Markov Alexander G, Aschenbach Jörg R, Amasheh Salah
Department of General Physiology, St. Petersburg State University, Russia.
Department of Veterinary Medicine, Freie Universität Berlin, Institute of Veterinary Physiology, Berlin, Germany.
IUBMB Life. 2017 May;69(5):290-296. doi: 10.1002/iub.1622. Epub 2017 Mar 29.
Epithelial cell layers are interconnected by a meshwork of tight junction (TJ) protein strands, which are localized within apicolateral membranes. The proteins that form TJs are regarded to provide a static barrier, determining epithelial properties. However, recent findings in the field of barriology suggest that TJs contribute to more physiological aspects than indicated by the sum of the qualities of the single TJ proteins. Generally, TJs exhibit four major functions: (i) a "gate function," defining transepithelial permeability (i.e., barrier) properties, (ii) a "fence function" determining epithelial cell polarity, (iii) a "signaling function," affecting regulatory pathways, and (iv) a "stabilizing function," maintaining the integrity of the epithelium. This review presents a critical view on how the efficacy of physiological processes in epithelia and thus organ function might be improved by changes in the expression of claudins, the latter representing the largest and most variable family of TJ proteins. Major focus is set on (i) the coordinated regulation of transport and barrier in the intestine, (ii) the role of TJs in defining the route for antigen uptake and presentation in intestinal Peyer's patches, and (iii) the TJ function in mammary glands in response to milk accumulation, which represent impressive examples to highlight the amplification of epithelial functions by TJ proteins. © 2017 IUBMB Life, 69(5):290-296, 2017.
上皮细胞层通过紧密连接（TJ）蛋白链网络相互连接，这些蛋白链位于顶侧膜内。形成紧密连接的蛋白被认为提供了一个静态屏障，决定上皮细胞的特性。然而，屏障学领域的最新研究结果表明，紧密连接所起的生理作用比单个紧密连接蛋白的特性总和所表明的要多。一般来说，紧密连接具有四种主要功能：（i）“门控功能”，定义跨上皮通透性（即屏障）特性；（ii）“围栏功能”，决定上皮细胞极性；（iii）“信号功能”，影响调节途径；（iv）“稳定功能”，维持上皮的完整性。本综述批判性地探讨了紧密连接蛋白claudin表达的变化如何改善上皮生理过程的效能，进而改善器官功能，claudin是紧密连接蛋白中最大且最具多样性的家族。主要关注以下方面：（i）肠道中转运与屏障的协调调节；（ii）紧密连接在确定肠道派尔集合淋巴结中抗原摄取和呈递途径方面的作用；（iii）乳腺中紧密连接在应对乳汁积聚时的功能，这些都是突出紧密连接蛋白对上皮功能放大作用的显著例子。© 2017国际生物化学与分子生物学联盟生命科学部，69(5):290 - 296，2017年。
