Liu H H, Shen Q X, Guo L H
Shanghai Institute of Cell Biology, Academia Sinica.
Shi Yan Sheng Wu Xue Bao. 1995 Jun;28(2):157-62.
AFP is an oncodevelopmental protein. Its level decreases abruptly after birth and reaches almost undetectable level during normal adult life. However, reexpression of the gene can be observed during hepatocarcinogenesis. To further understand mechanism of regulating AFP expression, we checked several restriction enzyme map of 5' terminal and flanking sequences of AFP gene. There are no differences among adult rat liver, fetal liver and hepatoma cells. Using +2(-)-255 bp sequence probe of AFP gene to do southwestern blotting assay, the result showed that the gene-active cells, such as hepatoma cells, contained binding-proteins which were apparently lacking in adult rat liver, lung, spleen, heart and kidney cells. While the fractions of nuclear proteins from adult rat liver cells were devoid of any stimulatory effect on transcription, those of binding-proteins from hepatoma stimulated the transcription of AFP gene in vitro. The hepatoma binding-proteins can rescue transcription activity of fraction of nuclear proteins from adult rat liver cells. These results indicate that cell-specific expression of AFP gene is regulated by protein-factors.
甲胎蛋白是一种胚胎发育相关蛋白。其水平在出生后急剧下降，在正常成年期几乎检测不到。然而，在肝癌发生过程中可观察到该基因的重新表达。为了进一步了解甲胎蛋白表达的调控机制，我们检查了甲胎蛋白基因5'末端及侧翼序列的几种限制酶图谱。成年大鼠肝脏、胎儿肝脏和肝癌细胞之间没有差异。用甲胎蛋白基因的+2（-）-255bp序列探针进行蛋白质印迹分析，结果表明，基因活性细胞，如肝癌细胞，含有结合蛋白，而成年大鼠肝脏、肺、脾、心脏和肾脏细胞中明显缺乏这种结合蛋白。虽然成年大鼠肝细胞的核蛋白组分对转录没有任何刺激作用，但肝癌结合蛋白在体外刺激了甲胎蛋白基因的转录。肝癌结合蛋白可以挽救成年大鼠肝细胞的核蛋白组分的转录活性。这些结果表明，甲胎蛋白基因的细胞特异性表达受蛋白质因子调控。
