Severe hypoglycemia has a detrimental impact on the cerebrovasculature, but the molecular events that lead to the disruption of the integrity of the tight junctions remain unclear. Here, we report that the microvessel integrity was dramatically compromised (59.41% of wild-type mice) in TP53-induced glycolysis and apoptosis regulator (TIGAR) transgenic mice stressed by hypoglycemia. Melatonin, a potent antioxidant, protects against hypoglycemic stress-induced brain endothelial tight junction injury in the dosage of 400 nmol/L in vitro. FRET (fluorescence resonance energy transfer) imaging data of endothelial cells stressed by low glucose revealed that TIGAR couples with calmodulin to promote TIGAR tyrosine nitration. A tyrosine 92 mutation interferes with the TIGAR-dependent NADPH generation (55.60% decreased) and abolishes its protective effect on tight junctions in human brain microvascular endothelial cells. We further demonstrate that the low-glucose-induced disruption of occludin and Caludin5 as well as activation of autophagy was abrogated by melatonin-mediated blockade of nitrosative stress in vitro. Collectively, we provide information on the detailed molecular mechanisms for the protective actions of melatonin on brain endothelial tight junctions and suggest that this indole has translational potential for severe hypoglycemia-induced neurovascular damage.

中文翻译：

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褪黑素通过抑制TP53诱导的糖酵解和细胞凋亡调节剂的蛋白质硝化作用，改善了低血糖应激诱导的脑内皮细胞紧密连接的损伤。

严重的低血糖症对脑血管系统有不利影响，但是导致紧密连接完整性破坏的分子事件仍然不清楚。在这里，我们报道在低血糖症引起的TP53诱导的糖酵解和凋亡调节剂（TIGAR）转基因小鼠中，微血管的完整性受到严重损害（占野生型小鼠的59.41％）。褪黑激素是一种有效的抗氧化剂，在体外剂量为400 nmol / L时，可预防血糖不足引起的脑内皮紧密连接损伤。低葡萄糖对内皮细胞的FRET（荧光共振能量转移）成像数据显示，TIGAR与钙调蛋白偶联可促进TIGAR酪氨酸硝化。酪氨酸92突变会干扰TIGAR依赖性NADPH的产生（55。降低了60％），并取消了其对人脑微血管内皮细胞紧密连接的保护作用。我们进一步证明了低葡萄糖诱导的occludin和Caludin5的破坏以及自噬的激活被褪黑素介导的亚硝化应激的体外阻断所消除。总的来说，我们提供了有关褪黑素对脑内皮紧密连接的保护作用的详细分子机制的信息，并表明该吲哚具有严重低血糖引起的神经血管损伤的翻译潜能。