RESUMO
Serum urate levels are determined by the balance between uric acid production and uric acid excretion capacity from the kidneys and intestinal tract. Dysuricemia, including hyperuricemia and hypouricemia, develops when the balance shifts towards an increase or a decrease in the uric acid pool. Hyperuricemia is mostly a multifactorial genetic disorder involving several disease susceptibility genes and environmental factors. Hypouricemia, on the other hand, is caused by genetic abnormalities. The main genes involved in dysuricemia are xanthine oxidoreductase, an enzyme that produces uric acid, and the urate transporters urate transporter 1/solute carrier family 22 member 12 (URAT1/SLC22A12), glucose transporter 9/solute carrier family 2 member 9 (GLUT9/SLC2A9) and ATP binding cassette subfamily G member 2 (ABCG2). Deficiency of xanthine oxidoreductase results in xanthinuria, a rare disease with marked hypouricemia. Xanthinuria can be due to a single deficiency of xanthine oxidoreductase or in combination with aldehyde oxidase deficiency as well. The latter is caused by a deficiency in molybdenum cofactor sulfurase, which is responsible for adding sulphur atoms to the molybdenum cofactor required for xanthine oxidoreductase and aldehyde oxidase to exert their action. URAT1/SLC22A12 and GLUT9/SLC2A9 are involved in urate reabsorption and their deficiency leads to renal hypouricemia, a condition that is common in Japanese due to URAT1/SLC22A12 deficiency. On the other hand, ABCG2 is involved in the secretion of urate, and many Japanese have single nucleotide polymorphisms that result in its reduced function, leading to hyperuricemia. In particular, severe dysfunction of ABCG2 leads to hyperuricemia with reduced extrarenal excretion.
Assuntos
Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Proteínas Facilitadoras de Transporte de Glucose , Hiperuricemia , Proteínas de Neoplasias , Transportadores de Ânions Orgânicos , Ácido Úrico , Xantina Desidrogenase , Humanos , Hiperuricemia/etiologia , Hiperuricemia/metabolismo , Hiperuricemia/genética , Ácido Úrico/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Transportadores de Ânions Orgânicos/metabolismo , Transportadores de Ânions Orgânicos/genética , Proteínas Facilitadoras de Transporte de Glucose/metabolismo , Proteínas Facilitadoras de Transporte de Glucose/genética , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Xantina Desidrogenase/metabolismo , Xantina Desidrogenase/genética , Xantina Desidrogenase/deficiência , Animais , Proteínas de Transporte de Cátions Orgânicos/genética , Proteínas de Transporte de Cátions Orgânicos/metabolismo , Erros Inatos do Transporte Tubular Renal/genética , Erros Inatos do Transporte Tubular Renal/etiologia , Erros Inatos do Transporte Tubular Renal/metabolismo , Cálculos Urinários/etiologia , Cálculos Urinários/metabolismo , Cálculos Urinários/genética , Erros Inatos do MetabolismoRESUMO
Xanthine oxidoreductase (XOR) contributes to reactive oxygen species production. We investigated the cytoprotective mechanisms of XOR inhibition against high glucose (HG)-induced glomerular endothelial injury, which involves activation of the AMP-activated protein kinase (AMPK). Human glomerular endothelial cells (GECs) exposed to HG were subjected to febuxostat treatment for 48 h and the expressions of AMPK and its associated signaling pathways were evaluated. HG-treated GECs were increased xanthine oxidase/xanthine dehydrogenase levels and decreased intracellular AMP/ATP ratio, and these effects were reversed by febuxostat treatment. Febuxostat enhanced the phosphorylation of AMPK, the activation of peroxisome proliferator-activated receptor (PPAR)-gamma coactivator (PGC)-1α and PPAR-α and suppressed the phosphorylation of forkhead box O (FoxO)3a in HG-treated GECs. Febuxostat also decreased nicotinamide adenine dinucleotide phosphate oxidase (Nox)1, Nox2, and Nox4 expressions; enhanced superoxide dismutase activity; and decreased malondialdehyde levels in HG-treated GECs. The knockdown of AMPK inhibited PGC-1α-FoxO3a signaling and negated the antioxidant effects of febuxostat in HG-treated GECs. Despite febuxostat administration, the knockdown of hypoxanthine phosphoribosyl transferase 1 (HPRT1) also inhibited AMPK-PGC-1α-FoxO3a in HG-treated GECs. XOR inhibition alleviates oxidative stress by activating AMPK-PGC-1α-FoxO3a signaling through the HPRT1-dependent purine salvage pathway in GECs exposed to HG conditions.
