Schanstra J P, Bataillé E, Marin Castaño M E, Barascud Y, Hirtz C, Pesquero J B, Pecher C, Gauthier F, Girolami J P, Bascands J L
Institut National de la Santé et de la Recherche Médicale (INSERM) U388, Institut Louis BUGNARD, CHU Rangueil, 31052 Toulouse, France.
J Clin Invest. 1998 May 15;101(10):2080-91. doi: 10.1172/JCI1359.
The bradykinin B1-receptor is strongly upregulated under chronic inflammatory conditions. However, the mechanism and reason are not known. Because a better understanding of the mechanism of the upregulation will help in understanding its potential importance in inflammation, we have studied the molecular mechanism of B1-receptor upregulation in cultured human lung fibroblasts (IMR 90) in response to IL-1beta and the B1-agonist [des-Arg10]-kallidin. We show that treatment of human IMR 90 cells by IL-1beta stimulates the expression of both B1-receptor mRNA and protein. The latter was studied by Western blot analysis using antipeptide antibodies directed against the COOH-terminal part of the human B1-receptor. We furthermore report the novel observation that the B1-receptor is upregulated by its own agonist which was completely blocked by the specific B1-antagonist [des-Arg10-Leu9]-kallidin, indicating an upregulation entirely mediated through cell surface B1-receptors. The increased population of B1-receptors was functionally coupled as exemplified by an enhancement of the B1-agonist induced increase in free cytosolic calcium. Upregulation by the B1-agonist was blocked by a specific protein kinase C inhibitor. B1-agonist-induced upregulation was correlated to the induction of transcription factor nuclear factor kappaB (NF-kappaB) which efficiently bound to the NF-kappaB-like sequence located in the promoter region of the human B1-receptor gene. This correlation was further confirmed by reporter gene assays which showed that this NF-kappaB-like sequence, in the B1-receptor promoter context, could contribute to IL-1beta and DLBK-induced B1-receptor transcription activation, and by the effect of NF-kappaB inhibitor pyrrolidinedithiocarbamate which diminished both B1-receptor upregulation and NF-kappaB activation. NF-kappaB is now recognized as a key inflammatory mediator which is activated by the B1-agonist but which is also involved in B1-receptor upregulation.
缓激肽B1受体在慢性炎症条件下强烈上调。然而，其机制和原因尚不清楚。由于更好地理解上调机制将有助于理解其在炎症中的潜在重要性，我们研究了培养的人肺成纤维细胞（IMR 90）中B1受体上调的分子机制，以响应IL-1β和B1激动剂[去精氨酸10]-胰激肽。我们发现，用IL-1β处理人IMR 90细胞可刺激B1受体mRNA和蛋白的表达。后者通过使用针对人B1受体COOH末端部分的抗肽抗体进行蛋白质印迹分析来研究。我们还报告了一个新的观察结果，即B1受体被其自身的激动剂上调，这被特异性B1拮抗剂[去精氨酸10-亮氨酸9]-胰激肽完全阻断，表明上调完全是通过细胞表面B1受体介导的。B1受体数量的增加在功能上是偶联的，例如B1激动剂诱导的游离细胞质钙增加增强。B1激动剂的上调被特异性蛋白激酶C抑制剂阻断。B1激动剂诱导的上调与转录因子核因子κB（NF-κB）的诱导相关，NF-κB有效地结合到人B1受体基因启动子区域中的NF-κB样序列。报告基因分析进一步证实了这种相关性，该分析表明在B1受体启动子背景下，这种NF-κB样序列可促进IL-1β和DLBK诱导的B1受体转录激活，以及NF-κB抑制剂吡咯烷二硫代氨基甲酸盐的作用，该抑制剂减少了B1受体上调和NF-κB激活。NF-κB现在被认为是一种关键的炎症介质，它被B1激动剂激活，但也参与B1受体的上调。
