Sreedharan S P, Patel D R, Xia M, Ichikawa S, Goetzl E J
Department of Medicine, University of California, San Francisco 94143-0711.
Biochem Biophys Res Commun. 1994 Aug 30;203(1):141-8. doi: 10.1006/bbrc.1994.2160.
Vasoactive intestinal peptide (VIP) is a potent neuropeptide mediator of central and peripheral nervous system function. A human VIP1 receptor (HVR) cDNA clone was previously obtained from HT29 intestinal epithelial cells and lung tissue. Stably-transfected human embryonic kidney 293 cells and chinese hamster ovary (CHO) cells expressing about 10(6) HVRs per cell that bind [125I]VIP with a Kd of 0.2-0.8 nM, and specifically recognized by anti-HVR antibodies, were established and characterized. VIP induced increases in intracellular cAMP levels ([cAMP]i) dose-dependently with an EC50 of 0.2 nM in 293 and CHO stable transfectants and concurrently evoked dose-dependent increases in intracellular calcium concentrations ([Ca2+]i), as determined by fluorescence-dye spectroscopy. Untransfected 293 and CHO cells showed minimal binding or intracellular effects of VIP; however, native VIP1 receptors of HT29 cells also increased [cAMP]i and [Ca2+]i in dose-dependent responses to VIP. Thus recombinant and native human VIP1 receptors both couple to two distinct signal transduction pathways within a single cell type.
血管活性肠肽（VIP）是中枢和外周神经系统功能的一种强效神经肽介质。人VIP1受体（HVR）cDNA克隆先前已从HT29肠上皮细胞和肺组织中获得。建立并鉴定了稳定转染的人胚肾293细胞和中国仓鼠卵巢（CHO）细胞，这些细胞每细胞表达约10^6个HVR，其与[125I]VIP结合的解离常数（Kd）为0.2 - 0.8 nM，并能被抗HVR抗体特异性识别。在293和CHO稳定转染细胞中，VIP以剂量依赖性方式诱导细胞内cAMP水平（[cAMP]i）升高，其半数有效浓度（EC50）为0.2 nM，同时通过荧光染料光谱法测定，VIP还能引起细胞内钙浓度（[Ca2+]i）呈剂量依赖性升高。未转染的293和CHO细胞对VIP的结合或细胞内效应极小；然而，HT29细胞的天然VIP1受体对VIP的剂量依赖性反应也会使[cAMP]i和[Ca2+]i升高。因此，重组和天然的人VIP1受体在单一细胞类型中均与两种不同的信号转导途径偶联。