Assuntos
Proteínas Quinases Ativadas por AMP , Injúria Renal Aguda , Células Endoteliais , Glucose , Purinas , Xantina Desidrogenase , Humanos , Proteínas Quinases Ativadas por AMP/efeitos dos fármacos , Proteínas Quinases Ativadas por AMP/metabolismo , Células Endoteliais/metabolismo , Células Endoteliais/efeitos dos fármacos , Febuxostat/farmacologia , Glucose/metabolismo , Glomérulos Renais/metabolismo , Glomérulos Renais/patologia , Glomérulos Renais/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Purinas/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Xantina Desidrogenase/antagonistas & inibidores , Xantina Desidrogenase/metabolismo , Injúria Renal Aguda/induzido quimicamente , Injúria Renal Aguda/metabolismoRESUMO
Xanthine oxidoreductase (XOR) and uric acid transporter 1 (URAT1) are two most widely studied targets involved in production and reabsorption of uric acid, respectively. Marketed drugs almost target XOR or URAT1, but sometimes, single agents might not achieve aim of lowering uric acid to ideal value in clinic. Thus, therapeutic strategies of combining XOR inhibitors with uricosuric drugs were proposed and implemented. Based on our initial work of virtual screening, A and B were potential hits for dual-targeted inhibitors on XOR/URAT1. By docking A/B with XOR/URAT1 respectively, compounds I1-7 were designed to get different degree of inhibition effect on XOR and URAT1, and I7 showed the best inhibitory effect on XOR (IC50 = 0.037 ± 0.001 µM) and URAT1 (IC50 = 546.70 ± 32.60 µM). Further docking research on I7 with XOR/URAT1 led to the design of compounds II with the significantly improved inhibitory activity on XOR and URAT1, such as II11 and II15. Especially, for II15, the IC50 of XOR is 0.006 ± 0.000 µM, superior to that of febuxostat (IC50 = 0.008 ± 0.000 µM), IC50 of URAT1 is 12.90 ± 2.30 µM, superior to that of benzbromarone (IC50 = 27.04 ± 2.55 µM). In acute hyperuricemia mouse model, II15 showed significant uric acid lowering effect. The results suggest that II15 had good inhibitory effect on XOR/URAT1, with the possibility for further investigation in in-vivo models of hyperuricemia.
Assuntos
Desenho de Fármacos , Inibidores Enzimáticos , Transportadores de Ânions Orgânicos , Proteínas de Transporte de Cátions Orgânicos , Piridinas , Animais , Piridinas/farmacologia , Piridinas/química , Piridinas/síntese química , Camundongos , Humanos , Relação Estrutura-Atividade , Transportadores de Ânions Orgânicos/antagonistas & inibidores , Transportadores de Ânions Orgânicos/metabolismo , Proteínas de Transporte de Cátions Orgânicos/antagonistas & inibidores , Proteínas de Transporte de Cátions Orgânicos/metabolismo , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Estrutura Molecular , Simulação de Acoplamento Molecular , Xantina Desidrogenase/antagonistas & inibidores , Xantina Desidrogenase/metabolismo , Relação Dose-Resposta a Droga , Hiperuricemia/tratamento farmacológico , Hiperuricemia/metabolismo , Masculino , Ácido Úrico/metabolismoRESUMO
Upregulation of free radical-generating NADPH oxidases (NOX), xanthine oxidoreductase (XOR), and neutrophil infiltration-induced, NOX2-mediated respiratory burst contribute to renal ischemia-reperfusion injury (IRI), but their roles may depend on the severity of IRI. We investigated the role of NOX, XOR, and neutrophils in developing IRI of various severities. C57BL/6 and Mcl-1ΔMyelo neutrophil-deficient mice were used. Oxidases were silenced by RNA interference (RNAi) or pharmacologically inhibited. Kidney function, morphology, immunohistochemistry and mRNA expression were assessed. After reperfusion, the expression of NOX enzymes and XOR increased until 6 h and from 15 h, respectively, while neutrophil infiltration was prominent from 3 h. NOX4 and XOR silencing or pharmacological XOR inhibition did not protect the kidney from IRI. Attenuation of NOX enzyme-induced oxidative stress by apocynin and neutrophil deficiency improved kidney function and ameliorated morphological damage after mild but not moderate/severe IRI. The IR-induced postischemic renal functional impairment (BUN, Lcn-2), tubular necrosis score, inflammation (TNF-α, F4/80), and decreases in the antioxidant enzyme (GPx3) mRNA expression were attenuated by both apocynin and neutrophil deficiency. Inhibition of NOX enzyme-induced oxidative stress or the lack of infiltration by NOX2-expressing neutrophils can attenuate reperfusion injury after mild but not moderate/severe renal IR.
