D1-D2 Dopamine Receptor Synergy Promotes Calcium Signaling via Multiple Mechanisms
D1-D2 Dopamine Receptor Synergy Promotes Calcium Signaling via Multiple Mechanisms
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DOI：
10.1124/mol.113.085175
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发表时间：
2013-08-01
影响因子：
3.6
通讯作者：
Sibley, David R.
中科院分区：
文献类型：
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作者：
Chun, Lani S.;Free, R. Benjamin;Sibley, David R.
已经提出D-1多巴胺受体（D1 R）与D（2 dop）胺受体（D2 R）形成异源寡聚体，这进而导致与磷脂酶C介导的细胞内钙释放偶联的复合物。我们试图阐明这一假定的信号通路的药理学和作用机制。多巴胺的剂量-反应曲线测定细胞内钙动员异源表达的D-1和D-2亚型，无论是单独或组合，并使用亚型选择性配体显示，同时刺激耦合是必需的。令人惊讶的是，一个假定的D-1-D-2异聚体选择性配体，6-氯-2，3，4，5-四氢-3-甲基-1-（3-甲基苯基）-1H-3-苯并氮杂卓-7，8-二醇（SKF 83959）的表征，发现没有刺激钙释放，但它确实发现了广泛的交叉反应性与其他G蛋白偶联受体。相反，SKF 83959似乎是钙动员的拮抗剂。D-1和D-2多巴胺受体G（q α）的过表达增强了多巴胺刺激的钙反应。然而，这也在仅用D1 R表达G（β γ）的细胞中观察到。分别用百日咳毒素或霍乱毒素灭活G（i）或G（s），在很大程度上但不是完全地降低了D1 R和D2 R共转染细胞中的钙反应。此外，隔离的Gbg亚基通过过度表达G蛋白受体激酶2突变体完全或大部分消除多巴胺刺激的钙动员。我们的数据表明，D1 R/D2 R介导的钙信号传导机制涉及的不仅仅是受体介导的G（q）蛋白激活，可能主要涉及下游信号传导途径，并且可能不是完全异源聚体特异性的。此外，SKF 83959可能不会表现出D-1-D-2异聚体的选择性激活，并且其与其他受体的显著交叉反应性保证了对其体内使用的仔细解释。
The D-1 dopamine receptor (D1R) has been proposed to form a hetero-oligomer with the D(2 dop)amine receptor (D2R), which in turn results in a complex that couples to phospholipase C-mediated intracellular calcium release. We have sought to elucidate the pharmacology and mechanism of action of this putative signaling pathway. Dopamine dose-response curves assaying intracellular calcium mobilization in cells heterologously expressing the D-1 and D-2 subtypes, either alone or in combination, and using subtype selective ligands revealed that concurrent stimulation is required for coupling. Surprisingly, characterization of a putative D-1-D-2 heteromer-selective ligand, 6-chloro-2,3,4,5-tetrahydro-3-methyl-1-(3-methylphenyl)-1H-3-benzazepine- 7,8-diol (SKF83959), found no stimulation of calciumrelease, but it did find a broad range of cross-reactivity with other G protein-coupled receptors. In contrast, SKF83959 appeared to be an antagonist of calcium mobilization. Overexpression of G(q alpha) with the D-1 and D-2 dopamine receptors enhanced the dopamine-stimulated calcium response. However, this was also observed in cells expressing G(beta gamma) with only the D1R. Inactivation of G(i) or G(s) with pertussis or cholera toxin, respectively, largely, but not entirely, reduced the calcium response in D1R and D2R cotransfected cells. Moreover, sequestration of Gbg subunits through overexpression of G protein receptor kinase 2 mutants either completely or largely eliminated dopamine-stimulated calcium mobilization. Our data suggest that the mechanism of D1R/D2R-mediated calcium signaling involves more than receptor-mediated G(q) protein activation, may largely involve downstream signaling pathways, and may not be completely heteromer-specific. In addition, SKF83959 may not exhibit selective activation of D-1-D-2 heteromers, and its significant cross-reactivity to other receptors warrants careful interpretation of its use in vivo.