The kinetochore protein Bub1 participates in the DNA damage response

Abstract

The DNA damage response (DDR) and the spindle assembly checkpoint (SAC) are two critical mechanisms by which mammalian cells maintain genome stability. There is a growing body of evidence that DDR elements and SAC components crosstalk. Here we report that Bub1 (Budding Uninhibited by Benzimidazoles 1), one of the critical kinetochore proteins essential for SAC, is required for optimal DDRs. We found that knocking-down Bub1 resulted in prolonged H2AX foci and comet tail formation as well as hypersensitivity in response to ionizing radiation (IR). Further, we found that Bub1-mediated Histone H2A Threonine 121 phosphorylation was induced after IR in an ATM-dependent manner. We demonstrated that ATM phosphorylated Bub1 on serine 314 in response to DNA damage in vivo. Finally, we showed that ATM-mediated Bub1 serine 314 phosphorylation was required for IR-induced Bub1 activation and for the optimal DDR. Together, we elucidate the molecular mechanism of DNA damage-induced Bub1 activation and highlight a critical role of Bub1 in DDR.

Spindle Checkpoint Factors Bub1 and Bub2 Promote DNA Double-Strand Break Repair by Nonhomologous End Joining

“…Consistent with the critical roles of the SAC and DDR pathway proteins in checkpoint activation (21), our data indicate that phosphorylation of both Rad53 and ␥-H2A is continuously altered in bub mutants in response to HO-induced DNA damage, whereas these DSB signatures are rapidly diminished in wild-type cells. This suggests DSB repair and resumption of the cell cycle are much quicker in wild-type cells than in the bub mutants, which display these signatures for much longer periods.…”

“…Moreover, the ability of these Bub proteins to interchangeably stimulate the Rad9 and Rad53 DNA damage checkpoint kinases suggests that the Bub pathways provide robust and redundant protection against spindle damage (20) and also implies a likely role for these proteins in response to mitotic DSBs. In fact, recent observations in mammalian cells have indicated that Bub1 functions in the DDR signaling pathway (21), but its role in supporting NHEJ efficiency remains unclear.…”

Ku70 and non-homologous end joining protect testicular cells from DNA damage

“…The observed 1.4-fold increase of meiotic metaphases with cH2AX focus signals (possibly marking unrepaired or not completely repaired DSBs) might explain the ,1.6-fold increase in meiotic metaphase apoptosis in Ku70 2/2 stage XII tubules noted by TUNEL staining. A cross talk between the DNA damage response and the spindle assembly checkpoint has been noted previously (Choi and Lee, 2008;Maringele and Lydall, 2002;Yang et al, 2012) and might be instrumental for this situation.…”

Centrosomal Che-1 Protein Is Involved in the Regulation of Mitosis and DNA Damage Response by Mediating Pericentrin (PCNT)-dependent Chk1 Protein Localization

“…The DNA damage response and the spindle assembly checkpoint are two critical mechanisms by which mammalian cells maintain genome stability, and there is a growing body of evidence of a cross-talk between these two checkpoint, Indeed, a number of DNA damage responsive elements, including ATM, Chk1, Chk2, and Brca1, have been reported to play a role in spindle checkpoint activation (6,17,32,33). In addition, several proteins involved in SAC such as Bub1 and Mad2 have been shown to play an important role in G 2 /M checkpoint (33)(34)(35)(36).…”

“…In addition, several proteins involved in SAC such as Bub1 and Mad2 have been shown to play an important role in G 2 /M checkpoint (33)(34)(35)(36). In particular, Chk1 kinase has been found to sustain activation of SAC in response to DNA damage (36).…”