糖氧醛酸酶系统在星形胶质细胞介导的神经保护中的作用。
Role of the glyoxalase system in astrocyte-mediated neuroprotection.
机构信息
Laboratory of Neuroenergetics and Cellular Dynamics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
出版信息
J Neurosci. 2011 Dec 14;31(50):18338-52. doi: 10.1523/JNEUROSCI.1249-11.2011.
The glyoxalase system is the most important pathway for the detoxification of methylglyoxal (MG), a highly reactive dicarbonyl compound mainly formed as a by-product of glycolysis. MG is a major precursor of advanced glycation end products (AGEs), which are associated with several neurodegenerative disorders. Although the neurotoxic effects of MG and AGEs are well characterized, little is known about the glyoxalase system in the brain, in particular with regards to its activity in different neural cell types. Results of the present study reveal that both enzymes composing the glyoxalase system [glyoxalase-1 (Glo-1) and Glo-2] were highly expressed in primary mouse astrocytes compared with neurons, which translated into higher enzymatic activity rates in astrocytes (9.9- and 2.5-fold, respectively). The presence of a highly efficient glyoxalase system in astrocytes was associated with lower accumulation of AGEs compared with neurons (as assessed by Western blotting), a sixfold greater resistance to MG toxicity, and the capacity to protect neurons against MG in a coculture system. In addition, Glo-1 downregulation using RNA interference strategies resulted in a loss of viability in neurons, but not in astrocytes. Finally, stimulation of neuronal glycolysis via lentiviral-mediated overexpression of 6-phosphofructose-2-kinase/fructose-2,6-bisphosphatase-3 resulted in increased MG levels and MG-modified proteins. Since MG is largely produced through glycolysis, this suggests that the poor capacity of neurons to upregulate their glycolytic flux as compared with astrocytes may be related to weaker defense mechanisms against MG toxicity. Accordingly, the neuroenergetic specialization taking place between these two cell types may serve as a protective mechanism against MG-induced neurotoxicity.
糖氧还蛋白系统是甲基乙二醛 (MG) 解毒的最重要途径,MG 是一种高度反应性的二羰基化合物,主要作为糖酵解的副产物形成。MG 是高级糖基化终产物 (AGEs) 的主要前体,与几种神经退行性疾病有关。尽管 MG 和 AGEs 的神经毒性作用已经得到很好的描述,但关于大脑中的糖氧还蛋白系统知之甚少,特别是关于其在不同神经细胞类型中的活性。本研究的结果表明,糖氧还蛋白系统中的两种酶(糖氧还蛋白-1 (Glo-1) 和 Glo-2)在原代小鼠星形胶质细胞中的表达水平均明显高于神经元,这转化为星形胶质细胞中更高的酶活性率(分别为 9.9 倍和 2.5 倍)。星形胶质细胞中存在高效的糖氧还蛋白系统与神经元相比 AGEs 的积累较低(通过 Western blot 评估)、对 MG 毒性的抗性高 6 倍,以及在共培养系统中保护神经元免受 MG 侵害的能力相关。此外,使用 RNA 干扰策略下调 Glo-1 导致神经元活力丧失,但星形胶质细胞没有。最后,通过慢病毒介导的 6-磷酸果糖-2-激酶/果糖-2,6-二磷酸酶-3 的过表达来刺激神经元糖酵解导致 MG 水平和 MG 修饰蛋白增加。由于 MG 主要通过糖酵解产生,这表明神经元上调其糖酵解通量的能力不如星形胶质细胞,这可能与它们对 MG 毒性的防御机制较弱有关。因此,这两种细胞类型之间发生的神经能量特化可能是一种针对 MG 诱导的神经毒性的保护机制。