Owens Dewi W, Lane E Birgitte
Cancer Research UK Cell Structure Research Group, School of Life Sciences, University of Dundee, Scotland.
Bioessays. 2003 Aug;25(8):748-58. doi: 10.1002/bies.10316.
Simple epithelial keratins K8 and K18 are components of the intracellular cytoskeleton in the cells of the single-layered sheet tissues inside the body. As members of the intermediate filament family of proteins, their function has been a matter for debate since they were first discovered. Whilst there is an indisputable case for a structural cell-reinforcing function for keratins in the mutilayered squamous epithelia of external barrier tissues, some very different stress-protective features now seem to be emerging for the simple epithelial keratins. Even the emerging evidence of pathological mutations in K8/K18 looks very different from mutations in stratified epithelial keratins. K8/K18-like keratins were probably the first to evolve and, whilst stratified epithelial (keratinocyte) keratins have diversified into a large group of keratins highly specialised for providing mechanical stability, the simple epithelial keratins have retained early features that may protect the internal epithelia from a broader range of stresses, including osmotic stress and chemical toxicity.
简单上皮角蛋白K8和K18是体内单层片状组织细胞内细胞骨架的组成部分。作为中间丝蛋白家族的成员，自它们首次被发现以来，其功能一直存在争议。虽然角蛋白在外部屏障组织的复层鳞状上皮中具有无可争议的增强细胞结构的功能，但简单上皮角蛋白现在似乎正呈现出一些截然不同的应激保护特性。甚至K8/K18病理性突变的新证据看起来也与分层上皮角蛋白的突变大不相同。K8/K18样角蛋白可能是最早进化出来的，当分层上皮（角质形成细胞）角蛋白已经分化成一大组高度专门用于提供机械稳定性的角蛋白时，简单上皮角蛋白保留了早期特征，这些特征可能保护内部上皮免受更广泛的应激，包括渗透压应激和化学毒性。
