Roop D R, Hawley-Nelson P, Cheng C K, Yuspa S H
Proc Natl Acad Sci U S A. 1983 Feb;80(3):716-20. doi: 10.1073/pnas.80.3.716.
The major differentiation products of mouse epidermis are keratins of 40-70 kilodaltons (kDal). We have prepared a library of cDNA clones from total poly(A)+ RNA from newborn mouse epidermis. Clones corresponding to the major in vivo keratins of 55, 59, and 67 kDal have been isolated and characterized. By RNA blot analysis of poly(A)+ RNA from newborn mouse epidermis, we have identified RNA species that are approximately 1,600, 2,000, and 2,400 nucleotides in length and are complementary to the cDNAs for the 55-, 59-, and 67-kDal keratins, respectively. Analysis of RNA from primary cultures of newborn mouse epidermis by this same technique shows greatly reduced levels of these RNAs. Transcripts complementary to all three cloned cDNAs are abundant in 14- to 16-day embryonic and adult mouse skin. Thus, altered expression in culture does not appear to be due to induction of a developmentally programmed switch by placing the cells in culture but instead is due to factors modulating expression within the culture system. Because the 55-, 59-, and 67-kDal keratins are the major proteins in epidermis they probably represent keratin associated with terminal differentiation. The expression data suggest that cultured cells are blocked in expression of differentiation keratins but instead synthesize other keratin family members probably related to cytoskeletal functions.
小鼠表皮的主要分化产物是40 - 70千道尔顿（kDal）的角蛋白。我们从新生小鼠表皮的总聚腺苷酸加尾（poly(A)+）RNA制备了一个cDNA克隆文库。已分离并鉴定出与55、59和67 kDal的主要体内角蛋白相对应的克隆。通过对新生小鼠表皮的poly(A)+ RNA进行RNA印迹分析，我们鉴定出长度约为1600、2000和2400个核苷酸的RNA种类，它们分别与55 -、59 -和67 - kDal角蛋白的cDNA互补。用同样的技术分析新生小鼠表皮原代培养物中的RNA，结果显示这些RNA的水平大幅降低。与所有三个克隆的cDNA互补的转录本在14至16天的胚胎和成年小鼠皮肤中大量存在。因此，培养中表达的改变似乎不是由于将细胞置于培养中诱导了发育程序开关，而是由于调节培养系统内表达的因素。由于55 -、59 -和67 - kDal角蛋白是表皮中的主要蛋白质，它们可能代表与终末分化相关的角蛋白。表达数据表明，培养的细胞在分化角蛋白的表达上受阻，而是合成可能与细胞骨架功能相关的其他角蛋白家族成员。
