The sigma-1 receptor modulates dopamine transporter conformation and cocaine binding and may thereby potentiate cocaine self-administration in rats
The sigma-1 receptor modulates dopamine transporter conformation and cocaine binding and may thereby potentiate cocaine self-administration in rats
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DOI：
10.1074/jbc.m116.774075
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发表时间：
2017-07-07
影响因子：
4.8
通讯作者：
Katz, Jonathan L.
中科院分区：
文献类型：
--
作者：
Hong, Weimin Conrad;Yano, Hideaki;Katz, Jonathan L.
多巴胺转运蛋白（DAT）通过将多巴胺（DA）重新捕获到突触前末梢来调节DA的神经传递，并且是精神兴奋剂可卡因的主要靶点。sigma-1受体（sigma R-1）是一种分子伴侣，其配体已被证明可以调节DA神经元信号传导，尽管它们对DAT活性的影响尚不清楚。在这里，我们报告了原型σ R-1激动剂（+）-喷他佐辛增强了大鼠中可卡因自我给药的剂量反应，这与先前报道的σ R激动剂PRE-084和DTG（1，3-二-邻甲苯基胍）的作用一致。用（+）-喷他佐辛或PRE 084预孵育可增加大鼠纹状体突触体和转染细胞中[3 H] WIN 35428与DAT结合的B-max值。通过免疫共沉淀和生物发光共振能量转移试验检测到sigma R-1和DAT之间的特异性相互作用。突变分析表明sigma R-1的跨膜结构域可能介导这种相互作用。此外，半胱氨酸可及性分析表明，σ R-1激动剂预孵育加强可卡因诱导的DAT构象的变化，这是由特定的σ R-1拮抗剂CM 304阻断。此外，sigma R-1配体对sigma R-1多聚化具有明显的影响。CM 304增加多聚体σ（1）Rs的比例，而（+）-喷他佐辛增加单体σ（1）Rs。总之，这些结果支持以下假设：σ R-1激动剂促进σ R-1多聚体解离成单体，然后与DAT相互作用以稳定面向外的DAT构象并增强可卡因结合。我们提出，这种新的分子机制的基础上的行为增强可卡因自我管理的sigma R-1激动剂在动物模型中。
The dopamine transporter (DAT) regulates dopamine (DA) neurotransmission by recapturing DA into the presynaptic terminals and is a principal target of the psychostimulant cocaine. The sigma-1 receptor (sigma R-1) is a molecular chaperone, and its ligands have been shown to modulate DA neuronal signaling, although their effects on DAT activity are unclear. Here, we report that the prototypical sigma R-1 agonist (+)-pentazocine potentiated the dose response of cocaine self-administration in rats, consistent with the effects of the sigma R agonists PRE-084 and DTG (1,3-di-o-tolylguanidine) reported previously. These behavioral effects appeared to be correlated with functional changes of DAT. Preincubation with (+)-pentazocine or PRE084 increased the B-max values of [ 3H] WIN35428 binding toDAT in rat striatal synaptosomes and transfected cells. A specific interaction between sigma R-1 andDATwas detected by co-immunoprecipitation and bioluminescence resonance energy transfer assays. Mutational analyses indicated that the transmembrane domain of sigma R-1 likely mediated this interaction. Furthermore, cysteine accessibility assays showed that sigma R-1 agonist preincubation potentiated cocaine-induced changes in DAT conformation, which were blocked by the specific sigma R-1 antagonist CM304. Moreover, sigma R-1 ligands had distinct effects on sigma R-1 multimerization. CM304 increased the proportion of multimeric sigma(1)Rs, whereas (+)-pentazocine increased monomeric sigma(1)Rs. Together these results support the hypothesis that sigma R-1 agonists promote dissociation of sigma R-1 multimers into monomers, which then interact with DAT to stabilize an outward-facing DAT conformation and enhance cocaine binding. We propose that this novel molecular mechanism underlies the behavioral potentiation of cocaine self-administration by sigma R-1 agonists in animal models.