Nishikawa A, Shimizu-Nishikawa K, Miller L
Department of Biological Sciences, University of Illinois, Chicago 60680.
Dev Biol. 1992 May;151(1):145-53. doi: 10.1016/0012-1606(92)90222-3.
To study the mechanism of hormone-induced keratin expression in the epidermis during Xenopus metamorphosis, a monospecific antibody was raised against a unique carboxy-terminal peptide of the 63-kDa keratin. Immunohistological analysis demonstrated that the onset of 63-kDa keratin expression showed distinct regional and temporal differences. The expression started at stage 54 in the hindlimb epidermis, at stage 57 in the head, and over 1 month later at stage 63 in the tail. The amount of 63-kDa keratin was further regulated during epidermal stratification and differentiation. The 63-kDa keratin was expressed first in basal epidermal cells before stratification began. The outer layer of the larval epidermis (periderm) did not express the 63-kDa keratin. As the cells moved out of basal layer, they stained more intensely with the anti-keratin antibody indicating that 63-kDa keratin synthesis is up-regulated during differentiation. Similar results were obtained with cultures of purified epidermal cells grown in high calcium conditions. Since we have shown that thyroid hormone (T3) induces 63-kDa keratin gene expression and hydrocortisone (HC) modulates T3 action we examined the effects of T3 and HC at the single cell level with the anti-keratin antibody. Immunostaining demonstrated that T3 alone and T3 plus HC increased the number of 63-kDa keratin-positive cells as well as the amount of 63-kDa keratin per cell. Unexpectedly these hormones had the same effects on head and tail epidermal cells even though the latter cells degenerate during metamorphosis. The major difference between tail and head cells was that the percentage 63-kDa keratin-producing cells was much greater in the head than in the tail.
为研究非洲爪蟾变态发育过程中激素诱导表皮中角蛋白表达的机制，制备了一种针对63 kDa角蛋白独特羧基末端肽的单特异性抗体。免疫组织学分析表明，63 kDa角蛋白表达的起始呈现出明显的区域和时间差异。其表达始于后肢表皮的第54阶段，头部为第57阶段，而尾部则在1个多月后的第63阶段开始。在表皮分层和分化过程中，63 kDa角蛋白的量进一步受到调控。63 kDa角蛋白在分层开始前首先在基底表皮细胞中表达。幼虫表皮的外层（周皮）不表达63 kDa角蛋白。随着细胞从基底层移出，它们用抗角蛋白抗体染色更强烈，表明63 kDa角蛋白的合成在分化过程中上调。在高钙条件下培养的纯化表皮细胞也得到了类似的结果。由于我们已经表明甲状腺激素（T3）诱导63 kDa角蛋白基因表达，而氢化可的松（HC）调节T3的作用，因此我们用抗角蛋白抗体在单细胞水平上研究了T3和HC的作用。免疫染色表明，单独的T3以及T3加HC增加了63 kDa角蛋白阳性细胞的数量以及每个细胞中63 kDa角蛋白的量。出乎意料的是，尽管尾部细胞在变态发育过程中会退化，但这些激素对头部和尾部表皮细胞具有相同的作用。头部和尾部细胞的主要区别在于，产生63 kDa角蛋白的细胞百分比在头部比在尾部大得多。
