The Role of Myosin 2 in Contact Guidance

National Heart, Lung, And Blood Institute

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Abstract

To investigate the contribution of NM2s to cell contact guidance (CG) we established a microprinting technique. We tested the effect of the NM2B isoform knockout by visualizing cell spreading and dynamics of the cytoarchitecture on fibronectin coated micro-patterns on complex polydimethylsiloxane surfaces. This allows us to elucidate proteins that guide directional spreading and migration of fibroblast cells in response to CG cues. We found that absence of NM2B altered contact guidance of fibroblasts manifesting in a substantial loss of cellular projections and uniaxial directional polarization as well as the accumulation of the contractile apparatus in cells. Using cytoskeleton targeting compounds and a series of genetic transformations we verified a possible role for the NM2B isoform in contact guidance and proposed a model in which the roles of NM2A and NM2B isoforms diverge in control over the structure of the actin cytoskeleton and its crosstalk with microtubules. Analyses using super-resolution live cell imaging provide evidence supporting that the NM2A actomyosin cytoskeleton serves as an intracellular geometrical scaffold for microtubules. The loss of microtubules results in a loss of spontaneous linearization and loss of adaptive cell morphogenesis during CG. The loss of actomyosin scaffold results in a selective loss of spontaneous linearization restricted to the isotropic surface, but it preserves CG on the anisotropic surface where microtubules are guided by an extracellular geometrical scaffold. In cooperation with microtubules, the NM2A paralog works towards cell linearization and directional locomotion whereas the NM2B paralog works towards cell multiaxiality that is important for random walk motility and cell steering in complex environments.