Assuntos
Acetofenonas , Injúria Renal Aguda , Traumatismo por Reperfusão , Camundongos , Animais , NADPH Oxidases/metabolismo , Neutrófilos/metabolismo , Camundongos Endogâmicos C57BL , Rim/metabolismo , Traumatismo por Reperfusão/genética , Xantina Desidrogenase/metabolismo , RNA MensageiroRESUMO
Xanthine oxidoreductase (XOR) is a rate-limiting enzyme in the formation of uric acid (UA) and is involved in the generation of reactive oxygen species (ROS). Overproduction of ROS has been linked to the pathogenesis of hypertension, atherosclerosis, and cardiovascular disease, with multiple studies over the last 30 years demonstrating that XOR inhibition is beneficial. The involvement of XOR and its constituents in the advancement of chronic inflammation and ROS, which are responsible for endothelial dysfunction, is the focus of this evidence-based review. An overabundance of XOR products and ROS appears to drive the inflammatory response, resulting in significant endothelium damage. It has also been demonstrated that XOR activity and ED are connected. Diabetes, hypertension, and cardiovascular disease are all associated with endothelial dysfunction. ROS mainly modifies the activity of vascular cells and can be important in normal vascular physiology as well as the development of vascular disease. Suppressing XOR activity appears to decrease endothelial dysfunction, probably because it lessens the generation of reactive oxygen species and the oxidative stress brought on by XOR. Although there has long been a link between higher vascular XOR activity and worse clinical outcomes, new research suggests a different picture in which positive results are mediated by XOR enzymatic activity. Here in this study, we aimed to review the association between XOR and vascular endothelial dysfunction. The prevention and treatment approaches against vascular endothelial dysfunction in atherosclerotic disease.
Assuntos
Endotélio Vascular , Estresse Oxidativo , Espécies Reativas de Oxigênio , Xantina Desidrogenase , Humanos , Xantina Desidrogenase/metabolismo , Endotélio Vascular/fisiopatologia , Endotélio Vascular/metabolismo , Endotélio Vascular/enzimologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Hipertensão/fisiopatologia , Hipertensão/enzimologia , Hipertensão/metabolismo , Doenças Cardiovasculares/fisiopatologia , Doenças Cardiovasculares/enzimologia , Doenças Cardiovasculares/metabolismo , Ácido Úrico/metabolismo , Ácido Úrico/sangue , Inibidores Enzimáticos/farmacologiaRESUMO
The development of the kidney involves essential cellular processes, such as cell proliferation and differentiation, which are led by interactions between multiple signaling pathways. Xanthine dehydrogenase (XDH) catalyzes the reaction producing uric acid in the purine catabolism, which plays a multifaceted role in cellular metabolism. Our previous study revealed that the genetic ablation of the Xdh gene in rats leads to smaller kidneys, kidney damage, decline of renal functions, and failure to thrive. Rats, unlike humans, continue their kidney development postnatally. Therefore, we explored whether XDH plays a critical role in kidney development using SS-/- rats during postnatal development phase. XDH expression was significantly increased from postnatal day 5 to 15 in wild-type but not homozygote rat kidneys. The transcriptomic profile of renal tissue revealed several dysregulated pathways due to the lack of Xdh expression with the remodeling in inflammasome, purinergic signaling, and redox homeostasis. Further analysis suggested that lack of Xdh affects kidney development, likely via dysregulation of epidermal growth factor and its downstream STAT3 signaling. The present study showed that Xdh is essential for kidney maturation. Our data, alongside the previous research, suggests that loss of Xdh function leads to developmental issues, rendering them vulnerable to kidney diseases in adulthood.
Assuntos
Rim , Xantina Desidrogenase , Humanos , Ratos , Animais , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo , Rim/metabolismo , Ácido ÚricoRESUMO
Xanthine oxidoreductase (XOR) catalyzes the oxidation of purines (hypoxanthine and xanthine) to uric acid. XOR is widely used in various therapeutic and biotechnological applications. In this study, we characterized the biophysical and mechanistic properties of a novel bacterial XOR from Sulfobacillus acidophilus TPY (SaXOR). Our results showed that SaXOR is a heterotrimer consisting of three subunits, namely XoA, XoB, and XoC, which denote the molybdenum cofactor (Moco), 2Fe-2S, and FAD-binding domains, respectively. XoC was found to be stable when co-expressed with XoB, forming an XoBC complex. Furthermore, we prepared a fusion of XoB and XoC via a flexible linker (fusXoBC) and evaluated its function in comparison to that of XoBC. Spectroscopic analysis revealed that XoB harbors two 2Fe-2S clusters, whereas XoC bears a single-bound FAD cofactor. Electron transfer from reduced forms of XoC, XoBC, and fusXoBC to molecular oxygen (O2 ) during oxidative half-reaction yielded no flavin semiquinones, implying ultrafast single-electron transfer from 2Fe-2Sred to FAD. In the presence of XoA, XoBC and fusXoBC exhibited comparable XoA affinity and exploited a shared overall mechanism. Nonetheless, the linkage may accelerate the two-step, single-electron transfer cascade from 2Fe-2Sred to FAD while augmenting protein stability. Collectively, our findings provide novel insights into SaXOR properties and oxidation mechanisms divergent from prior mammalian and bacterial XOR paradigms.
