title: Efficiency of nonhomologous DNA end joining varies among somatic tissues, despite similarity in mechanism.
abstract: Failure to repair DNA double-strand breaks (DSBs) can lead to cell death or cancer. Although nonhomologous end joining (NHEJ) has been studied extensively in mammals, little is known about it in primary tissues. Using oligomeric DNA mimicking endogenous DSBs, NHEJ in cell-free extracts of rat tissues were studied. Results show that efficiency of NHEJ is highest in lungs compared to other somatic tissues. DSBs with compatible and blunt ends joined without modifications, while noncompatible ends joined with minimal alterations in lungs and testes. Thymus exhibited elevated joining, followed by brain and spleen, which could be correlated with NHEJ gene expression. However, NHEJ efficiency was poor in terminally differentiated organs like heart, kidney and liver. Strikingly, NHEJ junctions from these tissues also showed extensive deletions and insertions. Hence, for the first time, we show that despite mode of joining being generally comparable, efficiency of NHEJ varies among primary tissues of mammals.
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore, India.
authors.forename: Sheetal
authors.initials: S
authors.lastname: Sharma
authors.forename: Bibha
authors.initials: B
authors.lastname: Choudhary
authors.forename: Sathees C
authors.initials: SC
authors.lastname: Raghavan
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004247:DNA / Q000235:genetics* / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D007668:Kidney / Q000378:metabolism; D000072200:Ku Autoantigen; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D004247:DNA; C000606511:Xrcc6 protein, rat; D000072200:Ku Autoantigen; D011088:DNA Ligases; D045643:DNA Repair Enzymes; D000072481:DNA Ligase ATP