Function of Human Damaged DNA Binding Protein (DDB)

描述(由申请人提供)： DDB是哺乳动物p127(DDB1)和P48(DDB2)的异源二聚体。它与DNA损伤结合，并与许多蛋白质复合体相互作用，包括E2F1、p300、STAGA和DNA聚合酶epsilon，以及与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。DDB2的突变导致着色性干皮病E组。目前尚不清楚人类自然发生的DDB1突变。DDB1和DDB2很可能具有超越DDB异源二聚体DNA损伤结合的单独功能。这个项目的长期目标是了解DDB的作用(S)，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DDB2(-/-)和(-/+)小鼠及其来源的细胞进行表征和研究。还将探索DDB1与RNAi在人类细胞中的基因破坏，以及同样在实验室分离的分裂酵母S.pombe的DDB1同源物的缺失突变体。实验室最近发现，XP-E细胞实际上对紫外线辐射具有异常的抵抗力，因为它们结构性地或对紫外线辐射产生很少或根本不产生P53，因此不会经历P53介导的细胞凋亡。这些现象将被进一步研究。最后，将进一步研究最近观察到的DDB与DNA聚合酶epsilon的相互作用。总之，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.