Non-muscle myosins 2A and 2B drive changes in cell morphology that occur as myoblasts align and fuse.
The interaction of non-muscle myosins 2A and 2B with actin may drive changes in cell movement, shape and adhesion. To investigate this, we used cultured myoblasts as a model system. These cells characteristically change shape from triangular to bipolar when they form groups of aligned cells. Antisense oligonucleotide knockdown of non-muscle myosin 2A, but not non-muscle myosin 2B, inhibited this shape change, interfered with cell-cell adhesion, had a minor effect on tail retraction and prevented myoblast fusion. By contrast, non-muscle myosin 2B knockdown markedly inhibited tail retraction, increasing cell length by over 200% by 72 hours compared with controls. In addition it interfered with nuclei redistribution in myotubes. Non-muscle myosin 2C is not involved as western analysis showed that it is not expressed in myoblasts, but only in myotubes. To understand why non-muscle myosins 2A and 2B have such different roles, we analysed their distributions by immuno-electron microscopy, and found that non-muscle myosin 2A was more tightly associated with the plasma membrane than non-muscle myosin 2B. This suggests that non-muscle myosin 2A is more important for bipolar shape formation and adhesion owing to its preferential interaction with membrane-associated actin, whereas the role of non-muscle myosin 2B in retraction prevents over-elongation of myoblasts.
Swailes
Nathan T
NT
Institute of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
Colegrave
Melanie
M
Knight
Peter J
PJ
Peckham
Michelle
M
D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology; D048430:Cell Shape; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D016253:Microscopy, Immunoelectron; D032446:Myoblasts / Q000378:metabolism / Q000648:ultrastructure; D024507:Nonmuscle Myosin Type IIA / Q000235:genetics / Q000378:metabolism*; D024501:Nonmuscle Myosin Type IIB / Q000235:genetics / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism
D000199:Actins; D016376:Oligonucleotides, Antisense; D024507:Nonmuscle Myosin Type IIA; D024501:Nonmuscle Myosin Type IIB