Role of SVIL phosphorylation by PLK1 in myosin II activation and cytokinetic furrowing

Abstract

PLK1 is a widely conserved serine/threonine kinase that regulates progression of multiple stages of mitosis. Although extensive studies about PLK1 functions during cell division have been performed, it still remains elusive how PLK1 regulates myosin II activation at the equatorial cortex and ingression of cleavage furrow. In this report, we show that an actin/myosin II binding protein, supervillin (SVIL), is a novel substrate of PLK1. PLK1 phosphorylates Ser238 of SVIL, which can promote the localization of SVIL to the central spindle and an association with PRC1. Expression of a PLK1 phosphorylation site mutant, S238A-SVIL, inhibited myosin II activation at the equatorial cortex and induced aberrant furrowing. SVIL has both actin and myosin II binding regions in the N-terminus. Expression of ΔMyo-SVIL (deleted of myosin II binding region), but not of ΔAct-SVIL (deleted of actin binding region), reduced myosin II activation and promoted defect in furrowing. Our study indicates a possible role of phosphorylated SVIL as a molecular link between the central spindle and the contractile ring to coordinate the activation of myosin II for the ingression of the cleavage furrow.