Dysregulation of tetrahydrobiopterin metabolism in myalgic encephalomyelitis/chronic fatigue syndrome by pentose phosphate pathway.

IF 2.6 Q2 CLINICAL NEUROLOGY
Journal of Central Nervous System Disease Pub Date : 2024-08-19 eCollection Date: 2024-01-01 DOI:10.1177/11795735241271675
Sarojini Bulbule, Carl Gunnar Gottschalk, Molly E Drosen, Daniel Peterson, Leggy A Arnold, Avik Roy
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引用次数: 0

Abstract

Background: Tetrahydrobiopterin (BH4) and its oxidized derivative dihydrobiopterin (BH2) were found to be strongly elevated in ME/CFS patients with orthostatic intolerance (ME + OI).

Objective: However, the molecular mechanism of biopterin biogenesis is poorly understood in ME + OI subjects. Here, we report that the activation of the non-oxidative pentose phosphate pathway (PPP) plays a critical role in the biogenesis of biopterins (BH4 and BH2) in ME + OI subjects.

Research design and results: Microarray-based gene screening followed by real-time PCR-based validation, ELISA assay, and finally enzyme kinetic studies of glucose-6-phosphate dehydrogenase (G6PDH), transaldolase (TALDO1), and transketolase (TK) enzymes revealed that the augmentation of anaerobic PPP is critical in the regulations of biopterins. To further investigate, we devised a novel cell culture strategy to induce non-oxidative PPP by treating human microglial cells with ribose-5-phosphate (R5P) under a hypoxic condition of 85%N2/10%CO2/5%O2 followed by the analysis of biopterin metabolism via ELISA, immunoblot, and dual immunocytochemical analyses. Moreover, the siRNA knocking down of the taldo1 gene strongly inhibited the bioavailability of phosphoribosyl pyrophosphate (PRPP), reduced the expressions of purine biosynthetic enzymes, attenuated GTP cyclohydrolase 1 (GTPCH1), and suppressed subsequent production of BH4 and its metabolic conversion to BH2 in R5P-treated and hypoxia-induced C20 human microglia cells. These results confirmed that the activation of non-oxidative PPP is indeed required for the upregulation of both BH4 and BH2 via the purine biosynthetic pathway. To test the functional role of ME + OI plasma-derived biopterins, exogenously added plasma samples of ME + OI plasma with high BH4 upregulated inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in human microglial cells indicating that the non-oxidative PPP-induced-biopterins could stimulate inflammatory response in ME + OI patients.

Conclusion: Taken together, our current research highlights that the induction of non-oxidative PPP regulates the biogenesis of biopterins contributing to ME/CFS pathogenesis.

肌痛性脑脊髓炎/慢性疲劳综合征中磷酸戊糖途径对四氢生物蝶呤代谢的失调。
背景:四氢生物蝶呤(BH4)及其氧化衍生物双氢生物蝶呤(BH2)在伴有正性静力性不耐受(ME + OI)的ME/CFS患者中明显升高。在此,我们报告了非氧化磷酸戊糖途径(PPP)的激活在 ME + OI 患者生物蝶呤(BH4 和 BH2)的生物生成过程中起着关键作用:微阵列基因筛选、实时 PCR 验证、ELISA 检测以及葡萄糖-6-磷酸脱氢酶 (G6PDH)、反式脱氢酶 (TALDO1) 和反式酮化酶 (TK) 的酶动力学研究表明,厌氧磷酸戊糖途径 (PPP) 的增强在生物蝶呤的生成过程中起着关键作用。为了进一步研究,我们设计了一种新的细胞培养策略,在85%N2/10%CO2/5%O2的缺氧条件下,用核糖-5-磷酸(R5P)处理人小胶质细胞,诱导非氧化性PPP,然后通过ELISA、免疫印迹和双重免疫细胞化学分析分析生物蝶呤的代谢。此外,在 R5P 处理和缺氧诱导的 C20 人小胶质细胞中,siRNA 敲除 taldo1 基因可强烈抑制磷酸核糖基焦磷酸盐(PRPP)的生物利用率,降低嘌呤生物合成酶的表达,减弱 GTP 环化酶 1(GTPCH1),抑制 BH4 的后续产生及其向 BH2 的代谢转化。这些结果证实,通过嘌呤生物合成途径上调 BH4 和 BH2 确实需要激活非氧化性 PPP。为了测试 ME + OI 血浆衍生生物蝶呤的功能作用,外源添加了高 BH4 的 ME + OI 血浆样本可上调人小胶质细胞中的诱导型一氧化氮合酶(iNOS)和一氧化氮(NO),这表明非氧化性 PPP 诱导的生物蝶呤可刺激 ME + OI 患者的炎症反应:综上所述,我们目前的研究强调,非氧化性 PPP 诱导调节生物蝶呤的生物生成,有助于 ME/CFS 的发病机制。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
6.90
自引率
0.00%
发文量
39
审稿时长
8 weeks
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