UNLABELLED: Xanthinurias are rare inherited disorders of purine metabolism. Xanthinuria type III is caused by molybdenum cofactor deficiency (MoCD) due to pathogenic variants in MOCS1, MOCS2, MOCS3, or GEPH genes. Here, we described five Roma patients from four unrelated families with hypouricemia, accumulation of xanthine/hypoxanthine, deficiency of xanthine oxidase activity, variable age of diagnosis, and only asymptomatic or mild clinical course. Whole exome sequencing was performed on all probands, aged 3 to 43 years, due to lack of genetic confirmation for xanthinuria types I and II. The causality of the putative pathogenic variant was confirmed by analysis of sulfite and related metabolites and in vitro functional characterization of metal-binding pterin (MPT) synthesis and protein complex formation. Considering the rarity of the condition and recessive inheritance, 34 candidate variants were identified after filtering out allele frequency threshold in non-Finnish Europeans. An ultra-rare MOCS2 variant rs776441627 in two overlapping reading frames (c.244A > T (NM_176806.4; p.Ile82Phe) = c.57A > T (NM_004531.5; p.Leu19Phe)) segregated with the disease in all five patients (four homozygotes, one compound heterozygote). The variant has an allele frequency of 3.6% in a Roma population control group. Functional characterization revealed the significantly decreased MPT synthesis activity and confirmed the causality of rs776441627 in MoCD. CONCLUSION: The rs776441627 is a functional variant for MoCD with a mild to asymptomatic clinical phenotype and fully penetrant biochemical phenotype. Hypouricemia should be considered in the differential diagnostic algorithm of pediatric and adult patients with neurological symptoms, and MOCS2 should be considered in gene panels for xanthinuria screening. WHAT IS KNOWN: • Xanthinuria type III is caused by molybdenum cofactor deficiency (MoCD) due to pathogenic variants in MOCS1, MOCS2, MOCS3, or GEPH genes. • The majority of patients with xanthinuria III present with classical early-onset MoCD due to autosomal recessive variants in the MOCS1 gene, manifesting severe progressive neurological complications during the first postnatal days. • To date, approximately 40 patients with MoCD due to pathogenic MOCS2 variants have been reported; most were diagnosed during the neonatal period with intractable seizures and feeding disorders. WHAT IS NEW: • A novel ultra-rare variant, rs776441627, located in two overlapping reading frames of the MOCS2, was identified in five Roma patients presenting a mild to asymptomatic clinical MoCD phenotype and a fully penetrant biochemical phenotype. • Functional studies of p.Ile82Phe (small MOCS2A subunit) and p.Leu19Phe (large MOCS2B subunit) demonstrate a strong reduction in molydopterin synthase complex formation and activity, consistent with the changes in biomarkers of MoCD observed in affected individuals. • The rs776441627 variant shows significantly elevated frequency among the Roma population, highlighting the importance of considering ethnic background in the differential diagnosis of MoCD. • Hypouricemia may provide an initial, generally available biochemical key marker indicator of molybdenum cofactor deficiency.

• Klíčová slova
• Genetic screening test, MOCS, MoCD, Sulfite, Uric acid, Xanthinuria,
• MeSH
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• molybdenové kofaktory MeSH
• předškolní dítě MeSH
• rodokmen MeSH
• Romové * genetika   MeSH
• sekvenování exomu MeSH
• sulfurtransferasy * genetika   MeSH
• vrozené poruchy metabolismu kovů * genetika   etnologie   diagnóza   MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• molybdenové kofaktory MeSH
• sulfurtransferasy * MeSH

BACKGROUND: Cystathionine β-synthase (CBS)-deficient homocystinuria (HCU) is an inherited disorder of sulfur amino acid metabolism with varying severity and organ complications, and a limited knowledge about underlying pathophysiological processes. Here we aimed at getting an in-depth insight into disease mechanisms using a transgenic mouse model of HCU (I278T). METHODS: We assessed metabolic, proteomic and sphingolipidomic changes, and mitochondrial function in tissues and body fluids of I278T mice and WT controls. Furthermore, we evaluated the efficacy of methionine-restricted diet (MRD) in I278T mice. RESULTS: In WT mice, we observed a distinct tissue/body fluid compartmentalization of metabolites with up to six-orders of magnitude differences in concentrations among various organs. The I278T mice exhibited the anticipated metabolic imbalance with signs of an increased production of hydrogen sulfide and disturbed persulfidation of free aminothiols. HCU resulted in a significant dysregulation of liver proteome affecting biological oxidations, conjugation of compounds, and metabolism of amino acids, vitamins, cofactors and lipids. Liver sphingolipidomics indicated upregulation of the pro-proliferative sphingosine-1-phosphate signaling pathway. Liver mitochondrial function of HCU mice did not seem to be impaired compared to controls. MRD in I278T mice improved metabolic balance in all tissues and substantially reduced dysregulation of liver proteome. CONCLUSION: The study highlights distinct tissue compartmentalization of sulfur-related metabolites in normal mice, extensive metabolome, proteome and sphingolipidome disruptions in I278T mice, and the efficacy of MRD to alleviate some of the HCU-related biochemical abnormalities.

