title: MEK, ERK, and p90RSK are present on mitotic tubulin in Swiss 3T3 cells: a role for the MAP kinase pathway in regulating mitotic exit.
abstract: The mitogen-activated protein (MAP) kinase pathway has been implicated in cell cycle control for some time. Several reports have suggested a role for this pathway in growth factor stimulation of DNA synthesis, while other reports have proposed a role in the transition of cells through mitosis. Here, we have examined the potential involvement of the extracellular signal-related kinase (ERK)1/2 MAP kinases, their upstream regulators, and downstream effectors in the regulation of mitosis. Inhibition of MAP kinase/ERK kinase (MEK) activity reduced the serum-stimulated DNA synthesis and proliferation of Swiss 3T3 cells. To study the potential mechanisms of this effect, we examined the subcellular localization of members of the MAP kinase pathway including regulators (MEK1/2), substrates (90-kDa ribosomal S6 kinases (RSKs): RSK1, RSK2 and RSK3), and ERK itself. We show that there is enrichment of ERK, MEK, and the RSK enzymes on both the spindle and midbody tubulin of dividing cells. Inhibition of MEK1/2 activity in cells released from mitotic arrest results in an inability of cells to complete mitosis. This failure to exit mitosis correlated with altered cyclin-dependent kinase (cdk) activities. Thus, the MAP kinase pathway may act to coordinate passage through mitosis in Swiss 3T3 fibroblasts by regulation of cdk activity.
authors.affiliation: Molecular Signalling Group, Division of Neuroscience, John Curtin School of Medical Research, Australian National University, GPO Box 334, A.C.T. 2601, Canberra, Australia. francis.willard@anu.edu.au
authors.forename: F S
authors.initials: FS
authors.lastname: Willard
authors.forename: M F
authors.initials: MF
authors.lastname: Crouch
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007150:Immunohistochemistry; D018386:Kinetochores / Q000737:chemistry; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020935:MAP Kinase Signaling System; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000032:analysis* / Q000276:immunology; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000276:immunology; D020928:Mitogen-Activated Protein Kinases / Q000032:analysis* / Q000276:immunology; D008938:Mitosis; D009570:Nitriles / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000276:immunology; D011505:Protein-Tyrosine Kinases / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000276:immunology; D019893:Ribosomal Protein S6 Kinases / Q000032:analysis* / Q000276:immunology; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D014404:Tubulin / Q000737:chemistry*
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; D014404:Tubulin; C113580:U 0126; D004247:DNA; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D019893:Ribosomal Protein S6 Kinases; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C512964:Rps6ka1 protein, mouse; D016203:CDC2 Protein Kinase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases