Fission yeast Pak1 phosphorylates anillin-like Mid1 for spatial control of cytokinesis

J Cell Biol. 2020 Aug 3;219(8):e201908017. doi: 10.1083/jcb.201908017.


Protein kinases direct polarized growth by regulating the cytoskeleton in time and space and could play similar roles in cell division. We found that the Cdc42-activated polarity kinase Pak1 colocalizes with the assembling contractile actomyosin ring (CAR) and remains at the division site during septation. Mutations in pak1 led to defects in CAR assembly and genetic interactions with cytokinesis mutants. Through a phosphoproteomic screen, we identified novel Pak1 substrates that function in polarized growth and cytokinesis. For cytokinesis, we found that Pak1 regulates the localization of its substrates Mid1 and Cdc15 to the CAR. Mechanistically, Pak1 phosphorylates the Mid1 N-terminus to promote its association with cortical nodes that act as CAR precursors. Defects in Pak1-Mid1 signaling lead to misplaced and defective division planes, but these phenotypes can be rescued by synthetic tethering of Mid1 to cortical nodes. Our work defines a new signaling mechanism driven by a cell polarity kinase that promotes CAR assembly in the correct time and place.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actomyosin / genetics
  • Actomyosin / metabolism
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cytokinesis*
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism
  • Gene Expression Regulation, Fungal
  • Mutation
  • Phosphorylation
  • Schizosaccharomyces / enzymology*
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces pombe Proteins / genetics
  • Schizosaccharomyces pombe Proteins / metabolism*
  • Signal Transduction
  • Time Factors
  • p21-Activated Kinases / genetics
  • p21-Activated Kinases / metabolism*


  • CDC15 protein
  • Cell Cycle Proteins
  • Mid1 protein, S pombe
  • Schizosaccharomyces pombe Proteins
  • Actomyosin
  • p21-Activated Kinases
  • shk1 protein, S pombe
  • GTP-Binding Proteins