Department of Dermatology, University of Turku and Turku University Hospital, P.O.B 52, 20521, Turku, Finland.
Arch Dermatol Res. 2014 Mar;306(2):131-41. doi: 10.1007/s00403-013-1391-0. Epub 2013 Jul 16.
Increasing evidence has recognized tight junctions (TJs) as the lower epidermal inside-out diffusion barrier located in granular cell layers of the epidermis. However, little is known about the regulation of TJ components in epidermis. p38 pathway is one of the mitogen-activated protein kinase pathways, which controls cell growth, differentiation, and apoptosis. We have investigated the role of p38 signaling pathway in the regulation of selected desmosomal, adherens and TJ components in human primary keratinocytes during Ca(2+)-induced differentiation, as well as in cultured squamous cell carcinoma cell lines. p38 signaling pathway was inhibited in cultured keratinocytes and cutaneous squamous cell carcinoma cells using recombinant adenoviruses, small inhibitory RNAs (siRNA) and chemical inhibitors. Expression of intercellular junction proteins was investigated using Western analysis and indirect immunofluorescence (IIF). The results showed that inhibition of p38δ function by siRNA or adenovirally delivered dominant negative mutant led to markedly decreased levels of Zonula occludens-1 (ZO-1) protein in keratinocytes, while the expression of other junctional proteins studied was not altered. Immunolocalization of ZO-1 revealed that intercellular junction areas were depleted from ZO-1. Inhibition of ZO-1 by siRNA silencing did not however result in an altered expression or subcellular localization of other TJ components studied. The expression of ZO-1 in carcinoma cells was also regulated by p38. The results indicate that ZO-1 is regulated by p38δ while the other junction proteins studied are not. Since ZO-1 is an integral component of functional TJs, various pathological processes affecting signaling via p38δ may also interfere with epithelial maturation and the formation and function of TJs.
越来越多的证据表明紧密连接（TJ）是位于表皮颗粒层中的表皮内向外扩散屏障。然而，对于表皮中 TJ 成分的调节知之甚少。p38 途径是丝裂原活化蛋白激酶途径之一，可控制细胞生长、分化和凋亡。我们研究了 p38 信号通路在钙诱导分化过程中以及在培养的鳞状细胞癌细胞系中对选定的桥粒、黏附连接和 TJ 成分的调节作用。使用重组腺病毒、小干扰 RNA（siRNA）和化学抑制剂抑制培养的角质形成细胞和皮肤鳞状细胞癌细胞中的 p38 信号通路。使用 Western 分析和间接免疫荧光（IIF）研究细胞间连接蛋白的表达。结果表明，siRNA 或腺病毒递送的显性失活突变体抑制 p38δ 功能导致角质形成细胞中 Zonula occludens-1（ZO-1）蛋白水平明显降低，而研究的其他连接蛋白的表达没有改变。ZO-1 的免疫定位显示细胞间连接区域缺乏 ZO-1。然而，通过 siRNA 沉默抑制 ZO-1 不会导致研究的其他 TJ 成分的表达或亚细胞定位改变。ZO-1 在癌细胞中的表达也受 p38 调节。结果表明 ZO-1 受 p38δ 调节，而研究的其他连接蛋白不受调节。由于 ZO-1 是功能性 TJ 的组成部分，因此影响 p38δ 信号的各种病理过程也可能干扰上皮成熟和 TJ 的形成和功能。
