CB1 Receptor Allosteric Modulators Display Both Agonist and Signaling Pathway Specificity
CB1 Receptor Allosteric Modulators Display Both Agonist and Signaling Pathway Specificity
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DOI：
10.1124/mol.112.080879
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发表时间：
2013-02-01
影响因子：
3.6
通讯作者：
Ross, Ruth A.
中科院分区：
文献类型：
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作者：
Baillie, Gemma L.;Horswill, James G.;Ross, Ruth A.
我们以前已经确定了大麻素CB 1受体（PSN 27569，PSNCBAM-1）的变构调节剂，显示出矛盾的药理学特征：增加CB 1受体激动剂[H-3] CP 55940的特异性结合，但降低CB 1受体激动剂的功效。在这里，我们研究了一种或两种化合物在与CB 1受体活化相关的广泛信号传导终点中的作用。我们评估了这些化合物对CB 1受体激动剂诱导的[S-35]GTP γ S结合、抑制和刺激毛喉素刺激的cAMP产生、细胞外信号调节激酶（ERK）磷酸化和β-抑制蛋白募集的影响。我们还研究了这些变构调节剂对CB 1激动剂结合动力学的影响。两种化合物均显示配体依赖性，与WIN 55212相比，作为CP 55940信号传导的调节剂显著更有效，并且对[H-3] WIN 55212结合几乎没有影响。CYP 27569表现出偏向性拮抗作用，从而抑制：激动剂诱导的鸟苷5 '-O-（3-[S-35]硫代）三磷酸（[S-35]GTP γ S）结合、cAMP产生和β-抑制蛋白募集的模拟（G α（s）介导）和抑制（G α（i）介导）。相反，它作为激动剂诱导的ERK磷酸化的增强剂。单独使用时，该化合物也可作为变构激动剂，增加cAMP产生和ERK磷酸化。我们发现，在饱和和动力学结合实验中，PSN 27569和PSNCBAM-1似乎只影响正构配体的最大占有率，而不是亲和力。数据表明，变构调节剂有一个共同的机制，即它们增加了可用的高亲和力CB 1激动剂结合位点。由变构稳定的受体构象似乎诱导信号传导，并且还通过ERK磷酸化途径选择性地运输正构激动剂信号传导。
We have previously identified allosteric modulators of the cannabinoid CB1 receptor (Org 27569, PSNCBAM-1) that display a contradictory pharmacological profile: increasing the specific binding of the CB1 receptor agonist [H-3]CP55940 but producing a decrease in CB1 receptor agonist efficacy. Here we investigated the effect one or both compounds in a broad range of signaling endpoints linked to CB1 receptor activation. We assessed the effect of these compounds on CB1 receptor agonist-induced [S-35]GTP gamma S binding, inhibition, and stimulation of forskolin-stimulated cAMP production, phosphorylation of extracellular signal-regulated kinases (ERK), and beta-arrestin recruitment. We also investigated the effect of these allosteric modulators on CB1 agonist binding kinetics. Both compounds display ligand dependence, being significantly more potent as modulators of CP55940 signaling as compared with WIN55212 and having little effect on [H-3]WIN55212 binding. Org 27569 displays biased antagonism whereby it inhibits: agonist-induced guanosine 5'-O-(3-[S-35]thio)triphosphate ([S-35]GTP gamma S) binding, simulation (G alpha(s)-mediated), and inhibition (G alpha(i)-mediated) of cAMP production and beta-arrestin recruitment. In contrast, it acts as an enhancer of agonist-induced ERK phosphorylation. Alone, the compound can act also as an allosteric agonist, increasing cAMP production and ERK phosphorylation. We find that in both saturation and kinetic-binding experiments, the Org 27569 and PSNCBAM-1 appeared to influence only orthosteric ligand maximum occupancy rather than affinity. The data indicate that the allosteric modulators share a common mechanism whereby they increase available high-affinity CB1 agonist binding sites. The receptor conformation stabilized by the allosterics appears to induce signaling and also selectively traffics orthosteric agonist signaling via the ERK phosphorylation pathway.