Accumulation of cyclic AMP in Swiss 3T3 cells adhering to a cellulose biomaterial substratum through interaction with adenylyl cyclase

Controlling cell shape induced by cell–substrata interaction appears of prime importance to influence subsequent biological processes such as cell migration, proliferation, differentiation or apoptosis. Studies on Swiss 3T3 fibroblasts have recently provided evidence that cell spreading is mediated by integrins and RhoA. Our previous studies showed that on Cuprophan, a cellulose membrane (CU) to which vitronectin adhesive protein is poorly adsorbed, Swiss 3T3 cells are rounded and undergo cAMP-dependent aggregation. In contrast, on a polyacrylonitrile membrane (AN69) that favours the adsorption of vitronectin and fibronectin, cells spread out and contain low concentrations of cAMP. We have now examined the parts played by the three components in the cAMP pathway (receptors, G-proteins and adenylyl cyclase itself) in cAMP-dependent cell aggregation on CU. Experiments with intact cells showed no interaction between the CU and receptors, or between the CU and G-proteins. Assays on membrane preparations plus the Mn–ATP substrate, which uncouples G-proteins and adenylyl cyclase, demonstrated that activation of the cAMP pathway by CU depends primarily on the catalytic activity of the adenylyl cyclase. These investigations provide essential data for the development of biomaterials that favour cell functionality.