Kinesin-14 family proteins and microtubule dynamics define S. pombe mitotic and meiotic spindle assembly, and elongation

To segregate the chromosomes faithfully during cell division, cells assemble a spindle that captures the kinetochores and pulls them towards opposite poles. Proper spindle function requires correct interplay between microtubule motors and non-motor proteins. Defects in spindle assembly or changes in spindle dynamics are associated with diseases, such as cancer or developmental disorders. Here, we compared mitotic and meiotic spindles in fission yeast. We show that, even though mitotic and meiotic spindles underwent the typical three phases of spindle elongation, they have distinct features. We found that the relative concentration of the kinesin-14 family protein Pkl1 is decreased in meiosis I compared to mitosis, while the concentration of the kinesin-5 family protein Cut7 remains constant. We identified the second kinesin-14 family protein Klp2 and microtubule dynamics as factors necessary for proper meiotic spindle assembly. This work defines the differences between mitotic and meiotic spindles in fission yeast Schizosaccharomyces pombe, and provides prospect for future comparative studies.
We acknowledge the Cell and Tissue Imaging (PICT-IBiSA), Institute Curie, member of the French National Research Infrastructure France-BioImaging (ANR10-INBS-04). Ana Loncar is supported by a PhD fellowship from the European Union ITN-Divide Network (Marie Skłodowska-Curie grant agreement No 675737s). This work is supported by grants from INCa, Fondation ARC, and La Ligue National Contre le Cancer. The Tran lab is a member of the Labex CelTisPhyBio, part of IdEx PSL.