Activation of CaMKKbeta/AMPKalfa pathway by 2-AG in human platelets

The objective of this study was to determine whether AMPK is activated by 2-arachidonoylglycerol (2-AG) and participates to the cytoskeleton control in human platelets. We found that 2-AG stimulates the AMPKalfa activation through a Ca2+/Calmodulin-dependent pathway as the specific inhibition of the CaMKKbeta by STO-609 inhibits the AMPKalfa phosphorylation/activation. Moreover, the CaMKKbeta/AMPKalfa pathway activated by 2-AG is involved in the phosphorylation of cofilin, vasodilator stimulated phosphoprotein (VASP), and myosin light chain (MLCs). These proteins participate to actin cytoskeletal remodelling during aggregation. We found that the phosphorylation/activation inhibition of these proteins is associated with a significant reduction in actin polymerization, aggregation, ATP, and alfa-granule secretion. Finally, AMPKalfa activation, Cofilin, VASP, and MLCs phosphorylation are significantly reduced by SR141716, the specific inhibitor of type 1 cannabinoid (CB1) receptor, suggesting that the CB1 receptor is involved in the 2-AG effect. In conclusion, we have shown that the CaMKKbeta/AMPKalfa pathway is activated by 2-AG in human platelets and controls the phosphorylation of key proteins involved in actin polymerization and aggregation.