Watt F M, Boukamp P, Hornung J, Fusenig N E
Arch Dermatol Res. 1987;279(5):335-40. doi: 10.1007/BF00431227.
Involucrin, the major protein precursor of the cornified envelope, is expressed during terminal differentiation of human keratinocytes, both in vivo and in vitro. In epidermis, the onset of synthesis is several layers above the basal layer, but in stratified cultures of keratinocytes on tissue culture plastic involucrin synthesis begins in the first suprabasal layer. To investigate the reason for this premature expression, the distribution of involucrin was studied in epidermis from different body sites, in organotypic cultures and in transplants of keratinocytes onto nude mice. We found that premature expression was not associated with poor morphological differentiation, because involucrin synthesis began immediately above the basal layer even when distinct basal, spinous, granular and cornified layers were formed in organotypic cultures recombined with dermis. The site of involucrin expression in culture did not depend on the number of cornified layers present. The only conditions which resulted in an upward shift in the site of synthesis were in 3-week old transplants on nude mice. We conclude that the site of onset of involucrin synthesis is not determined by the degree of morphological differentiation of the tissue, and discuss other factors which may be involved.
兜甲蛋白是角质包膜的主要蛋白质前体，在人角质形成细胞的终末分化过程中，无论在体内还是体外均有表达。在表皮中，兜甲蛋白的合成起始于基底层上方数层，但在组织培养塑料上的角质形成细胞分层培养物中，兜甲蛋白的合成始于最上层的基底层。为了探究这种过早表达的原因，我们研究了不同身体部位表皮、器官型培养物以及角质形成细胞移植到裸鼠身上后的兜甲蛋白分布情况。我们发现，过早表达与形态分化不良无关，因为即使在与真皮重组的器官型培养物中形成了明显的基底层、棘层、颗粒层和角质层，兜甲蛋白的合成仍在基底层上方立即开始。培养物中兜甲蛋白的表达位点并不取决于角质层的数量。导致合成位点向上移动的唯一条件是在裸鼠身上进行的3周龄移植。我们得出结论，兜甲蛋白合成起始位点不是由组织的形态分化程度决定的，并讨论了可能涉及的其他因素。
