LaRocca Timothy J, Sosunov Sergey A, Shakerley Nicole L, Ten Vadim S, Ratner Adam J
From the Department of Basic and Social Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York 12208.
the Department of Pediatrics, Columbia University, New York, New York 10032, and.
J Biol Chem. 2016 Jun 24;291(26):13753-61. doi: 10.1074/jbc.M116.716027. Epub 2016 Apr 29.
Necroptosis is a RIP1-dependent programmed cell death (PCD) pathway that is distinct from apoptosis. Downstream effector pathways of necroptosis include formation of advanced glycation end products (AGEs) and reactive oxygen species (ROS), both of which depend on glycolysis. This suggests that increased cellular glucose may prime necroptosis. Here we show that exposure to hyperglycemic levels of glucose enhances necroptosis in primary red blood cells (RBCs), Jurkat T cells, and U937 monocytes. Pharmacologic or siRNA inhibition of RIP1 prevented the enhanced death, confirming it as RIP1-dependent necroptosis. Hyperglycemic enhancement of necroptosis depends upon glycolysis with AGEs and ROS playing a role. Total levels of RIP1, RIP3, and mixed lineage kinase domain-like (MLKL) proteins were increased following treatment with high levels of glucose in Jurkat and U937 cells and was not due to transcriptional regulation. The observed increase in RIP1, RIP3, and MLKL protein levels suggests a potential positive feedback mechanism in nucleated cell types. Enhanced PCD due to hyperglycemia was specific to necroptosis as extrinsic apoptosis was inhibited by exposure to high levels of glucose. Hyperglycemia resulted in increased infarct size in a mouse model of brain hypoxia-ischemia injury. The increased infarct size was prevented by treatment with nec-1s, strongly suggesting that increased necroptosis accounts for exacerbation of this injury in conditions of hyperglycemia. This work reveals that hyperglycemia represents a condition in which cells are extraordinarily susceptible to necroptosis, that local glucose levels alter the balance of PCD pathways, and that clinically relevant outcomes may depend on glucose-mediated effects on PCD.
坏死性凋亡是一种依赖于受体相互作用蛋白1（RIP1）的程序性细胞死亡（PCD）途径，与凋亡不同。坏死性凋亡的下游效应途径包括晚期糖基化终末产物（AGEs）和活性氧（ROS）的形成，二者均依赖糖酵解。这表明细胞内葡萄糖增加可能引发坏死性凋亡。在此我们表明，暴露于高血糖水平的葡萄糖会增强原代红细胞（RBC）、Jurkat T细胞和U937单核细胞中的坏死性凋亡。RIP1的药理学抑制或小干扰RNA（siRNA）抑制可阻止这种增强的细胞死亡，证实其为依赖RIP1的坏死性凋亡。高血糖对坏死性凋亡的增强作用依赖于糖酵解，AGEs和ROS发挥了作用。在Jurkat和U937细胞中，用高浓度葡萄糖处理后，RIP1、RIP3和混合谱系激酶结构域样蛋白（MLKL）的总水平升高，且这并非由转录调控所致。观察到的RIP1、RIP3和MLKL蛋白水平升高表明在有核细胞类型中存在潜在的正反馈机制。高血糖导致的PCD增强对坏死性凋亡具有特异性，因为暴露于高浓度葡萄糖会抑制外源性凋亡。高血糖导致脑缺氧缺血损伤小鼠模型中的梗死面积增加。用nec-1s治疗可防止梗死面积增加，强烈提示坏死性凋亡增加是高血糖条件下该损伤加重的原因。这项研究揭示，高血糖代表一种细胞极易发生坏死性凋亡的状态，局部葡萄糖水平改变了PCD途径的平衡，且临床相关结果可能取决于葡萄糖对PCD的介导作用。