Assuntos
Clostridiales , Proteínas Ferro-Enxofre , Xantina Desidrogenase , Animais , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo , Ferro/metabolismo , Oxirredução , Flavinas/metabolismo , Enxofre/metabolismo , Proteínas Ferro-Enxofre/metabolismo , Mamíferos/metabolismoRESUMO
We recently reported a previously unknown salutary role for xanthine oxidoreductase (XOR) in intravascular heme overload whereby hepatocellular export of XOR to the circulation was identified as a seminal step in affording protection. However, the cellular signaling and export mechanisms underpinning this process were not identified. Here, we present novel data showing hepatocytes upregulate XOR expression/protein abundance and actively release it to the extracellular compartment following exposure to hemopexin-bound hemin, hemin or free iron. For example, murine (AML-12 cells) hepatocytes treated with hemin (10 µM) exported XOR to the medium in the absence of cell death or loss of membrane integrity (2.0 ± 1.0 vs 16 ± 9 µU/mL p < 0.0001). The path of exocytosis was found to be noncanonical as pretreatment of the hepatocytes with Vaculin-1, a lysosomal trafficking inhibitor, and not Brefeldin A inhibited XOR release and promoted intracellular XOR accumulation (84 ± 17 vs 24 ± 8 hemin vs 5 ± 3 control µU/mg). Interestingly, free iron (Fe2+ and Fe3+) induced similar upregulation and release of XOR compared to hemin. Conversely, concomitant treatment with hemin and the classic transition metal chelator DTPA (20 µM) or uric acid completely blocked XOR release (p < 0.01). Our previously published time course showed XOR release from hepatocytes likely required transcriptional upregulation. As such, we determined that both Sp1 and NF-kB were acutely activated by hemin treatment (â¼2-fold > controls for both, p < 0.05) and that silencing either or TLR4 with siRNA prevented hemin-induced XOR upregulation (p < 0.01). Finally, to confirm direct action of these transcription factors on the Xdh gene, chromatin immunoprecipitation was performed indicating that hemin significantly enriched (â¼5-fold) both Sp1 and NF-kB near the transcription start site. In summary, our study identified a previously unknown pathway by which XOR is upregulated via SP1/NF-kB and subsequently exported to the extracellular environment. This is, to our knowledge, the very first study to demonstrate mechanistically that XOR can be specifically targeted for export as the seminal step in a compensatory response to heme/Fe overload.
Assuntos
Hemina , Xantina Desidrogenase , Animais , Camundongos , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo , Hemina/farmacologia , Ferro , NF-kappa B , Heme , Hepatócitos/metabolismoRESUMO
Several rare genetic variations of human XDH have been shown to alter xanthine oxidoreductase (XOR) activity leading to impaired purine catabolism. However, XOR is a multi-functional enzyme that depending upon the environmental conditions also expresses oxidase activity leading to both O2·- and H2O2 and nitrite (NO2-) reductase activity leading to nitric oxide (·NO). Since these products express important, and often diametrically opposite, biological activity, consideration of the impact of XOR mutations in the context of each aspect of the biochemical activity of the enzyme is needed to determine the potential full impact of these variants. Herein, we show that known naturally occurring hXDH mutations do not have a uniform impact upon the biochemical activity of the enzyme in terms of uric acid (UA), reactive oxygen species (ROS) and nitric oxide ·NO formation. We show that the His1221Arg mutant, in the presence of xanthine, increases UA, O2·- and NO generation compared to the WT, whilst the Ile703Val increases UA and ·NO formation, but not O2·-. We speculate that this change in the balance of activity of the enzyme is likely to endow those carrying these mutations with a harmful or protective influence over health that may explain the current equipoise underlying the perceived importance of XDH mutations. We also show that, in presence of inorganic NO2-, XOR-driven O2·- production is substantially reduced. We suggest that targeting enzyme activity to enhance the NO2--reductase profile in those carrying such mutations may provide novel therapeutic options, particularly in cardiovascular disease.
