Institut de Recherches Servier, Psychopharmacology Department, 125 Chemin de Ronde, 78290 Croissy sur Seine, France.
Mol Pharmacol. 2011 Jan;79(1):91-105. doi: 10.1124/mol.110.065409. Epub 2010 Oct 15.
Although dopamine (DA) regulates the serine/threonine kinase Akt and its downstream substrate glycogen synthase kinase-3β (GSK-3β), the direct influence of dopaminergic receptors remains poorly characterized. Short-term incubation of Chinese hamster ovary (CHO)-expressed human (h)D(₂L) and hD₃) receptors with DA (maximal effect, 5-10 min) phosphorylated Akt (Thr308 and Ser473) and GSK-3β (Ser9), actions blocked by the selective D₂ and D₃ antagonists, 3-[4-(4-chlorophenyl)-4-hydroxypiperidin-l-yl]methyl-1H-indole (L741,626) and (3aR,9bS)-N[4-(8-cyano-1,3a,4,9b-tetrahydro-3H-benzopyrano[3,4-c]pyrrole-2-yl)-butyl] (4-phenyl)benzamide (S33084), respectively. Similar findings were acquired with the specific D₂/D₃ receptor agonist quinelorane, which also enhanced (10 min after administration) levels of p-Akt and p-GSK-3β in rat nucleus accumbens, an action blocked by the D₂/D₃ receptor antagonist raclopride. Akt and GSK-3β phosphorylation mediated via CHO-expressed hD(₂L) and hD₃ receptors was prevented by pertussis toxin and by inhibitors of insulin-like growth factor-1 receptors as well as phosphatidylinositol 3-kinase and Src. Likewise, chelation of intracellular Ca²+ and interference with an "atypical" phorbol ester-insensitive protein kinase C (PKC) abolished recruitment of Akt and GSK-3β. Inactivation of PKCμ blocked Akt and GSK-3β phosphorylation at hD(₂L) receptors. However, blockade of conventional PKC isoforms attenuated the actions of DA at hD₃ receptors only. Furthermore, phospholipase C (PLC), calmodulin, and Akt inhibitors abolished DA-induced GSK-3β phosphorylation by hD₃ receptors, whereas phosphorylation by hD(₂L) receptors partially involved calmodulin, Akt, and extracellular signal-regulated kinase (ERK) 1/2. In conclusion, at both hD(₂L) and hD₃ receptors, DA elicited a G(i/o)- and Ca²+/calmodulin-dependent phosphorylation of Akt and GSK-3β via transactivation of insulin-like growth factor 1 receptor. However, significant differences were seen regarding the involvement of PLC, calmodulin, and ERK1/2.
尽管多巴胺（DA）调节丝氨酸/苏氨酸激酶 Akt 和其下游底物糖原合酶激酶-3β（GSK-3β），但多巴胺能受体的直接影响仍知之甚少。用 DA（最大效应，5-10 分钟）孵育中国仓鼠卵巢（CHO）表达的人（h）D₂L 和 hD₃）受体可磷酸化 Akt（Thr308 和 Ser473）和 GSK-3β（Ser9），该作用被选择性 D₂和 D₃拮抗剂 3-[4-(4-氯苯基)-4-羟基哌啶-1-基]甲基-1H-吲哚（L741,626）和（3aR,9bS）-N[4-(8-氰基-1,3a,4,9b-四氢-3H-苯并吡喃[3,4-c]吡咯-2-基)-丁基]（4-苯基）苯甲酰胺（S33084）阻断。用特异性 D₂/D₃受体激动剂喹那洛尔也获得了类似的发现，该激动剂还增强了大鼠伏隔核中（给药 10 分钟后）p-Akt 和 p-GSK-3β 的水平，该作用被 D₂/D₃受体拮抗剂 raclopride 阻断。通过百日咳毒素和胰岛素样生长因子-1 受体抑制剂以及磷脂酰肌醇 3-激酶和 Src 阻断通过 CHO 表达的 hD₂L 和 hD₃ 受体介导的 Akt 和 GSK-3β 磷酸化。同样，细胞内 Ca²+螯合和干扰“非典型”佛波醇酯不敏感蛋白激酶 C（PKC）也消除了 Akt 和 GSK-3β 的募集。PKCμ 的失活阻断了 hD₂L 受体上的 Akt 和 GSK-3β 磷酸化。然而，仅阻断常规 PKC 同工型可减弱 DA 在 hD₃ 受体上的作用。此外，PLC、钙调蛋白和 Akt 抑制剂消除了 hD₃ 受体诱导的 DA 诱导的 GSK-3β 磷酸化，而 hD₂L 受体的磷酸化部分涉及钙调蛋白、Akt 和细胞外信号调节激酶（ERK）1/2。总之，在 hD₂L 和 hD₃ 受体上，DA 通过胰岛素样生长因子 1 受体的转激活引发 G(i/o)-和 Ca²+/钙调蛋白依赖性 Akt 和 GSK-3β 的磷酸化。然而，在 PLC、钙调蛋白和 ERK1/2 的参与方面存在显著差异。
