Mrsny Randall J, Brown G Thomas, Gerner-Smidt Kirsten, Buret Andre G, Meddings Jon B, Quan Clifford, Koval Michael, Nusrat Asma
Department of Pathology & Laboratory Medicine, Emory University School of Medicine, Whitehead Biomedical Research Building, 615 Michael Street, Atlanta, GA 30322, USA.
Am J Pathol. 2008 Apr;172(4):905-15. doi: 10.2353/ajpath.2008.070698. Epub 2008 Mar 18.
Intercellular tight junctions (TJs) regulate epithelial barrier properties. Claudins are major structural constituents of TJs and belong to a large family of tetra-spanning membrane proteins that have two predicted extracellular loops (ELs). Given that claudin-1 is widely expressed in epithelia, we further defined the role of its EL domains in determining TJ function. The effects of several claudin-1 EL mimetic peptides on epithelial barrier structure and function were examined. Incubation of model human intestinal epithelial cells with a 27-amino acid peptide corresponding to a portion of the first EL domain (Cldn-1(53-80)) reversibly interfered with epithelial barrier function by inducing the rearrangement of key TJ proteins: occludin, claudin-1, junctional adhesion molecule-A, and zonula occludens-1. Cldn-1(53-80) associated with both claudin-1 and occludin, suggesting both the direct interference with the ability of these proteins to assemble into functional TJs and their close interaction under physiological conditions. These effects were specific for Cldn-1(53-80), because peptides corresponding to other claudin-1 EL domains failed to influence TJ function. Furthermore, the oral administration of Cldn-1(53-80) to rats increased paracellular gastric permeability. Thus, the identification of a critical claudin-1 EL motif, Cldn-1(53-80), capable of regulating TJ structure and function, offers a useful adjunct to treatments that require drug delivery across an epithelial barrier.
细胞间紧密连接（TJs）调节上皮屏障特性。紧密连接蛋白是紧密连接的主要结构成分，属于一个具有两个预测的细胞外环（ELs）的跨膜四次蛋白大家族。鉴于紧密连接蛋白-1在上皮细胞中广泛表达，我们进一步确定了其EL结构域在决定紧密连接功能中的作用。研究了几种紧密连接蛋白-1 EL模拟肽对上皮屏障结构和功能的影响。用对应于第一个EL结构域一部分的27个氨基酸肽（Cldn-1(53-80)）孵育模型人肠上皮细胞，通过诱导关键紧密连接蛋白（闭合蛋白、紧密连接蛋白-1、连接黏附分子A和闭合小带蛋白-1）的重排，可逆地干扰上皮屏障功能。Cldn-1(53-80)与紧密连接蛋白-1和闭合蛋白都相关，表明其既直接干扰这些蛋白组装成功能性紧密连接的能力，又在生理条件下与其密切相互作用。这些效应是Cldn-1(53-80)特有的，因为对应于紧密连接蛋白-1其他EL结构域的肽未能影响紧密连接功能。此外，给大鼠口服Cldn-1(53-80)会增加胃黏膜旁通透性。因此，鉴定出一个能够调节紧密连接结构和功能的关键紧密连接蛋白-1 EL基序Cldn-1(53-80)，为需要跨上皮屏障进行药物递送的治疗提供了有用的辅助手段。
