Crish J F, Howard J M, Zaim T M, Murthy S, Eckert R L
Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106.
Differentiation. 1993 Jul;53(3):191-200. doi: 10.1111/j.1432-0436.1993.tb00708.x.
Involucrin is a precursor of the keratinocyte cornified envelope that is specifically expressed in the suprabasal layers of the epidermis and other stratifying squamous epithelia. To study involucrin gene expression and the function of involucrin, we expressed a 6 kb DNA fragment of the human involucrin gene, containing approximately 2.5 kb of upstream sequence and 0.5 kb of downstream sequence, in transgenic mice. The transgene produces a 68 kDa protein that is detected by a human involucrin-specific antibody, and is expressed in a tissue-specific and differentiation-appropriate manner (i.e., expression is confined to the suprabasal layers of the epidermis, extocervix, trachea, esophagus and conjunctiva). Soluble involucrin levels are two to four times higher in transgenic epidermal keratinocytes compared to human foreskin keratinocytes. Newborn heterozygous animals have a normal birth weight and a normal appearing epidermis and hair growth begins at 4 to 5 days of age (i.e., the same time as hair growth in non-transgenic animals). In a subpopulation of the newborn homozygous animals birth weight is reduced, the epidermis is scaly and hair growth begins late, at around 9 to 10 days of age. In addition, the hair tends to stand erect on both heterozygous and homozygous adult animals giving the appearance of diffuse alopecia. Immunofluorescent and electron microscopy localize involucrin in the hair follicle and cornified envelope, respectively. These results suggest that overexpression of involucrin may cause abnormalities in hair follicle structure/function and cornified envelope structure. These animals provide a new model for the study of cornified envelope structure and function.
兜甲蛋白是角质形成细胞角化包膜的前体，在表皮的基底层上方各层及其他复层鳞状上皮中特异性表达。为了研究兜甲蛋白基因表达及兜甲蛋白的功能，我们在转基因小鼠中表达了人兜甲蛋白基因的一个6 kb DNA片段，该片段包含约2.5 kb的上游序列和0.5 kb的下游序列。转基因产生一种68 kDa的蛋白质，可被人兜甲蛋白特异性抗体检测到，并以组织特异性和分化适宜的方式表达（即表达局限于表皮、子宫颈外口、气管、食管和结膜的基底层上方各层）。与人类包皮角质形成细胞相比，转基因表皮角质形成细胞中可溶性兜甲蛋白水平高两到四倍。新生杂合子动物出生体重正常，表皮外观正常，毛发在4至5日龄时开始生长（即与非转基因动物毛发开始生长的时间相同）。在新生纯合子动物的一个亚群中，出生体重降低，表皮有鳞屑，毛发在约9至10日龄时开始生长且较晚。此外，杂合子和纯合子成年动物的毛发都倾向于直立，呈现弥漫性脱发的外观。免疫荧光和电子显微镜检查分别将兜甲蛋白定位在毛囊和角化包膜中。这些结果表明，兜甲蛋白的过表达可能导致毛囊结构/功能和角化包膜结构异常。这些动物为研究角化包膜的结构和功能提供了一个新模型。
