Kansanen Emilia, Kuosmanen Suvi M, Ruotsalainen Anna-Kaisa, Hynynen Heidi, Levonen Anna-Liisa
A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland (E.K., S.M.K, A.-K.R., H.H., A.-L.L.).
A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland (E.K., S.M.K, A.-K.R., H.H., A.-L.L.)
Mol Pharmacol. 2017 Oct;92(4):481-490. doi: 10.1124/mol.117.109751. Epub 2017 Aug 4.
Nitro-fatty acids are reactive signaling mediators that are formed when unsaturated fatty acids react with nitric oxide or nitric oxide-derived species. Nitro-fatty acids can modify specific signaling pathways via post-translational modifications of Cys residues in key regulatory proteins. One of the signaling cascades activated by nitro-fatty acids is the Keap1-Nrf2 pathway. We have previously studied the effects of nitro-oleic acid (OA-NO) on the human endothelial cell transcriptome. We observed that endothelin receptor B [ET-B (gene name )], the receptor mediating the vasodilatory effects of endothelin-1 (ET-1) is induced by OA-NO Inasmuch as ET-1 is one of the key regulators of vascular tone, we chose to examine in more detail the effect of OA-NO on endothelin signaling in human endothelial cells. Nrf2 was found to regulate the OA-NO-induced transcription of ET-B in human and mouse endothelial cells. Furthermore, chromatin immunoprecipitation analysis revealed that OA-NO increased the binding of Nrf2 to an antioxidant response element in the enhancer region of the gene. In addition, we show that the overexpression of both OA-NO and Nrf2 substantially decreased and that Nrf2 silencing increased the ET-1 concentration in the culture media of endothelial cells. The change in the extracellular ET-1 concentration was dependent on ET-B receptor expression. These data suggest that OA-NO modulates endothelin signaling by increasing Nrf2-dependent expression of the ET-B receptor in endothelial cells, which in turn mediates the decrease in extracellular ET-1 concentration. Based on these results, we propose that OA-NO and Nrf2 may alleviate the vasoconstrictive effects of ET-1 by removing it from the circulation.
硝基脂肪酸是反应性信号介质，当不饱和脂肪酸与一氧化氮或一氧化氮衍生的物质反应时形成。硝基脂肪酸可通过对关键调节蛋白中半胱氨酸残基的翻译后修饰来改变特定的信号通路。由硝基脂肪酸激活的信号级联反应之一是Keap1-Nrf2通路。我们之前研究了硝基油酸（OA-NO）对人内皮细胞转录组的影响。我们观察到，介导内皮素-1（ET-1）血管舒张作用 的内皮素受体B [ET-B（基因名称）] 由OA-NO诱导。由于ET-1是血管张力的关键调节因子之一，我们选择更详细地研究OA-NO对人内皮细胞中内皮素信号传导的影响。发现Nrf2调节人及小鼠内皮细胞中OA-NO诱导的ET-B转录。此外，染色质免疫沉淀分析表明，OA-NO增加了Nrf2与该基因增强子区域中抗氧化反应元件的结合。此外，我们表明，OA-NO和Nrf2的过表达均显著降低，而Nrf2沉默增加了内皮细胞培养基中ET-1的浓度。细胞外ET-1浓度的变化取决于ET-B受体的表达。这些数据表明，OA-NO通过增加内皮细胞中Nrf2依赖的ET-B受体表达来调节内皮素信号传导，这反过来又介导细胞外ET-1浓度的降低。基于这些结果，我们提出OA-NO和Nrf2可能通过将ET-1从循环中清除来减轻其血管收缩作用。
