title: Involvement of human small fragment nuclease in the resistance of human cells to UV-C-induced cell death.
abstract: Human small fragment nuclease (Sfn) is one of the cellular proteins that were reported to degrade small, single-stranded DNA and RNA. However, the biological role of Sfn in cellular response to various stressors such as UV-C (mainly 254 nm wavelength ultraviolet ray) remains unclear. We have examined whether modulation of human SFN gene expression affects cell survival capacity against UV-C-induced cell death, analyzing colony survival ability in UV-C-sensitive human RSa cells treated with short double-stranded RNA (siRNA) specific for SFN messenger RNA (mRNA). The expression levels of SFN mRNA in the siRNA-treated RSa cells decreased to about 15% compared with those in the control siRNA-treated cells. The siRNA-treated RSa cells showed lower colony survival and higher activity of caspase-3 after UV-C irradiation than the control siRNA-treated RSa cells. Furthermore, the removal capacity of cyclobutane pyrimidine dimers (CPD) in the siRNA-treated RSa cells decreased compared with the control siRNA-treated RSa cells. There was no difference in the colony survival and CPD removal capacity after UV-C irradiation between the control siRNA-treated RSa cells and mock-treated RSa cells. These results suggest that SFN expression is involved in resistance of RSa cells to UV-C-induced cell death through the roles it plays in the DNA repair process.
authors.affiliation: Department of Neurosurgery, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan.
authors.forename: Seiro
authors.initials: S
authors.lastname: Ito
authors.forename: Kazuko
authors.initials: K
authors.lastname: Kita
authors.forename: Ling
authors.initials: L
authors.lastname: Zhai
authors.forename: Chieko
authors.initials: C
authors.lastname: Wano
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Suzuki
authors.forename: Akira
authors.initials: A
authors.lastname: Yamaura
authors.forename: Nobuo
authors.initials: N
authors.lastname: Suzuki
mesh_terms: D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D005092:Exonucleases / Q000235:genetics* / Q000378:metabolism*; D005095:Exoribonucleases; D006801:Humans; D007700:Kinetics; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism*; D011740:Pyrimidine Dimers / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D011740:Pyrimidine Dimers; D012333:RNA, Messenger; D005092:Exonucleases; D005095:Exoribonucleases; C413442:SFN protein, human; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases