Department of Nutrition and Exercise Physiology, University of Missouri , Columbia, Missouri.
Department of Child Health, University of Missouri , Columbia, Missouri.
Am J Physiol Heart Circ Physiol. 2018 Jan 1;314(1):H52-H64. doi: 10.1152/ajpheart.00478.2017. Epub 2017 Sep 29.
Hyperglycemia-induced production of endothelin (ET)-1 is a hallmark of endothelial dysfunction in diabetes. Although the detrimental vascular effects of increased ET-1 are well known, the molecular mechanisms regulating endothelial synthesis of ET-1 in the setting of diabetes remain largely unidentified. Here, we show that adapter molecule TRAF3 interacting protein 2 (TRAF3IP2) mediates high glucose-induced ET-1 production in endothelial cells and ET-1-mediated endothelial cell inflammation. Specifically, we found that high glucose upregulated TRAF3IP2 in human aortic endothelial cells, which subsequently led to activation of JNK and IKKβ. shRNA-mediated silencing of TRAF3IP2, JNK1, or IKKβ abrogated high-glucose-induced ET-converting enzyme 1 expression and ET-1 production. Likewise, overexpression of TRAF3IP2, in the absence of high glucose, led to activation of JNK and IKKβ as well as increased ET-1 production. Furthermore, ET-1 transcriptionally upregulated TRAF3IP2, and this upregulation was prevented by pharmacological inhibition of ET-1 receptor B using BQ-788, or inhibition of NADPH oxidase-derived reactive oxygen species using gp91ds-tat and GKT137831. Notably, we found that knockdown of TRAF3IP2 abolished ET-1-induced proinflammatory and adhesion molecule (IL-1β, TNF-α, monocyte chemoattractant protein 1, ICAM-1, VCAM-1, and E-selectin) expression and monocyte adhesion to endothelial cells. Finally, we report that TRAF3IP2 is upregulated and colocalized with CD31, an endothelial marker, in the aorta of diabetic mice. Collectively, findings from the present study identify endothelial TRAF3IP2 as a potential new therapeutic target to suppress ET-1 production and associated vascular complications in diabetes. NEW & NOTEWORTHY This study provides the first evidence that the adapter molecule TRAF3 interacting protein 2 mediates high glucose-induced production of endothelin-1 by endothelial cells as well as endothelin-1-mediated endothelial cell inflammation. The findings presented herein suggest that TRAF3 interacting protein 2 may be an important therapeutic target in diabetic vasculopathy characterized by excess endothelin-1 production.
高血糖诱导内皮素 (ET)-1 的产生是糖尿病内皮功能障碍的标志。尽管增加的 ET-1 的有害血管作用是众所周知的，但在糖尿病环境中调节内皮细胞合成 ET-1 的分子机制在很大程度上仍未被确定。在这里，我们表明衔接分子 TRAF3 相互作用蛋白 2 (TRAF3IP2) 介导内皮细胞中高葡萄糖诱导的 ET-1 产生和 ET-1 介导的内皮细胞炎症。具体而言，我们发现高葡萄糖在上皮细胞中上调 TRAF3IP2，随后导致 JNK 和 IKKβ 的激活。TRAF3IP2、JNK1 或 IKKβ 的 shRNA 介导的沉默消除了高葡萄糖诱导的 ET 转换酶 1 表达和 ET-1 产生。同样，在没有高葡萄糖的情况下过表达 TRAF3IP2 导致 JNK 和 IKKβ 的激活以及 ET-1 的产生增加。此外，ET-1 转录上调 TRAF3IP2，并且这种上调被使用 BQ-788 抑制 ET-1 受体 B 或使用 gp91ds-tat 和 GKT137831 抑制 NADPH 氧化酶衍生的活性氧来阻止。值得注意的是，我们发现 TRAF3IP2 的敲低消除了 ET-1 诱导的促炎和粘附分子（IL-1β、TNF-α、单核细胞趋化蛋白 1、ICAM-1、VCAM-1 和 E-选择素）表达和单核细胞与内皮细胞的粘附。最后，我们报告在糖尿病小鼠的主动脉中，TRAF3IP2 上调并与内皮标记物 CD31 共定位。总之，本研究的结果表明内皮 TRAF3IP2 是抑制糖尿病中 ET-1 产生和相关血管并发症的潜在新治疗靶点。
