Downregulation of kinin B1 receptor function by B2 receptor heterodimerization and signaling.
Downregulation of kinin B1 receptor function by B2 receptor heterodimerization and signaling.
复制标题
通过 B2 受体异二聚化和信号传导下调激肽 B1 受体功能。
DOI：
10.1016/j.cellsig.2014.09.019
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发表时间：
2015
影响因子：
4.8
通讯作者：
Skidgel,RandalA
中科院分区：
文献类型：
--
作者：
Zhang,Xianming;Brovkovych,Viktor;Zhang,Yongkang;Tan,Fulong;Skidgel,RandalA
通过G蛋白偶联激动素受体B1(KB1R)和B2(KB2R)传递的信号在激肽释放酶-激动素系统激活所介导的炎症反应中起着关键作用。KB2R是结构性表达的，并对激动剂迅速脱敏，而kB1R的表达受炎性刺激上调，对内化和脱敏具有抵抗力。在这里，我们发现在共转染的HEK293细胞中，kB1R与kB2R异源二聚体，并自然表达内皮细胞，导致经kB2R激动剂处理的细胞中kB1R反应显著内化和脱敏。然而，用kB1R激动剂预先处理细胞并不影响随后的kB2R反应。其他G蛋白偶联受体的激动剂(凝血酶、溶血磷脂酸)对随后的kB1R反应没有影响。KB2R突变体Y129S阻断kB2R信号而不影响内吞作用，或T342a信号类似野生型但不内吞，部分逆转了kB2R激动剂预处理后kB1R反应的丧失。KB1R和kB2R的共吞噬作用依赖于β-arrestin和笼状蛋白包被的小窝，而不是小窝。内吞后kB1R和kB2R的分选途径不同，kB1R循环到细胞表面的速度比kB2R慢得多。在细胞因子处理的人肺微血管内皮细胞中，kB2R激动剂可抑制由kB1R刺激(产生一氧化氮)引起的跨内皮细胞电阻(TER)的增加，并阻断在焦性没食子酸(一种超氧化物生成物)存在下KB1R激活引起的TER的显著下降。因此，kB1R的功能可以被kB2R共内吞和信号下调，这为在病理条件下控制kB1R信号提供了新的途径。
Signaling through the G protein-coupled kinin receptors B1 (kB1R) and B2 (kB2R) plays a critical role in inflammatory responses mediated by activation of the kallikrein–kinin system. The kB2R is constitutively expressed and rapidly desensitized in response to agonist whereas kB1R expression is upregulated by inflammatory stimuli and it is resistant to internalization and desensitization. Here we show that the kB1R heterodimerizes with kB2Rs in co-transfected HEK293 cells and natively expressing endothelial cells, resulting in significant internalization and desensitization of the kB1R response in cells pre-treated with kB2R agonist. However, pre-treatment of cells with kB1R agonist did not affect subsequent kB2R responses. Agonists of other G protein-coupled receptors (thrombin, lysophosphatidic acid) had no effect on a subsequent kB1R response. The loss of kB1R response after pretreatment with kB2R agonist was partially reversed with kB2R mutant Y129S, which blocks kB2R signaling without affecting endocytosis, or T342A, which signals like wild type but is not endocytosed. Co-endocytosis of the kB1R with kB2R was dependent on β-arrestin and clathrin-coated pits but not caveolae. The sorting pathway of kB1R and kB2R after endocytosis differed as recycling of kB1R to the cell surface was much slower than that of kB2R. In cytokine-treated human lung microvascular endothelial cells, pre-treatment with kB2R agonist inhibited kB1R-mediated increase in transendothelial electrical resistance (TER) caused by kB1R stimulation (to generate nitric oxide) and blocked the profound drop in TER caused by kB1R activation in the presence of pyrogallol (a superoxide generator). Thus, kB1R function can be downregulated by kB2R co-endocytosis and signaling, suggesting new approaches to control kB1R signaling in pathological conditions.