• Klíčová slova
• Cystathionine beta-synthase, Homocystinuria, Metabolomics, Methionine restriction, Proteomics,
• MeSH
• cystathionin-beta-synthasa * metabolismus   nedostatek   genetika   MeSH
• homocystinurie * metabolismus   genetika   MeSH
• játra * metabolismus   MeSH
• lipidomika metody   MeSH
• metabolomika * metody   MeSH
• mitochondrie metabolismus   MeSH
• modely nemocí na zvířatech * MeSH
• myši transgenní * MeSH
• myši MeSH
• proteom metabolismus   MeSH
• proteomika * metody   MeSH
• sfingolipidy * metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cystathionin-beta-synthasa * MeSH
• proteom MeSH
• sfingolipidy * MeSH

BACKGROUND: In animals, dietary sulfur amino acid restriction (SAAR) improves metabolic health, possibly mediated by altering sulfur amino acid metabolism and enhanced anti-obesogenic processes in adipose tissue. AIM: To assess the effects of SAAR over time on the plasma and urine SAA-related metabolites (sulfurome) in humans with overweight and obesity, and explore whether such changes were associated with body weight, body fat and adipose tissue gene expression. METHODS: Fifty-nine subjects were randomly allocated to SAAR (∼2 g SAA, n = 31) or a control diet (∼5.6 g SAA, n = 28) consisting of plant-based whole-foods and supplemented with capsules to titrate contents of SAA. Sulfurome metabolites in plasma and urine at baseline, 4 and 8 weeks were measured using HPLC and LC-MS/MS. mRNA-sequencing of subcutaneous white adipose tissue (scWAT) was performed to assess changes in gene expression. Data were analyzed with mixed model regression. Principal component analyses (PCA) were performed on the sulfurome data to identify potential signatures characterizing the response to SAAR. RESULTS: SAAR led to marked decrease of the main urinary excretion product sulfate (p < 0.001) and plasma and/or 24-h urine concentrations of cystathionine, sulfite, thiosulfate, H2S, hypotaurine and taurine. PCA revealed a distinct metabolic signature related to decreased transsulfuration and H2S catabolism that predicted greater weight loss and android fat mass loss in SAAR vs. controls (all pinteraction < 0.05). This signature correlated positively with scWAT expression of genes in the tricarboxylic acid cycle, electron transport and β-oxidation (FDR = 0.02). CONCLUSION: SAAR leads to distinct alterations of the plasma and urine sulfurome in humans, and predicted increased loss of weight and android fat mass, and adipose tissue lipolytic gene expression in scWAT. Our data suggest that SAA are linked to obesogenic processes and that SAAR may be useful for obesity and related disorders. TRIAL IDENTIFIER: https://clinicaltrials.gov/study/NCT04701346.

• Klíčová slova
• Adipose tissue, Cysteine, Gene expression, Hydrogen sulfide, Methionine, Randomized controlled trial, Sulfur amino acid restriction, Transsulfuration,
• MeSH
• aminokyseliny sírové * metabolismus   krev   MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• metabolom MeSH
• nadváha * metabolismus   genetika   MeSH
• obezita * metabolismus   genetika   MeSH
• regulace genové exprese MeSH
• tuková tkáň * metabolismus   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• randomizované kontrolované studie MeSH
• Názvy látek
• aminokyseliny sírové * MeSH

Regulation of H2S homeostasis in humans is poorly understood. Therefore, we assessed the importance of individual enzymes in synthesis and catabolism of H2S by studying patients with respective genetic defects. We analyzed sulfur compounds (including bioavailable sulfide) in 37 untreated or insufficiently treated patients with seven ultrarare enzyme deficiencies and compared them to 63 controls. Surprisingly, we observed that patients with severe deficiency in cystathionine β-synthase (CBS) or cystathionine γ-lyase (CSE) - the enzymes primarily responsible for H2S synthesis - exhibited increased and normal levels of bioavailable sulfide, respectively. However, an approximately 21-fold increase of urinary homolanthionine in CBS deficiency strongly suggests that lacking CBS activity is compensated for by an increase in CSE-dependent H2S synthesis from accumulating homocysteine, which suggests a control of H2S homeostasis in vivo. In deficiency of sulfide:quinone oxidoreductase - the first enzyme in mitochondrial H2S oxidation - we found normal H2S concentrations in a symptomatic patient and his asymptomatic sibling, and elevated levels in an asymptomatic sibling, challenging the requirement for this enzyme in catabolizing H2S under physiological conditions. Patients with ethylmalonic encephalopathy and sulfite oxidase/molybdenum cofactor deficiencies exhibited massive accumulation of thiosulfate and sulfite with formation of large amounts of S-sulfocysteine and S-sulfohomocysteine, increased renal losses of sulfur compounds and concomitant strong reduction in plasma total cysteine. Our results demonstrate the value of a comprehensive assessment of sulfur compounds in severe disorders of homocysteine/cysteine metabolism and provide evidence for redundancy and compensatory mechanisms in the maintenance of H2S homeostasis.

