NADPH production by the oxidative pentose-phosphate pathway supports folate metabolism
NADPH production by the oxidative pentose-phosphate pathway supports folate metabolism
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DOI：
10.1038/s42255-019-0043-x
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发表时间：
2019-03-01
影响因子：
20.8
通讯作者：
Rabinowitz, Joshua D.
中科院分区：
文献类型：
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作者：
Chen, Li;Zhang, Zhaoyue;Rabinowitz, Joshua D.
NADPH为抗氧化防御和还原性生物合成提供高能电子。胞质NADP通过氧化戊糖-磷酸途径（oxPPP）、苹果酸酶1（ME 1）和异柠檬酸脱氢酶1（IDH 1）再循环为NADPH。在这里，我们表明，这些途径中的任何一种都可以支持细胞生长，但oxPPP是唯一需要保持正常的NADPH/NADP比，哺乳动物二氢叶酸还原酶（DHFR）的活性和叶酸代谢。这些发现基于HCT 116结肠癌细胞中葡萄糖-6-磷酸脱氢酶（G6 PD，定向oxPPP酶）、ME 1、IDH 1及其组合的CRISPR缺失。G6 PD的丧失导致高NADP，其诱导ME 1和IDH 1通量的代偿性增加。但是高NADP抑制DHFR，导致叶酸介导的生物合成受损，这被大肠杆菌DHFR的重组表达逆转。在不同的癌细胞系中，G6 PD缺失产生了叶酸相关代谢物的一致变化，表明oxPPP支持叶酸代谢的一般要求。
NADPH donates high-energy electrons for antioxidant defence and reductive biosynthesis. Cytosolic NADP is recycled to NADPH by the oxidative pentose-phosphate pathway (oxPPP), malic enzyme 1 (ME1) and isocitrate dehydrogenase 1 (IDH1). Here we show that any one of these routes can support cell growth, but the oxPPP is uniquely required to maintain a normal NADPH/NADP ratio, mammalian dihydrofolate reductase (DHFR) activity and folate metabolism. These findings are based on CRISPR deletions of glucose-6-phosphate dehydrogenase (G6PD, the committed oxPPP enzyme), ME1, IDH1 and combinations thereof in HCT116 colon cancer cells. Loss of G6PD results in high NADP, which induces compensatory increases in ME1 and IDH1 flux. But the high NADP inhibits DHFR, resulting in impaired folate-mediated biosynthesis, which is reversed by recombinant expression of Escherichia coli DHFR. Across different cancer cell lines, G6PD deletion produced consistent changes in folate-related metabolites, suggesting a general requirement for the oxPPP to support folate metabolism.