Li E R, Owens D M, Djian P, Watt F M
Keratinocyte Laboratory, Imperial Cancer Research Fund, London, England.
Exp Dermatol. 2000 Dec;9(6):431-8. doi: 10.1034/j.1600-0625.2000.009006431.x.
Involucrin is a protein precursor of the epidermal cornified envelope. Although expression of the human protein has been documented extensively, studies in the mouse have been hampered by a shortage of good antibodies. We describe the production of recombinant mouse involucrin and preparation of rabbit antisera to the protein that work well by immunohistochemistry and Western blotting. We confirm that in normal mouse epidermis the onset of involucrin expression is in the upper spinous layers and inner root sheath of the hair follicle. Involucrin was also detected in the differentiating epithelial cells of normal tongue, oesophagus and bladder. Involucrin was expressed in a subpopulation of mouse keratinocytes cultured in standard or low calcium medium and the proportion of involucrin-positive cells increased during suspension-induced terminal differentiation. Western blotting of keratinocytes from several inbred mouse strains revealed a remarkable heterogeneity in the electrophoretic mobility of involucrin, reflecting inter-strain variation in the number of tandem repeats in the protein. In the hyperproliferative epidermis of healing wounds involucrin was expressed in most of the suprabasal layers. In epidermal papillomas and carcinomas involucrin expression correlated well with degree of histological differentiation. The sites of expression of the mouse protein were thus the same as those previously reported for human involucrin. With the development of the new antibodies we anticipate that involucrin will become as widely used a marker of keratinocyte differentiation in the mouse as it is in the human.
兜甲蛋白是表皮角质化包膜的一种蛋白质前体。尽管人类该蛋白的表达已有广泛记录，但小鼠研究因缺乏优质抗体而受阻。我们描述了重组小鼠兜甲蛋白的产生以及针对该蛋白制备的兔抗血清，其在免疫组织化学和蛋白质印迹中表现良好。我们证实，在正常小鼠表皮中，兜甲蛋白表达始于毛囊的棘层上部和内根鞘。在正常舌、食管和膀胱的分化上皮细胞中也检测到了兜甲蛋白。在标准或低钙培养基中培养的小鼠角质形成细胞亚群中表达兜甲蛋白，且在悬浮诱导的终末分化过程中，兜甲蛋白阳性细胞的比例增加。对几种近交系小鼠品系的角质形成细胞进行蛋白质印迹分析显示，兜甲蛋白的电泳迁移率存在显著异质性，这反映了该蛋白串联重复序列数量的品系间差异。在愈合伤口的过度增殖表皮中，兜甲蛋白在大多数基底上层表达。在表皮乳头状瘤和癌中，兜甲蛋白表达与组织学分化程度密切相关。因此，小鼠该蛋白的表达部位与先前报道的人类兜甲蛋白相同。随着新抗体的开发，我们预计兜甲蛋白将成为小鼠中与人类一样广泛使用的角质形成细胞分化标志物。
