title: Sustained activation of MEK1-ERK1/2 pathway in membrane skeleton occurs dependently on cell adhesion in megakaryocytic differentiation.
abstract: A human megakaryoblastic cell line, CMK, was treated with 12-o-tetradecanoylphorbol-13-acetate (TPA) for differentiation-induction. We examined TPA-induced activation of the MEK1-ERK1/2 pathway in the 100,000g Triton X-insoluble fraction of CMK cells as the membrane skeleton and researched the relation of the MEK1-ERK1/2 activation with integrin expression. We found that this activation was divided into two phases: the first activation occurred transiently in the membrane skeleton fraction of the suspended cell status and diminished after 1h; and the second sustained activation was maintained by cell adhesion. TPA-treated CMK cells revealed increased expression of integrins alphaIIb and beta3 only when the cell adhesion persisted, regardless of the difference of culture substratum. Sustained activation of the MEK1-ERK1/2 pathway is generated in the membrane skeleton by continuous cell adhesion and seems to be essential to TPA-induced megakaryocytic differentiation of CMK cells.
authors.affiliation: The Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Chisato
authors.initials: C
authors.lastname: Mizutani
authors.forename: Yumi
authors.initials: Y
authors.lastname: Tohyama
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Miura
authors.forename: Terutoshi
authors.initials: T
authors.lastname: Hishita
authors.forename: Toshio
authors.initials: T
authors.lastname: Nishihara
authors.forename: Hirohei
authors.initials: H
authors.lastname: Yamamura
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ichiyama
authors.forename: Takashi
authors.initials: T
authors.lastname: Uchiyama
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tohyama
mesh_terms: D002070:Butadienes / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology*; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007700:Kinetics; D007938:Leukemia; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008533:Megakaryocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; C113580:U 0126; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D013755:Tetradecanoylphorbol Acetate