Winter H, Siry P, Tobiasch E, Schweizer J
Research Program 2, German Cancer Research Center, Heidelberg.
Exp Cell Res. 1994 Jun;212(2):190-200. doi: 10.1006/excr.1994.1134.
A cDNA library was constructed with poly(A)+ RNA from mouse tail epidermis which contained all hair follicles of tail skin. The library was subjected to sequential screening procedures aimed at selecting cDNA clones coding for acidic, type I hair keratins. Two clones, pktI-2 and pktI-3, encoded keratins that could be identified as murine type I hair keratins mHa2 and mHa3, respectively, by positive hybridization selection analysis. Sequence comparisons with the known murine type I hair keratins mHa1 (Bertolino et al., J. Invest. Dermatol. 91, 541-546, 1988) and mHa4 (Bertolino et al., J. Invest. Dermatol. 94, 297-303, 1990) revealed a structural heterogeneity within the type I hair keratin subfamily. Three keratins, mHa1, mHa3, and mHa4, are highly related, differing mainly in the penultimate part of their amino and carboxy termini. In contrast, mHa2 is structurally distinct from the three other keratins in both the alpha-helix and, in particular, the non-alpha-helical domains. These findings are confirmed by evolutionary investigations and flexibility calculations which indicate a more flexible nature of the mHa2 amino terminus when compared to the corresponding region of the three other keratins. In situ hybridization experiments with specific 3' fragments of mHa2 and mHa3 show that mHa3 is expressed in cortex cells, whereas mHa2 transcripts are strictly limited to the cuticle of the hair shaft. mHa3 mRNA expression can also be demonstrated in the central unit of the murine lingual filiform papillae, whereas the cuticular keratin mHa2 is not expressed in this body site. These data indicate that the structural heterogeneity within the type I hair keratin subfamily is functionally relevant in the morphogenesis of hard alpha-keratin-expressing tissues.
利用来自小鼠尾部表皮的聚腺苷酸加尾RNA构建了一个cDNA文库，该表皮包含尾部皮肤的所有毛囊。对该文库进行了一系列筛选程序，旨在选择编码酸性I型毛发角蛋白的cDNA克隆。通过阳性杂交选择分析，两个克隆pktI - 2和pktI - 3编码的角蛋白可分别鉴定为鼠I型毛发角蛋白mHa2和mHa3。与已知的鼠I型毛发角蛋白mHa1（Bertolino等人，《皮肤病学研究杂志》91，541 - 546，1988）和mHa4（Bertolino等人，《皮肤病学研究杂志》94，297 - 303，1990）进行序列比较，揭示了I型毛发角蛋白亚家族内的结构异质性。三种角蛋白mHa1、mHa3和mHa4高度相关，主要在其氨基和羧基末端的倒数第二个部分有所不同。相比之下，mHa2在α - 螺旋结构域，特别是非α - 螺旋结构域中，在结构上与其他三种角蛋白不同。进化研究和柔韧性计算证实了这些发现，这些研究和计算表明，与其他三种角蛋白的相应区域相比，mHa2氨基末端具有更灵活的性质。用mHa2和mHa3的特异性3'片段进行原位杂交实验表明，mHa3在皮质细胞中表达，而mHa2转录本严格局限于毛干的角质层。在鼠舌丝状乳头的中央单元中也可检测到mHa3 mRNA的表达，而角质层角蛋白mHa2在该身体部位不表达。这些数据表明，I型毛发角蛋白亚家族内的结构异质性在表达硬α - 角蛋白的组织的形态发生中具有功能相关性。
