MOLECULAR ASPECTS OF COLON EPITHELIUM DIFFERENTIATION AND TUMOR FORMATION

我们报道了用差异杂交技术分离到的一条cdna。 分化和未分化的结肠癌细胞。这部小说 转录本，CORI-1，是对基因5‘非翻译区的补充 Krev-1抑癌基因mRNA.CORI-1mRNA有一个开放阅读框架， 编码一种与大鼠S29核糖体蛋白相同的蛋白质。这 蛋白质有一个潜在的锌指基序，由四个半胱氨酸组成 残留物。为了检测蛋白质的生物学功能， 在大肠杆菌中合成的突变的Cori-1蛋白被固定在膜上 变性后与55Zn孵育。只有野生型的 用55Zn标记，表明这种形式的蛋白质，而不是 突变形式，可能采取锌指构象。野生型和 将突变的Cori-1基因插入到表达载体中， 转染HT1080人纤维肉瘤细胞。在HT1080细胞中 转导突变型Cori-1后，细胞的体内外生长均明显增强 与仅转载体的细胞相比，其表达增强。论 另一方面，细胞在体外和体内的生长在以下情况下并没有得到促进 介绍了野生型CORI-1。KREV-1 AS的表达 由mRNA或蛋白质决定的基因不会因导入而改变。 野生型或突变型Cori-1导入HT1080细胞。这些结果 提示内源性CORI-1的反显性抑制 基因突变型促进细胞生长和致癌 表型。突变体Cori-1的这一功能是由 干扰依赖于锌指结构域的功能而不需要 影响krev-1的表达。

We have reported a cDNA isolated by differential hybridization between differentiated and undifferentiated colon carcinoma cells. The novel transcript, cori-1, is complementary to the 5' untranslated region of the krev-1 anti-oncogene mRNA. Cori-1 mRNA has an open reading frame which encodes a protein identical with the rat S29 ribosomal protein. This protein has a potential zinc finger motif consisting of four cysteine residues. In order to examine the biological function of the protein, mutant cori-1 proteins synthesized in E. coli were fixed on a membrane and incubated with 55Zn after denaturation. Only the wild type was labeled with 55Zn, indicating that this form of the protein, but not the mutant form, may take a zinc finger conformation. The wild type and mutant cori-1 genes were inserted into an expression vector and transfected into HT1080 human fibrosarcoma cells. In HT1080 cells transfected with mutant cori-1, both in vitro and in vivo cell growth was enhanced compared with the cells transfected with vector only. On the other hand, cell growth both in vitro and in vivo was not enhanced when the wild type cori-1 was introduced. The expression of krev-1 as determined by either mRNA or protein was not changed by introducing either wild type or mutant cori-1 into HT1080 cells. These results suggest that the trans-dominant suppression of endogenous cori-1 by the mutant form of the gene enhanced cell growth and the tumorigenic phenotype. This function of the mutant cori-1 is conferred by interfering with a function dependent on the zinc finger domain without affecting krev-1 expression.