Department of Anatomy, Cardiovascular Research Institute, and UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California 94143-0452, USA.
Cold Spring Harb Perspect Med. 2022 Dec 1;12(12):a041178. doi: 10.1101/cshperspect.a041178.
Button-like junctions are discontinuous contacts at the border of oak-leaf-shaped endothelial cells of initial lymphatic vessels. These junctions are distinctively different from continuous zipper-like junctions that create the endothelial barrier in collecting lymphatics and blood vessels. Button junctions are point contacts, spaced about 3 µm apart, that border valve-like openings where fluid and immune cells enter lymphatics. In intestinal villi, openings between button junctions in lacteals also serve as entry routes for chylomicrons. Like zipper junctions that join endothelial cells, buttons consist of adherens junction proteins (VE-cadherin) and tight junction proteins (claudin-5, occludin, and others). Buttons in lymphatics form from zipper junctions during embryonic development, can convert into zippers in disease or after experimental genetic or pharmacological manipulation, and can revert back to buttons with treatment. Multiple signaling pathways and local microenvironmental factors have been found to contribute to button junction plasticity and could serve as therapeutic targets in pathological conditions ranging from pulmonary edema to obesity.
瓣状连接是初始淋巴管的呈橡树叶状内皮细胞边缘的不连续接触。这些连接与在收集淋巴管和血管中形成内皮屏障的连续拉链状连接明显不同。瓣状连接是点状接触，间隔约 3 µm，位于瓣膜样开口的边缘，液体和免疫细胞由此进入淋巴管。在肠绒毛中，乳糜管之间瓣状连接的开口也可作为乳糜微粒进入的途径。像连接内皮细胞的拉链连接一样，瓣状连接由黏着连接蛋白（VE-钙黏蛋白）和紧密连接蛋白（claudin-5、occludin 等）组成。淋巴管中的瓣状连接是在胚胎发育过程中由拉链连接形成的，可以在疾病或实验性遗传或药理学操作后转化为拉链连接，并可以通过治疗恢复为瓣状连接。已经发现多种信号通路和局部微环境因素有助于瓣状连接的可塑性，并可作为从肺水肿到肥胖等病理状况的治疗靶点。
