fold and induced efficient (66.4%) GJ endocytosis as evidenced by a 5.9-fold increase in Cx43/clathrin co-precipitation.
间隙连接（GJ）穿过相邻细胞的膜，通过信号分子的被动扩散来介导细胞间通讯。我们之前已经表明，细胞利用网格蛋白机制内吞 GJ。内吞作用会产生细胞质双层膜囊泡，称为环形间隙连接或连接小体。然而，触发 GJ 内吞的信号通路和蛋白修饰在很大程度上仍是未知的。用表皮生长因子（EGF）处理内源性表达 GJ 蛋白连接蛋白 43（Cx43）的小鼠胚胎干细胞集落，可使细胞间通讯抑制 64%，并激活 MAPK 和 PKC 信号级联反应，使 Cx43 的丝氨酸 262、279/282 和 368 磷酸化。在 EGF 处理后，Cx43 的磷酸化短暂增加了 4 倍，并诱导了有效的（66.4%）GJ 内吞作用，这可以通过 Cx43/网格蛋白共沉淀增加 5.9 倍来证明。
