Function of Human Damaged DNA Binding Protein (DDB)

描述（由申请人提供）： DDB是p127（DDB 1）和p48（DDB 2）的哺乳动物异源二聚体。它与DNA损伤结合，并与许多蛋白质复合物相互作用，包括E2 F1，p300，STAGA和DNA聚合酶β，以及转化病毒的反式激活蛋白，包括HB病毒蛋白X和EB病毒EBNA 2。DDB 2的突变导致E组着色性干皮病。没有已知的DDB 1的自然发生的人类突变。DDB 1和DDB 2可能具有超出DDB异二聚体DNA损伤结合的单独功能。该项目的长期目标是了解DDB的作用，特别是作为癌症拮抗剂。在接下来的一段时间里，建议对实验室刚刚获得的DDB 2（-/-）和（-/+）小鼠及其衍生细胞进行表征和研究。在人类细胞中用RNAi破坏DDB 1的基因也将被探索，同样也将探索分裂酵母S.在实验室里也被分离出来的粟酒酵母。该实验室最近表明，XP-E细胞实际上对紫外线辐射具有异常抗性，因为它们组成性地或响应于紫外线辐射产生很少或不产生p53，因此不经历p53介导的凋亡。这些现象将进一步研究。最后，最近观察到DDB与DNA聚合酶的相互作用将进一步研究。这些研究将有助于我们了解紫外线照射后癌症的发生，特别是在着色性干皮病中，以及病毒感染如何导致细胞转化。

DESCRIPTION (provided by applicant): DDB is a mammalian heterodimer of p127 (DDB1) and p48 (DDB2). It binds to DNA damages and interacts with a number of protein complexes, including E2F1, p300, STAGA and DNA polymerase epsilon, as well as with transactivator proteins of transforming viruses, including HB virus protein X and EB virus EBNA 2. Mutations in DDB2 give rise to xeroderma pigmentosum group E. No naturally occurring human mutations of DDB1 are known. It is likely that DDB1 and DDB2 have individual functions beyond the DDB heterodimeric DNA damage binding. The long-term goals of this project are to understand the role(s) of DDB, especially as a cancer antagonist. During the coming period it is proposed to characterize and study the DDB2 (-/-) and (-/+) mice just obtained in the laboratory and cells derived from them. Gene disruptions of DDB1 with RNAi in human cells will also be explored as will a deletion mutant of the DDB1 homologue of the fission yeast, S. pombe that was also just isolated in the laboratory. The laboratory recently showed that XP-E cells are actually abnormally resistant to UV radiation as they produce little or no p53 constitutively or in response to UV irradiation and hence do not undergo p53-mediated apoptosis. These phenomena will be further studied. Finally, a recent observation that DDB interacts with DNA polymerase epsilon will be further studied. Together these studies will help us to understand the genesis of cancers after UV irradiation, especially in xeroderma pigmentosum, as well as how viral infection can lead to cellular transformations.