Self-sorting of nonmuscle myosins IIA and IIB polarizes the cytoskeleton and modulates cell motility

J Cell Biol. 2017 Sep 4;216(9):2877-2889. doi: 10.1083/jcb.201705167. Epub 2017 Jul 12.


Nonmuscle myosin II (NMII) is uniquely responsible for cell contractility and thus defines multiple aspects of cell behavior. To generate contraction, NMII molecules polymerize into bipolar minifilaments. Different NMII paralogs are often coexpressed in cells and can copolymerize, suggesting that they may cooperate to facilitate cell motility. However, whether such cooperation exists and how it may work remain unknown. We show that copolymerization of NMIIA and NMIIB followed by their differential turnover leads to self-sorting of NMIIA and NMIIB along the front-rear axis, thus producing a polarized actin-NMII cytoskeleton. Stress fibers newly formed near the leading edge are enriched in NMIIA, but over time, they become progressively enriched with NMIIB because of faster NMIIA turnover. In combination with retrograde flow, this process results in posterior accumulation of more stable NMIIB-rich stress fibers, thus strengthening cell polarity. By copolymerizing with NMIIB, NMIIA accelerates the intrinsically slow NMIIB dynamics, thus increasing cell motility and traction and enabling chemotaxis.

Publication types

  • Video-Audio Media

MeSH terms

  • Animals
  • COS Cells
  • Cell Polarity*
  • Chemotaxis*
  • Chlorocebus aethiops
  • Cytoskeleton / genetics
  • Cytoskeleton / metabolism*
  • Microscopy, Fluorescence
  • Microscopy, Video
  • Nonmuscle Myosin Type IIA / genetics
  • Nonmuscle Myosin Type IIA / metabolism*
  • Nonmuscle Myosin Type IIB / genetics
  • Nonmuscle Myosin Type IIB / metabolism*
  • Protein Multimerization
  • Protein Stability
  • RNA Interference
  • Rats
  • Signal Transduction
  • Stress Fibers / metabolism
  • Time Factors
  • Transfection


  • Nonmuscle Myosin Type IIA
  • Nonmuscle Myosin Type IIB