title: Characterization of new G protein-coupled adenine receptors in mouse and hamster.
abstract: The nucleobase adenine has previously been reported to activate G protein-coupled receptors in rat and mouse. Adenine receptors (AdeR) thus constitute a new family of purine receptors, for which the designation "P0-receptors" has been suggested. We now describe the cloning and characterization of two new members of the AdeR family from mouse (MrgA10, termed mAde1R) and hamster (cAdeR). Both receptors were expressed in Sf9 insect cells, and radioligand binding studies were performed using [(3)H]adenine. Specific binding of the radioligand was detected in transfected, but not in untransfected cells, and K D values of 286 nM (mAde1R, B max 1.18 pmol/mg protein) and 301 nM (cAdeR, B max 17.7 pmol/mg protein), respectively, were determined. A series of adenine derivatives was investigated in competition binding assays. Minor structural modifications generally led to a reduction or loss of affinity, with one exception: 2-fluoroadenine was at least as potent as adenine itself at the cAdeR. Structure-activity relationships at all AdeR orthologs and subtypes investigated so far were similar, but not identical. For functional analyses, the cAdeR was homologously expressed in Chinese hamster ovary (CHO) cells, while the mAde1R was heterologously expressed in 1321N1 astrocytoma cells. Like the previously described AdeRs from rat (rAdeR) and mouse (mAde2R), the mAde1R (EC50 9.77 nM) and the cAdeR (EC50 51.6 nM) were coupled to inhibition of adenylate cyclase. In addition, the cAdeR from hamster expressed in CHO cells produced an increase in intracellular calcium concentrations (EC50 6.24 nM) and was found to be additionally coupled to Gq proteins.
authors.affiliation: PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Thimm
authors.forename: Melanie
authors.initials: M
authors.lastname: Knospe
authors.forename: Aliaa
authors.initials: A
authors.lastname: Abdelrahman
authors.forename: Miguel
authors.initials: M
authors.lastname: Moutinho
authors.forename: Bernt B A
authors.initials: BB
authors.lastname: Alsdorf
authors.forename: Ivar
authors.initials: I
authors.lastname: von Kügelgen
authors.forename: Anke C
authors.initials: AC
authors.lastname: Schiedel
authors.forename: Christa E
authors.initials: CE
authors.lastname: Müller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D051379:Mice; D008969:Molecular Sequence Data; D011869:Radioligand Assay; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000378:metabolism*; D011983:Receptors, Purinergic / Q000737:chemistry / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
chemical_list: D043562:Receptors, G-Protein-Coupled; D011983:Receptors, Purinergic