The role of nonmuscle myosin in vertebrate cells is being explored by expression of a cDNA for the nonmuscle myosin heavy chain in tissue cultured cells. Nonmuscle myosin IT heavy chain isoforms bear some sequence homology to sarcomeric myosin heavy chains, and may be expected to have structural and functional homology as well. Sarcomeric myosin functions in muscle contraction by a sliding of myosin filaments with respect to actin filaments. Nonmuscle myosin also appears to function in contractile events within the cell. Evidence from non-vertebrate eukaryotic systems, including Acanthamoeba, Dictyostelium and Drosophila, implicates nonmuscle myosin in cellular functions such as cytokinesis, capping, cell shape, phagocytosis and morphogenetic movements. In this study, the role of nonmuscle myosin in vertebrates will be studied. Sense and antisense expression of nonmuscle myosin heavy chain cDNA in mammalian cells growing in tissue culture may interfere with the synthesis or function of the endogenous nonmuscle myosin heavy chains, and may provide evidence for those functions.
