- 作者: Nian-Kang Sun a,b, Hsin-Pang Lu a, Chuck C.K. Chao a
- 作者服務機構: a Tumor Biology Laboratory, Department of Biochemistry, Chang Gung, University, Taoyuan, and b Institute of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan, ROC
- 中文摘要: --
- 英文摘要: highly conserved sequencing (greater than 98% similari-ty) with those of mouse, human, and monkey. Rat andfruit fly DDB1 exhibit 62.23% identity and 57.66% homol-ogy. The evolutionary conservation of the DDB1 se-quence suggests that DDB1 may play a pivotal role inmammals as well as in other eukaryotes. However, over-expression of DDB1 did not augment UV-damaged-DNArecognition activity in human HeLa, hamster V79, or ratPC12 cells. In contrast, restricting DDB2 expression byantisense ddb2 partially inhibited UV-damaged-DNA rec-ognition activity in cells, whereas overexpressing DDB2through a recombinant ddb2 adenovirus partly restoredthe recognition activity of these cells. These findings sup-port the notion that DDB abundance is functionally corre-lated with UV-damaged-DNA recognition activity. Theseresults also suggest that the profusion of DDB2, but notDDB1, may moderate UV-damaged-DNA recognition ac-tivity.Recognition and incision of UV-DNA adducts play keyroles in the efficacy of nucleotide excision repair. Dam-aged-DNA recognition activity has been identified fromprimate cells as a complex of DDB1 (127-kD) and DDB2(48-kD) subunits. However, the function of damaged-DNA binding proteins (DDBs) in damaged-DNA recogni-tion is not we llunderstood. To assess the functional cor-relation between DDBs and UV-damaged-DNA recogni-tion activity, we identified UV-damaged-DNA recogni-tion activities in rodent cell lines. There is a cell type-dependent expression of DDB1 and DDB2. Rodent cellshad less abundant DDBs and lower UV-damaged-DNArecognition activity than did human tumor cells. Interest-ingly, the profusion of DDBs is associated with UV-dam-aged-DNA recognition activity in these cell lines. We alsodiscovered tissue-dependent expression of DDBs and itsfunctional correlation with UV-damaged-DNA recogni-tion activity. cDNA (3850 nucleotides) from rat ddb1 wasisolated. It contained the complete length of the openreading frame that encodes an 1140-amino-acid poly-peptide with a predicted molecular weight of 126.8 kD.The predicted protein size from the rat ddb1 gene resem-bles that from human DDB1 (127 kD). Rat DDB1 shares
- 中文關鍵字: --
- 英文關鍵字: DDBI, DNA repair, Ultraviolet radiation, XPE