Ueno K, Katoh K, Kondoh H
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
Mol Cell Biol. 1988 Oct;8(10):4529-32. doi: 10.1128/mcb.8.10.4529-4532.1988.
N-myc expression is under stage- and tissue-specific regulation in mammalian development, but its function is totally unknown. We sought agents to block N-myc activity in order to infer from the effect the possible function of N-myc in the apparently complex processes. As candidates for such agents, we tested fusion genes encoding N-myc:beta-galactosidase fusion proteins for their effects on the formation of transformed foci of rat embryo primary fibroblasts as the result of transfection with N-myc and activated H-ras. One of the gene constructs very efficiently antagonized N-myc activity, as assessed by its effect on focus formation, but did not appreciably affect cell viability. The product of this gene was not only targeted to the nucleus but also accumulated in subnuclear loci which may represent the sites where normal N-myc proteins reside. The occurrence of antagonistic effect at a low stoichiometric ratio suggested that the fusion protein gene competed with the N-myc gene in a fashion analogous to a dominant negative mutation.
在哺乳动物发育过程中，N - myc的表达受到阶段和组织特异性调控，但其功能完全未知。我们寻找能够阻断N - myc活性的因子，以便从其效应推断N - myc在明显复杂的过程中可能具有的功能。作为此类因子的候选物，我们测试了编码N - myc:β - 半乳糖苷酶融合蛋白的融合基因对大鼠胚胎原代成纤维细胞转化灶形成的影响，这些转化灶是由N - myc和活化的H - ras转染所致。通过对灶形成的影响评估，其中一种基因构建体非常有效地拮抗了N - myc活性，但对细胞活力没有明显影响。该基因的产物不仅定位于细胞核，还在核内亚位点积累，这些亚位点可能代表正常N - myc蛋白所在的位置。在低化学计量比下出现拮抗作用表明，融合蛋白基因与N - myc基因竞争的方式类似于显性负突变。
