Functional coupling of rat metabotropic glutamate 1a receptors to phospholipase D in CHO cells: involvement of extracellular Ca2+, protein kinase C, tyrosine kinase and Rho-A

• Published in: Neuropharmacology 2002, Vol.42 (1), p.1-8
• Main Authors: KANUMILLI, S, TOMS, N. J, VENKATESWARLU, K, MELLOR, H, ROBERTS, P. J
• Format: Article
• Language: English
• Subjects: Aminoacid receptors (glycine, glutamate, gaba); Animals; Biological and medical sciences; Calcium - metabolism; Cell receptors; Cell structures and functions; CHO Cells; Cricetinae; Down-Regulation - drug effects; Down-Regulation - physiology; Excitatory Amino Acid Antagonists - pharmacology; Extracellular Space - drug effects; Extracellular Space - enzymology; Fundamental and applied biological sciences. Psychology; GTP-Binding Proteins - metabolism; Molecular and cellular biology; Phospholipase D - metabolism; Protein Kinase C - antagonists & inhibitors; Protein Kinase C - metabolism; Protein-Tyrosine Kinases - antagonists & inhibitors; Protein-Tyrosine Kinases - metabolism; Rats; Receptors, Metabotropic Glutamate - metabolism; rhoA GTP-Binding Protein - metabolism; Transfection
• ISSN: 0028-3908; 1873-7064
• DOI: 10.1016/S0028-3908(01)00161-7

We report here that metabotropic glutamate 1a (mGlu1a) receptors, stably expressed in CHO cells, stimulate phospholipase D (PLD) activity. Several mGlu receptor agonists were found to exert this effect, with a rank order of potency of: L-quisqualate>L-glutamate>(1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid [(1S,3R)-ACPD]=(S)-3,5-dihydroxyphenylglycine [(S)-DHPG]. Both L-glutamate- and (1S,3R)-ACPD-stimulated PLD activity were attenuated by the selective mGlu receptor antagonist (S)-alpha-methyl-4-carboxyphenylglycine. mGlu1a receptor-stimulated PLD was inhibited either by the selective protein kinase C (PKC) inhibitor, GF109203X, or via PKC downregulation. MGlu1a receptor-PLD coupling required extracellular Ca2+ and was sensitive to La3+ and Zn2+, inhibitors of intracellular Ca2+ store-operated Ca2+ influx. mGlu1a receptor-PLD coupling was inhibited by the selective tyrosine kinase inhibitor, genistein. In addition, mGlu1a receptor-PLD coupling was also inhibited by cell transfection with the selective Rho (small GTP-binding protein) inhibitors: C3-exoenzyme and dominant negative mutant RhoA constructs. Brefeldin A, a selective ADP-ribosylation factor (ARF) inhibitor, and a dominant negative ARF6 mutant, failed to significantly influence mGlu1a receptor-stimulated PLD activity. We conclude that mGlu1a receptors activate PLD via a mechanism that is dependent on extracellular Ca2+, PKC, tyrosine kinase and RhoA but independent of ARF.