Evidence for functional adenosine A3 receptors in microglia cells
Evidence for functional adenosine A3 receptors in microglia cells
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DOI：
10.1046/j.1471-4159.2003.01919.x
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发表时间：
2003-08-01
影响因子：
4.7
通讯作者：
Fredholm, BB
中科院分区：
文献类型：
--
作者：
Hammarberg, C;Schulte, G;Fredholm, BB
腺苷通过四种G蛋白偶联受体（GPCRs）亚型发挥作用：腺苷A(1)和A(3)受体（A(3)R），它们通常与G(i)蛋白偶联；以及腺苷A(2A)和A(2B)受体，它们激活G(s)蛋白。尽管有证据表明中枢神经系统中存在A(3)R的mRNA表达，但功能性受体的证据依赖于特异性不确定的药物。在此，我们表明介导功能性反应的A(3)R存在于小胶质细胞中。通过用激动剂Cl - IB - MECA选择性刺激原代小鼠小胶质细胞和N13小胶质细胞系中的A(3)R，我们发现对细胞外信号调节蛋白激酶1/2（ERK1/2）的磷酸化存在一种双相的、部分依赖G(i)蛋白的影响。通过用磷酸化特异性抗体进行免疫印迹来评估ERK1/2的激活。通过证明从缺乏A(3)R基因的小鼠中分离出的原代小鼠小胶质细胞中不存在这些效应，证实了A(3)R参与Cl - IB - MECA诱导的ERK1/2磷酸化。
Adenosine exerts its effects through four subtypes of G-protein-coupled receptors (GPCRs): adenosine A(1) and A(3) receptors (A(3) R), which generally couple to G(i) proteins and adenosine A(2A) and A(2B) receptors that activate G(s) proteins. Though there is evidence for the expression of mRNA for the A(3) R in the central nervous system, evidence for functional receptors has depended on drugs with uncertain specificity. Here, we show that A(3) Rs mediating functional responses are present in microglia cells. By selectively stimulating the A(3) R in both primary mouse microglia cells and the N13 microglia cell line with the agonist Cl-IB-MECA, we have found a biphasic, partly G(i) protein-dependent influence on the phosphorylation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2). ERK1/2 activation was assessed by immunoblotting with phospho-specific antibodies. The involvement of the A(3) R in Cl-IB-MECA-induced ERK1/2 phosphorylation was confirmed by demonstrating that those effects are absent in primary mouse microglia cells isolated from mice lacking the gene for the A(3) R.