El-Sabban Marwan E, Abi-Mosleh Lina F, Talhouk Rabih S
Department of Human Morphology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.
J Mammary Gland Biol Neoplasia. 2003 Oct;8(4):463-73. doi: 10.1023/B:JOMG.0000017432.04930.76.
Gap junctions play a critical role in the development and differentiation of many tissues. Formed by the joining of two connexons on opposing membranes of two cells, gap junctions permit passage of ions and small molecules. Six connexins (Cx) belonging to a family of closely related tetraspan transmembrane proteins form a connexon. Connexin expression peaks in lactation, and those identified in the gland, thus far, are Cx26, Cx30, Cx32, and Cx43. Cx43 associates with myoepithelial cells, while others associate with epithelial and ductular cells. In vitro, assembly of functional gap junctions appears to be essential for differentiation of mammary epithelial cells. However, the role of gap junction intercellular communication (GJIC) in differentiation and growth remains unclear. Recent evidence challenges the view that gap junctions are simply pore-forming proteins and suggests that cell adhesion-associated proteins interact with the cytosolic carboxy-terminus of connexins and participate in signaling events. The possible implications on mammary cell function are discussed.
缝隙连接在许多组织的发育和分化中起着关键作用。缝隙连接由两个细胞相对膜上的两个连接子连接形成，允许离子和小分子通过。属于密切相关的四跨膜蛋白家族的六种连接蛋白（Cx）形成一个连接子。连接蛋白的表达在哺乳期达到峰值，迄今为止在腺体中鉴定出的连接蛋白是Cx26、Cx30、Cx32和Cx43。Cx43与肌上皮细胞相关，而其他连接蛋白与上皮细胞和导管细胞相关。在体外，功能性缝隙连接的组装似乎是乳腺上皮细胞分化所必需的。然而，缝隙连接细胞间通讯（GJIC）在分化和生长中的作用仍不清楚。最近的证据对缝隙连接仅仅是成孔蛋白的观点提出了挑战，并表明细胞粘附相关蛋白与连接蛋白的胞质羧基末端相互作用并参与信号转导事件。文中讨论了其对乳腺细胞功能的可能影响。
