title: An ECT2-centralspindlin complex regulates the localization and function of RhoA.
abstract: In anaphase, the spindle dictates the site of contractile ring assembly. Assembly and ingression of the contractile ring involves activation of myosin-II and actin polymerization, which are triggered by the GTPase RhoA. In many cells, the central spindle affects division plane positioning via unknown molecular mechanisms. Here, we dissect furrow formation in human cells and show that the RhoGEF ECT2 is required for cortical localization of RhoA and contractile ring assembly. ECT2 concentrates on the central spindle by binding to centralspindlin. Depletion of the centralspindlin component MKLP1 prevents central spindle localization of ECT2; however, RhoA, F-actin, and myosin still accumulate on the equatorial cell cortex. Depletion of the other centralspindlin component, CYK-4/MgcRacGAP, prevents cortical accumulation of RhoA, F-actin, and myosin. CYK-4 and ECT2 interact, and this interaction is cell cycle regulated via ECT2 phosphorylation. Thus, central spindle localization of ECT2 assists division plane positioning and the CYK-4 subunit of centralspindlin acts upstream of RhoA to promote furrow assembly.
authors.affiliation: Research Institute of Molecular Pathology, 1030, Vienna, Austria.
authors.forename: Ozlem
authors.initials: O
authors.lastname: Yüce
authors.forename: Alisa
authors.initials: A
authors.lastname: Piekny
authors.forename: Michael
authors.initials: M
authors.lastname: Glotzer
mesh_terms: D000199:Actins / Q000378:metabolism; D000705:Anaphase / Q000187:drug effects; D064127:Aurora Kinases; D018797:Cell Cycle Proteins / Q000378:metabolism; D048749:Cytokinesis / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008677:Metaphase / Q000187:drug effects; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000378:metabolism*; D024462:Myosin Type II / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D021381:Protein Transport / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D008941:Spindle Apparatus / Q000187:drug effects / Q000201:enzymology; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D000199:Actins; D018797:Cell Cycle Proteins; C489850:ECT2 protein, human; D004791:Enzyme Inhibitors; C092935:KIF23 protein, human; D008869:Microtubule-Associated Proteins; D046912:Multiprotein Complexes; D011518:Proto-Oncogene Proteins; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D024462:Myosin Type II; D020742:rhoA GTP-Binding Protein