PDF(Pubmed)
Abstract：
In Alzheimer\'s disease (AD), dysfunctional mitochondrial metabolism is associated with synaptic loss, the major pathological correlate of cognitive decline. Mechanistic insight for this relationship, however, is still lacking. Here, comparing isogenic wild-type and AD mutant human induced pluripotent stem cell (hiPSC)-derived cerebrocortical neurons (hiN), evidence is found for compromised mitochondrial energy in AD using the Seahorse platform to analyze glycolysis and oxidative phosphorylation (OXPHOS). Isotope-labeled metabolic flux experiments revealed a major block in activity in the tricarboxylic acid (TCA) cycle at the α-ketoglutarate dehydrogenase (αKGDH)/succinyl coenzyme-A synthetase step, metabolizing α-ketoglutarate to succinate. Associated with this block, aberrant protein S-nitrosylation of αKGDH subunits inhibited their enzyme function. This aberrant S-nitrosylation is documented not only in AD-hiN but also in postmortem human AD brains versus controls, as assessed by two separate unbiased mass spectrometry platforms using both SNOTRAP identification of S-nitrosothiols and chemoselective-enrichment of S-nitrosoproteins. Treatment with dimethyl succinate, a cell-permeable derivative of a TCA substrate downstream to the block, resulted in partial rescue of mitochondrial bioenergetic function as well as reversal of synapse loss in AD-hiN. These findings have therapeutic implications that rescue of mitochondrial energy metabolism can ameliorate synaptic loss in hiPSC-based models of AD.
摘要：
在阿尔茨海默病（AD）中，线粒体代谢异常与突触丢失有关，认知功能下降的主要病理相关因素。对这种关系的机械洞察力，然而,仍然缺乏。这里,比较等基因野生型和AD突变体人类诱导多能干细胞（hiPSC）来源的大脑皮层神经元（hiN），使用海马平台分析糖酵解和氧化磷酸化（OXPHOS），发现AD中线粒体能量受损的证据。同位素标记的代谢通量实验显示，在α-酮戊二酸脱氢酶（αKGDH）/琥珀酰辅酶A合成酶步骤中，三羧酸（TCA）循环的活性存在主要障碍，代谢α-酮戊二酸为琥珀酸。与此块关联，αKGDH亚基的异常蛋白S-亚硝基化抑制了它们的酶功能。这种异常的S-亚硝基化不仅在AD-hiN中而且在死后的人类AD大脑与对照中都有记录。通过两个单独的无偏质谱平台评估，使用SNOTRAP鉴定S-亚硝基硫醇和化学选择性富集S-亚硝基蛋白质。用琥珀酸二甲酯处理，块下游的TCA底物的细胞可渗透衍生物，导致线粒体生物能量功能的部分挽救以及AD-hiN中突触丢失的逆转。这些发现具有治疗意义，即在基于hiPSC的AD模型中，线粒体能量代谢的挽救可以改善突触损失。
