Involvement of G-protein betagamma subunits in coupling the adenosine A1 receptor to phospholipase C in transfected CHO cells

Eur J Pharmacol. 1998 Aug 14;355(1):85-93. doi: 10.1016/s0014-2999(98)00468-3.


In transfected Chinese hamster ovary (CHO-A1) cells the human adenosine A1 receptor directly stimulates pertussis toxin-sensitive increases in inositol phosphate production and potentiates (synergistically) the inositol phosphate responses mediated by Gq-coupled P2Y2 purinoceptor and CCK(A) receptors. In the present study we have investigated the role of Gbetagamma subunits in mediating adenosine A1 receptor effects on phospholipase C activation (both direct and synergistic) by transiently transfecting CHO-A1 cells with a scavenger of Gbetagamma subunits: the C-terminus of beta-adrenoceptor kinase 1 (beta ark1 residues 495-689). [3H]inositol phosphate responses to the selective adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA; 1 microM) were inhibited (41 +/- 1%) in CHO-A1 cells transiently transfected with the Gbetagamma scavenger, beta ark1 (495-689). Expression of beta ark1 (495-689) protein was confirmed by Western blotting. In contrast, adenosine A1 receptor-mediated inhibition of forskolin stimulated [3H]cyclic AMP accumulation was unaffected by transient expression of beta ark1 (495-689). Beta ark1 (495-689) expression had no significant effect on the [3H]inositol phosphate responses produced by activation of the endogenous P2Y2 purinoceptor (100 microM UTP; 92 +/- 0.8% of control). [3H]inositol phosphate accumulation in response to adenosine A receptor activation was also attenuated in CHO-K1 cells co-transfected with the beta ark1 (495-689) minigene (59 +/- 4% inhibition of control response to 1 microM CPA). Finally, transient expression of beta ark1 (495-689) in CHO-A1 cells inhibited the augmentation of [3H]inositol phosphate responses resulting from co-activation of adenosine A1 receptors and P2Y2 purinoceptors. These experiments indicate that Gbetagamma subunits are involved in the direct coupling the adenosine A1 receptor to phospholipase C and that they also participate in the augmentation of P2Y2 purinoceptor-mediated [3H]inositol phosphate responses by the adenosine A1 receptor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine / analogs & derivatives
  • Adenosine / pharmacology
  • Animals
  • Blotting, Western
  • CHO Cells
  • Cricetinae
  • Cyclic AMP-Dependent Protein Kinases / genetics
  • Cyclic AMP-Dependent Protein Kinases / pharmacology
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / metabolism*
  • Humans
  • Inositol Phosphates / metabolism*
  • Peptide Fragments / genetics
  • Peptide Fragments / pharmacology
  • Purinergic P1 Receptor Agonists
  • Purinergic P2 Receptor Agonists
  • Receptors, Adrenergic, beta / genetics
  • Receptors, Adrenergic, beta / metabolism
  • Receptors, Purinergic P1 / drug effects
  • Receptors, Purinergic P1 / metabolism*
  • Recombinant Proteins*
  • Transfection
  • Type C Phospholipases / metabolism*


  • Inositol Phosphates
  • Peptide Fragments
  • Purinergic P1 Receptor Agonists
  • Purinergic P2 Receptor Agonists
  • Receptors, Adrenergic, beta
  • Receptors, Purinergic P1
  • Recombinant Proteins
  • N(6)-cyclopentyladenosine
  • Cyclic AMP-Dependent Protein Kinases
  • BARKct protein, recombinant
  • Type C Phospholipases
  • GTP-Binding Proteins
  • Adenosine