Cooperation of EB1-Mal3 and the Bub1 spindle checkpoint

EB1 is a conserved microtubule binding protein that preferentially localizes to the growing tips of the microtubule plus end. Whilst the function of EB1 in cell polarity control is well established, its role during mitosis remains largely elusive. Here we discuss our recent work of roles for Mal3, the fission yeast EB1 homologue, in mitotic progression and chromosome stability. Our analysis sheds light upon the requirement of Mal3 for bipolar microtubule attachment and its cooperative role with the spindle assembly checkpoint. In particular Mal3 collaborates with a specific branch of this checkpoint pathway, which is dependent upon Bub1, but not Mad2. As malfunctioning of the EB1-mediated pathway might be directly related to chromosome instability in some types of human cancers, a new knowledge of Mal3's mitotic role would be of direct relevance to understanding the molecular defects in these cancer cells.