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.
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.
Biochem Pharmacol. 2014 Aug 1;90(3):297-306. doi: 10.1016/j.bcp.2014.05.008. Epub 2014 May 20.
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.
G 蛋白偶联 A2B 腺苷受体 (AR) 调节许多重要的生理功能，但它对不同 A2BAR 激动剂的激活作用尚未得到充分描述。我们在表达不同水平内源性或重组 A2BAR 的细胞系中探测潜在的部分和/或偏性激动作用。在 cAMP 积累测定中，5'-取代的 NECA 和 C2-取代的 MRS3997 均为完全激动剂。然而，只有 5'-取代的腺苷类似物在钙动员、ERK1/2 磷酸化和β-arrestin 易位中为完全激动剂。A2BAR 在 HEK293 细胞中的过表达显著增加了 cAMP 积累中的激动剂效力和最大效应，但在钙和 ERK1/2 中则较少。A2BAR siRNA 沉默在减少非核苷激动剂 BAY60-6583 的最大 cAMP 效应方面比 NECA 更有效。一种定量的“操作性模型”将 C2-取代的 MRS3997 描述为平衡（cAMP 积累，ERK1/2）或强烈偏向激动剂（针对钙、β-arrestin）。N6-取代偏向 ERK1/2（弱）和钙和β-arrestin（强）途径。BAY60-6583 是 ERK1/2 偏向激动剂，表明其作用机制与腺苷衍生物不同。BAY60-6583 作为在表达低水平 A2BAR 的 MIN-6 小鼠胰腺β细胞中的 A2BAR 拮抗剂，诱导胰岛素释放。这是对这一新兴药物靶点的结构-功效关系的首次相对系统研究。
