title: Phosphorylation of MyoGEF on Thr-574 by Plk1 promotes MyoGEF localization to the central spindle.
abstract: We reported previously that a guanine nucleotide exchange factor, MyoGEF, localizes to the central spindle, activates RhoA, and is required for cytokinesis. In this study, we have found that Plk1 (polo-like kinase 1) can phosphorylate MyoGEF, thereby recruiting MyoGEF to the central spindle as well as enhancing MyoGEF activity toward RhoA. The in vitro kinase assay shows that Plk1 can phosphorylate MyoGEF on threonine 574. Immunoprecipitation/immunoblot analysis demonstrates that mutation of threonine 574 to alanine dramatically decreases threonine phosphorylation of MyoGEF in transfected HeLa cells, suggesting that threonine 574 is phosphorylated in vivo. Consistent with these observations, immunofluorescence shows that Plk1 and MyoGEF colocalize at the spindle pole and central spindle during mitosis and cytokinesis. Importantly, RNA interference-mediated depletion of Plk1 interferes with the localization of MyoGEF at the spindle pole and central spindle. Moreover, mutation of threonine 574 to alanine in MyoGEF or depletion of Plk1 by RNA interference leads to a decrease in MyoGEF activity toward RhoA in HeLa cells. Therefore, our results suggest that Plk1 can regulate MyoGEF activity and localization, contributing to the regulation of cytokinesis.
authors.affiliation: Department of Biochemistry, Kansas State University, Manhattan, Kansas 66506, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Asiedu
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.forename: Fumio
authors.initials: F
authors.lastname: Matsumura
authors.forename: Qize
authors.initials: Q
authors.lastname: Wei
mesh_terms: D000409:Alanine / Q000737:chemistry; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000502:physiology*; D048749:Cytokinesis; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods; D008938:Mitosis; D008954:Models, Biological; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000502:physiology*; D012313:RNA / Q000737:chemistry; D008941:Spindle Apparatus; D013912:Threonine / Q000737:chemistry*; D000097869:Polo-Like Kinase 1
chemical_list: D000409:Alanine; D018797:Cell Cycle Proteins; D020662:Guanine Nucleotide Exchange Factors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D012313:RNA; D013912:Threonine; D000097869:Polo-Like Kinase 1; C527325:PLEKHG6 protein, human