Rice R H, Wong V J, Pinkerton K E
Department of Environmental Toxicology, University of California, Davis 95616.
J Cell Sci. 1994 Jul;107 ( Pt 7):1985-92. doi: 10.1242/jcs.107.7.1985.
Upon vigorous extraction with ionic detergent under reducing conditions, the macroscopic structures of mammalian hair, bird feather and horny teeth of the hagfish become swollen and flexible but were substantially preserved. In each case, removal in this way of solubilizable constituents, such as disulfide-bonded keratins and associated matrix proteins, left a residue of epsilon-(gamma-glutamyl)lysine cross-linked protein. Residual features in hair included cell envelopes in the cortex, cell envelopes and intracellular deposits in the medulla, and nearly the entire cuticle cells. In feather, extraction left largely intact the macroscopic barb structures but caused collapse of the rachis. In both rachis and barbs, considerable material resembling cell envelopes remained. In extracted hagfish teeth the cellular organization was clearly visible microscopically, including cell borders and remnant nuclei. Unlike the cornified envelopes of mature epidermal keratinocytes, which appear as doublets, reflecting their formation immediately beneath each plasma membrane of apposing cells, the borders of cells of hair cortex and hagfish teeth appeared single and continuous from one cell to the next. Thus the observed cross-linked features comprised four types: (i) condensation immediately beneath the plasma membrane (feather, hair medulla and cuticle) similar to cornified envelopes of epidermal keratinocytes; (ii) deposition between cells (hair cortex, horny teeth); (iii) cytoplasmic deposits (hair cuticle and medulla); and (iv) nuclear condensation (hair medulla, horny teeth). The results emphasize the importance of transglutaminases and their substrate proteins for the function of epidermal appendages and may provide a useful diagnostic test for perturbation of their normal structures.
在还原条件下用离子去污剂剧烈提取后，哺乳动物毛发、鸟类羽毛和盲鳗角质齿的宏观结构会肿胀并变得柔韧，但基本得以保留。在每种情况下，通过这种方式去除可溶成分，如二硫键连接的角蛋白和相关的基质蛋白，会留下ε-（γ-谷氨酰）赖氨酸交联蛋白的残余物。毛发中的残余特征包括皮质中的细胞包膜、髓质中的细胞包膜和细胞内沉积物，以及几乎整个角质层细胞。在羽毛中，提取后羽枝的宏观结构基本保持完整，但羽轴会塌陷。在羽轴和羽枝中，都有相当多类似细胞包膜的物质残留。在提取后的盲鳗牙齿中，细胞组织在显微镜下清晰可见，包括细胞边界和残余细胞核。与成熟表皮角质形成细胞的角质包膜不同，后者表现为双联体，反映了它们在相邻细胞的每个质膜下方立即形成，毛发皮质细胞和盲鳗牙齿细胞的边界看起来是单一且连续的，从一个细胞延伸到下一个细胞。因此，观察到的交联特征包括四种类型：（i）质膜下方的凝聚（羽毛、毛发髓质和角质层），类似于表皮角质形成细胞的角质包膜；（ii）细胞间沉积（毛发皮质、角质齿）；（iii）细胞质沉积（毛发角质层和髓质）；以及（iv）核凝聚（毛发髓质、角质齿）。这些结果强调了转谷氨酰胺酶及其底物蛋白对表皮附属器功能的重要性，并可能为其正常结构的扰动提供一种有用的诊断测试。
