title: Dose response and adaptive response of non-homologous end joining repair genes and proteins in resting human peripheral blood mononuclear cells exposed to γ radiation.
abstract: Ionising radiation induces single-strand breaks, double-strand breaks (DSB) and base damages in human cell. DSBs are the most deleterious and if not repaired may lead to genomic instability and cell death. DSB can be repaired through non-homologous end joining (NHEJ) pathway in resting lymphocytes. In this study, NHEJ genes and proteins were studied in irradiated human peripheral blood mononuclear cells (PBMC) at resting stage. Dose-response, time point kinetics and adaptive-response studies were conducted in irradiated PBMC at various end points such as DNA damage quantitation, transcription and protein expression profile. Venous blood samples were collected from 20 random, normal and healthy donors with written informed consent. PBMC was separated and irradiated with various doses between 0.1 and 2.0 Gy ((60)CO-γ source) for dose-response study. Repair kinetics of DNA damage and time point changes in expression of genes and proteins were studied in post-irradiated PBMC at 2.0 Gy at various time points up to 240 min. Adaptive-response study was conducted with a priming dose of 0.1 Gy followed by a challenging dose of 2.0 Gy after 4-h incubation. Our results revealed that Ku70, Ku80, XLF and Ligase IV were significantly upregulated (P < 0.05) at 4-h post-irradiation at transcript and protein level. Adaptive-response study showed significantly increased expression of the proteins involved in NHEJ, suggesting their role in adaptive response in human PBMC at G0/G1, which has important implications to human health.
authors.affiliation: Low Level Radiation Research Section, Radiation Biology and Health Sciences Division, Bio-Sciences Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
authors.forename: Shridevi
authors.initials: S
authors.lastname: Shelke
authors.affiliation: Low Level Radiation Research Section, Radiation Biology and Health Sciences Division, Bio-Sciences Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India birajalaxmi@yahoo.co.in biraj@barc.gov.in.
authors.forename: Birajalaxmi
authors.initials: B
authors.lastname: Das
mesh_terms: D002478:Cells, Cultured; D020552:Comet Assay; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000502:physiology* / Q000528:radiation effects; D011836:Radiation Tolerance; D059467:Transcriptome / Q000528:radiation effects
chemical_list: D045643:DNA Repair Enzymes