Department of Anatomy and Cell Biology, University of Western Ontario and the London Health Sciences Center, London, ON, Canada.
Int J Neuropsychopharmacol. 2012 Aug;15(7):965-79. doi: 10.1017/S146114571100109X. Epub 2011 Jul 22.
The dopamine D2 receptor (D2DR) regulates Akt and may also target the Wnt pathway, two signalling cascades that inhibit glycogen synthase kinase-3 (GSK-3). This study examined whether the Wnt pathway is regulated by D2DR and the role of Akt and dishevelled-3 (Dvl-3) in regulating GSK-3 and the transcription factor β-catenin in the rat brain. Western blotting showed that subchronic treatment of raclopride (D2DR antagonist) increase phosphorylated Akt, Dvl-3, GSK-3, phosphorylated GSK-3 and β-catenin, whereas subchronic treatment of quinpirole (D2DR agonist) induced the opposite response. Co-immunopreciptations revealed an association between GSK-3 and the D2DR complex that was altered following raclopride and quinpirole, albeit in opposite directions. SCH23390 (D1DR antagonist) and nafadotride (D3DR antagonist) were also used to determine if the response was specific to the D2DR. Neither subchronic treatment affected Dvl-3, GSK-3, Akt nor β-catenin protein levels, although nafadotride altered the phosphorylation state of Akt and GSK-3. In addition, in-vitro experiments were conducted to manipulate Akt and Dvl-3 activity in SH-SY5Y cells to elucidate how the pattern of change observed following manipulation of D2DR developed. Results indicate that Akt affects the phosphorylation state of GSK-3 but has no effect on β-catenin levels. However, altering Dvl-3 levels resulted in changes in Akt and the Wnt pathway similar to what was observed following raclopride or quinpirole treatment. Collectively, the data suggests that the D2DR very specifically regulates Wnt and Akt signalling via Dvl-3.
多巴胺 D2 受体（D2DR）调节 Akt，也可能靶向 Wnt 通路，这两条信号通路抑制糖原合酶激酶-3（GSK-3）。本研究探讨了 D2DR 是否调节 Wnt 通路，以及 Akt 和 Dvl-3 在调节 GSK-3 和转录因子β-连环蛋白（β-catenin）在大鼠脑中的作用。Western blot 显示，氯氮平（D2DR 拮抗剂）的亚慢性治疗增加了磷酸化 Akt、Dvl-3、GSK-3、磷酸化 GSK-3 和 β-连环蛋白，而喹吡罗（D2DR 激动剂）的亚慢性治疗则产生相反的反应。共免疫沉淀显示 GSK-3 与 D2DR 复合物之间存在关联，这种关联在氯氮平和喹吡罗处理后发生了改变，尽管方向相反。SCH23390（D1DR 拮抗剂）和纳曲酮（D3DR 拮抗剂）也被用于确定反应是否特异性地针对 D2DR。两种亚慢性治疗均未影响 Dvl-3、GSK-3、Akt 或 β-连环蛋白的蛋白水平，尽管纳曲酮改变了 Akt 和 GSK-3 的磷酸化状态。此外，还进行了体外实验来操纵 SH-SY5Y 细胞中的 Akt 和 Dvl-3 活性，以阐明观察到的 D2DR 操纵后变化模式是如何发展的。结果表明，Akt 影响 GSK-3 的磷酸化状态，但对 β-连环蛋白水平没有影响。然而，改变 Dvl-3 水平会导致 Akt 和 Wnt 通路的变化，类似于氯氮平或喹吡罗处理后的变化。总的来说，数据表明 D2DR 非常特异性地通过 Dvl-3 调节 Wnt 和 Akt 信号。
