Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Jiangsu Key Laboratory of Neuropsychiatric Diseases, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China.
Department of Neurology, The First Affiliated Hospital of Harbin Medical University, 23 Post Street, Nangang District, Harbin, HeiLongjiang 150081, China.
Biochem Biophys Res Commun. 2024 Dec 10;737:150500. doi: 10.1016/j.bbrc.2024.150500. Epub 2024 Aug 6.
Nicotinamide Adenine Dinucleotide Phosphate (NADPH) plays a vital role in regulating redox homeostasis and reductive biosynthesis. However, if exogenous NADPH can be transported across the plasma membrane has remained elusive. In this study, we present evidence supporting that NADPH can traverse the plasma membranes of cells through a mechanism mediated by the P2X7 receptor (P2X7R). Notably, we observed an augmentation of intracellular NADPH levels in cultured microglia upon exogenous NADPH supplementation in the presence of ATP. The P2X7R-mediated transmembrane transportation of NADPH was validated with P2X7R antagonists, including OX-ATP, BBG, and A-438079, or through P2X7 knockdown, which impeded NADPH transportation into cells. Conversely, overexpression of P2X7 resulted in an enhanced capacity for NADPH transport. Furthermore, transfection of hP2X7 demonstrated the ability to complement NADPH uptake in native HEK293 cells. Our findings provide evidence for the first time that NADPH is transported across the plasma membrane via a P2X7R-mediated pathway. Additionally, we propose an innovative avenue for modulating intracellular NADPH levels. This discovery holds promise for advancing our understanding of the role of NADPH in redox homeostasis and neuroinflammation.
烟酰胺腺嘌呤二核苷酸磷酸（NADPH）在调节氧化还原平衡和还原性生物合成中起着至关重要的作用。然而，外源性 NADPH 是否可以穿过质膜仍然难以捉摸。在这项研究中，我们提供了证据支持 NADPH 可以通过 P2X7 受体（P2X7R）介导的机制穿过细胞的质膜。值得注意的是，我们观察到在存在 ATP 的情况下，外源性 NADPH 补充后培养的小神经胶质细胞内 NADPH 水平增加。通过 P2X7R 拮抗剂（如 OX-ATP、BBG 和 A-438079）或通过 P2X7 敲低验证了 P2X7R 介导的 NADPH 跨膜转运，这阻碍了 NADPH 向细胞内的转运。相反，P2X7 的过表达导致 NADPH 转运能力增强。此外，hP2X7 的转染证明了在天然 HEK293 细胞中补充 NADPH 摄取的能力。我们的研究结果首次提供了证据，证明 NADPH 通过 P2X7R 介导的途径穿过质膜。此外，我们提出了一种调节细胞内 NADPH 水平的创新途径。这一发现有望增进我们对 NADPH 在氧化还原平衡和神经炎症中的作用的理解。
