Ohkura Masamichi, Tanaka Naoko, Kobayashi Hideyuki, Wada Akihiko, Nakai Junichi, Yamamoto Ryuichi
First Department of Pharmacology, School of Pharmaceutical Sciences, Kyushu University of Health and Welfare, Yoshino, Nobeoka 882-8508, Japan.
Eur J Pharmacol. 2005 Jul 25;518(1):18-21. doi: 10.1016/j.ejphar.2005.06.011.
To visualize the 5-hydroxytryptamine2A (5-HT2A) receptor, we developed a 5-HT2A receptor fused with yellow fluorescent protein (5-HT2A-YFP) and expressed this receptor in HEK293 cells. In 5-HT2A-YFP-expressing cells, but not in YFP-expressing or non-expressing cells, 5-HT induced a transient increase in the intracellular Ca(2+) concentration (Ca(2+) transient) in the Fluo 3 assay, suggesting that 5-HT2A-YFP possesses a function similar to the wild-type 5-HT2A receptor. Interestingly, not only 5-HT but also insulin induced the internalization of 5-HT2A-YFP. Insulin also inhibited the 5-HT-induced Ca(2+) transient. Genistein, an inhibitor of tyrosine kinase, blocked these insulin effects. Our results provide the first evidence that insulin receptor signaling via tyrosine kinase activation induces internalization of the plasma membrane 5-HT2A receptor, and demonstrate crosstalk between the 5-HT2A receptor and the insulin receptor.
为了可视化5-羟色胺2A（5-HT2A）受体，我们构建了一种与黄色荧光蛋白融合的5-HT2A受体（5-HT2A-YFP），并在人胚肾293（HEK293）细胞中表达该受体。在表达5-HT2A-YFP的细胞中，而非表达YFP或不表达任何蛋白的细胞中，5-羟色胺在Fluo 3检测中诱导细胞内钙离子浓度出现瞬时升高（钙离子瞬变），这表明5-HT2A-YFP具有与野生型5-HT2A受体相似的功能。有趣的是，不仅5-羟色胺，胰岛素也能诱导5-HT2A-YFP的内化。胰岛素还抑制5-羟色胺诱导的钙离子瞬变。酪氨酸激酶抑制剂染料木黄酮可阻断这些胰岛素效应。我们的结果首次证明，通过酪氨酸激酶激活的胰岛素受体信号传导可诱导质膜5-HT2A受体的内化，并证明了5-HT2A受体与胰岛素受体之间存在相互作用。
