title: Cytochalasin D disruption of actin filaments in 3T3 cells produces an anti-apoptotic response by activating gelatinase A extracellularly and initiating intracellular survival signals.
abstract: Disruption of actin filaments affects multiple cell functions including motility, signal transduction and cell division, ultimately culminating in cell death. Although this is the usual sequence of events, we have made the interesting observation that disruption of actin filaments by the potent toxin cytochalasin D (Cyto D) causes one cell type, mouse mesangial cells (MMC), to undergo apoptosis, while in another cell type (NIH 3T3), it has the opposite effect, resulting in production of survival signals. The purpose of this study was to investigate the molecular basis for these observed differences. In the present communication, we demonstrate that exposure to Cyto D induces the pro-apoptotic pathways, p38 and stress-activated protein kinase (SAPK)/jun amino-terminal kinase (JNK), in both cell types. However, in 3T3, but not MMC, the extracellular signal regulated kinase (ERK) 1/2 pathway is protected from inhibition following treatment with Cyto D-leading to phosphorylation of Bclxi/Bcl 2-associated death promoter (BAD). Inhibition of Cyto D-induced secretion and activation of gelatinase A in 3T3 cells reverses the production of survival signals by Cyto-D. To investigate this effect further we employed CS-1 cells, a well-characterized melanoma cell line that lacks integrin beta3, and also does not secrete gelatinase A. Co-transfection of CS-1 cells with integrin beta3 and a gelatinase A transgene, which enables the cells to secrete constituitively active gelatinase A, enhances CS-1 cell survival signals. Together, our findings suggest that extracellularly activated gelatinase A, through interaction with integrin alphaVbeta3, elicits survival signals mediated through ERK 1/2 that override activation of p38 and SAPK/JNK stress pathways.
authors.affiliation: CIHR Group in Membrane Biology, Department of Medicine, Room 7207, Medical Science Building, University of Toronto, M5S 1A8, Toronto, Ontario, Canada.
authors.forename: Menachem
authors.initials: M
authors.lastname: Ailenberg
authors.forename: Mel
authors.initials: M
authors.lastname: Silverman
mesh_terms: D016475:3T3 Cells; D008841:Actin Cytoskeleton / Q000187:drug effects*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D015638:Cytochalasin D / Q000494:pharmacology*; D004789:Enzyme Activation; D005920:Glomerular Mesangium / Q000187:drug effects; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis / Q000378:metabolism*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D014162:Transfection
chemical_list: D039302:Integrin alphaVbeta3; D015638:Cytochalasin D; D020928:Mitogen-Activated Protein Kinases; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D020778:Matrix Metalloproteinase 2