Fission yeast Rad26^ATRIP delays spindle-pole-body separation following interphase microtubule damage

The conserved fission yeast protein Rad26^ATRIP preserves genomic stability by occupying central positions within DNA-structure checkpoint pathways. It is also required for proper cellular morphology, chromosome stability and following treatment with microtubule poisons. Here, we report that mutation of a putative nuclear export sequence in Rad26^ATRIP disrupted its cytoplasmic localization in untreated cells and conferred abnormal cellular morphology, minichromosome instability and sensitivity to microtubule poisons without affecting DNA-structure checkpoint signaling. This mutation also disrupted a delay to spindle-pole-body separation that occurred following microtubule damage in G₂. Together, these results demonstrate that Rad26^ATRIP participates in two genetically defined checkpoint pathways - one that responds to genomic damage and the other to microtubule damage. This response to microtubule damage delays spindle-pole-body separation and, in doing so, might preserve both cellular morphology and chromosome stability.