Malic enzyme tracers reveal hypoxia-induced switch in adipocyte NADPH pathway usage.
Malic enzyme tracers reveal hypoxia-induced switch in adipocyte NADPH pathway usage.
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DOI：
10.1038/nchembio.2047
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发表时间：
2016-05
影响因子：
14.8
通讯作者：
Rabinowitz JD
中科院分区：
文献类型：
--
作者：
Liu L;Shah S;Fan J;Park JO;Wellen KE;Rabinowitz JD
关键的细胞氢化物供体NADPH通过各种途径产生，包括氧化戊糖磷酸途径（oxPPP）、叶酸代谢和苹果酸酶。在生长的细胞中，通过oxPPP和叶酸代谢有效产生NADPH，这也会产生核苷酸前体。在非增殖性脂肪细胞中，涉及苹果酸酶的代谢循环具有制造脂肪合成的NADPH和二碳单元的潜力。最近开发的氘（2 H）示踪方法使得能够直接测量通过oxPPP和叶酸代谢产生的NADPH。在这里，我们能够跟踪苹果酸酶与[2，2，3，3 - 2 H]二甲基琥珀酸酯和[4- 2 H]葡萄糖的NADPH生产。使用这些示踪剂，我们表明，大多数NADPH在分化的3 T3-L1小鼠脂肪细胞是由苹果酸酶。相关的代谢循环被缺氧破坏，这将主要的脂肪细胞NADPH来源转换为oxPPP。因此，2 H标记的示踪剂能够在细胞类型和环境条件下分解NADPH生产途径。
The critical cellular hydride donor NADPH is produced through various means, including the oxidative pentose phosphate pathway (oxPPP), folate metabolism and malic enzyme. In growing cells, it is efficient to produce NADPH via the oxPPP and folate metabolism, which also make nucleotide precursors. In nonproliferating adipocytes, a metabolic cycle involving malic enzyme holds the potential to make both NADPH and two-carbon units for fat synthesis. Recently developed deuterium (2H) tracer methods have enabled direct measurement of NADPH production by the oxPPP and folate metabolism. Here we enable tracking of NADPH production by malic enzyme with [2,2,3,3-2H]dimethyl-succinate and [4-2H]glucose. Using these tracers, we show that most NADPH in differentiating 3T3-L1 mouse adipocytes is made by malic enzyme. The associated metabolic cycle is disrupted by hypoxia, which switches the main adipocyte NADPH source to the oxPPP. Thus, 2H-labeled tracers enable dissection of NADPH production routes across cell types and environmental conditions.