Mammalian SEPT2 is required for scaffolding nonmuscle myosin II and its kinases.
Mammalian septin SEPT2 belongs to a conserved family of filamentous GTPases that are associated with actin stress fibers in interphase cells and the contractile ring in dividing cells. Although SEPT2 is essential for cytokinesis, its role in this process remains undefined. Here, we report that SEPT2 directly binds nonmuscle myosin II (myosin II), and this association is important for fully activating myosin II in interphase and dividing cells. Inhibition of the SEPT2-myosin II interaction in interphase cells results in loss of stress fibers, while in dividing cells this causes instability of the ingressed cleavage furrow and dissociation of the myosin II from the Rho-activated myosin kinases ROCK and citron kinase. We propose that SEPT2-containing filaments provide a molecular platform for myosin II and its kinases to ensure the full activation of myosin II that is necessary for the final stages of cytokinesis.
Joo
Emily
E
Program in Cell Biology, Hospital for Sick Children, Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1X8, Canada.
Surka
Mark C
MC
Program in Cell Biology, Hospital for Sick Children, Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1X8, Canada.
Trimble
William S
WS
Program in Cell Biology, Hospital for Sick Children, Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1X8, Canada. Electronic address: wtrimble@sickkids.ca.
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D048749:Cytokinesis; D020558:GTP Phosphohydrolases / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D024462:Myosin Type II / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D054460:rho-Associated Kinases / Q000378:metabolism
D047908:Intracellular Signaling Peptides and Proteins; C115635:citron-kinase; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020558:GTP Phosphohydrolases; D024462:Myosin Type II