Attenuation of apoptosis in vitro and ischemia/reperfusion injury in vivo in mouse skeletal muscle by P2Y6 receptor activation

Activation of the Gq-coupled P2Y6 receptor heterologously expressed in astrocytes significantly attenuates apoptosis induced by tumor necrosis factor α (TNFα). We have extended the analysis of P2Y6 receptor-induced cytoprotection to mouse skeletal muscle cells endogenously expressing this receptor. The endogenous P2Y6 receptor agonist UDP and synthetic agonist MRS2693 protected C2C12 skeletal muscle cells against apoptosis in a concentration-dependent manner (0.1–10 nM) as determined by propidium iodide staining, histochemical analysis using hematoxylin and Hoechst 33258, and DNA fragmentation. The insurmountable P2Y6 receptor antagonist MRS2578 blocked the protection. TNFα-induced apoptosis in C2C12 cells correlated with activation of the transcription factor NF-κB. The NF-κB activation was attenuated by 10 nM MRS2693, which activated the antiapoptic ERK1/2 pathway. In an in vivo mouse hindlimb model, MRS2693 protected against skeletal muscle ischemia/reperfusion injury. The P2Y6 receptor is a novel cytoprotective receptor that deserves further exploration in ameliorating skeletal muscle injury.