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against UV irradiation in human cells and Drosophila

By Nian-kang Sun, Chun-ling Sun, Chia-hua Lin, Li-mai Pai and Chuck Ck Chao

Abstract

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 deathreceptor 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

Year: 2013
OAI identifier: oai:CiteSeerX.psu:10.1.1.319.2568
Provided by: CiteSeerX
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