title: The p42/p44 MAP kinase pathway prevents apoptosis induced by anchorage and serum removal.
abstract: Anchorage removal like growth factor removal induces apoptosis. In the present study we have characterized signaling pathways that can prevent this cell death using a highly growth factor- and anchorage-dependent line of lung fibroblasts (CCL39). After anchorage removal from exponentially growing cells, annexin V-FITC labeling can be detected after 8 h. Apoptosis was confirmed by analysis of sub-G1 DNA content and Western blotting of the caspase substrate poly (ADP-ribose) polymerase. Growth factor withdrawal accelerates and potentiates suspension-induced cell death. Activation of Raf-1 kinase in suspension cultures of CCL39 or Madin-Darby canine kidney cells stably expressing an estrogen-inducible activated-Raf-1 construct (DeltaRaf-1:ER) suppresses apoptosis induced by growth factor and/or anchorage removal. This protective effect appears to be mediated by the Raf, mitogen- or extracellular signal-regulated kinase kinase (MEK), and mitogen-activated protein kinase module because it is sensitive to pharmacological inhibition of MEK-1 and it can be mimicked by expression of constitutively active MEK-1 in CCL39 cells. Finally, apoptosis induced by disruption of the actin cytoskeleton with the Rho-directed toxin B (Clostridium difficile) is prevented by activation of the DeltaRaf-1:ER chimeric construct. These findings highlight the ability of p42/p44 mitogen-activated protein kinase to generate survival signals that counteract cell death induced by loss of matrix contact, cytoskeletal integrity, and extracellular mitogenic factors.
authors.affiliation: Centre National de la Recherche Scientifique, Unite Mixte de Recherche, 6543, Centre A. Lacassagne, 06189 Nice Cedex 2, France.
authors.forename: M
authors.initials: M
authors.lastname: Le Gall
authors.forename: J C
authors.initials: JC
authors.lastname: Chambard
authors.forename: J P
authors.initials: JP
authors.lastname: Breittmayer
authors.forename: D
authors.initials: D
authors.lastname: Grall
authors.forename: J
authors.initials: J
authors.lastname: Pouysségur
authors.forename: E
authors.initials: E
authors.lastname: Van Obberghen-Schilling
mesh_terms: D000818:Animals; D017209:Apoptosis; D001769:Blood; D002448:Cell Adhesion; D002478:Cells, Cultured; D006224:Cricetinae; D004285:Dogs; D004789:Enzyme Activation; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D019908:Proto-Oncogene Proteins c-raf; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020741:rho GTP-Binding Proteins