title: Differential coupling of the human P2Y(11) receptor to phospholipase C and adenylyl cyclase.
abstract: 1. The human P2Y(11) (hP2Y(11)) receptor was stably expressed in two cell lines, 1321N1 human astrocytoma cells (1321N1-hP2Y(11)) and Chinese hamster ovary cells (CHO-hP2Y(11)), and its coupling to phospholipase C and adenylyl cyclase was assessed. 2. In 1321N1-hP2Y(11) cells, ATP promoted inositol phosphate (IP) accumulation with low microM potency (EC(50)=8.5+/-0.1 microM), whereas it was 15 fold less potent (130+/-10 microM) in evoking cyclic AMP production. 3. In CHO-hP2Y(11) cells, ATP promoted IP accumulation with slightly higher potency (EC(50)=3.6+/-1.3 microM) than in 1321N1-hP2Y(11) cells, but it was still 15 fold less potent in promoting cyclic AMP accumulation (EC(50)=62.4+/-15.6 microM) than for IP accumulation. Comparable differences in potencies for promoting the two second messenger responses were observed with other adenosine nucleotide analogues. 4. In 1321N1-hP2Y(11) and CHO-hP2Y(11) cells, down regulation of PKC by chronic treatment with phorbol ester decreased ATP-promoted cyclic AMP accumulation by 60--80% (P<0.001) with no change in its potency. Likewise, chelation of intracellular Ca(2+) decreased ATP-promoted cyclic AMP accumulation by approximately 45% in 1321N1-hP2Y(11) cells, whereas chelation had no effect on either the efficacy or potency of ATP in CHO-hP2Y(11) cells. 5. We conclude that coupling of hP2Y(11) receptors to adenylyl cyclase in these cell lines is much weaker than coupling to phospholipase C, and that activation of PKC and intracellular Ca(2+) mobilization as consequences of inositol lipid hydrolysis potentiates the capacity of ATP to increase cyclic AMP accumulation in both 1321N1-hP2Y(11) and CHO-hP2Y(11) cells.
authors.affiliation: Department of Pharmacology, Mary Ellen Jones Building, CB7365, University of North Carolina School of Medicine at Chapel Hill, Chapel Hill, North Carolina, NC 27599-7365, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Qi
authors.forename: C
authors.initials: C
authors.lastname: Kennedy
authors.forename: T K
authors.initials: TK
authors.lastname: Harden
authors.forename: R A
authors.initials: RA
authors.lastname: Nicholas
mesh_terms: D000227:Adenine Nucleotides / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D006224:Cricetinae; D000242:Cyclic AMP / Q000096:biosynthesis; D004789:Enzyme Activation; D006801:Humans; D007295:Inositol Phosphates / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011493:Protein Kinase C / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000096:biosynthesis; D018048:Receptors, Purinergic P2 / Q000378:metabolism* / Q000502:physiology; D015290:Second Messenger Systems / Q000502:physiology; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism* / Q000502:physiology
chemical_list: D000227:Adenine Nucleotides; D007295:Inositol Phosphates; C109734:P2RY11 protein, human; D010726:Phosphodiesterase Inhibitors; D017447:Receptors, Dopamine D1; D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D011493:Protein Kinase C; D010738:Type C Phospholipases; D000262:Adenylyl Cyclases; D002118:Calcium