Molloy C J, Laskin J D
Department of Environmental and Community Medicine, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854.
Differentiation. 1988;37(2):86-97. doi: 10.1111/j.1432-0436.1988.tb00800.x.
Adult mouse epidermis contains up to 11 distinct keratin polypeptides, as resolved by two-dimensional gel electrophoresis. These include both basic (Type II; 67-, 65-, 63-, 62-, and 60-kDa) and acidic (Type I; 61- to 59-, 54-, 52-, 49-, and 48-kDa) keratins that exhibit multiple isoelectric forms. Several, but not all, of these keratins, identified by immunoblotting, were found to be actively synthesized in the skin when assayed in short-term pulse-labeling experiments. When compared to the adult, newborn mouse epidermis expresses fewer keratin subunits. However, greater amounts of keratins associated with differentiated suprabasal cells and stratum corneum, which is more pronounced morphologically in the newborn, were identified. We also observed strain-specific differences in the expression of a Type I acidic keratin. This 61-kDa (pI, approx. 5.3) keratin was produced exclusively by the CF-1 mouse and, based on peptide mapping, appeared to be related to the acidic 59-kDa keratin that was identified in this strain as well as all other mouse strains. The 61-kDa keratin was not expressed in vitamin A-deficient animals, suggesting that its appearance may be related to a retinoid-dependent posttranslational modification. In comparison to keratin expression in vivo, primary mouse keratinocyte monolayer cultures maintained in low Ca2+ (less than 0.08 mM) did not express the terminal differentiation keratins of 67-kDa (basic) or 59-kDa (acidic), although enhanced synthesis of the 60-kDa (basic) and the 52-kDa and 59-kDa (acidic) keratins associated with proliferation were observed. In addition, a subpopulation of nonadherent cells was continuously produced by the primary keratinocyte cultures that expressed the 67-kDa (basic) keratin specific for terminal differentiation. When the keratinocyte cultures were induced to terminally differentiate with Ca2+, the overall pattern of keratin expression was not changed significantly. Taken together, these results provide further evidence for the variable nature of keratin expression in mouse epidermal keratinocytes under different growth conditions.
通过二维凝胶电泳分析，成年小鼠表皮含有多达11种不同的角蛋白多肽。这些角蛋白包括碱性角蛋白（II型；67 kDa、65 kDa、63 kDa、62 kDa和60 kDa）和酸性角蛋白（I型；61 kDa至59 kDa、54 kDa、52 kDa、49 kDa和48 kDa），它们呈现出多种等电形式。通过免疫印迹鉴定发现，其中几种（但并非全部）角蛋白在短期脉冲标记实验中检测时，在皮肤中处于活跃合成状态。与成年小鼠相比，新生小鼠表皮表达的角蛋白亚基较少。然而，与分化的基底上层细胞和角质层相关的角蛋白含量更高，这在新生小鼠中在形态学上更为明显。我们还观察到I型酸性角蛋白表达存在品系特异性差异。这种61 kDa（pI约为5.3）的角蛋白仅由CF - 1小鼠产生，基于肽图谱分析，它似乎与在该品系以及所有其他小鼠品系中鉴定出的59 kDa酸性角蛋白相关。61 kDa的角蛋白在维生素A缺乏的动物中不表达，这表明它的出现可能与类视黄醇依赖性翻译后修饰有关。与体内角蛋白表达相比，在低钙（低于0.08 mM）条件下培养 的原代小鼠角质形成细胞单层不表达67 kDa（碱性）或59 kDa（酸性）的终末分化角蛋白，尽管观察到与增殖相关的60 kDa（碱性）以及52 kDa和59 kDa（酸性）角蛋白的合成增强。此外，原代角质形成细胞培养物持续产生一群非贴壁细胞，这些细胞表达终末分化特异性的67 kDa（碱性）角蛋白。当角质形成细胞培养物用钙诱导终末分化时，角蛋白表达的总体模式没有显著变化。综上所述，这些结果为不同生长条件下小鼠表皮角质形成细胞中角蛋白表达的可变性质提供了进一步的证据。
