Probing biased/partial agonism at the G protein-coupled A(2B) adenosine receptor.
G protein-coupled A(2B) adenosine receptor (AR) regulates numerous important physiological functions, but its activation by diverse A(2B)AR agonists is poorly profiled. We probed potential partial and/or biased agonism in cell lines expressing variable levels of endogenous or recombinant A(2B)AR. In cAMP accumulation assays, both 5'-substituted NECA and C2-substituted MRS3997 are full agonists. However, only 5'-substituted adenosine analogs are full agonists in calcium mobilization, ERK1/2 phosphorylation and β-arrestin translocation. A(2B)AR overexpression in HEK293 cells markedly increased the agonist potency and maximum effect in cAMP accumulation, but less in calcium and ERK1/2. A(2B)AR siRNA silencing was more effective in reducing the maximum cAMP effect of non-nucleoside agonist BAY60-6583 than NECA's. A quantitative 'operational model' characterized C2-substituted MRS3997 as either balanced (cAMP accumulation, ERK1/2) or strongly biased agonist (against calcium, β-arrestin). N⁶-substitution biased against ERK1/2 (weakly) and calcium and β-arrestin (strongly) pathways. BAY60-6583 is ERK1/2-biased, suggesting a mechanism distinct from adenosine derivatives. BAY60-6583, as A(2B)AR antagonist in MIN-6 mouse pancreatic β cells expressing low A(2B)AR levels, induced insulin release. This is the first relatively systematic study of structure-efficacy relationships of this emerging drug target.
Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Blg. 8A, Rm B1 A-17, NDDK 8 Center Dr., 9000 Rockville Pike, Bethesda, MD 20892-0810, USA. Electronic address: zg21o@nih.gov.
Zhan-Guo
ZG
Gao
Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Blg. 8A, Rm B1 A-17, NDDK 8 Center Dr., 9000 Rockville Pike, Bethesda, MD 20892-0810, USA.
Ramachandran
R
Balasubramanian
Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Blg. 8A, Rm B1 A-17, NDDK 8 Center Dr., 9000 Rockville Pike, Bethesda, MD 20892-0810, USA.
Evgeny
E
Kiselev
Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Blg. 8A, Rm B1 A-17, NDDK 8 Center Dr., 9000 Rockville Pike, Bethesda, MD 20892-0810, USA.
Qiang
Q
Wei
Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Blg. 8A, Rm B1 A-17, NDDK 8 Center Dr., 9000 Rockville Pike, Bethesda, MD 20892-0810, USA. Electronic address: kajacobs@helix.nih.gov.
Kenneth A
KA
Jacobson
D058908:Adenosine A2 Receptor Agonists / Q000737:chemistry / Q000494:pharmacology*; D058917:Adenosine A2 Receptor Antagonists / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D019390:Arrestins / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D002460:Cell Line; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism; D054333:Drug Partial Agonism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D007700:Kinetics; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008954:Models, Biological; D021381:Protein Transport / Q000187:drug effects; D043704:Receptor, Adenosine A2B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D000071557:beta-Arrestins
D058908:Adenosine A2 Receptor Agonists; D058917:Adenosine A2 Receptor Antagonists; D019390:Arrestins; D043704:Receptor, Adenosine A2B; D011994:Recombinant Proteins; D000071557:beta-Arrestins; D000242:Cyclic AMP; D019205:GTP-Binding Protein alpha Subunits, Gs
Adenosine receptor; Arrestin; Calcium; Cyclic AMP; GPCR; Purines