P2Y2 purinergic and M3 muscarinic acetylcholine receptors activate different phospholipase C-beta isoforms that are uniquely susceptible to protein kinase C-dependent phosphorylation and inactivation.
Activation of phospholipase C-beta (PLC-beta) by G protein-coupled receptors typically results in rapid but transient second messenger generation. Although PLC-beta deactivation may contribute to the transient nature of this response, the mechanisms governing PLC-beta deactivation are poorly characterized. We investigated the involvement of protein kinase C (PKC) in the termination of PLC-beta activation induced by endogenous P2Y(2) purinergic receptors and transfected M(3) muscarinic acetylcholine receptors (mAChR) in Chinese hamster ovary cells. Activation of P2Y(2) receptors causes Galpha(q/11) to associate with PLC-beta3, whereas M(3) mAChR activation causes Galpha(q/11) to associate with both PLC-beta1 and PLC-beta3 in these cells. Phosphorylation of PLC-beta3, but not PLC-beta1, is induced by activating either P2Y(2) receptors or M(3) mAChR. We demonstrate that PKC rather than protein kinase A mediates the G protein-coupled receptor-induced phosphorylation of PLC-beta3. The PKC-mediated phosphorylation of PLC-beta3 diminishes the interaction of Galpha(q/11) with PLC-beta3, thereby contributing to the termination PLC-beta3 activity. These findings indicate that the distinct temporal profiles of PLC activation by P2Y(2) receptors and mAChR may arise from the differential activation of PLC-beta1 and PLC-beta3 by the receptors, coupled with a selective PKC-mediated negative feedback mechanism that targets PLC-beta3 but not PLC-beta1.
Strassheim
D
D
Molecular Pharmacology Laboratory, Guthrie Research Institute, Sayre, Pennsylvania 18840, USA.
Williams
C L
CL
D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D006224:Cricetinae; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D054799:Phospholipase C beta; D010766:Phosphorylation; D011233:Precipitin Tests; D020033:Protein Isoforms; D011493:Protein Kinase C / Q000378:metabolism*; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058473:Receptors, Purinergic P2Y2; D013997:Time Factors; D014162:Transfection; D010738:Type C Phospholipases / Q000737:chemistry / Q000378:metabolism*
D007527:Isoenzymes; C546385:P2RY2 protein, human; D020033:Protein Isoforms; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D010738:Type C Phospholipases; C518033:PLCB1 protein, human; C518039:PLCB3 protein, human; D054799:Phospholipase C beta; D002118:Calcium