Assuntos
Nitritos , Xantina Desidrogenase , Humanos , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo , Nitritos/metabolismo , Óxido Nítrico/metabolismo , Oxirredutases/metabolismo , Dióxido de Nitrogênio , Peróxido de Hidrogênio , Oxirredução , Ácido Úrico/metabolismo , Mutação , Xantina Oxidase/metabolismoRESUMO
The xanthine oxidoreductase (XOR) family are metal-containing enzymes that use the molybdenum cofactor (Moco), 2Fe-2S clusters, and flavin adenine dinucleotide (FAD) for their catalytic activity. This large molybdoenzyme family includes xanthine, aldehyde, and CO dehydrogenases. XORs are widely distributed from bacteria to humans due to their key roles in the catabolism of purines, aldehydes, drugs, and xenobiotics, as well as interconversions between CO and CO2. Assessing the effect of excess metals on the Rubrivivax gelatinosus bacterium, we found that exposure to copper (Cu) or cadmium (Cd) caused a dramatic decrease in the activity of a high-molecular-weight soluble complex exhibiting nitroblue tetrazolium reductase activity. Mass spectrometry and genetic analyses showed that the complex corresponds to a putative CO dehydrogenase (pCOD). Using mutants that accumulate either Cu+ or Cd2+ in the cytoplasm, we show that Cu+ or Cd2+ is a potent inhibitor of XORs (pCOD and the xanthine dehydrogenase [XDH]) in vivo. This is the first in vivo demonstration that Cu+ affects Moco-containing enzymes. The specific inhibitory effect of these compounds on the XOR activity is further supported in vitro by direct addition of competing metals to protein extracts. Moreover, emphasis is given on the inhibitory effect of Cu on bovine XOR, showing that the XOR family could be a common target of Cu. Given the conservation of XOR structure and function across the tree of life, we anticipate that our findings could be transferable to other XORs and organisms. IMPORTANCE The high toxicity of Cu, Cd, Pb, As, and other metals arises from their ability to cross membranes and target metalloenzymes in the cytoplasm. Identifying these targets provides insights into the toxicity mechanisms. The vulnerability of metalloenzymes arises from the accessibility of their cofactors to ions. Accordingly, many enzymes whose cofactors are solvent exposed are likely to be targets of competing metals. Here, we describe for the first time, with in vivo and in vitro experiments, a direct effect of excess Cu on the xanthine oxidoreductase family (XOR/XDH/pCOD). We show that toxic metal affects these Moco enzymes, and we suggest that access to the Moco center by Cu ions could explain the Cu inhibition of XORs in living organisms. Human XOR activity is associated with hyperuricemia, xanthinuria, gout arthritis, and other diseases. Our findings in vivo highlight XOR as a Cu target and thus support the potential use of Cu in metal-based therapeutics against these diseases.
Assuntos
Metaloproteínas , Xantina Desidrogenase , Animais , Bovinos , Humanos , Xantina Desidrogenase/química , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo , Cádmio/toxicidade , MetaisRESUMO
Xanthine oxidoreductase (XOR) is an enzyme found in various organisms. It converts hypoxanthine to xanthine and urate, which are crucial steps in purine elimination in humans. Elevated uric acid levels can lead to conditions like gout and hyperuricemia. Therefore, there is significant interest in developing drugs that target XOR for treating these conditions and other diseases. Oxipurinol, an analogue of xanthine, is a well-known inhibitor of XOR. Crystallographic studies have revealed that oxipurinol directly binds to the molybdenum cofactor (MoCo) in XOR. However, the precise details of the inhibition mechanism are still unclear, which would be valuable for designing more effective drugs with similar inhibitory functions. In this study, molecular dynamics and quantum mechanics/molecular mechanics calculations are employed to investigate the inhibition mechanism of XOR by oxipurinol. The study examines the structural and dynamic effects of oxipurinol on the pre-catalytic structure of the metabolite-bound system. Our results provide insights on the reaction mechanism catalyzed by the MoCo center in the active site, which aligns well with experimental findings. Furthermore, the results provide insights into the residues surrounding the active site and propose an alternative mechanism for developing alternative covalent inhibitors.
Assuntos
Metaloproteínas , Oxipurinol , Humanos , Xantina Desidrogenase/química , Xantina Desidrogenase/metabolismo , Xantina/metabolismo , Ácido Úrico/metabolismo , Coenzimas/metabolismo , Metaloproteínas/químicaRESUMO
The author will outline the research history of the main issues addressed in this paper. The author has worked on this research himself. XDH, which is responsible for purine degradation, is present in various organisms. However, conversion to XO only occurs in mammals. The molecular mechanism of this conversion was elucidated in this study. The physiological and pathological significance of this conversion is presented. Finally, enzyme inhibitors were successfully developed, two of which are used as therapeutic agents for gout. Their wide application potential is also discussed.
