Actin turnover ensures uniform tension distribution during cytokinetic actomyosin ring contraction

Mol Biol Cell. 2019 Apr 1;30(8):933-941. doi: 10.1091/mbc.E18-08-0511. Epub 2019 Feb 13.

Abstract

In many eukaryotes, cytokinesis is facilitated by the contraction of an actomyosin ring (AMR). The exact mechanisms that lead to this contractility are unknown, although some models posit that actin turnover in the AMR is essential. The effect of reduced actin dynamics during AMR formation has been well studied in Schizosaccharomyces pombe; however, the corresponding effects on AMR contraction are not well understood. By using mutants of the fission yeast actin severing protein Adf1, we observed that contracting AMRs display a "peeling" phenotype, where bundles of actin and myosin peel off from one side of the AMR, and are pulled across to the opposite side. This occurs multiple times during cytokinesis and is dependent on the activity of myosins Myo2, Myp2, and Myo51. We found that the distribution of Myo2 in the AMR anticorrelates with the location of peeling events, suggesting that peeling is caused by a nonuniform tension distribution around the AMR, and that one of the roles of actin turnover is to maintain a uniform tension distribution around the AMR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actin Depolymerizing Factors / metabolism
  • Actins / metabolism*
  • Actomyosin / metabolism
  • Actomyosin / physiology*
  • Cell Division / physiology
  • Cytokinesis / physiology*
  • Microfilament Proteins / metabolism
  • Myosin Heavy Chains / metabolism
  • Myosin Type II / metabolism
  • Myosins / metabolism
  • Phenotype
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces / metabolism
  • Schizosaccharomyces pombe Proteins / genetics
  • Schizosaccharomyces pombe Proteins / metabolism

Substances

  • Actin Depolymerizing Factors
  • Actins
  • MYO2 protein, S pombe
  • Microfilament Proteins
  • Myp2 protein, S pombe
  • Schizosaccharomyces pombe Proteins
  • Actomyosin
  • Myosin Type II
  • Myo51 protein, S pombe
  • Myosin Heavy Chains
  • Myosins