Allosterism within δ Opioid-κ Opioid Receptor Heteromers in Peripheral Sensory Neurons: Regulation of κ Opioid Agonist Efficacy
Allosterism within δ Opioid-κ Opioid Receptor Heteromers in Peripheral Sensory Neurons: Regulation of κ Opioid Agonist Efficacy
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DOI：
10.1124/mol.117.109975
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发表时间：
2018-04-01
影响因子：
3.6
通讯作者：
Berg, Kelly A.
中科院分区：
文献类型：
--
作者：
Jacobs, Blaine A.;Pando, Miryam M.;Berg, Kelly A.
有大量的证据表明，在异源表达系统中形成G蛋白偶联受体异聚体，但很少有人知道异聚体在天然系统中的功能。δ和κ阿片受体的异聚体（DOR-KOR异聚体）已经在天然系统中被鉴定。我们以前报道，激活DOR-KOR异聚体表达的大鼠痛感受神经元（伤害感受器）产生强大的，外周介导的抗伤害感受。此外，DOR激动剂效力和功效由KOR拮抗剂经由DOR-KOR异聚体内的变构相互作用以配体依赖性方式调节。在这里，我们评估的相互调节KOR激动剂功能的DOR拮抗剂在成年大鼠伤害性感受器的文化和伤害性感受的行为测定。纳曲吲哚使KOR激动剂2-（3，4-二氯苯基）-N-甲基-N-[（1 S）-1-苯基-2-吡咯烷-1-基乙基]乙酰胺（ICI-199441）的效力增强10- 20倍，但未改变对2-（3，4-二氯苯基）-N-甲基-N-[（1 R，2 R）-2-吡咯烷-1-基环己基]乙酰胺（U 50488）的反应。相比之下，U 50488的效力被7-亚苄基甲萘醌增强20倍。6 '-胍基那曲吲哚（6'-guanidinonaltrindole，6 'GNTI）抑制伤害感受器的功效被DOR或KOR的小干扰RNA敲低所阻断。用纳曲吲哚或7-亚苄基纳曲酮替代DOR的6 '-GNTI占据消除了6' GNTI功效。此外，衍生自与细胞膜穿透HIV转录反式激活因子肽融合的DOR跨膜区段1的肽也在离体和体内阻断6 '-GNTI介导的应答，表明6' GNTI在伤害感受器中的功效是由于其通过DOR-KOR异聚体中DOR的占据对KOR的正变构调节。总之，这些结果提供了证据的存在功能DOR-KOR异聚体在大鼠外周感觉神经元和互惠，配体依赖性变构相互作用之间发生的DOR和KOR的原体。
There is abundant evidence for formation of G protein-coupled receptor heteromers in heterologous expression systems, but little is known of the function of heteromers in native systems. Heteromers of delta and kappa opioid receptors (DOR-KOR heteromers) have been identified in native systems. We previously reported that activation of DOR-KOR heteromers expressed by rat painsensing neurons (nociceptors) produces robust, peripherally mediated antinociception. Moreover, DOR agonist potency and efficacy is regulated by KOR antagonists via allosteric interactions within the DOR-KOR heteromer in a ligand-dependent manner. Here we assessed the reciprocal regulation of KOR agonist function by DOR antagonists in adult rat nociceptors in culture and in a behavioral assay of nociception. Naltrindole enhanced the potency of the KOR agonist 2-(3,4-dichlorophenyl)-Nmethyl-N-[(1S)-1-phenyl-2-pyrrolidin-1-ylethyl]acetannide (ICI-199441) 10- to 20-fold, but did not alter responses to 2-(3,4-dichlorophenyl)-N- methyl-N-[(1R,2R)-2-pyrrolidin-1-ylcyclohexyl]acetamide (U50488). By contrast, the potency of U50488 was enhanced 20-fold by 7-benzylidenenaltrexone. The efficacy of 6'-guanidinonaltrindole (6'GNTI) to inhibit nociceptors was blocked by small interfering RNA knockdown of DOR or KOR. Replacing 6'-GNTI occupancy of DOR with either naltrindole or 7-benzylidenenaltrexone abolished 6'GNTI efficacy. Further, peptides derived from DOR transmembrane segment 1 fused to the cell membrane-penetrating HIV transactivator of transcription peptide also blocked 6'-GNTI- mediated responses ex vivo and in vivo, suggesting that 6'GNTI efficacy in nociceptors is due to its positive allosteric regulation of KOR via occupancy of DOR in a DOR-KOR heteromer. Together, these results provide evidence for the existence of functional DOR-KOR heteromers in rat peripheral sensory neurons and that reciprocal, ligand-dependent allosteric interactions occur between the DOR and KOR protomers.