Genedani Susanna, Guidolin Diego, Leo Giuseppina, Filaferro Monica, Torvinen Maria, Woods Amina S, Fuxe Kjell, Ferré Sergi, Agnati Luigi F
Section of Pharmacology, University of Modena and Reggio Emilia, 41100 Modena, Italy.
J Mol Neurosci. 2005;26(2-3):177-84. doi: 10.1385/JMN:26:2-3:177.
A functional aspect of horizontal molecular networks has been investigated experimentally, namely the heteromerization between adenosine A2A and dopamine D2 receptors and the possible role of caveolin-1 in the co-trafficking of these molecular complexes. This study has been carried out by means of computer-assisted image analysis procedure of laser images of membrane immunoreactivity of caveolin-1, A2A, D1, and D2 receptors obtained in two clones of Chinese hamster ovary cells one transfected with A2A and dopamine D1 receptors and the other one with A2A and D2 receptors. Cells were treated for 3 h with 10 microM D1 receptor agonist SKF 38393, 50 microM D2-D3 receptor agonist quinpirole, and 200 nM A2A receptor agonist CGS 21680. In A2A-D1-cotransfected cells, caveolin-1 was found to colocalize with both A2A and D1 receptors and treatment with SKF 38393 induced internalization of caveolin-1 and D1 receptors, with a preferential internalization of D1 receptors colocalized with caveolin-1. In A2A-D2-cotransfected cells, caveolin-1 was found to colocalize with both A2A and D2 receptors and either CGS 21680 or quinpirole treatment induced internalization of caveolin-1 and A2A and D2 receptors, with a preferential internalization of A2A and D2 receptors colocalized with caveolin-1. The results suggest that A2A and D2 receptors and caveolin-1 likely interact forming a macrocomplex that internalizes upon agonist treatment. These observations are discussed in the frame of receptor oligomerization and of the possible functional role of caveolin-1 in the process of co-internalization and, hence, in controlling the permanence of receptors at the plasma membrane level (prerequisite for receptor mosaic organization and plastic adjustments) and in the control of receptor desensitization.
已通过实验研究了水平分子网络的一个功能方面，即腺苷A2A受体与多巴胺D2受体之间的异源二聚化以及小窝蛋白-1在这些分子复合物共同转运中的可能作用。本研究借助计算机辅助图像分析程序，对在中国仓鼠卵巢细胞的两个克隆中获得的小窝蛋白-1、A2A、D1和D2受体的膜免疫反应性激光图像进行分析。其中一个克隆转染了A2A和多巴胺D1受体，另一个克隆转染了A2A和D2受体。用10微摩尔/升的D1受体激动剂SKF 38393、50微摩尔/升的D2-D3受体激动剂喹吡罗和200纳摩尔/升的A2A受体激动剂CGS 21680处理细胞3小时。在A2A-D1共转染的细胞中，发现小窝蛋白-1与A2A和D1受体都共定位，用SKF 38393处理可诱导小窝蛋白-1和D1受体内化，与小窝蛋白-1共定位的D1受体优先内化。在A2A-D2共转染的细胞中，发现小窝蛋白-1与A2A和D2受体都共定位，用CGS 21680或喹吡罗处理可诱导小窝蛋白-1、A2A和D2受体内化，与小窝蛋白-1共定位的A2A和D2受体优先内化。结果表明，A2A和D2受体以及小窝蛋白-可能相互作用形成一个大分子复合物，该复合物在激动剂处理后内化。在受体寡聚化以及小窝蛋白-1在共同内化过程中的可能功能作用的框架内，进而在控制受体在质膜水平的持久性（受体镶嵌组织和可塑性调节的先决条件）以及受体脱敏控制方面，对这些观察结果进行了讨论。
