Mercier T, Gaillard-Sanchez I, Martel P, Seillan-Heberden C
Laboratoire de Nutrition et Sécurité Alimentaire, INRA-CRJ, Jouy-en-Josas, France.
Biochim Biophys Acta. 1995 Apr 6;1266(1):64-72. doi: 10.1016/0167-4889(94)00240-f.
We have previously shown that rat liver epithelial cells were more sensitive to TGF-beta 1 when they were transfected with c-fos cDNA. We analyzed the production of TGF-beta and TGF-beta 1 binding proteins in transfected and parental cells. TGF-beta-like activity released in the medium was reduced in c-fos expressing cells. TGF-beta 1 binding sites were more numerous in transfected cells (x3). Cross-linking studies confirmed that c-fos transfected cells showed increased binding of 125I-TGF-beta 1 to membrane binding sites corresponding to type I, II and III receptors. Transfected cells internalized and degraded 125I-TGF-beta 1 more rapidly than parental cells. TGF-beta 1 incubation rapidly down-regulated the receptors. In parental cells, the down-regulation was total, while in transfected cells, a few binding proteins could still be detected. The c-fos cell line is an interesting tool in analysing the mechanism of action of TGF-beta.
我们之前已经表明，当大鼠肝上皮细胞用c-fos cDNA转染后，它们对TGF-β1更为敏感。我们分析了转染细胞和亲本细胞中TGF-β和TGF-β1结合蛋白的产生情况。在表达c-fos的细胞中，培养基中释放的TGF-β样活性降低。转染细胞中的TGF-β1结合位点更多（增加了3倍）。交联研究证实，c-fos转染细胞显示125I-TGF-β1与对应于I型、II型和III型受体的膜结合位点的结合增加。转染细胞比亲本细胞更快地内化和降解125I-TGF-β1。TGF-β1孵育迅速下调受体。在亲本细胞中，下调是完全的，而在转染细胞中，仍可检测到一些结合蛋白。c-fos细胞系是分析TGF-β作用机制的一个有趣工具。
