Inhibition of phospholipase c-beta 1-mediated signaling by O-GlcNAc modification

Abstract

Here we report inhibition of phospholipase C-beta 1 (PLC-beta 1)-mediated signaling by post-translational glycosylation with beta-N-acetylglucosamine (O-GIcNAc modification). In C2C12 myoblasts, isoform-specific knock-down experiments using siRNA showed that activation of bradykinin (BK) receptor led to Stimulation of PLC-beta 1 and subsequent intracellular Ca2+ mobilization. In C2C12 myotubes, O-GlcNAc modification of PLC-beta 1 was markedly enhanced in response to treatment with glucosamine (GIcNH(2)), an inhibitor of O-GIcNAase (PUGNAc) and hyperglycemia. This was associated with more than 50% inhibition of intracellular production of IP3 and Ca2+ mobilization in response to BK. Since the abundance of PLC-beta 1 remained unchanged, these data suggest that O-GIcNAc modification of PLC-PI led to inhibition of its activity. Moreover, glucose uptake stimulated by BK was significantly blunted by treatment with PUGNAc. These data support the notion that O-GIcNAc modification negatively modulates the activity of PLC-beta 1.