Mitotic kinases CDK1 and PLK1 phosphorylate 53BP1 to inhibit its recruitment to the ends of DSBs [72]. In contrast to 53BP1, pDNA-PK is required for the normal function of spindle assembly. BL-hydrolase expression. Some differences in DSB repair process between BL-treated young and presenescent Syrian hamster cells were observed: (1) the kinetics of gH2AX focus loss in G0 fibroblasts IFITM1 of young culture was faster than in cells that prematurely stopped dividing; (2) presenescent cells were characterized by a slower recruitment of DSB repair proteins 53BP1, phospho-DNA-PK and phospho-ATM to gH2AX focal sites, while the rate of phosphorylated ATM/ATR substrate accumulation was the same as that in young cells. Conclusions Our results demonstrate an impairment of DSB repair in prematurely aged Syrian hamster fibroblasts in comparison with young fibroblasts, suggesting age-related differences in response to BL therapy. Electronic supplementary material The online version of this article (doi:10.1186/s12867-015-0046-4) contains supplementary material, which is available to authorized users. and belongs to a family of DNA-cleaving glycopeptides. BL is considered to be a radiomimetic agent because it produces lesions similar to those induced by IR. BL is used in combination therapy of lymphomas, testicular cancers and carcinomas of the cervix, head and neck [12]. DSBs produced by BL have blunt ends or 1-base 5-overhangs. At the 3-ends, deoxyribose sugar moiety is usually oxidized at the C-4 position that leads to 3-phosphoglycolate (PG) formation [13]. For repair of DSBs made up of 3-PG termini, end processing is required. DSBs are especially dangerous for cells because they inhibit transcription and replication [14, 15], and lead to genomic rearrangements and the appearance of chromosome aberrations. DSBs are repaired by non-homologous end-joining (NHEJ) GS-9901 or homologous recombinational repair (HR). NHEJ is considered to be the main pathway of DSB repair that occurs during all phases of the cell cycle, but is usually predominant in G0/G1 [16], while HR is usually absent in G1, the most energetic in G2 and S, and reduces when cells improvement to G2/M stage [17]. DNA-PK, DNA-ligase IV, XRCC4, XLF, PNKP, Tdp1, DNA-polymerases and Artemis and operate in NHEJ [13, 16, 18, 19]. HR starts with the reputation of DSB by Mre11/Rad50/NBS1 (MRN complicated) accompanied by resection of damaged DNA ends by MRN as well as CtIP. Generated 3 DNA ends are included in RPA, which can be changed by Rad51, and Rad51-shaped filaments invade homologous series [20]. The induction from the phosphorylated type of histone H2AX, known as gamma-H2AX (gH2AX), is among the earliest events involved with DDR. gH2AX induction can be an essential event GS-9901 in DSB restoration leading towards the recruitment of several other restoration proteins at the websites of DSBs [21, 22]. H2AX phosphorylation could possibly be detected by European immunostaining or blotting in conjunction with fluorescence microscopy. DSB sites could be quickly visualized in cell nuclei as regional dots of H2AX histone phosphorylation. It’s been shown that the real amount of DSBs corresponds to the amount of gH2AX foci GS-9901 in cell nuclei. The same amount of DSBs Around, 35 per Gy per cell, can be induced in various cells treated by IR [23]. The immunofluorescence recognition of gH2AX is recognized as the most delicate method of reputation of DSB sites in cell nuclei. Using these techniques, we studied the potency of BL-induced DSB restoration in youthful and presenescent Syrian hamster fibroblasts as well as the kinetics of recruitment of phospho-(Ser1981) ATM (pATM), 53BP1 and phospho-(Ser2056) DNA-PK (pDNA-PK) DSB restoration protein to DSB sites designated by gH2AX. Using immunoblotting technique, we’re able to not discover any difference in kinetics of gH2AX reduction during 24?h after BL treatment of cells in the 1st as well as the 5th passages. However, we noticed some differences in DDR between presenescent and young Syrian hamster cells using immunofluorescence.