Lady Davis Research Institute, McGill University, Montreal, Quebec, Canada.
Lady Davis Research Institute, McGill University, Montreal, Quebec, Canada.
Cell Signal. 2017 Sep;37:31-39. doi: 10.1016/j.cellsig.2017.05.014. Epub 2017 May 26.
Metabolic syndrome is associated with overactive bladder syndrome (OAB) and increased circulating levels of succinate, an intermediate of the Krebs cycle. The urothelium is an essential regulator of bladder muscle contraction. This study aimed to determine if GPR91, the succinate receptor, is expressed and functional in the bladder. Urothelial and smooth muscle cells (SMCs) were cultured and characterized. PCR revealed that urothelial cells express GPR91, twice as much as SMCs. Incubation of cells with succinate stimulated phosphorylation of ERK and JNK in urothelial cells. Succinate also potently inhibited forskolin-stimulated cyclic AMP production in urothelial cells, an effect prevented by a protein G inhibitor. ERK phosphorylation stimulated by succinate was abolished by inhibitors of protein G, phospholipase C, MAPK pathway and PKC. Incubation of urothelial cells with succinate potently increased iNOS synthesis and secretion of nitric oxide (NO), and decreased secretion of prostaglandin E (PGE). Finally, succinate triggered entry of calcium in urothelial cells. GPR91 knockdown by shRNA abolished most of these signaling effects. We conclude that in the bladder, urothelial cells are a primary target of succinate through its receptor GPR91. Its activation leads to signaling via phospholipase C, MAPK, PKC pathway and protein G and G. Succinate binding to GPR91 triggers a rise in intracellular calcium, an increase in secretion of NO and a decrease in the release of PGE. Succinate might be essential in the understanding of OAB that occurs in metabolic syndrome.
代谢综合征与膀胱过度活动症（OAB）和琥珀酸循环中间产物的循环水平升高有关。尿路上皮是膀胱肌肉收缩的重要调节者。本研究旨在确定琥珀酸受体 GPR91 是否在膀胱中表达和发挥功能。培养和鉴定尿路上皮细胞和平滑肌细胞（SMCs）。PCR 显示尿路上皮细胞表达 GPR91，是 SMCs 的两倍。用琥珀酸孵育细胞可刺激尿路上皮细胞中 ERK 和 JNK 的磷酸化。琥珀酸还强烈抑制尿路上皮细胞中forskolin 刺激的环 AMP 产生，该作用可被蛋白 G 抑制剂阻止。蛋白 G、磷脂酶 C、MAPK 途径和 PKC 抑制剂可消除琥珀酸刺激的 ERK 磷酸化。用琥珀酸孵育尿路上皮细胞可强力增加 iNOS 合成和一氧化氮（NO）的分泌，并减少前列腺素 E（PGE）的分泌。最后，琥珀酸触发尿路上皮细胞内钙进入。用 shRNA 敲低 GPR91 可消除这些信号转导作用的大部分。我们的结论是，在膀胱中，尿路上皮细胞是琥珀酸通过其受体 GPR91 的主要靶标。其激活导致通过 PLC、MAPK、PKC 途径和蛋白 G 和 G 的信号转导。琥珀酸与 GPR91 结合触发细胞内钙升高、NO 分泌增加和 PGE 释放减少。琥珀酸可能对代谢综合征中发生的 OAB 的理解至关重要。
