Fission yeast Ase1 PRC1  is required for the G 2 -microtubule damage response.
 Schizosaccharomyces pombe  delays entry into mitosis following G 2  microtubule damage. This pathway is dependent on Rad26 ATRIP , the regulatory subunit of the Rad26 ATRIP /Rad3 ATR  DNA damage response (DDR) complex. However, this G 2  microtubule damage response pathway acts independently of the G 2  DNA damage checkpoint pathway. To identify other proteins in this G 2  microtubule damage pathway, we previously screened a cDNA overexpression library for genes that rescued the sensitivity of  rad26Δ  cells to the microtubule poison thiabendazole. A partial cDNA fragment encoding only the C-terminal regulatory region of the microtubule bundling protein  Ase1   PRC1  was isolated. This fragment lacks the Ase1 PRC1  dimerization and microtubule binding domains and retains the conserved C-terminal unstructured regulatory region. Here, we report that  ase1Δ  cells fail to delay entry into mitosis following G 2  microtubule damage. Microscopy revealed that Rad26 ATRIP  foci localized alongside Ase1 PRC1  filaments, although we suggest that this is related to microtubule-dependent double strand break mobility that facilitates homologous recombination events. Indeed, we report that the DNA repair protein Rad52 co-localizes with Rad26 ATRIP  at these foci, and that localization of Rad26 ATRIP  to these foci depends on a Rad26 ATRIP  N-terminal region containing a checkpoint recruitment domain. To our knowledge, this is the first report implicating Ase1 PRC1  in regulation of the G 2 /M transition.
Doss RM, Xhunga S, Klimczak D, Cameron M, Verlare J, Wolkow TD