Gi/o-Coupled Receptors Compete for Signaling to Adenylyl Cyclase in SH-SY5Y Cells and Reduce Opioid-Mediated cAMP Overshoot
Gi/o-Coupled Receptors Compete for Signaling to Adenylyl Cyclase in SH-SY5Y Cells and Reduce Opioid-Mediated cAMP Overshoot
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DOI：
10.1124/mol.110.064816
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发表时间：
2011-03-01
影响因子：
3.6
通讯作者：
Traynor, John R.
中科院分区：
文献类型：
--
作者：
Levitt, Erica S.;Purington, Lauren C.;Traynor, John R.
组织G蛋白偶联受体和同源信号合作伙伴在质膜已提出发生通过多种机制，包括膜微区，受体寡聚化，和蛋白质支架。在这里，我们调查的组织中内源性表达的六种类型的G（i/o）偶联受体的SH-SY 5 Y细胞。这些细胞中最丰富的受体是μ-阿片受体（莫尔），其激活阻断了δ-阿片（DOR）、痛敏肽/β-FQ肽（NOPr）、α（2）-肾上腺素能（α（2）AR）、大麻素1和5-羟色胺1A受体激动剂对腺苷酸环化酶（AC）的急性抑制。我们进一步证明，所有受体对共享一个共同的AC池。莫尔激动剂[D-Ala（2），N-Me-Phe（4），Gly（5）-ol]-脑啡肽（DAMGO）也阻断DOR激动剂刺激G蛋白的能力。然而，在较低的激动剂浓度和较短的孵育时间，当G蛋白不受限制时，莫尔和DOR激动剂之间的关系是相加的。通过等辐射分析证实了加性关系。长期共同管理的莫尔和DOR激动剂引起的cAMP过冲，这是不加性的，表明这两种受体介导的AC的敏化发生的共同途径。此外，通过DOR、NOPr和α（2）AR的激动剂异源抑制AC可降低DAMGO依赖性细胞中cAMP过冲的表达。然而，这种串扰并没有导致异源耐受性。这些结果表明，多种受体可以与同源信号传导蛋白结合成复合物，并且多种受体类型对共享AC的访问可以提供防止阿片类药物戒断的手段。
Organization of G protein-coupled receptors and cognate signaling partners at the plasma membrane has been proposed to occur via multiple mechanisms, including membrane microdomains, receptor oligomerization, and protein scaffolding. Here, we investigate the organization of six types of G(i/o)-coupled receptors endogenously expressed in SH-SY5Y cells. The most abundant receptor in these cells was the mu-opioid receptor (MOR), the activation of which occluded acute inhibition of adenylyl cyclase (AC) by agonists to delta-opioid (DOR), nociceptin/orphanin FQ peptide (NOPr), alpha(2)-adrenergic (alpha(2)AR), cannabinoid 1, and serotonin 1A receptors. We further demonstrate that all receptor pairs share a common pool of AC. The MOR agonist [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO) also occluded the ability of DOR agonist to stimulate G proteins. However, at lower agonist concentrations and at shorter incubation times when G proteins were not limiting, the relationship between MOR and DOR agonists was additive. The additive relationship was confirmed by isobolographic analysis. Long-term coadministration of MOR and DOR agonists caused cAMP overshoot that was not additive, suggesting that sensitization of AC mediated by these two receptors occurs by a common pathway. Furthermore, heterologous inhibition of AC by agonists to DOR, NOPr, and alpha(2)AR reduced the expression of cAMP overshoot in DAMGO-dependent cells. However, this cross-talk did not lead to heterologous tolerance. These results indicate that multiple receptors could be tethered into complexes with cognate signaling proteins and that access to shared AC by multiple receptor types may provide a means to prevent opioid withdrawal.