Allosteric modulation of metabotropic glutamate receptor 5 affects phosphorylation, internalization, and desensitization of the μ-opioid receptor
Allosteric modulation of metabotropic glutamate receptor 5 affects phosphorylation, internalization, and desensitization of the μ-opioid receptor
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DOI：
10.1016/j.neuropharm.2008.12.010
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发表时间：
2009-03-01
影响因子：
4.7
通讯作者：
Koch, T.
中科院分区：
文献类型：
--
作者：
Schroeder, H.;Wu, D. -F.;Koch, T.
最近的证据表明，阿片镇痛和耐受性可由代谢性谷氨酸受体调节。因此，我们研究了在人胚胎肾（HEK） 293细胞中共表达代谢性谷氨酸受体5 （mGluR5）的mu-阿片受体（MOR）的功能偶联和脱敏。通过D-Ala(2)、N-MePhe(4)、Gl-ol(5)-enkephalin （DAMGO）诱导细胞内cAMP水平的抑制和结合研究表明，mGIuR5的共表达对MOR的激动剂结合位点和功能偶联没有实质性影响。然而，在MOR/mGIuR5共表达细胞中，非竞争性mGluR5拮抗剂MPEP（2-甲基-6-（苯乙基）吡啶）可降低damgo诱导的MOR磷酸化、内化和脱敏，而非选择性竞争性mGluR拮抗剂或激动剂则没有作用。这些发现表明mGIuR5的变构调节可以影响激动剂诱导的MOR信号传导和调节。我们提出MOR与mGluR5相互作用/异二聚化的机制基础是damgo诱导MOR与mGIuR5共内化，MOR共表达后MPEP结合位点（B-max）增加，mGIuR5受体结合亲和力（K-D）改变。此外，共免疫沉淀实验揭示了MPEP治疗促进MOR和mGIuR5相互作用的证据。(C) 2008 Elsevier Ltd版权所有。
Recent evidence suggests that opioid analgesia and tolerance can be modulated by metabotropic glutamate receptors. Therefore, we studied the functional coupling and desensitization of the mu-opioid receptor (MOR) in human embryonic kidney (HEK) 293 cells which co-express metabotropic glutamate receptor 5 (mGluR5). As demonstrated by the D-Ala(2),N-MePhe(4),Gl-ol(5)-enkephalin (DAMGO)-induced inhibition of intracellular cAMP level and by binding studies, the co-expression of mGIuR5 had no substantial effect on the agonist binding sites and functional coupling of the MOR. However, in MOR/mGIuR5 co-expressing cells, the non-competitive mGluR5 antagonist MPEP (2-methyl-6-(phenylethynyl)-pyridine) decreases the DAMGO-induced MOR phosphorylation, internalization, and desensitization, whereas non-selective competitive mGluR antagonists or agonists had no effects. These findings indicate that an allosteric modulation of mGIuR5 can affect the agonist-induced MOR signalling and regulation. As a mechanistic basis for the observed effects we suggested an interaction/hetero-dimerization of MOR and mGluR5, which is supported by the DAMGO-induced co-internalization of MOR and mGIuR5 and by the increase of MPEP binding sites (B-max) and a change of the binding affinity (K-D) Of mGIuR5 receptors after the co-expression of MOR. In addition, co-immunoprecipitation experiments revealed evidence for an interaction between MOR and mGIuR5 which is facilitated by MPEP treatment. (C) 2008 Elsevier Ltd. All rights reserved.