Sirtuin 6 (SIRT6) rescues the decline of homologous recombination repair during replicative senescence

Zhiyong Mao, Xiao Tian, Michael Van Meter, Zhonghe Ke, Vera Gorbunova1, and Andrei Seluanov1

Genomic instability is a hallmark of aging tissues. Genomic instability may arise from the inefficient or aberrant function of DNA double-stranded break (DSB) repair. DSBs are repaired by homologous recombination (HR) and nonhomologous DNA end joining (NHEJ). HR is a precise pathway, whereas NHEJ frequently leads to deletions or insertions at the repair site. Here, we used normal human fibroblasts with a chromosomally integrated HR reporter cassette to examine the changes in HR efficiency as cells progress to replicative senescence. We show that HR declines sharply with increasing replicative age, with an up to 38-fold decrease in efficiency in presenescent cells relative to young cells. This decline is not explained by a reduction of the number of cells in S/G2/M stage as presenescent cells are actively dividing. Expression of proteins involved in HR such as Rad51, Rad51C, Rad52, NBS1, and Sirtuin 6 (SIRT6) diminished with cellular senescence. Supplementation of Rad51, Rad51C, Rad52, and NBS1 proteins, either individually or in combination, did not rescue the senescence-related decline of HR. However, overexpression of SIRT6 in “middle-aged” and presenescent cells strongly stimulated HR repair, and this effect was dependent on mono-ADP ribosylation activity of poly(ADP-ribose) polymerase (PARP1). These results suggest that in aging cells, the precise HR pathway becomes repressed giving way to a more error-prone NHEJ pathway. These changes in the processing of DSBs may contribute to age-related genomic instability and a higher incidence of cancer with age. SIRT6 activation provides a potential therapeutic strategy to prevent the decline in genome maintenance./P>

• 以上资料由西亚试剂：http://www.xiyashiji.com/ 提供此产品的详细信息如密度,含量,分子式,分子量等均可在西亚官网查询   
• 相关产品如汞乙酸汞氯化汞氧化汞碘化汞硫酸汞硝酸汞溴化汞硝酸亚汞氯化亚汞乙酸苯汞碘化汞钾硫氰酸汞氯化氨基汞三氯生三氯氧磷三氯乙烯水合氯醛三氯化磷三氯化钌三氯化钛三氯化铱三氯化铑三氯硫磷三氯乙烷三氯甲烷三氯卡班TCC1,3,5-三氯苯1,2,4-三氯苯1,2,3-三氯苯无水氯化铝三氯乙酸酐三氯乙酸钠碘甲烷二碘甲烷三碘甲烷 三氟碘甲烷硫酸二甲酯氯磺酸苯硫酚苯硫酚钠3-氨基苯硫酚2,6-二氯苯硫酚2,4-二氯苯硫酚2,5-二氯苯硫酚2-甲氧基苯硫酚等均有销售.欢迎订购