title: G protein-coupled receptor-induced sensitization of phospholipase C stimulation by receptor tyrosine kinases.
abstract: Activation of stably expressed M(2) and M(3) muscarinic acetylcholine receptors (mAChRs) as well as of endogenously expressed lysophosphatidic acid and purinergic receptors in HEK-293 cells can induce a long lasting potentiation of phospholipase C (PLC) stimulation by these and other G protein-coupled receptors (GPCRs). Here, we report that GPCRs can induce an up-regulation of PLC stimulation by receptor tyrosine kinases (RTKs) as well and provide essential mechanistic characteristics of this sensitization process. Pretreatment of HEK-293 cells for 2 min with carbachol, a mAChR agonist, lysophosphatidic acid, or ATP, followed by agonist washout, strongly increased (by 2-3-fold) maximal PLC stimulation (measured >/=40 min later) by epidermal growth factor and platelet-derived growth factor, but not insulin, and largely enhanced PLC sensitivity to these RTK agonists. The up-regulation of RTK-induced PLC stimulation was cycloheximide-insensitive and was observed for up to approximately 90 min after removal of the GPCR agonist. Sensitization of receptor-induced PLC stimulation caused by prior M(2) mAChR activation was fully prevented by pertussis toxin and strongly reduced by expression of Gbetagamma scavengers. Furthermore, inhibition of conventional protein kinase C (PKC) isoenzymes and chelation of intracellular Ca(2+) suppressed the sensitization process, while overexpression of PKC-alpha, but not PKC-betaI, further enhanced the M(2) mAChR-induced sensitization of PLC stimulation. None of these treatments affected acute PLC stimulation by either GPCR or RTK agonists. Taken together, short term activation of GPCRs can induce a strong and long lasting sensitization of PLC stimulation by RTKs, a process apparently involving G(i)-derived Gbetagammas as well as increases in intracellular Ca(2+) and activation of a PKC isoenzyme, most likely PKC-alpha.
authors.affiliation: Institut für Pharmakologie, Universitätsklinikum Essen, D-45122 Essen, Germany. martina.schmidt@uni-essen.de
authors.forename: M
authors.initials: M
authors.lastname: Schmidt
authors.forename: M
authors.initials: M
authors.lastname: Frings
authors.forename: M L
authors.initials: ML
authors.lastname: Mono
authors.forename: Y
authors.initials: Y
authors.lastname: Guo
authors.forename: P A
authors.initials: PA
authors.lastname: Weernink
authors.forename: S
authors.initials: S
authors.lastname: Evellin
authors.forename: L
authors.initials: L
authors.lastname: Han
authors.forename: K H
authors.initials: KH
authors.lastname: Jakobs
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D002460:Cell Line; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000502:physiology*; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism*
chemical_list: D007295:Inositol Phosphates; D007527:Isoenzymes; D010982:Platelet-Derived Growth Factor; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic; D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002217:Carbachol; D020794:Receptor Protein-Tyrosine Kinases; C496628:PRKCA protein, human; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins