Glucose 6 phosphatase dehydrogenase (G6PD) and neurodegenerative disorders: Mapping diagnostic and therapeutic opportunities

Inactivation of human glucose 6-phosphate dehydrogenase (G6PDH) by peroxyl radicals is strongly modulated by its substrate and cofactor

Glucose 6-phosphate dehydrogenase (G6PDH) is the rate-limiting enzyme of the pentose phosphate pathway (PPP). This enzyme catalyzes the oxidation of glucose 6-phosphate (G6P) into 6-phosphogluconolactone with concomitant reduction of NADP+ to NADPH. Despite the link between the PPP and oxidative stress, the oxidation and consequences on the activity of the human G6PDH (hG6PDH) has not been investigated. In the present work we report the oxidative inactivation of hG6PDH mediated by peroxyl radicals (ROO•) generated by AAPH (2,2'-azobis(2-methylpropionamidine) dihydrochloride) thermolysis. hG6PDH (46.4 μM, monomers) was incubated at 37 °C with 10 or 100 mM AAPH. At defined times, enzyme activity was determined (NADPH release followed at 340 nm), mapping of modifications studied by LC-MS, structural changes analyzed by circular dichroism, and results rationalized by in silico analysis of the three-dimensional structure of the enzyme. Analogous experiments were developed in the presence of NADP+ or G6P at excess or 1:1 (hG6PDH:NADP+ or G6P) molar ratios. High susceptibility to inactivation by ROO• was observed, 3.6 mol of ROO• inactivated 1 mol of hG6PDH. This behavior is rationalized, at least in part, by oxidation at Trp349 which is located close to the structural site of NADP+. The presence of G6P significantly increased the ROO•-mediated inactivation of hG6PDH, while an opposite effect was observed in the presence of NADP+ where, despite oxidation at different sites, the enzyme activity was practically unaltered by ROO•. These results demonstrate that hG6PDH is highly susceptible to inactivation mediated by ROO• with these processes strongly modulated by G6P and NADP+.

Oxidative Stress and Redox Imbalance: Common Mechanisms in Cancer Stem Cells and Neurodegenerative Diseases

Oxidative stress (OS) is an established hallmark of cancer and neurodegenerative disorders (NDDs), which contributes to genomic instability and neuronal loss. This review explores the contrasting role of OS in cancer stem cells (CSCs) and NDDs. Elevated levels of reactive oxygen species (ROS) contribute to genomic instability and promote tumor initiation and progression in CSCs, while in NDDs such as Alzheimer's and Parkinson's disease, OS accelerates neuronal death and impairs cellular repair mechanisms. Both scenarios involve disruption of the delicate balance between pro-oxidant and antioxidant systems, which leads to chronic oxidative stress. Notably, CSCs and neurons display alterations in redox-sensitive signaling pathways, including Nrf2 and NF-κB, which influence cell survival, proliferation, and differentiation. Mitochondrial dynamics further illustrate these differences: enhanced function in CSCs supports adaptability and survival, whereas impairments in neurons heighten vulnerability. Understanding these common mechanisms of OS-induced redox imbalance may provide insights for developing interventions, addressing aging hallmarks, and potentially mitigating or preventing both cancer and NDDs.

Decoding microglial immunometabolism: a new frontier in Alzheimer's disease research

Alzheimer's disease (AD) involves a dynamic interaction between neuroinflammation and metabolic dysregulation, where microglia play a central role. These immune cells undergo metabolic reprogramming in response to AD-related pathology, with key genes such as TREM2, APOE, and HIF-1α orchestrating these processes. Microglial metabolism adapts to environmental stimuli, shifting between oxidative phosphorylation and glycolysis. Hexokinase-2 facilitates glycolytic flux, while AMPK acts as an energy sensor, coordinating lipid and glucose metabolism. TREM2 and APOE regulate microglial lipid homeostasis, influencing Aβ clearance and immune responses. LPL and ABCA7, both associated with AD risk, modulate lipid processing and cholesterol transport, linking lipid metabolism to neurodegeneration. PPARG further supports lipid metabolism by regulating microglial inflammatory responses. Amino acid metabolism also contributes to microglial function. Indoleamine 2,3-dioxygenase controls the kynurenine pathway, producing neurotoxic metabolites linked to AD pathology. Additionally, glucose-6-phosphate dehydrogenase regulates the pentose phosphate pathway, maintaining redox balance and immune activation. Dysregulated glucose and lipid metabolism, influenced by genetic variants such as APOE4, impair microglial responses and exacerbate AD progression. Recent findings highlight the interplay between metabolic regulators like REV-ERBα, which modulates lipid metabolism and inflammation, and Syk, which influences immune responses and Aβ clearance. These insights offer promising therapeutic targets, including strategies aimed at HIF-1α modulation, which could restore microglial function depending on disease stage. By integrating metabolic, immune, and genetic factors, this review underscores the importance of microglial immunometabolism in AD. Targeting key metabolic pathways could provide novel therapeutic strategies for mitigating neuroinflammation and restoring microglial function, ultimately paving the way for innovative treatments in neurodegenerative diseases.

Correlation of NADH/NAD+ electrochemical potential and enzymatic activity for investigating protein folding and kinetics

The biological activity of a protein is determined by its native three-dimensional structure. Various stress factors induce structural changes in the proteins that leads to altered protein homeostasis with the accumulation of misfolded and aggregated protein conformers. Standard methods such as spectrophotometry, luminometry and fluorimetry are conventionally used to study protein activity. Here, an electrochemical method has been developed to measure the change in anodic peak current (Ip,a) of NADH generated during the oxidation reaction. The method showed a linear range of detection from 62.5 μM to 1.0 mM (R2 = 0.999) for NADH with calculated detection limit of 16.02 μM and sensitivity of 1.75 × 103 μA mM-1 cm-2. The method was further employed to investigate the enzymatic activity and folding kinetics of malate dehydrogenase (MDH) and glucose-6-phosphate dehydrogenase (G6PDH). Also, the effect of aluminium ion (Al3+) on the activity and folding kinetics was investigated electrochemically. The Al3+ induced structural alterations in MDH and G6PDH were assessed using circular dichroism (CD), Thioflavin-T (ThT) and nuclear magnetic resonance (NMR). The developed label-free electrochemical method provides an alternative method for investigating protein activity and folding kinetics.

Enhancing NADPH to restore redox homeostasis and lysosomal function in G6PD-deficient microglia

Microglia, the immune cells of the central nervous system (CNS), play key roles in neurogenesis, myelination, synaptic transmission, immune surveillance, and neuroinflammation. Inflammatory responses in microglia can lead to oxidative stress and neurodegeneration, contributing to diseases like Parkinson's and Alzheimer's. The enzyme glucose-6-phosphate dehydrogenase (G6PD) is essential for producing nicotinamide adenine dinucleotide phosphate hydrogen (NADPH), which neutralizes oxidative stress. G6PD deficiency has been linked to several disorders, including neurological conditions. Our study shows that G6PD deficiency in microglia reduces NADPH levels, disrupting redox balance and lysosomal function. To address this, we explored alternative metabolic pathways by targeting enzymes like isocitrate dehydrogenase 1 (IDH1) and malic enzyme 1 (ME1), both crucial for NADPH production. Supplementing metabolites such as citric and malic acid improved NADPH levels, while small molecules like dieckol and resveratrol enhanced IDH1 and ME1 expression. The combination of these approaches restored redox homeostasis and lysosomal function, offering potential therapeutic strategies for G6PD deficiency.

Glucose Metabolic Reprogramming in Microglia: Implications for Neurodegenerative Diseases and Targeted Therapy

As intrinsic immune cells in the central nervous system, microglia play a crucial role in maintaining brain homeostasis. Microglia can transition from homeostasis to various responsive states in reaction to different external stimuli, undergoing corresponding alterations in glucose metabolism. In neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), microglial glucose metabolic reprogramming is widespread. This reprogramming leads to changes in microglial function, exacerbating neuroinflammation and the accumulation of pathological products, thereby driving the progression of neurodegeneration. This review summarizes the specific alterations in glucose metabolism within microglia in AD, PD, ALS, and MS, as well as the corresponding treatments aimed at reprogramming glucose metabolism. Compounds that inhibit key glycolytic enzymes like hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2), or activate regulators of energy metabolism such as AMP-activated protein kinase (AMPK), have shown significant potential in the treatment of various neurodegenerative diseases. However, current research faces numerous challenges, including side effects and blood-brain barrier (BBB) penetration of compounds. Screening relevant drugs from natural products, especially flavonoids, is a reliable approach. On the one hand, longtime herbal medical practices provide a certain degree of assurance regarding clinical safety, and their chemical properties contribute to effective BBB permeability. On the other hand, the concurrent anti-tumor and anti-neuroinflammatory activities of flavonoids suggest that regulation of glucose metabolism reprogramming might be a potential common mechanism of action. Notably, considering the dynamic nature of microglial metabolism, there is an urgent need to develop technologies for real-time monitoring of glucose metabolism processes, which would significantly advance research in this field.

Revealing the secrets of Blue Zones

Aging is influenced by cellular senescence mechanisms that are associated with oxidative stress. Oxidative stress is the imbalance between antioxidants and free radicals. This imbalance affects enzyme activities and causes mitochondrial dysfunction. It also slows down cellular energy production and disrupts cellular homeostasis. Additionally, oxidative stress stimulates inflammation, increases the number of point mutations, and alters intercellular communication. It can lead to epigenetic alterations, genomic instability, telomere attrition, and loss of proteostasis. Ultimately, these factors contribute to aging and the development of chronic diseases. Glucose-6-phosphate dehydrogenase (G6PD) is an antioxidant enzyme that protects cells from oxidative and nitrosative damage. It helps restore redox balance, preserve macromolecule function, and rescue cells from cellular senescence, autophagy, and stress-induced apoptosis. G6PD is considered an anti-senescence enzyme. The World Health Organization classifies G6PD variants into five groups based on the enzyme's residual activity. The first four classes are categorized according to the degree of G6PD deficiency, while the fifth class includes variants with enzyme activities greater than normal. Increased G6PD activity does not exhibit clinical manifestations. Consequently, the full spectrum of mutations and the prevalence of increased G6PD activity in the population remain unknown. The world's oldest and healthiest people live in Blue Zones. These comprise isolated populations, and there may be a geographic prevalence of high-activity G6PD variants that protect against oxidative stress-induced senescence. To uncover the secret of centenarians' longevity, additional research is needed to determine whether the hidden factor is the increased activity of the G6PD enzyme.

Molecular signature underlying (R)-ketamine rapid antidepressant response on anhedonic-like behavior induced by sustained exposure to stress

Anhedonia induced by sustained stress exposure is a hallmark symptom of major depressive disorder (MDD) and in rodents, it can be accessed through the sucrose preference test (SPT). (R)-ketamine is a fast-acting antidepressant with less detrimental side effects and abuse liability compared to racemic ketamine. The present study combined high-throughput proteomics and network analysis to identify molecular mechanisms involved in chronic variable stress (CVS)-induced anhedonia and promising targets underlying (R)-ketamine rapid antidepressant response. Male Wistar rats were subjected to CVS for five weeks. Based on the SPT, animals were clustered into resilient or anhedonic-like (ANH) groups. ANH rats received a single dose of saline or (R)-ketamine (20 mg/kg, i.p.), which was proceeded by treatment response evaluation. After prefrontal cortex collection, proteomic analysis was performed to uncover the differentially expressed proteins (DEPs) related to both anhedonic-like behavior and pharmacological response. The behavioral assessment showed that the ANH animals had a significant decrease in SPT, and that (R)-ketamine responders showed a reversal of anhedonic-like behavior. On a molecular level, anhedonia-like behavior was associated with the downregulation of Neuronal Pentraxin Receptor (Nptxr) and Galectin-1 (Gal-1). These data reinforce a disruption in the inflammatory response, neurotransmitter receptor activity, and glutamatergic synapses in chronic stress-induced anhedonia. (R)-ketamine response-associated DEPs included novel potential targets involved in the modulation of oxidative stress, energetic metabolism, synaptogenesis, dendritic arborization, neuroinflammation, gene expression, and telomere length, converging to biological themes extensively documented in MDD physiopathology. Our data provide valuable insights into the molecular mechanisms underlying the response to (R)-ketamine and highlight these pathways as potential therapeutic targets for anhedonia. By addressing proteins involved in oxidative stress, energy metabolism, synaptogenesis, dendritic arborization, neuroinflammation, gene expression, and telomere length, we can target multiple key factors involved in the pathophysiology of MDD. Modulating these proteins could open avenues for novel therapeutic strategies and deepen our understanding of anhedonia, offering hope for improved outcomes in individuals facing this challenging condition. However, additional studies will be essential to validate these findings and further explore their therapeutic implications.

Modulation of brain energy metabolism in hepatic encephalopathy: impact of glucose metabolic dysfunction

Cerebral function is linked to a high level of metabolic activity and relies on glucose as its primary energy source. Glucose aids in the maintenance of physiological brain activities; as a result, a disruption in metabolism has a significant impact on brain function, launching a chain of events that leads to neuronal death. This metabolic insufficiency has been observed in a variety of brain diseases and neuroexcitotoxicity disorders, including hepatic encephalopathy. It is a significant neurological complication that develops in people with liver disease, ranging from asymptomatic abnormalities to coma. Hyperammonemia is the main neurotoxic villain in the development of hepatic encephalopathy and induces a wide range of complications in the brain. The neurotoxic effects of ammonia on brain function are thought to be mediated by impaired glucose metabolism. Accordingly, in this review, we provide an understanding of deranged brain energy metabolism, emphasizing the role of glucose metabolic dysfunction in the pathogenesis of hepatic encephalopathy. We also highlighted the differential metabolic profiles of brain cells and the status of metabolic cooperation between them. The major metabolic pathways that have been explored are glycolysis, glycogen metabolism, lactate metabolism, the pentose phosphate pathway, and the Krebs cycle. Furthermore, the lack of efficacy in current hepatic encephalopathy treatment methods highlights the need to investigate potential therapeutic targets for hepatic encephalopathy, with regulating deficient bioenergetics being a viable alternative in this case. This review also demonstrates the importance of the development of glucose metabolism-focused disease diagnostics and treatments, which are now being pursued for many ailments.

Exploring the ameliorative potential of rutin against High-Sucrose Diet-induced oxidative stress and reproductive toxicity in Drosophila melanogaster

Sucrose is a vital ingredient in numerous food items consumed regularly. However, exposure to excessive sucrose for a prolonged period can promote health issues. The reproductive system has a delicate physiology that can be targeted by various chemical stressors, including sucrose. Hence, the present in vivo study aims to unveil the impacts of High-Sucrose Diet (HSD) on the reproductive fitness of Drosophila melanogaster. In addition, the present work has also assessed the protective potential of a bioactive compound, rutin, against it. Here, first instar larvae were exposed to HSD (30 %) alone and in combination with rutin (100-300 µM) till their adult stage. HSD disturbed sex comb morphology in adult males, while fecundity and hatchability of eggs in females. Moreover, HSD triggered gonadal ROS production, oxidative stress, and modulated endogenous antioxidants such as SOD, catalase, and glutathione in both sexes. Nuclear fragmentation and tissue injuries, along with protein and lipid oxidation, were also apparent. Elevated levels of cytosolic Iron suggested an active Fenton reaction in adults. Further, HSD modulated the activities of reproductive and metabolic mediators, including vitellogenin, malate dehydrogenase, glucose-6-phosphate dehydrogenase, and angiotensin-converting enzymes that are critical to maintain the overall reproductive fitness. Interestingly, co-treatment with rutin, mainly at 200 µM, mitigated these adverse effects and restored reproductive fitness. The protective potential of rutin might be attributed to its ability to normalize redox homeostasis, reduce oxidative stress, and optimize critical enzymes involved in reproductive physiology. These findings suggest that rutin has potential therapeutic implications for counteracting the reproductive hazards induced by HSD.

G6PD deficiency mediated impairment of iNOS and lysosomal acidification affecting phagocytotic clearance in microglia in response to SARS-CoV-2

The glucose-6-phosphate dehydrogenase (G6PD) deficiency is X-linked and is the most common enzymatic deficiency disorder globally. It is a crucial enzyme for the pentose phosphate pathway and produces NADPH, which plays a vital role in regulating the oxidative stress of many cell types. The deficiency of G6PD primarily causes hemolytic anemia under oxidative stress triggered by food, drugs, or infection. G6PD-deficient patients infected with SARS-CoV-2 showed an increase in hemolysis and thrombosis. Patients also exhibited prolonged COVID-19 symptoms, ventilation support, neurological impacts, and high mortality. However, the mechanism of COVID-19 severity in G6PD deficient patients and its neurological manifestation is still ambiguous. Here, using a CRISPR-edited G6PD deficient human microglia cell culture model, we observed a significant reduction in NADPH level and an increase in basal reactive oxygen species (ROS) in microglia. Interestingly, the deficiency of the G6PD-NAPDH axis impairs induced nitric oxide synthase (iNOS) mediated nitric oxide (NO) production, which plays a fundamental role in inhibiting viral replication. Surprisingly, we also observed that the deficiency of the G6PD-NADPH axis reduced lysosomal acidification and free radical production, further abrogating the lysosomal clearance of viral particles. Thus, impairment of NO production, lysosomal functions, and redox dysregulation in G6PD deficient microglia altered innate immune response, promoting the severity of SARS-CoV-2 pathogenesis.

Glucose 6 phosphate dehydrogenase overexpression rescues the loss of cognition in the double transgenic APP/PS1 mouse model of Alzheimer's disease

Mice models of Alzheimer's disease (APP/PS1) typically experience cognitive decline with age. G6PD overexpressing mice (G6PD-Tg) exhibit better protection from age-associated functional decline including improvements in metabolic and muscle functions as well as reduced frailty compared to their wild-type counterparts. Importantly G6PD-Tg mice show diminished accumulation of DNA oxidation in the brain at different ages in both males and females. To further explore the potential benefits of modulating the G6PD activity in neurodegenerative diseases, triple transgenic mice (3xTg G6PD) were generated, overexpressing APP, PSEN1, and G6PD genes. The cognitive decline characteristic of APP/PS1 mice was prevented in 3xTg G6PD mice, despite similar amyloid-β (Aβ) levels in the hippocampus. This challenges the dominant hypothesis in Alzheimer's disease (AD) etiology and the majority of therapeutic efforts in the field, based on the notion that Aβ is pivotal in cognitive preservation. Notably, the antioxidant properties of G6PD led to a decrease in oxidative stress parameters, such as improved GSH/GSSG and GSH/CysSSG ratios, without major changes in oxidative damage markers. Additionally, metabolic changes in 3xTg G6PD mice increased brain energy status, countering the hypometabolism observed in Alzheimer's models. Remarkably, a higher respiratory exchange ratio suggested increased carbohydrate utilization. The relative failures of Aβ-targeted clinical trials have raised significant skepticism on the amyloid cascade hypothesis and whether the development of Alzheimer's drugs has followed the correct path. Our findings highlight the significance of targeting glucose-metabolizing enzymes rather than solely focusing on Aβ in Alzheimer's research, advocating for a deeper exploration of glucose metabolism's role in cognitive preservation.

Significance and amplification methods of the purine salvage pathway in human brain cells

Previous studies suggest that uric acid or reactive oxygen species, products of xanthine oxidoreductase (XOR), may associate with neurodegenerative diseases. However, neither relationship has ever been firmly established. Here, we analyzed human brain samples, obtained under protocols approved by research ethics committees, and found no expression of XOR and only low levels of uric acid in various regions of the brain. In the absence of XOR, hypoxanthine will be preserved and available for incorporation into the purine salvage pathway. To clarify the importance of salvage in the brain, we tested using human-induced pluripotent stem cell-derived neuronal cells. Stable isotope analyses showed that the purine salvage pathway was more effective for ATP synthesis than purine de novo synthesis. Blood uric acid levels were related to the intracellular adenylate pool (ATP + ADP + AMP), and reduced levels of this pool result in lower uric acid levels. XOR inhibitors are related to extracellular hypoxanthine levels available for uptake into the purine salvage pathway by inhibiting the oxidation of hypoxanthine to xanthine and uric acid in various organs where XOR is present and can prevent further decreases in the intracellular adenylate pool under stress. Furthermore, adding precursors of the pentose phosphate pathway enhanced hypoxanthine uptake, indicating that purine salvage is activated by phosphoribosyl pyrophosphate replenishment. These findings resolve previous contradictions regarding XOR products and provide new insights into clinical studies. It is suggested that therapeutic strategies maximizing maintenance of intracellular adenylate levels may effectively treat pathological conditions associated with ischemia and energy depletion.

Delineation of the role of G6PD in Alzheimer's disease and potential enhancement through microfluidic and nanoparticle approaches

Alzheimer's disease (AD) is a neurodegenerative pathologic entity characterized by the abnormal presence of tau and macromolecular Aβ deposition that leads to the degeneration or death of neurons. In addition to that, glucose-6-phosphate dehydrogenase (G6PD) has a multifaceted role in the process of AD development, where it can be used as both a marker and a target. G6PD activity is dysregulated due to its contribution to oxidative stress, neuroinflammation, and neuronal death. In this context, the current review presents a vivid depiction of recent findings on the relationship between AD progression and changes in the expression or activity of G6PD. The efficacy of the proposed G6PD-based therapeutics has been demonstrated in multiple studies using AD mouse models as representative animal model systems for cognitive decline and neurodegeneration associated with this disease. Innovative therapeutic insights are made for the boosting of G6PD activity via novel innovative nanotechnology and microfluidics tools in drug administration technology. Such approaches provide innovative methods of surpassing the blood-brain barrier, targeting step-by-step specific neural pathways, and overcoming biochemical disturbances that accompany AD. Using different nanoparticles loaded with G6DP to target specific organs, e.g., G6DP-loaded liposomes, enhances BBB penetration and brain distribution of G6DP. Many nanoparticles, which are used for different purposes, are briefly discussed in the paper. Such methods to mimic BBB on organs on-chip offer precise disease modeling and drug testing using microfluidic chips, requiring lower sample amounts and producing faster findings compared to conventional techniques. There are other contributions to microfluid in AD that are discussed briefly. However, there are some limitations accompanying microfluidics that need to be worked on to be used for AD. This study aims to bridge the gap in understanding AD with the synergistic use of promising technologies; microfluid and nanotechnology for future advancements.

The Effect of Neuronal CoQ10 Deficiency and Mitochondrial Dysfunction on a Rotenone-Induced Neuronal Cell Model of Parkinson's Disease

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder currently affecting the ageing population. Although the aetiology of PD has yet to be fully elucidated, environmental factors such as exposure to the naturally occurring neurotoxin rotenone has been associated with an increased risk of developing PD. Rotenone inhibits mitochondrial respiratory chain (MRC) complex I activity as well as induces dopaminergic neuronal death. The aim of the present study was to investigate the underlying mechanisms of rotenone-induced mitochondrial dysfunction and oxidative stress in an in vitro SH-SY5Y neuronal cell model of PD and to assess the ability of pre-treatment with Coenzyme Q10 (CoQ10) to ameliorate oxidative stress in this model. Spectrophotometric determination of the mitochondrial enzyme activities and fluorescence probe studies of reactive oxygen species (ROS) production was assessed. Significant inhibition of MRC complex I and II-III activities was observed, together with a significant loss of neuronal viability, CoQ10 status, and ATP synthesis. Additionally, significant increases were observed in intracellular and mitochondrial ROS production. Remarkably, CoQ10 supplementation was found to reduce ROS formation. These results have indicated mitochondrial dysfunction and increased oxidative stress in a rotenone-induced neuronal cell model of PD that was ameliorated by CoQ10 supplementation.

WWP2 Regulates Renal Fibrosis and the Metabolic Reprogramming of Profibrotic Myofibroblasts

Key Points

WWP2 expression is elevated in the tubulointerstitium of fibrotic kidneys and contributes to CKD pathogenesis and progression. WWP2 uncouples the profibrotic activation and cell proliferation in renal myofibroblasts. WWP2 controls mitochondrial respiration in renal myofibroblasts through the metabolic regulator peroxisome proliferator-activated receptor gamma coactivator 1-alpha.

Background

Renal fibrosis is a common pathologic end point in CKD that is challenging to reverse, and myofibroblasts are responsible for the accumulation of a fibrillar collagen–rich extracellular matrix. Recent studies have unveiled myofibroblasts' diversity in proliferative and fibrotic characteristics, which are linked to different metabolic states. We previously demonstrated the regulation of extracellular matrix genes and tissue fibrosis by WWP2, a multifunctional E3 ubiquitin–protein ligase. Here, we investigate WWP2 in renal fibrosis and in the metabolic reprograming of myofibroblasts in CKD.

Methods

We used kidney samples from patients with CKD and WWP2 -null kidney disease mice models and leveraged single-cell RNA sequencing analysis to detail the cell-specific regulation of WWP2 in fibrotic kidneys. Experiments in primary cultured myofibroblasts by bulk-RNA sequencing, chromatin immunoprecipitation sequencing, metabolomics, and cellular metabolism assays were used to study the metabolic regulation of WWP2 and its downstream signaling.

Results

The tubulointerstitial expression of WWP2 was associated with fibrotic progression in patients with CKD and in murine kidney disease models. WWP2 deficiency promoted myofibroblast proliferation and halted profibrotic activation, reducing the severity of renal fibrosis in vivo . In renal myofibroblasts, WWP2 deficiency increased fatty acid oxidation and activated the pentose phosphate pathway, boosting mitochondrial respiration at the expense of glycolysis. WWP2 suppressed the transcription of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a metabolic mediator of fibrotic response, and pharmacologic inhibition of PGC-1α partially abrogated the protective effects of WWP2 deficiency on myofibroblasts.

Conclusions

WWP2 regulates the metabolic reprogramming of profibrotic myofibroblasts by a WWP2-PGC-1α axis, and WWP2 deficiency protects against renal fibrosis in CKD.

Cellular metabolism regulates the differentiation and function of T-cell subsets

T cells are an important component of adaptive immunity and protect the host from infectious diseases and cancers. However, uncontrolled T cell immunity may cause autoimmune disorders. In both situations, antigen-specific T cells undergo clonal expansion upon the engagement and activation of antigens. Cellular metabolism is reprogrammed to meet the increase in bioenergetic and biosynthetic demands associated with effector T cell expansion. Metabolites not only serve as building blocks or energy sources to fuel cell growth and expansion but also regulate a broad spectrum of cellular signals that instruct the differentiation of multiple T cell subsets. The realm of immunometabolism research is undergoing swift advancements. Encapsulating all the recent progress within this concise review in not possible. Instead, our objective is to provide a succinct introduction to this swiftly progressing research, concentrating on the metabolic intricacies of three pivotal nutrient classes-lipids, glucose, and amino acids-in T cells. We shed light on recent investigations elucidating the roles of these three groups of metabolites in mediating the metabolic and immune functions of T cells. Moreover, we delve into the prospect of "editing" metabolic pathways within T cells using pharmacological or genetic approaches, with the aim of synergizing this approach with existing immunotherapies and enhancing the efficacy of antitumor and antiinfection immune responses.

BRCC3 mediates inflammation and pyroptosis in cerebral ischemia/reperfusion injury by activating the NLRP6 inflammasome

AIMS

Neuroinflammation and pyroptosis are key mediators of cerebral ischemia/reperfusion (I/R) injury-induced pathogenic cascades. BRCC3, the human homolog of BRCC36, is implicated in neurological disorders and plays a crucial role in neuroinflammation and pyroptosis. However, its effects and potential mechanisms in cerebral I/R injury in mice are unclear.

METHODS

Cellular localization of BRCC3 and the interaction between BRCC3 and NLRP6 were assessed. Middle cerebral artery occlusion/reperfusion (MCAO) and oxygen-glucose deprivation/reoxygenation (OGD/R) models were established in mice and HT22 cells, respectively, to simulate cerebral I/R injury in vivo and in vitro.

RESULTS

BRCC3 protein expression peaked 24 h after MCAO and OGD/R. BRCC3 knockdown reduced the inflammation and pyroptosis caused by cerebral I/R injury and ameliorated neurological deficits in mice after MCAO. The effects of BRCC3 on inflammation and pyroptosis may be mediated by NLRP6 inflammasome activation. Moreover, both BRCC3 and its N- and C-terminals interacted with NLRP6, and both BRCC3 and its terminals reduced NLRP6 ubiquitination. Additionally, BRCC3 affected the interaction between NLRP6 and ASC, which may be related to inflammasome activation.

CONCLUSION

BRCC3 shows promise as a novel target to enhance neurological recovery and attenuate the inflammatory responses and pyroptosis caused by NLRP6 activation in cerebral I/R injury.

Molecular mechanism for combined toxicity of micro(nano)plastics and carbon nanofibers to freshwater microalgae Chlorella pyrenoidosa

The understanding of the environmental consequences resulting from the presence of micro(nano)plastics and carbon nanofibers (CNFs) in aquatic ecosystems is currently limited. This research endeavor sought to investigate the underlying molecular mechanisms by which engineered polystyrene-based microplastics (MPs)/nanoplastics (NPs) and CNFs, both individually and in combination, elicit toxic effects on an algal species Chlorella pyrenoidosa. The findings revealed that the combined toxicity of MPs/NPs and CNFs depended on the concentration of the mixture. As the concentration increased, the combined toxicity of MPs/NPs and CNFs was significantly greater than the toxicity of each component on its own. Furthermore, the combined toxicity of NPs and CNFs was higher than that of MPs and CNFs. The study integrated data on cell membrane integrity, oxidative stress, and antioxidant modulation to create an Integrated Biomarker Response index, which demonstrated that the co-exposure of algae to NPs and CNFs resulted in more severe cellular stress compared to exposure to NPs alone. Similarly, the combination of NPs and CNFs caused greater cellular stress than the combination of MPs and CNFs. Additionally, significant changes in the expression of stress-related genes caused by MPs/NPs alone and in combination with CNFs indicated that oxidative stress response, glucose metabolism, and energy metabolism played critical roles in particle-induced toxicity. Overall, this study provides the first insight into the toxicological mechanism of MPs/NPs and CNFs mixtures at the molecular level in freshwater microalgae.

Integrating Transcriptomic and Structural Insights: Revealing Drug Repurposing Opportunities for Sporadic ALS

Amyotrophic lateral sclerosis (ALS) is a progressive and devastating neurodegenerative disorder characterized by the loss of upper and lower motor neurons, resulting in debilitating muscle weakness and atrophy. Currently, there are no effective treatments available for ALS, posing significant challenges in managing the disease that affects approximately two individuals per 100,000 people annually. To address the urgent need for effective ALS treatments, we conducted a drug repurposing study using a combination of bioinformatics tools and molecular docking techniques. We analyzed sporadic ALS-related genes from the GEO database and identified key signaling pathways involved in sporadic ALS pathogenesis through pathway analysis using DAVID. Subsequently, we utilized the Clue Connectivity Map to identify potential drug candidates and performed molecular docking using AutoDock Vina to evaluate the binding affinity of short-listed drugs to key sporadic ALS-related genes. Our study identified Cefaclor, Diphenidol, Flubendazole, Fluticasone, Lestaurtinib, Nadolol, Phenamil, Temozolomide, and Tolterodine as potential drug candidates for repurposing in sporadic ALS treatment. Notably, Lestaurtinib demonstrated high binding affinity toward multiple proteins, suggesting its potential as a broad-spectrum therapeutic agent for sporadic ALS. Additionally, docking analysis revealed NOS3 as the gene that interacts with all the short-listed drugs, suggesting its possible involvement in the mechanisms underlying the therapeutic potential of these drugs in sporadic ALS. Overall, our study provides a systematic framework for identifying potential drug candidates for sporadic ALS therapy and highlights the potential of drug repurposing as a promising strategy for discovering new therapies for neurodegenerative diseases.

In Situ Mapping of the Glucose Metabolism Heterogeneity in Atherosclerosis: Correlation With 2-Deoxyglucose Uptake

Objective

2-Deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is widely used for noninvasive imaging of atherosclerosis. However, knowledge about metabolic processes underlying [18F]FDG uptake is mostly derived from in vitro cell culture studies, which cannot recapitulate the complexities of the plaque microenvironment. Here, we sought to address this gap by in situ mapping of the activity of selected major dehydrogenases involved in glucose metabolism in atherosclerotic plaques.

Methods

In situ activity of lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PD), succinate dehydrogenase (SDH), and isocitrate dehydrogenase (IDH) was assessed in plaques from murine aortic root and brachiocephalic arteries and human carotid arteries. High-resolution 2-deoxy-D-[1,2-3H]glucose ([3H]2-deoxyglucose) autoradiography of murine brachiocephalic plaques was performed.

Results

LDH activity was heterogeneous throughout the plaques with the highest activity in medial smooth muscle cells (SMCs). G6PD activity was mostly confined to the medial layer and to a lesser extent to SMCs along the fibrous cap. SDH and IDH activities were minimal in plaques. Plaque regions with increased [3H]2-deoxyglucose uptake were associated with a modestly higher LDH, but not G6PD, activity.

Conclusions

Our study reveals a novel aspect of the metabolic heterogeneity of the atherosclerotic plaques, enhancing our understanding of the complex immunometabolic biology that underlies [18F]FDG uptake in atherosclerosis.

Oxidative stress and mitochondrial damage in lambda-cyhalothrin toxicity: A comprehensive review of antioxidant mechanisms

Lambda-cyhalothrin, also known as cyhalothrin, is an efficient, broad-spectrum, quick-acting pyrethroid insecticide and acaricide and the most powerful pyrethroid insecticide in the world. However, there is increasing evidence that lambda-cyhalothrin is closely related to a variety of toxicity drawbacks (hepatotoxicity, nephrotoxicity, neurotoxicity and reproductive toxicity, among others) in non-target organisms, and oxidative stress seems to be the main mechanism of toxicity. This manuscript reviews the oxidative and mitochondrial damage induced by lambda-cyhalothrin and the signalling pathways involved in this process, indicating that oxidative stress occupies an important position in lambda-cyhalothrin toxicity. The mechanism of antioxidants to alleviate the toxicity of lambda-cyhalothrin is also discussed. In addition, the metabolites of lambda-cyhalothrin and the major metabolic enzymes involved in metabolic reactions are summarized. This review article reveals a key mechanism of lambda-cyhalothrin toxicity-oxidative damage and suggests that the use of antioxidants seems to be an effective method for preventing toxicity.

Pan-cancer analysis reveals that G6PD is a prognostic biomarker and therapeutic target for a variety of cancers

BACKGROUND

Despite accumulating evidence revealing that Glucose-6-phosphate dehydrogenase (G6PD) is highly expressed in many tumor tissues and plays a remarkable role in cancer tumorigenesis and progression, there is still a lack of G6PD pan-cancer analysis. This study was designed to analyze the expression status and prognostic significance of G6PD in pan-cancer.

METHODS

G6PD expression data were obtained from multiple data resources including the Genotype-Tissue Expression, the Cancer Genome Atlas, and the Tumor Immunity Estimation Resource. These data were used to assess the G6PD expression, prognostic value, and clinical characteristics. The ESTIMATE algorithms were used to analyze the association between G6PD expression and immune-infiltrating cells and the tumor microenvironment. The functional enrichment analysis was also performed across pan-cancer. In addition, the GDSC1 database containing 403 drugs was utilized to explore the relationship between drug sensitivity and G6PD expression levels. Furthermore, we also performed clinical validation and in vitro experiments to further validate the role of G6PD in hepatocellular carcinoma (HCC) cells and its correlation with prognosis. The R software was used for statistical analysis and data visualization.

RESULTS

G6PD expression was upregulated in most cancers compared to their normal counterparts. The study also revealed that G6PD expression was a prognostic indicator and high levels of G6PD expression were correlated with worse clinical prognosis including overall survival, disease-specific survival, and progression-free interval in multiple cancers. Furthermore, the G6PD level was also related to cancer immunity infiltration in most of the cancers, especially in KIRC, LGG, and LIHC. In addition to this, G6PD expression was positively related to pathological stages of KIRP, BRCA, KIRC, and LIHC. Functional analysis and protein-protein interactions network results revealed that G6PD was involved in metabolism-related activities, immune responses, proliferation, and apoptosis. Drug sensitivity analysis showed that IC50 values of most identified anti-cancer drugs were positively correlated with the G6PD expression. Notably, in vitro functional validation showed that G6PD knockdown attenuated the phenotypes of proliferation in HCC.

CONCLUSION

G6PD may serve as a potential prognostic biomarker for cancers and may be a potential therapeutic target gene for tumor therapy.

The pentose phosphate pathway in health and disease

The pentose phosphate pathway (PPP) is a glucose-oxidizing pathway that runs in parallel to upper glycolysis to produce ribose 5-phosphate and nicotinamide adenine dinucleotide phosphate (NADPH). Ribose 5-phosphate is used for nucleotide synthesis, while NADPH is involved in redox homoeostasis as well as in promoting biosynthetic processes, such as the synthesis of tetrahydrofolate, deoxyribonucleotides, proline, fatty acids and cholesterol. Through NADPH, the PPP plays a critical role in suppressing oxidative stress, including in certain cancers, in which PPP inhibition may be therapeutically useful. Conversely, PPP-derived NADPH also supports purposeful cellular generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) for signalling and pathogen killing. Genetic deficiencies in the PPP occur relatively commonly in the committed pathway enzyme glucose-6-phosphate dehydrogenase (G6PD). G6PD deficiency typically manifests as haemolytic anaemia due to red cell oxidative damage but, in severe cases, also results in infections due to lack of leucocyte oxidative burst, highlighting the dual redox roles of the pathway in free radical production and detoxification. This Review discusses the PPP in mammals, covering its roles in biochemistry, physiology and disease.

Cross-talk between DNA damage response and the central carbon metabolic network underlies selective vulnerability of Purkinje neurons in ataxia-telangiectasia

Cerebellar ataxia is often the first and irreversible outcome in the disease of ataxia-telangiectasia (A-T), as a consequence of selective cerebellar Purkinje neuronal degeneration. A-T is an autosomal recessive disorder resulting from the loss-of-function mutations of the ataxia-telangiectasia-mutated ATM gene. Over years of research, it now becomes clear that functional ATM-a serine/threonine kinase protein product of the ATM gene-plays critical roles in regulating both cellular DNA damage response and central carbon metabolic network in multiple subcellular locations. The key question arises is how cerebellar Purkinje neurons become selectively vulnerable when all other cell types in the brain are suffering from the very same defects in ATM function. This review intended to comprehensively elaborate the unexpected linkages between these two seemingly independent cellular functions and the regulatory roles of ATM involved, their integrated impacts on both physical and functional properties, hence the introduction of selective vulnerability to Purkinje neurons in the disease will be addressed.

Decoding the regulatory roles of non-coding RNAs in cellular metabolism and disease

Non-coding RNAs, including long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), are being studied extensively in a variety of fields. Their roles in metabolism have received increasing attention in recent years but are not yet clear. The regulation of glucose, fatty acid, and amino acid metabolism is an imperative physiological process that occurs in living organisms and takes part in cancer and cardiovascular diseases. Here, we summarize the important roles played by non-coding RNAs in glucose metabolism, fatty acid metabolism, and amino acid metabolism, as well as the mechanisms involved. We also summarize the therapeutic advances for non-coding RNAs in diseases such as obesity, cardiovascular disease, and some metabolic diseases. Overall, non-coding RNAs are indispensable factors in metabolism and have a significant role in the three major metabolisms, which may be exploited as therapeutic targets in the future.

Plasmodium vivax: the potential obstacles it presents to malaria elimination and eradication

Initiatives to eradicate malaria have a good impact on P. falciparum malaria worldwide. P. vivax, however, still presents significant difficulties. This is due to its unique biological traits, which, in comparison to P. falciparum, pose serious challenges for malaria elimination approaches. P. vivax's numerous distinctive characteristics and its ability to live for weeks to years in liver cells in its hypnozoite form, which may elude the human immune system and blood-stage therapy and offer protection during mosquito-free seasons. Many malaria patients are not fully treated because of contraindications to primaquine use in pregnant and nursing women and are still vulnerable to P. vivax relapses, although there are medications that could radical cure P. vivax. Additionally, due to CYP2D6's highly variable genetic polymorphism, the pharmacokinetics of primaquine may be impacted. Due to their inability to metabolize PQ, some CYP2D6 polymorphism alleles can cause patients to not respond to treatment. Tafenoquine offers a radical treatment in a single dose that overcomes the potentially serious problem of poor adherence to daily primaquine. Despite this benefit, hemolysis of the early erythrocytes continues in individuals with G6PD deficiency until all susceptible cells have been eliminated. Field techniques such as microscopy or rapid diagnostic tests (RDTs) miss the large number of submicroscopic and/or asymptomatic infections brought on by reticulocyte tropism and the low parasitemia levels that accompany it. Moreover, P. vivax gametocytes grow more quickly and are much more prevalent in the bloodstream. P. vivax populations also have a great deal of genetic variation throughout their genome, which ensures evolutionary fitness and boosts adaptation potential. Furthermore, P. vivax fully develops in the mosquito faster than P. falciparum. These characteristics contribute to parasite reservoirs in the human population and facilitate faster transmission. Overall, no genuine chance of eradication is predicted in the next few years unless new tools for lowering malaria transmission are developed (i.e., malaria elimination and eradication). The challenging characteristics of P. vivax that impede the elimination and eradication of malaria are thus discussed in this article.

Kinetic and data-driven modeling of pancreatic β-cell central carbon metabolism and insulin secretion

Pancreatic β-cells respond to increased extracellular glucose levels by initiating a metabolic shift. That change in metabolism is part of the process of glucose-stimulated insulin secretion and is of particular interest in the context of diabetes. However, we do not fully understand how the coordinated changes in metabolic pathways and metabolite products influence insulin secretion. In this work, we apply systems biology approaches to develop a detailed kinetic model of the intracellular central carbon metabolic pathways in pancreatic β-cells upon stimulation with high levels of glucose. The model is calibrated to published metabolomics datasets for the INS1 823/13 cell line, accurately capturing the measured metabolite fold-changes. We first employed the calibrated mechanistic model to estimate the stimulated cell's fluxome. We then used the predicted network fluxes in a data-driven approach to build a partial least squares regression model. By developing the combined kinetic and data-driven modeling framework, we gain insights into the link between β-cell metabolism and glucose-stimulated insulin secretion. The combined modeling framework was used to predict the effects of common anti-diabetic pharmacological interventions on metabolite levels, flux through the metabolic network, and insulin secretion. Our simulations reveal targets that can be modulated to enhance insulin secretion. The model is a promising tool to contextualize and extend the usefulness of metabolomics data and to predict dynamics and metabolite levels that are difficult to measure in vitro. In addition, the modeling framework can be applied to identify, explain, and assess novel and clinically-relevant interventions that may be particularly valuable in diabetes treatment.

G6PD deficiency: imbalance of functional dichotomy contributing to the severity of COVID-19

Human COVID-19 has affected more than 491 million people worldwide. It has caused over 6.1 million deaths and has especially perpetrated a high number of casualties among the elderly and those with comorbid illnesses. COVID-19 triggers a pro-oxidant response, leading to the production of reactive oxygen species (ROS) as a common innate defense mechanism. However, ROS are regulated by a key enzyme called G6PD via the production of reduced nicotinamide adenine dinucleotide phosphate (NADPH), which controls the generation and removal of ROS in a tissue-specific manner. Therefore, a deficiency of G6PD can lead to the dysregulation of ROS, which causes a severe inflammatory response in COVID-19 patients. This report highlights the G6PD dichotomy in the regulation of ROS and inflammatory responses, as well as its deficiency in severity among COVID-19 patients.

G6PD Deficiency Is Crucial for Insulin Signaling Activation in Skeletal Muscle

Glucose 6-P dehydrogenase (G6PD) is the first rate-limiting enzyme in pentose phosphate pathway (PPP), and it is proverbial that G6PD is absent in skeletal muscle. However, how and why G6PD is down-regulated during skeletal muscle development is unclear. In this study, we confirmed the expression of G6PD was down-regulated during myogenesis in vitro and in vivo. G6PD was absolutely silent in adult skeletal muscle. Histone H3 acetylation and DNA methylation act together on the expression of G6PD. Neither knock-down of G6PD nor over-expression of G6PD affects myogenic differentiation. Knock-down of G6PD significantly promotes the sensitivity and response of skeletal muscle cells to insulin; over-expression of G6PD significantly injures the sensitivity and response of skeletal muscle cells to insulin. High-fat diet treatment impairs insulin signaling by up-regulating G6PD, and knock-down of G6PD rescues the impaired insulin signaling and glucose uptake caused by high-fat diet treatment. Taken together, this study explored the importance of G6PD deficiency during myogenic differentiation, which provides new sight to treat insulin resistance and type-2 diabetes.

Near-infrared light reduces β-amyloid-stimulated microglial toxicity and enhances survival of neurons: mechanisms of light therapy for Alzheimer's disease

BACKGROUND

Low-intensity light can decelerate neurodegenerative disease progression and reduce amyloid β (Aβ) levels in the cortex, though the cellular and molecular mechanisms by which photobiomodulation (PBM) protects against neurodegeneration are still in the early stages. Microglia cells play a key role in the pathology of Alzheimer's disease by causing chronic inflammation. We present new results concerning the PBM of both oxidative stress and microglia metabolism associated with the activation of metabolic processes by 808 nm near-infrared light.

METHODS

The studies were carried out using healthy male mice to obtain the microglial cell suspension from the hippocampus. Oligomeric β-amyloid (1-42) was prepared and used to treat microglia cells. Light irradiation of cells was performed using diode lasers emitting at 808 nm (30 mW/cm² for 5 min, resulting in a dose of 10 J/cm²). Mitochondrial membrane potential, ROS level studies, cell viability, apoptosis, and necrosis assays were performed using epifluorescence microscopy. Phagocytosis, nitric oxide and H₂O₂ production, arginase, and glucose 6-phosphate dehydrogenase activities were measured using standard assays. Cytokines, glucose, lactate, and ATP were measurements with ELISA. As our data were normally distributed, two-way ANOVA test was used.

RESULTS

The light induces a metabolic shift from glycolysis to mitochondrial activity in pro-inflammatory microglia affected by oligomeric Aβ. Thereby, the level of anti-inflammatory microglia increases. This process is accompanied by a decrease in pro-inflammatory cytokines and an activation of phagocytosis. Light exposure decreases the Aβ-induced activity of glucose-6-phosphate dehydrogenase, an enzyme that regulates the rate of the pentose phosphate pathway, which activates nicotinamide adenine dinucleotide phosphate oxidases to further produce ROS. During co-cultivation of neurons with microglia, light prevents the death of neurons, which is caused by ROS produced by Aβ-altered microglia.

CONCLUSIONS

These original data clarify reasons for how PBM protects against neurodegeneration and support the use of light for therapeutic research in the treatment of Alzheimer's disease.

COVID-19 in G6PD-deficient patients, oxidative stress, and neuropathology

Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme that regulates energy metabolism mainly through the pentose phosphate pathway (PPP). It is well known that this enzyme participates in the antioxidant/oxidant balance via the synthesis of energy-rich molecules: nicotinamide adenine dinucleotide phosphate reduced (NADPH), the reduced form of flavin adenine dinucleotide (FADH) and glutathione (GSH), controlling reactive oxygen species generation. Coronavirus disease 19 (COVID-19), induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is considered a public health problem which has caused approximately 4.5 million deaths since December 2019. In relation to the role of G6PD in COVID-19 development, it is known from the existing literature that G6PD-deficient patients infected with SARS-CoV-2 are more susceptible to thrombosis and hemolysis, suggesting that G6PD deficiency facilitates infection by SARS-CoV-2. In relation to G6PD and neuropathology, it has been observed that deficiency of this enzyme is also present with an increase in oxidative markers. In relation to the role of G6PD and the neurological manifestations of COVID-19, it has been reported that the enzymatic deficiency in patients infected with SARS-CoV-2 exacerbates the disease, and, in some clinical reports, an increase in hemolysis and thrombosis was observed when patients were treated with hydroxychloroquine (OH-CQ), a drug with oxidative properties. In the present work, we summarize the evidence of the role of G6PD in COVID-19 and its possible role in the generation of oxidative stress and glucose metabolism deficits and inflammation present in this respiratory disease and its progression including neurological manifestations.

Role of glucose 6-phosphate dehydrogenase (G6PD) deficiency and its association to Autism Spectrum Disorders

Autism Spectrum Disorder (ASD) is a common group of neurodevelopmental disorders which causes significant alterations in social and communication skills along with repetitive behavior and limited interests. The physiological understanding of ASD is ambiguous. Several reports suggested that environmental, genetic and epigenetic changes, neuroinflammation, mitochondrial dysfunction and metabolic alterations orchestrate the pathological outcomes of ASD. A recent report from Saudi Arabia found a mutation in X-chromosomal housekeeping glucose 6-phosphate dehydrogenase (G6PD) gene in two male ASD patients. Although, the involvement of G6PD-deficiency in the pathogenesis of ASD is poorly understood. Several reports suggested that G6PD deficiency impedes cellular detoxification of reactive oxygen species (ROS), which may result in neuronal damage and neuroinflammation. A deficiency of G6PD in newborn children may play a fundamental role in the pathogenesis of ASD. In this review, we will discuss the implications of G6PD deficiency in pathogenesis, male biasness and theranostics in ASD patients.

Discovery and characterization of a novel glucose-6-phosphate dehydrogenase (G6PD) inhibitor via high-throughput screening

Altered glucose-6-phosphate dehydrogenase (G6PD) status is influential in many cellular pathophysiological processes and diseases, making G6PD a potential target for cancer therapy. However, the available G6PD inhibitors are very limited and restricted. Here we developed a reducing equivalent nicotinamide adenine dinucleotide phosphate (NADPH) absorption photometry assay based on enzyme kinetics to characterize G6PD activity. In this way, we performed a high-throughput screening (HTS) to an in house library. And then we identified compound named Wedelolactone inhibiting G6PD strongly in a non-competitive, reversible way. In addition, we did the surface Plasmon Resonance (SPR) assay and indicated the K_D between Wedelolactone and G6PD protein was 3.64 μM. Furthermore, our basic colony formation assay showed the inhibitory effect of Wedelolactone on the proliferation of ovarian cancer cells (IC₅₀ ~ 10 µM). Thus, we provided a high-throughput screening assay to quickly and efficiently discover G6PD inhibitors, and identified Wedelolactone as a G6PD inhibitor, implying that Wedelolactone suppresses ovarian cancer partly through targeting G6PD.

Molecular characterization of G6PD mutations reveals the high frequency of G6PD Aures in the Lao Theung population

Background

The prevalence and genotypes of G6PD deficiency vary worldwide, with higher prevalence in malaria endemic areas. The first-time assessment of G6PD deficiency prevalence and molecular characterization of G6PD mutations in the Lao Theung population were performed in this study.

Methods

A total of 252 unrelated Lao Theung participants residing in the Lao People’s Democratic Republic (PDR) were recruited. All participant samples were tested for G6PD enzyme activity and G6PD gene mutations. The amplification refractory mutation system (ARMS)-PCR for detecting G6PD Aures was developed.

Results

The G6PD mutations were detected in 11.51% (29/252) of the participants. Eight G6PD mutations were detected. The G6PD Aures was the most common mutation identified in this cohort, which represented 58.62% (17/29) of all mutation. The mutation pattern was homogenous, predominantly involving the G6PD Aures mutation (6.75%), followed by 1.19% G6PD Union and 0.79% each G6PD Jammu, G6PD Mahidol and G6PD Kaiping. One subject (0.4%) each carried G6PD Viangchan and G6PD Canton. Interestingly, one case of coinheritance of G6PD Aures and Quing Yan was detected in this cohort. Based on levels of G6PD enzyme activity, the prevalence of G6PD deficiency in the Lao Theung population was 9.13% (23/252). The prevalence of G6PD deficient males and females (activity < 30%) in the Lao Theung population was 6.41% (5/78) and 1.72% (3/174), respectively, and the prevalence of G6PD intermediate (activity 30–70%) was 5.95% (15/252).

Conclusions

The G6PD Aures mutation is highly prevalent in the Lao Theung ethnic group. The common G6PD variants in continental Southeast Asian populations, G6PD Viangchan, Canton, Kaiping, Union and Mahidol, were not prevalent in this ethnic group. The technical simplicity of the developed ARMS-PCR will facilitate the final diagnosis of the G6PD Aures.

G6PD overexpression protects from oxidative stress and age-related hearing loss

Aging of the auditory system is associated with the incremental production of reactive oxygen species (ROS) and the accumulation of oxidative damage in macromolecules, which contributes to cellular malfunction, compromises cell viability, and, ultimately, leads to functional decline. Cellular detoxification relies in part on the production of NADPH, which is an important cofactor for major cellular antioxidant systems. NADPH is produced principally by the housekeeping enzyme glucose‐6‐phosphate dehydrogenase (G6PD), which catalyzes the rate‐limiting step in the pentose phosphate pathway. We show here that G6PD transgenic mice (G6PD‐Tg), which show enhanced constitutive G6PD activity and NADPH production along life, have lower auditory thresholds than wild‐type mice during aging, together with preserved inner hair cell (IHC) and outer hair cell (OHC), OHC innervation, and a conserved number of synapses per IHC. Gene expression of antioxidant enzymes was higher in 3‐month‐old G6PD‐Tg mice than in wild‐type counterparts, whereas the levels of pro‐apoptotic proteins were lower. Consequently, nitration of proteins, mitochondrial damage, and TUNEL⁺ apoptotic cells were all lower in 9‐month‐old G6PD‐Tg than in wild‐type counterparts. Unexpectedly, G6PD overexpression triggered low‐grade inflammation that was effectively resolved in young mice, as shown by the absence of cochlear cellular damage and macrophage infiltration. Our results lead us to propose that NADPH overproduction from an early stage is an efficient mechanism to maintain the balance between the production of ROS and cellular detoxification power along aging and thus prevents hearing loss progression.

A Rose Extract Protects the Skin against Stress Mediators: A Potential Role of Olfactory Receptors

Olfactory receptors (ORs) are expressed and active in various human tissues, including the skin. Although the sense of smell plays an important physiological role in the regulation of mood and stress, a link between olfactive compounds, ORs, and skin stress has yet to be established. This study aims to investigate the role of newly identified skin ORs and agonists in the modulation of skin stress. Screening for odorant molecules was done with cAMP functional assay to identify OR agonists. RT-qPCR and immunofluorescence microscopy were conducted to identify and quantify ORs in epidermal keratinocytes (NHEKs) and human skin explants, as well as to evaluate specific markers (G6PDH, loricrin, and γH2AX) of stress-induced skin alterations. A randomized double-blinded, split-face clinical study was performed on a panel of stressed women to measure the benefits of OR agonist treatment for skin. Three new ORs (OR10A6, OR2AG2, and OR11H4) were identified in skin. A specific Rose extract and its major constituent (phenylethyl alcohol) were found to activate these ORs. The extract composition was revealed by both GC/FID and GC/MS analyses simultaneously and showed the presence of 34 volatiles molecules. Moreover, epinephrine induces a skin stress response characterized by increased expression of G6PD, loricrin, and γH2AX biomarkers, and a decrease of OR expression. These effects were prevented in the presence of rose extract and its benefits were confirmed clinically by a decrease in the appearance of under-eye dark circles. Altogether, our findings suggest that ORs may represent a new, promising way to treat stress-associated skin disorders.