Assuntos
Xantina Desidrogenase , Xantina Oxidase , Animais , Xantina Oxidase/metabolismo , Xantina Desidrogenase/metabolismo , Inibidores Enzimáticos/farmacologia , Descoberta de Drogas , Mamíferos/metabolismoRESUMO
Serum uric acid (UA) level is associated with the high cumulative incidence or prevalence of coronary artery disease (CAD), and hyperuricemia is considered as an independent risk marker for CAD. Sleep-disordered breathing (SDB) is also associated with an increased risk of CAD. Several studies have shown that SDB is associated with hyperuricemia, but the mechanisms are unclear. We measured serum levels of UA and xanthine oxidoreductase (XOR) activity and urinary levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), all of which were assessed at 6 p.m. and the following 6 a.m. in males with CAD. In addition, nocturnal pulse oximetry was performed for the night. Overall 32 eligible patients with CAD were enrolled. Serum UA levels significantly increased overnight. (5.32 ± 0.98 mg/dl to 5.46 ± 1.02 mg/dl, p < 0.001) Moreover, XOR activity and urinary 8-OHdG levels significantly increased from 6 p.m. to 6 a.m. Furthermore, 3% Oxygen desaturation index (ODI) was correlated with the overnight changes in XOR activity (r = 0.36, P = 0.047) and urinary 8-OHdG levels (r = 0.41, P = 0.02). In addition, 3%ODI was independently correlated with the changes in XOR activity (correlation coefficient, 0.36; P = 0.047) and 8-OHdG (partial correlation coefficient, 0.63; P = 0.004) in multivariable analyses. SDB severity was associated with the overnight changes in XOR activity and urinary 8-OHdG, suggesting that SDB may be associated with oxidative stress via UA production. This trial is registered at University Hospital Medical Information Network (UMIN), number: UMIN000021624.
Assuntos
Doença da Artéria Coronariana , Hiperuricemia , Síndromes da Apneia do Sono , Masculino , Humanos , Doença da Artéria Coronariana/complicações , Ácido Úrico , Xantina Desidrogenase/metabolismo , Hiperuricemia/complicações , Síndromes da Apneia do Sono/complicações , Estresse OxidativoRESUMO
Oxidative stress is a contributing factor to Parkinson's disease (PD). Considering the prevalence of sporadic PD, environmental exposures are postulated to increase reactive oxygen species and either incite or exacerbate neurodegeneration. We previously determined that exposure to the common soil bacterium, Streptomyces venezuelae (S. ven), enhanced oxidative stress and mitochondrial dysfunction in Caenorhabditis elegans, leading to dopaminergic (DA) neurodegeneration. Here, S. ven metabolite exposure in C. elegans was followed by RNA-Seq analysis. Half of the differentially identified genes (DEGs) were associated with the transcription factor DAF-16 (FOXO), which is a key node in regulating stress response. Our DEGs were enriched for Phase I (CYP) and Phase II (UGT) detoxification genes and non-CYP Phase I enzymes associated with oxidative metabolism, including the downregulated xanthine dehydrogenase gene, xdh-1. The XDH-1 enzyme exhibits reversible interconversion to xanthine oxidase (XO) in response to calcium. S. ven metabolite exposure enhanced XO activity in C. elegans. The chelation of calcium diminishes the conversion of XDH-1 to XO and results in neuroprotection from S. ven exposure, whereas CaCl2 supplementation enhanced neurodegeneration. These results suggest a defense mechanism that delimits the pool of XDH-1 available for interconversion to XO, and associated ROS production, in response to metabolite exposure.
Assuntos
Caenorhabditis elegans , Xantina Desidrogenase , Animais , Xantina Desidrogenase/metabolismo , Caenorhabditis elegans/metabolismo , Cálcio/metabolismo , Xantina Oxidase/metabolismo , Espécies Reativas de Oxigênio/metabolismoRESUMO
The lifetime risk of kidney disease in people with diabetes is 10-30%, implicating genetic predisposition in the cause of diabetic kidney disease (DKD). Here we identify an expression quantitative trait loci (QTLs) in the cis-acting regulatory region of the xanthine dehydrogenase, or xanthine oxidoreductase (Xor), a binding site for C/EBPß, to be associated with diabetes-induced podocyte loss in DKD in male mice. We examine mouse inbred strains that are susceptible (DBA/2J) and resistant (C57BL/6J) to DKD, as well as a panel of recombinant inbred BXD mice, to map QTLs. We also uncover promoter XOR orthologue variants in humans associated with high risk of DKD. We introduced the risk variant into the 5'-regulatory region of XOR in DKD-resistant mice, which resulted in increased Xor activity associated with podocyte depletion, albuminuria, oxidative stress and damage restricted to the glomerular endothelium, which increase further with type 1 diabetes, high-fat diet and ageing. Therefore, differential regulation of Xor contributes to phenotypic consequences with diabetes and ageing.
