Fleckman P, Dale B A, Holbrook K A
J Invest Dermatol. 1985 Dec;85(6):507-12. doi: 10.1111/1523-1747.ep12277306.
Filaggrin is a histidine-rich matrix protein of keratinized epidermis. Filaggrin is synthesized as a high-Mr, phosphorylated precursor, profilaggrin, that is processed to form the lower-Mr product present in cornified cells. This study reports the identification of profilaggrin in human epidermis and in unusually well-differentiated cultured human keratinocytes with the use of a polyclonal antihuman filaggrin antiserum. Polyclonal antiserum raised against human filaggrin stained keratohyaline granules and stratum corneum in tissue sections of human skin. Analysis of epidermal extracts showed an immunoreactive low-Mr band (37,000), previously identified as filaggrin, and an immunoreactive high-Mr band (greater than 220,000). Both [32P] phosphate and [3H]histidine were incorporated into the high-Mr band after pulse labeling for 3 h. After a 15-h chase, [3H]histidine, but not [32P]phosphate appeared in filaggrin. Human foreskin keratinocytes cultured on a 3T3 feeder layer were unusually well differentiated. Numerous well-formed keratohyaline granules, complete desmosomes, lamellar granules, and cornified cell envelopes were observed. Immunofluorescence with antihuman filaggrin antiserum showed a granular staining pattern in the more stratified cells. Extracts of cultured cells contained a diffuse high-Mr immunoreactive band but no immunoreactive equivalent of filaggrin. These studies suggest that human skin filaggrin, like rodent filaggrin, is synthesized as a high-Mr, phosphorylated, histidine-rich precursor (profilaggrin) that is processed via posttranslational modification to filaggrin. In human keratinocyte cultures a similar high-Mr precursor is present, but evidence of processing to the lower-Mr product, filaggrin, is lacking.
丝聚合蛋白是角质化表皮中富含组氨酸的基质蛋白。丝聚合蛋白以高分子量的磷酸化前体——前丝聚合蛋白的形式合成，该前体经过加工后形成存在于角质化细胞中的低分子量产物。本研究报告了利用多克隆抗人丝聚合蛋白抗血清在人表皮和分化异常良好的培养人角质形成细胞中鉴定出前丝聚合蛋白。针对人丝聚合蛋白产生的多克隆抗血清可使人体皮肤组织切片中的透明角质颗粒和角质层染色。对表皮提取物的分析显示出一条免疫反应性低分子量条带（37,000），该条带先前被鉴定为丝聚合蛋白，以及一条免疫反应性高分子量条带（大于220,000）。脉冲标记3小时后，[32P]磷酸盐和[3H]组氨酸均掺入高分子量条带中。经过15小时的追踪，[3H]组氨酸出现在丝聚合蛋白中，但[32P]磷酸盐未出现。在3T3饲养层上培养的人包皮角质形成细胞分化异常良好。观察到大量形态良好的透明角质颗粒、完整的桥粒、板层颗粒和角质化细胞包膜。用抗人丝聚合蛋白抗血清进行免疫荧光显示，在分层较多的细胞中呈颗粒状染色模式。培养细胞的提取物含有一条弥散的高分子量免疫反应性条带，但没有与丝聚合蛋白等效的免疫反应性条带。这些研究表明，人皮肤丝聚合蛋白与啮齿动物丝聚合蛋白一样，以高分子量、磷酸化、富含组氨酸的前体（前丝聚合蛋白）形式合成，该前体通过翻译后修饰加工成丝聚合蛋白。在人角质形成细胞培养物中存在类似的高分子量前体，但缺乏加工成低分子量产物——丝聚合蛋白的证据。