Biological sex and DNA repair deficiency drive Alzheimer's disease via systemic metabolic remodeling and brain mitochondrial dysfunction

Alzheimer's disease (AD) is an incurable neurodegenerative disease that is more prevalent in women. The increased risk of AD in women is not well understood. It is well established that there are sex differences in metabolism and that metabolic alterations are an early component of AD. We utilized a cross-species approach to evaluate conserved metabolic alterations in the serum and brain of human AD subjects, two AD mouse models, a human cell line, and two Caenorhabditis elegans AD strains. We found a mitochondrial complex I-specific impairment in cortical synaptic brain mitochondria in female, but not male, AD mice. In the hippocampus, Polβ haploinsufficiency caused synaptic complex I impairment in male and female mice, demonstrating the critical role of DNA repair in mitochondrial function. In non-synaptic, glial-enriched, mitochondria from the cortex and hippocampus, complex II-dependent respiration increased in female, but not male, AD mice. These results suggested a glial upregulation of fatty acid metabolism to compensate for neuronal glucose hypometabolism in AD. Using an unbiased metabolomics approach, we consistently observed evidence of systemic and brain metabolic remodeling with a shift from glucose to lipid metabolism in humans with AD, and in AD mice. We determined that this metabolic shift is necessary for cellular and organismal survival in C. elegans, and human cell culture AD models. We observed sex-specific, systemic, and brain metabolic alterations in humans with AD, and that these metabolite changes significantly correlate with amyloid and tau pathology. Among the most significant metabolite changes was the accumulation of glucose-6-phosphate in AD, an inhibitor of hexokinase and rate-limiting metabolite for the pentose phosphate pathway (PPP). Overall, we identified novel mechanisms of glycolysis inhibition, PPP, and tricarboxylic acid cycle impairment, and a neuroprotective augmentation of lipid metabolism in AD. These findings support a sex-targeted metabolism-modifying strategy to prevent and treat AD.

CRISPR-Mediated Single Nucleotide Polymorphism Modeling in Rats Reveals Insight Into Reduced Cardiovascular Risk Associated With Mediterranean G6PD Variant

Epidemiological studies suggest that individuals in the Mediterranean region with a loss-of-function, nonsynonymous single nucleotide polymorphism (S188F), in glucose-6-phosphate dehydrogenase (G6pd) are less susceptible to vascular diseases. However, this association has not yet been experimentally proven. Here, we set out to determine whether the Mediterranean mutation confers protection from vascular diseases and to discover the underlying protective mechanism. We generated a rat model with the Mediterranean single nucleotide polymorphism (G6PD^S188F) using CRISPR-Cas9 genome editing. In rats carrying the mutation, G6PD activity, but not expression, was reduced to 20% of wild-type (WT) littermates. Additionally, unbiased metabolomics analysis revealed that the pentose phosphate pathway and other ancillary metabolic pathways connected to the pentose phosphate pathway were reduced (P<0.05) in the arteries of G6PD^S188F versus WT rats. Intriguingly, G6PD^S188F mutants, as compared with WT rats, developed less large arterial stiffness and hypertension evoked by high-fat diet and nitric oxide synthase inhibition with L-N^G-nitroarginine methyl ester. Intravenous injection of a voltage-gated L-type Ca²⁺ channel agonist (methyl 2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)phenyl]-1,4-dihydropyridine-3-carboxylate; Bay K8644) acutely increased blood pressure in WT but not in G6PD^S188F rats. Finally, our results suggested that (1) lower resting membrane potential of smooth muscle caused by increased expression of K⁺ channel proteins and (2) decreased voltage-gated Ca²⁺ channel activity in smooth muscle contributed to reduced hypertension and arterial stiffness evoked by L-N^G-nitroarginine methyl ester and high-fat diet to G6PD^S188F mutants as compared with WT rats. In summary, a mutation resulting in the replacement of a single amino acid (S188F) in G6PD, the rate-limiting enzyme in the pentose phosphate pathway, ascribed properties to the vascular smooth muscle that shields the organism from risk factors associated with vascular diseases.

LncRNA OR3A4 Regulated the Growth of Osteosarcoma Cells by Modulating the miR-1207-5p/G6PD Signaling

Background

Increasing evidence has demonstrated the importance of non-coding RNAs including long non-coding RNA (lncRNA) and microRNAs (miRNAs) in the tumorigenesis of osteosarcoma (OS). Abnormal expression of lncRNA olfactory receptor family 3 subfamily A member 4 (OR3A4) was found in multiple human cancers; however, the function of OR3A4 in OS remains largely unknown.

Materials and Methods

The expression level of OR3A4 in OS tissues and cell lines was detected by RT-qPCR. Cell counting kit-8 assay, colony formation and flow cytometry analysis were performed to determine the growth of OS cells. The targets of OR3A4 were predicted using the miRDB database. The binding between OR3A4 and miRNAs was confirmed by dual-luciferase reporter assay.

Results

OR3A4 was overexpressed in OS tissues and correlated with the advanced progression of OS patients. Down-regulation of OR3A4 significantly inhibited the proliferation and colony formation of OS cells. Mechanistically, OR3A4 acted as a sponge of miR-1207-5p. Glucose-6-phosphate dehydrogenase (G6PD) was identified as a target of miR-1207-5p. Knockdown of OR3A4 increased the expression of miR-1207-5p and consequently, suppressed the level of G6PD in OS cells. Due to the essential role of G6PD in the pentose phosphate pathway (PPP), depletion of OR3A4 inhibited NADPH production, glucose consumption and lactate generation. Decreased level of NADPH by depletion of OR3A4 up-regulated the redox state (ROS) content and resulted in endoplasmic reticulum (ER) stress in OS cells. Restoration of G6PD significantly attenuated the cell growth inhibition induced by OR3A4 knockdown.

Conclusion

Our finding suggested the critical role of OR3A4 in the proliferation of OS cells via targeting the miR-1207-5p/G6PD axis.

Evaluation of glucose-6-phosphate dehydrogenase serum level in patients with multiple sclerosis and neuromyelitis optica

Background: Multiple sclerosis (MS) and neuromyelitis optica (NMO) are both demyelinating disorders and oxidative stress is suggested to have a role in their pathogenesis. Glucose-6-phosphate dehydrogenase (G6PD) produces nicotinamide adenine dinucleotide phosphate (NADPH) via the pentose phosphate pathway. NADPH is not only involved in the synthesis of fatty acids necessary for myelination, but also it is involved in the defense against oxidative stress. Prescribing supplementary vitamin D as a part of the MS treatment plan can increase G6PD gene expression. The aim of this study was to determine the serum level of G6PD in patients with MS and NMO and its relationship with vitamin D, since it is yet to be explored thoroughly. Methods: In this case-control study, subjects were divided into three experimental and control groups. The experimental groups comprised 50 patients with relapsing-remitting MS (RRMS) who had a history of vitamin D consumption, 50 newly-diagnosed MS patients, and 50 patients with NMO. Control group included 65 healthy individuals. Serum level of G6PD was measured and compared among these groups. Results: No significant difference was seen between the G6PD level in patients with MS and NMO, but it should be noted that this level was significantly lower than the healthy group. G6PD serum level was significantly higher in patients with MS who had previously consumed supplementary vitamin D compared to those who had not. Conclusion: G6PD deficiency is observed in patients with MS and NMO. Also, supplementary vitamin D may induce favorable results on the G6PD level.