Importantly, both upon expression of oncogenic Ras and NOX4, DDR activation in the form of γH2AX foci was induced in DNA replicating cells, as demonstrated by their staining for the DNA replication factor PCNA, hence further highlighting the common DNA replication stress induced by these two genes.
Stiff and coworkers (2004) reported that the similar number of γH2AX foci was induced by IR in human and mouse embryonic fibroblasts lacking either ATM or DNA-PK in comparison with control cell lines, but the kinetics of γH2AX release was delayed in DNA-PK−/− cell line M059J derived from human malignant glioma.
Mendes-Pereira and colleagues previously showed that PTEN loss reduced the formation of DSB-induced RAD51 foci20; however, other studies showed that RAD51 foci are induced normally in cells lacking PTEN19,22.
When the tumor promoter TPA was used, a significant number of transformed foci were induced concentration-dependently, whereas only a few foci were observed in control cultures.
We also found that 53BP1 foci were induced in a LET -and fluence-dependent manner and fewer foci were induced in G0 cells than G1 cells, however, the decrease of foci in 24 h after irradiation was highly relevant to the type of particles.
Previous studies have demonstrated that following genotoxic stress, micronuclei and apoptotic cells containing Rad51 and RPA residual foci are induced [37], [38].
At 0.5 h post-irradiation comparable levels of γH2AX-foci were induced in CD34+ and CD34− samples regardless of the donor age (data not shown).
53BP1 protein foci were induced in SSC, but were not formed in round and elongated spermatides.
In response to low-dose radiation, few BCLAF1 foci were induced close to the nuclei where γH2AX foci were also located.
Thus, formation of punctate actin foci is induced in an S-allele-specific manner in Arabidopsis PrpS-expressing pollen by Papaver PrsS.
