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RDC8 codes for an adenosine A2 receptor with physiological constitutive activity.
C Maenhaut1, J Van Sande, F Libert
1Institut de Recherche Interdisciplinaire, Faculté de Médecine, Université Libre de Bruxelles, Belgium.
Biochemical and Biophysical Research Communications
|December 31, 1990
Summary
Researchers identified a novel G protein-coupled receptor, RDC8, as the adenosine A2 receptor. This receptor is constitutively active, suggesting a role for endogenous adenosine in its signaling pathway.
Area of Science:
- Molecular Biology
- Neuroscience
- Pharmacology
Background:
- G protein-coupled receptors (GPCRs) represent a large family of cell surface receptors involved in numerous physiological processes.
- The specific function of the recently cloned RDC8 receptor remained unidentified.
Purpose of the Study:
- To characterize the function and identify the ligand for the novel G protein-coupled receptor RDC8.
- To investigate the signaling pathways activated by RDC8 expression.
Main Methods:
- Expression of RDC8 cDNA in various cell systems (Y1 adrenal cells, dog thyrocytes, Xenopus oocytes, Cos 7 cells).
- Measurement of adenylyl cyclase activity and cyclic AMP cascade activation.
- Pharmacological inhibition studies using adenosine deaminase and adenosine A2 receptor antagonists.
- Ligand binding assays on transfected Cos 7 cells.
- Analysis of RDC8 mRNA distribution in the brain.
Main Results:
- Expression of RDC8 resulted in constitutive activation of adenylyl cyclase and the cyclic AMP cascade across all tested systems.
- This constitutive activation was inhibited by adenosine deaminase and adenosine A2 receptor antagonists.
- Transfected Cos 7 cells exhibited binding characteristics of an adenosine A2 receptor.
- RDC8 mRNA distribution in the brain closely mirrored that of adenosine A2 receptors.
Conclusions:
- The RDC8 receptor is identified as an adenosine A2 receptor.
- RDC8 exhibits constitutive activity, implying potential involvement of endogenous adenosine.
- Further research is needed to determine the extent to which endogenous adenosine explains the constitutive activation.