Assuntos
Diabetes Mellitus , Nefropatias Diabéticas , Humanos , Masculino , Camundongos , Animais , Nefropatias Diabéticas/genética , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo , Predisposição Genética para Doença , Camundongos Endogâmicos DBA , Camundongos Endogâmicos C57BLRESUMO
Purines, such as adenine and guanine, perform several important functions in the cell. They are found in nucleic acids; are structural components of some coenzymes, including NADH and coenzyme A; and have a crucial role in the modulation of energy metabolism and signal transduction. Moreover, purines have been shown to play an important role in the physiology of platelets, muscles, and neurotransmission. All cells require a balanced number of purines for growth, proliferation, and survival. Under physiological conditions, enzymes involved in purines metabolism maintain a balanced ratio between their synthesis and degradation in the cell. In humans, the final product of purine catabolism is uric acid, while most other mammals possess the enzyme uricase that converts uric acid to allantoin, which can be easily eliminated with urine. During the last decades, hyperuricemia has been associated with a number of human extra-articular diseases (in particular, the cardiovascular ones) and their clinical severity. In this review, we go through the methods of investigation of purine metabolism dysfunctions, looking at the functionality of xanthine oxidoreductase and the formation of catabolites in urine and saliva. Finally, we discuss how these molecules can be used as markers of oxidative stress.
Assuntos
Purinas , Ácido Úrico , Animais , Humanos , Ácido Úrico/metabolismo , Purinas/metabolismo , Adenina , Guanina/metabolismo , Xantina Desidrogenase/metabolismo , Mamíferos/metabolismoRESUMO
Xanthine dehydrogenase (XDH) is the rate-limiting enzyme in purine catabolism by converting hypoxanthine to xanthine and xanthine to uric acid. The altered expression and activity of XDH are associated with the development and prognosis of multiple types of cancer, while its role in lung adenocarcinoma (LUAD) remains unknown. Herein, we demonstrated that XDH was highly expressed in LUAD and was significantly correlated with poor prognosis. Though inhibition of XDH displayed moderate effect on the viability of LUAD cells cultured in the complete medium, it significantly attenuated the survival of starved cells. Similar results were obtained in XDH-knockout cells. Nucleosides supplementation rescued the survival of starved LUAD cells upon XDH inhibition, while inhibition of purine nucleoside phosphorylase abrogated the process, indicating that nucleoside degradation is required for the XDH-mediated survival of LUAD cells. Accordingly, metabolic flux revealed that ribose derived from nucleoside fueled key carbon metabolic pathways to sustain the survival of starved LUAD cells. Mechanistically, down-regulation of XDH suppressed unfolded protein response (UPR) and autophagic flux in starved LUAD cells. Inhibition of XDH decreased the level of amino acids produced by autophagic degradation, which was accompanied with down-regulation of mTORC1 signaling. Supplementation of amino acids including glutamine or glutamate rescued the survival of starved LUAD cells upon knockout or inhibition of XDH. Finally, XDH inhibitors potentiated the anti-cancer activity of 2-deoxy-D-glucose that induced UPR and/or autophagy in vitro and in vivo. In summary, XDH plays a crucial role in the survival of starved LUAD cells and targeting XDH may improve the efficacy of drugs that induce UPR and autophagy in the therapy of LUAD.
Assuntos
Adenocarcinoma de Pulmão , Neoplasias Pulmonares , Humanos , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo , Nucleosídeos/metabolismo , Adenocarcinoma de Pulmão/genética , Autofagia/genética , Resposta a Proteínas não Dobradas , Neoplasias Pulmonares/patologia , Xantinas , Nutrientes , Aminoácidos/metabolismoRESUMO
De novo purine biosynthesis is required for the incorporation of fixed nitrogen in ureide exporting nodules, as formed on soybean [Glycine max (L.) Merr.] roots. However, in many cases, the enzymes involved in this pathway have been deduced strictly from genome annotations with little direct genetic evidence, such as mutant studies, to confirm their biochemical function or importance to nodule development. While efforts to develop large mutant collections of soybean are underway, research on this plant is still hampered by the inability to obtain mutations in any specific gene of interest. Using a forward genetic approach, as well as CRISPR/Cas9 gene editing via Agrobacterium rhizogenes-mediated hairy root transformation, we identified and characterized the role of GmUOX (Uricase) and GmXDH (Xanthine Dehydrogenase) in nitrogen fixation and nodule development in soybean. The gmuox knockout soybean mutants displayed nitrogen deficiency chlorosis and early nodule senescence, as exemplified by the reduced nitrogenase (acetylene reduction) activity in nodules, the internal greenish-white internal appearance of nodules, and diminished leghemoglobin production. In addition, gmuox1 nodules showed collapsed infected cells with degraded cytoplasm, aggregated bacteroids with no discernable symbiosome membranes, and increased formation of poly-ß-hydroxybutyrate granules. Similarly, knockout gmxdh mutant nodules, generated with the CRISPR/Cas9 system, also exhibited early nodule senescence. These genetic studies confirm the critical role of the de novo purine metabolisms pathway not only in the incorporation of fixed nitrogen but also in the successful development of a functional, nitrogen-fixing nodule. Furthermore, these studies demonstrate the great utility of the CRISPR/Cas9 system for studying root-associated gene traits when coupled with hairy root transformation.
