Intermediate Filament Proteins of Mid‐Gestation Trophoblast Giant Cells Are Simple Epithelial Cytokeratins a
Intermediate Filament Proteins of Mid‐Gestation Trophoblast Giant Cells Are Simple Epithelial Cytokeratins a
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妊娠中期滋养层巨细胞的中间丝蛋白是简单的上皮细胞角蛋白
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发表时间：
1985
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影响因子：
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通讯作者：
J. Julian
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作者：
S. Glasser;J. Julian
小鼠胚泡着床前的中间丝蛋白（IF）先前已被鉴定为细胞角蛋白，“尽管这受到其他人的质疑。”在着床时，啮齿动物的滋养外胚层，第一个表现出中间细丝的胚胎细胞，开始分化为滋养层巨细胞（TGC）。形态上，TGC是巨大的、不分裂的、多倍体的和多粒的。功能上，TGC表达蛋白水解酶、类固醇的分泌程序，并在妊娠中期表达肽激素、胎盘乳原。由于形态和功能分化与IF蛋白的表达变化有关，我们分析了妊娠中期大鼠TGC的IF。在图1中，通过二维聚丙烯酰胺凝胶电泳（PAGE）将大鼠第12天TGC（第0天=阴道塞的第1天）的高盐非离子洗涤剂抗性蛋白与来自各种大鼠简单上皮的细胞角蛋白进行了比较。除了先前研究人员在着床前囊胚中注意到的两种主要的IF蛋白（54K和46K）外，52K和40K处还有两种较小的蛋白。从质量上看，这种中频谱与单纯上皮细胞相同。来自TGC和成年大鼠肝脏的具有相同迁移系数的IF蛋白从二维PAGE上切除并经金黄色葡萄球菌蛋白酶部分消化后，显示出相同的带状模式。通过一、二维PAGE间接免疫荧光和电泳免疫印迹验证了4种TGC IF蛋白为细胞角蛋白。在二维PAGE的免疫印迹上，针对简单的、分层的或角化的上皮角蛋白制备的抗体识别各种TGC IF蛋白，尽管所有四种蛋白都被一种或多种抗角蛋白识别。在一维PAGE的免疫印迹上，TGC和简单上皮IF中可以识别出相同的条带。从间充质细胞（成年大鼠子宫基质和成年大鼠脾脏）制备的IF中未发现条带，表明抗体对角蛋白具有特异性。免疫印迹实验结果如表1所示。间接免疫荧光结果与免疫印迹结果一致。免疫印迹上识别一种或多种简单上皮细胞角蛋白的抗体修饰了TGC、成年大鼠子宫上皮和第12天壁的纤维网络
The intermediate filament (IF) proteins of preimplantation murine blastocysts have been previously identified as cytokeratins' although this has been questioned by others.*.' At implantation, rodent trophectoderm, the first embryonic cell to exhibit intermediate filaments, begins to differentiate into trophoblast giant cells (TGC). Morphologically, TGC are giant, nondividing, polyploid, and polytene. Functionally, TGC express secretory programs for proteolytic enzymes, steroids, and, at mid-gestation, a peptide hormone, placental lactogen. Because morphological and functional differentiation have been linked to changes in expression of IF proteins, we analyzed IF of mid-gestation rat TGC. In FIGURE 1, the high salt, non-ionic detergent-resistant proteins of rat day 12 TGC (day 0 = day of vaginal plug) are compared by two-dimensional polyacrylamide gel electrophoresis (PAGE) to cytokeratins from various rat simple epithelia. In addition to the two major IF proteins (54K and 46K) noted by previous investigators in preimplantation blastocysts,' there are two lesser proteins at 52K and 40K. Qualitatively this IF profile appears identical to that of simple epithelial cells. IF proteins from TGC and adult rat liver with identical migration coefficients exhibited identical banding patterns when excised from two-dimensional PAGE and subjected to partial digestion by Staphylococcus aureus protease. The identity of the four TGC IF proteins as cytokeratins was verified by indirect immunofluorescence and electrophoretic immunoblot of oneand two-dimensional PAGE. On immunoblots of two-dimensional PAGE, antibodies prepared against simple, stratified, or keratinized epithelial keratins recognized various TGC IF proteins, although all four proteins were recognized by one or more of the anti-keratins. On immunoblots of one-dimensional PAGE, the same bands were recognized in TGC and simple epithelial IF. No bands were recognized in IF preparations from mesenchymal cells (adult rat uterine stroma and adult rat spleen), indicating specificity of the antibodies for keratins. Results of the immunoblot experiments are also summarized in TABLE 1. Indirect immunofluorescence results agreed with the immunoblot results. Antibodies recognizing one or more simple epithelial cytokeratins on immunoblots decorated filament networks in TGC, adult rat uterine epithelium, and day 12 parietal