title: Cyclic AMP--dependent aggregation of Swiss 3T3 cells on a cellulose substratum (Cuprophan) and decreased cell membrane Rho A.
abstract: Cell surface integrin receptors and Rho family GTPases function together to mediate adhesion-dependent events in cells. We have shown that the attachment of Swiss 3T3 cells to a cellulose substratum (Cuprophan, CU) activates adenylyl cyclase, which catalyses cyclic AMP (cAMP) production. CU adsorbs vitronectin poorly, prevents cell spreading and causes cells to aggregate. By contrast, spread cells on polystyrene (PS) contain low cAMP concentrations. We have now investigated the shift between integrin signalling-Rho A and the cAMP pathway. CU did not support the formation of focal contacts and stress fibres. The plasma membranes of cells on CU had less Rho A than those of cells on PS. Also, blocking vitronectin (VN) or fibronectin (FN)-integrin receptors with echistatin, which activates cAMP production, decreased Rho A in the plasma membrane of cells attached to PS. But adsorption of VN or FN onto CU, which limits the production of the cAMP, increased the cell membrane Rho A. Adding an inhibitor of cAMP-dependent protein kinase PKA to the medium also increased the plasma membrane Rho A in aggregated cells attached to CU. These results highlight the importance of cAMP, generated by cell attachment to substratum, as a gating element in integrin-Rho A signalling.
authors.affiliation: Domaine Biomatériaux-Biocompatibilité UMR CNRS 6600 Université de Technologie de Compiègne, France.
authors.forename: N
authors.initials: N
authors.lastname: Faucheux
authors.forename: M D
authors.initials: MD
authors.lastname: Nagel
mesh_terms: D016475:3T3 Cells; D000199:Actins / Q000378:metabolism; D000818:Animals; D001672:Biocompatible Materials; D002449:Cell Aggregation / Q000187:drug effects / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology; D002482:Cellulose / Q000031:analogs & derivatives*; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005353:Fibronectins / Q000378:metabolism; D022001:Focal Adhesions / Q000187:drug effects / Q000502:physiology; D016023:Integrins / Q000378:metabolism; D008422:Materials Testing; D051379:Mice; D011137:Polystyrenes; D015398:Signal Transduction; D013499:Surface Properties; D019096:Vitronectin / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000502:physiology*
chemical_list: D000199:Actins; D001672:Biocompatible Materials; D004791:Enzyme Inhibitors; D005353:Fibronectins; D016023:Integrins; D011137:Polystyrenes; D019096:Vitronectin; D002482:Cellulose; C009865:cuprammonium cellulose; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020742:rhoA GTP-Binding Protein