Assuntos
Glycine max , Fixação de Nitrogênio , Glycine max/genética , Glycine max/microbiologia , Fixação de Nitrogênio/genética , Urato Oxidase/metabolismo , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo , Nitrogênio/metabolismo , PurinasRESUMO
Autophagy is a highly conserved cellular process that profoundly impacts the efficacy of genotoxic chemotherapeutic drugs. TGF-ß-activated kinase 1 (TAK1) is a serine/threonine kinase that activates several signaling pathways involved in inducing autophagy and suppressing cell death. Xanthine oxidoreductase (XOR) is a rate-limiting enzyme that converts hypoxanthine to xanthine, and xanthine to uric acid and hydrogen peroxide in the purine catabolism pathway. Recent studies showed that uric acid can bind to TAK1 and prolong its activation. We hypothesized that genotoxic drugs may induce autophagy and apoptosis resistance by activating TAK1 through XOR-generated uric acid. Here, we report that gemcitabine and 5-fluorouracil (5-FU), two genotoxic drugs, induced autophagy in HeLa and HT-29 cells by activating TAK1 and its two downstream kinases, AMP-activated kinase (AMPK) and c-Jun terminal kinase (JNK). XOR knockdown and the XOR inhibitor allopurinol blocked gemcitabine-induced TAK1, JNK, AMPK, and Unc51-like kinase 1 (ULK1)S555 phosphorylation and gemcitabine-induced autophagy. Inhibition of the ATM-Chk pathway, which inhibits genotoxic drug-induced uric acid production, blocked gemcitabine-induced autophagy by inhibiting TAK1 activation. Exogenous uric acid in its salt form, monosodium urate (MSU), induced autophagy by activating TAK1 and its downstream kinases JNK and AMPK. Gene knockdown or the inhibitors of these kinases blocked gemcitabine- and MSU-induced autophagy. Inhibition of autophagy by allopurinol, chloroquine, and 5Z-7-oxozeaenol (5Z), a TAK1-specific inhibitor, enhanced gemcitabine-induced apoptosis. Our study uncovers a previously unrecognized role of XOR in regulating genotoxic drug-induced autophagy and apoptosis and has implications for designing novel therapeutic strategies for cancer treatment.
Assuntos
Ácido Úrico , Xantina Desidrogenase , Humanos , Ácido Úrico/farmacologia , Ácido Úrico/metabolismo , Xantina Desidrogenase/genética , Xantina Desidrogenase/metabolismo , Alopurinol , Proteínas Quinases Ativadas por AMP/metabolismo , MAP Quinase Quinase Quinases/metabolismo , Autofagia , Dano ao DNA , ApoptoseRESUMO
In both animals and higher plants, xanthine dehydrogenase is a highly conserved housekeeping enzyme in purine degradation where it oxidizes hypoxanthine to xanthine and xanthine to uric acid. Previous reports demonstrated that xanthine dehydrogenase played a vital role in N metabolism and stress response. Is xanthine dehydrogenase involved in regulating leaf senescence? A recessive early senescence mutant with excess sugar accumulation, ossac3, was isolated previously by screening the EMS-induced mutant library. Here, we show that xanthine dehydrogenase not only plays a role in N metabolism but also involved in regulating carbon metabolism in rice. Based on map-based cloning, OsSAC3 was identified, which encodes the xanthine dehydrogenase. OsSAC3 was constitutively expressed in all examined tissues and the OsSAC3 protein located in the cytoplasm. Transcriptional analysis revealed purine metabolism, chlorophyll metabolism, photosynthesis, sugar metabolism and redox balance were affected in the ossac3 mutant. Moreover, carbohydrate distribution was changed, leading to the accumulation of sucrose and starch in the leaves containing ossac3 on account of decreased expression of OsSWEET3a, OsSWEET6a and OsSWEET14 and oxidized inactivation of starch degradation enzymes in ossac3. These results indicated that OsSAC3 played a vital role in leaf senescence by regulating carbon metabolism in rice.