Differential Association of Receptor-Gβγ Complexes with β-Arrestin2 Determines Recycling Bias and Potential for Tolerance of Delta Opioid Receptor Agonists
Differential Association of Receptor-Gβγ Complexes with β-Arrestin2 Determines Recycling Bias and Potential for Tolerance of Delta Opioid Receptor Agonists
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DOI：
10.1523/jneurosci.3734-11.2012
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发表时间：
2012-04-04
影响因子：
5.3
通讯作者：
Pineyro, Graciela
中科院分区：
文献类型：
--
作者：
Audet, Nicolas;Charfi, Iness;Pineyro, Graciela
阿片类药物倾向于产生止痛耐受，此前已被认为与偏向内化有关。在这里，我们评估了另一种可能性：增量阿片受体激动剂(DORs)的耐受性是否与激动剂特异性循环有关。第一系列实验表明，DPDPE和SNC-80对DOR的内化相似，但只有DPDPE诱导循环。然后我们确定了非循环激动剂SNC-80产生了急性止痛耐受，这在接受DPDPE治疗的小鼠中是不存在的。此外，两种激动剂都稳定了不同的构象，它们与Gβ伽马亚基的不同相互作用导致了不同形式的β-抑制素2(βarr2)募集。特别是，生物发光共振能量转移(BRET)分析表明，SNC-80的持续激活将受体C末端拉近G-Gamma 2的N-末端结构域，导致β-Arr2与受体和Gβ-Gamma亚单位相互作用。DPDPE使受体C-Tail远离Gβ-Gamma二聚体，导致β-arr2向受体募集，但不在G-Gamma 2附近。这些差异与稳定的DOR-βarr2结合、较差的循环和暴露于SNC-80后的显著脱敏有关，而DPDPE促进瞬时受体与β-arr2的相互作用和有效的循环，从而提供脱敏保护。综上所述，这些数据表明，DORS可能采用配体特异性构象，其独特的循环特性决定了脱敏的程度，并预测了止痛耐受。基于这些发现，我们认为，开发有利于回收的功能选择性DOR配体可以构成生产长效阿片类止痛药的有效策略。
Opioid tendency to generate analgesic tolerance has been previously linked to biased internalization. Here, we assessed an alternative possibility; whether tolerance of delta opioid receptor agonists (DORs) could be related to agonist-specific recycling. A first series of experiments revealed that DOR internalization by DPDPE and SNC-80 was similar, but only DPDPE induced recycling. We then established that the non-recycling agonist SNC-80 generated acute analgesic tolerance that was absent in mice treated with DPDPE. Furthermore, both agonists stabilized different conformations, whose distinct interaction with G beta gamma subunits led to different modalities of beta-arrestin2 (beta arr2) recruitment. In particular, bioluminescence resonance energy transfer (BRET) assays revealed that sustained activation by SNC-80 drew the receptor C terminus in close proximity of the N-terminal domain of G gamma 2, causing beta arr2 to interact with receptors and G beta gamma subunits. DPDPE moved the receptor C-tail away from the G beta gamma dimer, resulting in beta arr2 recruitment to the receptor but not in the vicinity of G gamma 2. These differences were associated with stable DOR-beta arr2 association, poor recycling, and marked desensitization following exposure to SNC-80, while DPDPE promoted transient receptor interaction with beta arr2 and effective recycling, which conferred protection from desensitization. Together, these data indicate that DORs may adopt ligand-specific conformations whose distinct recycling properties determine the extent of desensitization and are predictive of analgesic tolerance. Based on these findings, we propose that the development of functionally selective DOR ligands that favor recycling could constitute a valid strategy for the production of longer acting opioid analgesics.