美国马萨诸塞州综合医院Vamsi K. Mootha研究小组的一项最新工作构建了一种靶向循环乳酸的工程酶，可减轻细胞内NADH：NAD⁺失衡。相关论文2020年1月13日在线发表在《自然—生物技术》上。

研究人员表示，细胞内NADH：NAD⁺比例升高或“还原性压力”与多种疾病有关，包括线粒体电子传输链疾病。由于细胞内NADH：NAD⁺的比例可以与循环中的乳酸：丙酮酸的比例接近平衡，研究人员假设可以通过将细胞外乳酸氧化为丙酮酸来缓解还原性应激。

研究人员设计了LOXCAT，它是细菌乳酸氧化酶（LOX）和过氧化氢酶（CAT）的融合体，可将乳酸和氧气不可逆地转化为丙酮酸和水。将纯化的LOXCAT添加到具有缺陷电子传输链的培养的人类细胞培养基中会降低细胞外乳酸：丙酮酸的比例，使细胞内NADH：NAD⁺的比例正常化，上调糖酵解ATP的产生并恢复细胞增殖。在小鼠中，注射尾静脉的LOXCAT降低了循环中乳酸：丙酮酸的比率，减弱了二甲双胍引起的血液乳酸：丙酮酸比率的上升，并改善了心脏和大脑中的NADH：NAD⁺平衡。这项研究为通过直接靶向循环氧化还原偶联的代谢物减轻细胞内氧化还原失衡的一类可注射治疗性酶奠定了基础。

附：英文原文

Title: An engineered enzyme that targets circulating lactate to alleviate intracellular NADH:NAD + imbalance

Author: Anupam Patgiri, Owen S. Skinner, Yusuke Miyazaki, Grigorij Schleifer, Eizo Marutani, Hardik Shah, Rohit Sharma, Russell P. Goodman, Tsz-Leung To, Xiaoyan Robert Bao, Fumito Ichinose, Warren M. Zapol, Vamsi K. Mootha

Issue&Volume: 2020-01-13

Abstract: An elevated intracellular NADH:NAD+ ratio, or ‘reductive stress’, has been associated with multiple diseases, including disorders of the mitochondrial electron transport chain. As the intracellular NADH:NAD+ ratio can be in near equilibrium with the circulating lactate:pyruvate ratio, we hypothesized that reductive stress could be alleviated by oxidizing extracellular lactate to pyruvate. We engineered LOXCAT, a fusion of bacterial lactate oxidase (LOX) and catalase (CAT), which irreversibly converts lactate and oxygen to pyruvate and water. Addition of purified LOXCAT to the medium of cultured human cells with a defective electron transport chain decreased the extracellular lactate:pyruvate ratio, normalized the intracellular NADH:NAD+ ratio, upregulated glycolytic ATP production and restored cellular proliferation. In mice, tail-vein-injected LOXCAT lowered the circulating lactate:pyruvate ratio, blunted a metformin-induced rise in blood lactate:pyruvate ratio and improved NADH:NAD+ balance in the heart and brain. Our study lays the groundwork for a class of injectable therapeutic enzymes that alleviates intracellular redox imbalances by directly targeting circulating redox-coupled metabolites.

DOI: 10.1038/s41587-019-0377-7

Source: https://www.nature.com/articles/s41587-019-0377-7