Role of G-protein beta gamma subunits in the augmentation of P2Y2 (P2U)receptor-stimulated responses by neuropeptide Y Y1 Gi/o-coupled receptors.
Neuropeptide Y (NPY) significantly potentiates the constrictor actions of noradrenaline and ATP on blood vessels via a pertussis toxin (PTX)-sensitive mechanism involving Gi/o (alpha beta gamma) protein subunits (Gi/o, GTP-binding proteins sensitive to PTX). In Chinese hamster ovary K1 (CHO K1) cells expressing specific receptors for these neurotransmitters, stimulation of Gi/o protein-coupled receptors for NPY and other neurotransmitters can augment the Gq/11-coupled (Gq/11, GTP-binding proteins insensitive to PTX) alpha 1B adrenoceptor- or ATP receptor-induced arachidonic acid (AA) release and inositol phosphate (IP) production (early events which may precede vasoconstriction). In this study, we have assessed the role of G beta gamma subunits in the synergistic interaction between Gi/o- (NPY Y1, 5-hydroxytryptamine 5-HT1B, adenosine A1) and Gq/11- [ATP P2Y2 (P2U)]-coupled receptors on AA release by using the specific abilities of regions of the beta-adrenergic receptor kinase (beta ARK1 residues 495-689) and the transducin alpha subunit to associate with G-protein beta gamma subunit dimers and to act as G beta gamma subunit scavengers. Transient expression of beta ARK1(495-689) in CHO K1 cells heterologously expressing NPY Y1 receptors had no significant effect on the PTX-insensitive ability of ATP to stimulate AA release. Stimulation of NPY Y1 receptors (as well as the endogenous 5-hydroxytryptamine 5-HT1B receptor and the transiently expressed human adenosine A1 receptor) resulted in a PTX-sensitive augmentation of ATP-stimulated AA release, which was inhibited by expression of both G beta gamma subunit scavengers. Expression of beta ARK1(495-689) similarly inhibited NPY Y1 receptor augmentation of ATP-stimulated IP production (a measure of phospholipase C activity), a step thought to precede the NPY Y1 receptor-augmented protein kinase C-dependent AA release previously observed in these cells. These experiments demonstrate that G beta gamma subunits, as inhibited by two different G beta gamma scavengers, significantly contribute to the synergistic interaction between NPY Y1 Gi/o- and Gq/11-coupled receptor activity, and are required for the augmentation of IP production and AA release observed in this model cell system.
Selbie
L A
LA
Department of Physiology and Pharmacology, Queen's Medical Centre, University of Nottingham, U.K.
King
N V
NV
Dickenson
J M
JM
Hill
S J
SJ
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D016466:CHO Cells; D006224:Cricetinae; D004357:Drug Synergism; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology*; D006801:Humans; D007295:Inositol Phosphates / Q000096:biosynthesis; D058919:Purinergic P2 Receptor Antagonists; D020794:Receptor Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000502:physiology; D017476:Receptors, Neuropeptide Y / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D018048:Receptors, Purinergic P2 / Q000378:metabolism / Q000502:physiology*; D058473:Receptors, Purinergic P2Y2
D007295:Inositol Phosphates; C546385:P2RY2 protein, human; D058919:Purinergic P2 Receptor Antagonists; D017476:Receptors, Neuropeptide Y; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; C097212:neuropeptide Y-Y1 receptor; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D020794:Receptor Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins