The Influence Of Circadian Gene Period2 On Cell Damaged By Ultraviolet

Ultraviolet radiation (UV) is a common physical factor in the cause of DNAdamage. According to the different wavelength, ultraviolet radiation can be dividedinto three types: UVA (315—400nm), UVB(280—315nm) and UVC(200—280nm).UVC-induced DNA damage is heavier than that of the other two UV. Studiesshowed that overdose UV radiation on skin can induce skin cancer.In almost all living organisms, various physiological and behavioral functions,such as sleep-wake cycle, body temperature, blood pressure and heart rate, areexpressed rhythmically. These daily rhythms, referred to as circadian rhythm, are thestrongest biological rhythm.Period2 is a major participant of circadian family. Clinical studies foundPeriod2 had great relationship with tumor genesis. In our laboratory studies,overexpression of Period2 results in reduced cellular damage caused byγ-ray andradiosensitivity. UV also can cause cellular damage driven by the similar mechanismasγ-ray. So we inferred Period2 might be involved in cellular damage.The NIH3T3 cells were treated with radio at two different time points includingPeriod2 expression in peak level and in trough level. Apoptosis rate, cell cycle rateand growth ability of two different time treatment cells were detected withflowcytometry, colony formation assay and SCGE. Furthermore, We transfectedPeriod2-expression plasmid into cell in order to increase Period2 expression in cell.After radio treatment, Period2 high expression cell also show the difference in cellgrowth and apoptosis.UV irradiation can induce DNA damage such as single-bond breakage,double-bond breakage and Cyclobutane pyrimidine dimmer formation, which can berepaired by DNA repair system. Research results by SCGE showed the effects ofPeriod2 gene on inhibiting DNA damage and promoting DNA repair may play animportant role in prevention and therapy of UV-induced damage diseases.