The Study of Possible Mechanism of Myosin II inhibited Cytokinesis of Mammalian Cells

Adherent mammalian cells experience a series of elaborate,but simple morphological changes during cell division. This complex processwas mediated by mechanics and biological molecules. As a kind of motorproteins, myosin II plays an important role in cell division. Recentinvestigations showed that cells on substrates in the absence of myosin IIalso could finish cytokinesis. However, its mechanism is still unclear.In this study, morphology of NRK cells treated with 0.3%DMSO and 30\mumol blebbistatin (myosin II inhibitor) were investigated quantitatively byusing micro-image collecting and analysis system. Intercellular bridgedynamics was simulated using mechanical model of intercellular bridgethinning coupled with mechanical parameters of NRK cells. The distributionof actin in early cytokinesis was examined using immunofluorescence method.Our results showed that intercellular bridge thinning trajectory andmorphology of cells treated with 30 mol blebbistatin were fundamentallydifferent from cells treated with 0.3%DMSO. The surface tensioncontributed greatly to the trajectory of 30 mol blebbistatin group fromfluid mechanical considerations and the measured mechanical parameters.Immunofluorescence results indicated that a mass of actin was recruited tothe fan-shaped leading lamellipodia of daughter cells from the cytoplasm incells treated with 30 mol blebbistatin.Our study indicated that Laplace pressure determined by mechanicalproperties and the motility of cell orchestrated to dictate awell-controlled cytokinesis of cells in the absence of myosin II.