title: A requirement for MAP kinase in the assembly and maintenance of the mitotic spindle.
abstract: Circumstantial evidence has suggested the possibility of microtubule-associated protein (MAP) kinase's involvement in spindle regulation. To test this directly, we asked whether MAP kinase was required for spindle assembly in Xenopus egg extracts. Either the inhibition or the depletion of endogenous p42 MAP kinase resulted in defective spindle structures resembling asters or half-spindles. Likewise, an increase in the length and polymerization of microtubules was measured in aster assays suggesting a role for MAP kinase in regulating microtubule dynamics. Consistent with this, treatment of extracts with either a specific MAP kinase kinase inhibitor or a MAP kinase phosphatase resulted in the rapid disassembly of bipolar spindles into large asters. Finally, we report that mitotic progression in the absence of MAP kinase signaling led to multiple spindle abnormalities in NIH 3T3 cells. We therefore propose that MAP kinase is a key regulator of the mitotic spindle.
authors.affiliation: Department of Interdisciplinary Oncology, H. Lee Moffitt Comprehensive Cancer Center, Tampa, FL 33612, USA.
authors.forename: Melinda M
authors.initials: MM
authors.lastname: Horne
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Guadagno
mesh_terms: D016475:3T3 Cells; D000818:Animals; D018797:Cell Cycle Proteins; D002457:Cell Extracts; D054638:Dual Specificity Phosphatase 1; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005057:Eukaryotic Cells / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D005260:Female; D017874:Immediate-Early Proteins / Q000378:metabolism / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008870:Microtubules / Q000187:drug effects / Q000201:enzymology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000172:deficiency* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D009865:Oocytes; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism / Q000494:pharmacology; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000235:genetics / Q000378:metabolism; D008941:Spindle Apparatus / Q000187:drug effects / Q000201:enzymology*; D029867:Xenopus Proteins / Q000172:deficiency* / Q000235:genetics; D014982:Xenopus laevis
chemical_list: D018797:Cell Cycle Proteins; D002457:Cell Extracts; D004791:Enzyme Inhibitors; D017874:Immediate-Early Proteins; D029867:Xenopus Proteins; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C448499:p42 MAP kinase, Xenopus; D020929:Mitogen-Activated Protein Kinase Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; C517020:Dusp1 protein, mouse; D017027:Protein Tyrosine Phosphatases