Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Biochem Biophys Res Commun. 2011 Mar 4;406(1):47-52. doi: 10.1016/j.bbrc.2011.01.104. Epub 2011 Feb 1.
Adenosine-regulated glutamate signaling in astrocytes is implicated in many neurological and neuropsychiatric disorders. In this study, we examined whether adenosine A1 receptor regulates EAAT2 expression in astrocytes using pharmacological agents and siRNAs. We found that adenosine A1 receptor-specific antagonist DPCPX or PSB36 decreased EAAT2 expression in a dose-dependent manner. Consistently, knockdown of A1 receptor in astrocytes decreased EAAT2 mRNA expression while overexpression of A1 receptor upregulated EAAT2 expression and function. Since A1 receptor activation is mainly coupled to inhibitory G-proteins and inhibits the activity of adenylate cyclase, we investigated the effect of forskolin, which activates adenylate cyclase activity, on EAAT2 mRNA levels. Interestingly, we found that forskolin reduced EAAT2 expression in dose- and time-dependent manners. In contrast, adenylate cyclase inhibitor SQ22536 increased EAAT2 expression in dose- and time-dependent manners. In addition, forskolin blocked ethanol-induced EAAT2 upregulation. Taken together, these results suggest that A1 receptor-mediated signaling regulates EAAT2 expression in astrocytes.
腺苷调节星形胶质细胞中的谷氨酸信号转导与许多神经和神经精神疾病有关。在这项研究中，我们使用药理学试剂和 siRNA 研究了腺苷 A1 受体是否调节星形胶质细胞中的 EAAT2 表达。我们发现，腺苷 A1 受体特异性拮抗剂 DPCPX 或 PSB36 以剂量依赖性方式降低 EAAT2 的表达。一致地，星形胶质细胞中 A1 受体的敲低降低了 EAAT2 mRNA 表达，而 A1 受体的过表达上调了 EAAT2 的表达和功能。由于 A1 受体的激活主要与抑制性 G 蛋白偶联，并抑制腺苷酸环化酶的活性，我们研究了激活腺苷酸环化酶活性的 forskolin对 EAAT2 mRNA 水平的影响。有趣的是，我们发现 forskolin 以剂量和时间依赖性方式降低 EAAT2 的表达。相比之下，腺苷酸环化酶抑制剂 SQ22536 以剂量和时间依赖性方式增加 EAAT2 的表达。此外， forskolin 阻断了乙醇诱导的 EAAT2 上调。总之，这些结果表明 A1 受体介导的信号转导调节星形胶质细胞中的 EAAT2 表达。