• Klíčová slova
• Cystathionine β-synthase, Cystathionine γ-lyase, Molybdenum cofactor, Persulfide dioxygenase, Sulfide:quinone oxidoreductase, Sulfite oxidase,
• MeSH
• cystein MeSH
• homeostáza MeSH
• homocystein MeSH
• lidé MeSH
• síra MeSH
• sulfan * metabolismus   MeSH
• sulfidy metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cystein MeSH
• homocystein MeSH
• síra MeSH
• sulfan * MeSH
• sulfidy MeSH

Increased plasma total cysteine (tCys) has been associated with obesity and metabolic syndrome in human and some animal studies but the underlying mechanisms remain unclear. In this study, we aimed at evaluating the effects of high cysteine diet administered to SHR-CRP transgenic rats, a model of metabolic syndrome and inflammation. SHR-CRP rats were fed either standard (3.2 g cystine/kg diet) or high cysteine diet (HCD, enriched with additional 4 g L-cysteine/kg diet). After 4 weeks, urine, plasma and tissue samples were collected and parameters of metabolic syndrome, sulfur metabolites and hepatic gene expression were evaluated. Rats on HCD exhibited similar body weights and weights of fat depots, reduced levels of serum insulin, and reduced oxidative stress in the liver. The HCD did not change concentrations of tCys in tissues and body fluids while taurine in tissues and body fluids, and urinary sulfate were significantly increased. In contrast, betaine levels were significantly reduced possibly compensating for taurine elevation. In summary, increased Cys intake did not induce obesity while it ameliorated insulin resistance in the SHR-CRP rats, possibly due to beneficial effects of accumulating taurine.

• MeSH
• adipozita * MeSH
• cystein metabolismus   farmakologie   MeSH
• inzulinová rezistence * MeSH
• krysa rodu Rattus MeSH
• metabolismus lipidů MeSH
• potkani inbrední SHR MeSH
• potkani transgenní MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cystein MeSH

BACKGROUND: Dietary sulfur amino acid (SAA) restriction is an established animal model for increasing lifespan and improving metabolic health. Data from human studies are limited. In the study outlined in this protocol, we will evaluate if dietary SAA restriction can reduce body weight and improve resting energy expenditure (REE) and parameters related to metabolic health. METHOD/DESIGN: Men and women (calculated sample size = 60), aged 18-45 years, with body mass index of 27-35 kg/m2 will be included in a double-blind 8-week dietary intervention study. The participants will be randomized in a 1:1 manner to a diet with either low or high SAA. Both groups will receive an equal base diet consisting of low-SAA plant-based whole foods and an amino acid supplement free of SAA. Contrasting SAA contents will be achieved using capsules with or without methionine and cysteine (SAAhigh, total diet SAA ~ 50-60 mg/kg body weight/day; SAAlow, total diet SAA ~ 15-25 mg/kg body weight/day). The primary outcome is body weight change. Data and material collection will also include body composition (dual X-ray absorptiometry), resting energy expenditure (whole-room indirect calorimetry) and samples of blood, urine, feces and adipose tissue at baseline, at 4 weeks and at study completion. Measures will be taken to promote and monitor diet adherence. Data will be analyzed using linear mixed model regression to account for the repeated measures design and within-subject correlation. DISCUSSION: The strength of this study is the randomized double-blind design. A limitation is the restrictive nature of the diet which may lead to poor compliance. If this study reveals a beneficial effect of the SAAlow diet on body composition and metabolic health, it opens up for new strategies for prevention and treatment of overweight, obesity and its associated disorders. Trial registration ClinicalTrials.gov: NCT04701346, Registration date: January 8th, 2021.

• Klíčová slova
• Adipose tissue, Cysteine restriction, Dietary intervention, Gene expression, Metabolic health, Methionine restriction, Obesity, Plasma biomarkers, Sulfur amino acids, Translational research,
• MeSH
• aminokyseliny sírové * MeSH
• aminokyseliny MeSH
• dospělí MeSH
• energetický metabolismus MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• obezita * MeSH
• randomizované kontrolované studie jako téma MeSH
• složení těla MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• protokol klinické studie MeSH
• Názvy látek
• aminokyseliny sírové * MeSH
• aminokyseliny MeSH