THE MOLECULAR MECHANISMS OF ONCOGENE ACTION

分子生物学在上皮细胞中的应用进展 癌症导致了特定遗传病变的鉴定， 导致关键靶基因的激活或失活。 这些 癌基因参与细胞生长的各个方面 调控，并因此发挥重要作用，在早期致癌过程 “启蒙”和“提升”的区别。“现在至关重要的是要了解 这些基因发挥作用的精确机制， 最终可以衍生出药理学试剂来改变或抑制它们的 方面的影响. 这个项目的目的是阐明生物化学和分子生物学 癌基因转化哺乳动物细胞的机制。 为此我们 对myc、jun和 fos癌基因家族 这些研究揭示了各种结构 这些蛋白质的某些方面是必要的和足够的， 转型 我们对c-jun癌基因的研究表明，除了DNA 结合和二聚化结构域，N-末端反式激活结构域是 细胞转化所必需的。 此外，c-jun的能力， 反式激活与其转化细胞的能力相关。 因此，C-Jun 似乎通过调节基因表达来转化细胞。 此外，本发明还 详细的c-jun突变分析表明磷酸化 丝氨酸63/73处的cJun的增加导致反式激活增加， 最终转型。 这些位点的磷酸化发生在 部分通过ras/raf依赖途径，其提供重要的 这些致癌基因之间的生物化学联系。 最近的研究旨在 对c-jun其他翻译后修饰的更详细分析 及其生物化学和生物学效应，以及与c- fos癌基因检测磷酸化与 生物活性。 这项工作揭示了小氨基酸缺失 在N-末端的反式激活结构域导致组成型 c-jun的磷酸化和增加的反式激活。 我们对myc癌基因的研究集中在比较 c-myc和L-myc基因的反式激活和转化活性。 通过外显子改组，我们已经证明L-myc反式激活， 转化效率远低于c-myc，这种差异是 定位于第二外显子。 最近的工作集中在精确的 这些基因之间的结构差异及其在细胞凋亡中的作用。

Recent developments in the application of molecular biology to epithelial cancers have led to the identification of specific genetic lesions resulting in either activation or inactivation of key target genes. These genes, called oncogenes, are involved in various aspects of cell growth regulation and as such play major roles in the early carcinogenic processes of "initiation" and "promotion." It is now critical to understand the precise mechanisms by which these genes function so molecular or pharmacologic agents can ultimately be derived to alter or repress their effects. The purpose of this project is to elucidate the biochemical and molecular mechanisms by which oncogenes transform mammalian cells. To this end, we have performed structure/function analysis on members of the myc, jun and fos oncogene families. These studies have revealed various structural aspects of these proteins which are necessary and sufficient for transformation. Our studies of the c-jun oncogene revealed that in addition to the DNA binding and dimerization domains, the N-terminal transactivation domain is required for cellular transformation. In addition, the ability of c-jun to transactivate correlates with its ability to transform cells. Thus, c-jun appears to transform cells by regulating gene expression. Further, detailed mutation analysis of c-jun has demonstrated that phosphorylation of cJun at serines 63/73 results in increased transactivation and ultimately transformation. The phosphorylation of these sites occurs in part through a ras/raf dependent pathway which provides an important biochemical link between these oncogenes. More recent studies are aimed at a more detailed analysis on other c-jun post-translational modifications and their biochemical and biologic effects and parallel studies with the c- fos oncogene examining the relationship between phosphorylation and biologic activity. This work has revealed that small amino acid deletion in the N-terminus transactivation domain results in constitutive phosphorylation of c-jun and increased transactivation. Our studies of the myc oncogene have focused on comparing the transactivating and transforming activities of the c-myc and L-myc genes. By exon shuffling, we have demonstrated that L-myc transactivates and transforms much less efficiently than c-myc and this difference is localized to the second exon. More recent work has focused on the precise structural differences between these genes and their role in apotosis.