Distinct roles of dopamine D2L and D2S receptor isoforms in the regulation of protein phosphorylation at presynaptic and postsynaptic sites
Distinct roles of dopamine D2L and D2S receptor isoforms in the regulation of protein phosphorylation at presynaptic and postsynaptic sites
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DOI：
10.1073/pnas.0730708100
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发表时间：
2003-04-01
影响因子：
11.1
通讯作者：
Fisone, G
中科院分区：
文献类型：
--
作者：
Lindgren, N;Usiello, A;Fisone, G
多巴胺D2受体在背侧纹状体中高度表达，它们参与调节（i）黑质纹状体神经末梢中的酪氨酸羟化酶（TH），以及（ii）中等多棘神经元中32 kDa的多巴胺和环磷腺苷酸调节的磷蛋白（DARPP - 32）。D2受体的两种异构体由同一基因的选择性剪接产生，分别被称为短型（D2S）和长型（D2L）多巴胺受体。在此我们使用野生型小鼠、多巴胺D2受体敲除小鼠（D2 KO小鼠；缺乏D2S和D2L两种受体）以及D2L受体选择性敲除小鼠（D2L KO小鼠）来评估每种异构体在调节TH和DARPP - 32磷酸化中的作用。将野生型小鼠的纹状体切片与多巴胺D2受体激动剂喹吡罗一起孵育，会降低TH在丝氨酸 - 40位点的磷酸化状态及其酶活性。这两种效应在D2 KO小鼠中消失，但在D2L KO小鼠中仍然存在。在野生型小鼠中，喹吡罗抑制由多巴胺D1受体激动剂SKF81297诱导的DARPP - 32在苏氨酸 - 34位点磷酸化的增加。这种效应在D2 KO小鼠以及D2L KO小鼠中均不存在。喹吡罗在D2L KO小鼠中不能调节DARPP - 32磷酸化不能归因于D2S受体与G蛋白偶联的减少，因为喹吡罗在野生型和D2L KO小鼠中对[S - 35]GTPγS结合产生相似的刺激作用。这些结果表明D2S和D2L受体分别参与突触前和突触后的多巴胺能传递。
Dopamine D2 receptors are highly expressed in the dorsal striatum where they participate in the regulation of (i) tyrosine hydroxylase (TH), in nigrostriatal nerve terminals, and (if) the dopamine- and CAMP-regulated phosphoprotein of 32 kDa (DARPP-32), in medium spiny neurons. Two isoforms of the D2 receptor are generated by differential splicing of the same gene and are referred to as short (D2S) and long (D2L) dopamine receptors. Here we have used wild-type mice, dopamine D2 receptor knockout mice (D2 KO mice; lacking both D2S and D2L receptors) and D2L receptor-selective knockout mice (D2L KO mice) to evaluate the involvement of each isoform in the regulation of the phosphorylation of TH and DARPP-32. Incubation of striatal slices from wild-type mice with quinpirole, a dopamine D2 receptor agonist, decreased the state of phosphorylation of TH at Ser-40 and its enzymatic activity. Both effects were abolished in D2 KO mice but were still present in D2L KO mice. In wild-type mice, quinpirole inhibits the increase in DARPP-32 phosphorylation at Thr-34 induced by SKF81297, a dopamine D1 receptor agonist. This effect is absent in D2 KO as well as D2L KO mice. The inability of quinpirole to regulate DARPP-32 phosphorylation in D2L KO mice cannot be attributed to decreased coupling of D2S receptors to G proteins, because quinpirole produces a similar stimulation of [S-35]GTPgammaS binding in wild-type and D2L KO mice. These results demonstrate that D2S and D2L receptors participate in presynaptic and postsynaptic dopaminergic transmission, respectively.