- 作者: Nian-Kang Sun; Chun-Ling Sun; Chia-Hua Lin; Li-Mai Pai; Chuck C.-K. Chao
- 作者服務機構: Department of Biochemistry and Molecular Biology, Chang Gung University, Gueishan, Taiwan, Republic of China
- 中文摘要: --
- 英文摘要:
Background: We observed previously that cisplatin-resistant HeLa cells were
cross-resistant to UV light due to accumulation of DDB2, a protein implicated in
DNA repair. More recently, we found that cFLIP, which represents an anti-apoptotic
protein whose level is induced by DDB2, was implicated in preventing apoptosis
induced by death-receptor signaling. In the present study, we investigated whether
DDB2 has a protective role against UV irradiation and whether cFLIP is also involved
in this process.
Methods: We explored the role of DDB2 in mediating UV resistance in both human
cells and Drosophila. To do so, DDB2 was overexpressed by using a full-length open
reading frame cDNA. Conversely, DDB2 and cFLIP were suppressed by using
antisense oligonucleotides. Cell survival was measured using a colony forming assay.
Apoptosis was monitored by examination of nuclear morphology, as well as by flow
cytometry and Western blot analyses. A transcription reporter assay was also used to
assess transcription of cFLIP.
Results: We first observed that the cFLIP protein was upregulated in UV-resistant
HeLa cells. In addition, the cFLIP protein could be induced by stable expression of
DDB2 in these cells. Notably, the anti-apoptotic effect of DDB2 against UV
irradiation was largely attenuated by knockdown of cFLIP with antisense oligonucleotides in HeLa cells. Moreover, overexpression of DDB2 did not protect
against UV in VA13 and XP-A cell lines which both lack cFLIP. Interestingly, ectopic
expression of human DDB2 in Drosophila dramatically inhibited UV-induced fly
death compared to control GFP expression. On the other hand, expression of DDB2
failed to rescue a different type of apoptosis induced by the genes Reaper or eiger.
Conclusion: Our results show that DDB2 protects against UV stress in a
cFLIP-dependent manner. In addition, the protective role of DDB2 against UV
irradiation was found to be conserved in divergent living organisms such as human
and Drosophila. In addition, UV irradiation may activate a cFLIP-regulated apoptotic
pathway in certain cells. - 中文關鍵字: --
- 英文關鍵字: --