This review summarises progress in the research of homocystinuria (HCU) in the past three decades. HCU due to cystathionine β-synthase (CBS) was discovered in 1962, and Prof. Jan Peter Kraus summarised developments in the field in the first-ever Komrower lecture in 1993. In the past three decades, significant advancements have been achieved in the biology of CBS, including gene organisation, tissue expression, 3D structures, and regulatory mechanisms. Renewed interest in CBS arose in the late 1990s when this enzyme was implicated in biogenesis of H2S. Advancements in genetic and biochemical techniques enabled the identification of several hundreds of pathogenic CBS variants and the misfolding of missense mutations as a common mechanism. Several cellular, invertebrate and murine HCU models allowed us to gain insights into functional and metabolic pathophysiology of the disease. Establishing the E-HOD consortium and patient networks, HCU Network Australia and HCU Network America, offered new possibilities for acquiring clinical data in registries and data on patients' quality of life. A recent analysis of data from the E-HOD registry showed that the clinical variability of HCU is broad, extending from severe childhood disease to milder (late) adulthood forms, which typically respond to pyridoxine. Pyridoxine responsiveness appears to be the key factor determining the clinical course of HCU. Increased awareness about HCU played a role in developing novel therapies, such as gene therapy, correction of misfolding by chaperones, removal of methionine from the gut and enzyme therapies that decrease homocysteine or methionine in the circulation.
Závěrečná zpráva o řešení grantu Agentury pro zdravotnický výzkum MZ ČR
nestr.
Aminokyseliny obsahující síru jsou esenciálními složkami potravy a slouží k syntéze bílkovin a dalších sloučenin nezbytných pro methylační a redoxní reakce. Homocystein je meziproduktem při intracelulárních přeměnách methioninu a je považován za univerzální marker metabolismu sirných látek. V České republice se každoročně provede 65 000-74 000 vyšetření celkového homocysteinu a přibližně 1% výsledků má výrazně abnormální hodnoty. Tyto abnormality mohou být způsobené nerozpoznanými deficity vitaminů skupiny B, závažnými genetickými nemocemi a dalšími příčinami. Předmětem tohoto projektu je systematická analýza příčin výrazné hyperhomocysteinemie a hypohomocysteinemie v české populaci jako podklad pro personalizovanou péči. Řešení projektu má následující cíle: a/identifikovat osoby s výrazně abnormálními koncentracemi celkového homocysteinu ve spolupracujících pracovištích; b/vyšetřit příčinu kombinací cílené analýzy vitaminů a sirných sloučenin a dále metodami sekvenování nové generace a c/vypracovat národní doporučení pro vyšetřování celkového homocysteinu a následnou péči.; Sulfur amino acids are essential nutrients needed for proteosynthesis and production of compounds that are necessary for methylations and redox reactions. Homocysteine is an intermediate in the intracellular methionine turnover and may serve as a universal marker of sulfur metabolism. Each year about 65,000-74,000 total homocysteine analyses are performed in the Czech Republic and about 1% are grossly abnormal. These abnormalities may be caused by unrecognized B-vitamin deficiencies, severe genetic defects and other culprits. This project is focused on systematic analysis of the causes of intermediate hyperhomocysteinemia and of hypohomocysteinemia in the Czech population as a basis for personalized management. The project aims are as follows: as/to identify subject with severely abnormal total homocysteine concentrations in collaborating departments, b/to examine etiology by a combination of targeted vitamin analysis, analysis of sulfur compounds and next generation sequencing, and c/to develop national recommendations on total homocysteine testing and patient care.
- Klíčová slova
- genetika, genetics, sekvenování nové generace (NGS), foláty, homocystein, homocystinurie, vitamin B12, homocystinuria, Metabolomika, Metabolomics, vitamín B12, Hyperhomocysteinemie, Hypohomocysteinemie, Homocysteine, Hyperhomocysteinemia, Hypohomocysteinemia, Folates, Next-Generation Sequencing (NGS),
- NLK Publikační typ
- závěrečné zprávy o řešení grantu AZV MZ ČR
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.
- 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
Cystathionine β-synthase (CBS) deficiency has a wide clinical spectrum, ranging from neurodevelopmental problems, lens dislocation and marfanoid features in early childhood to adult onset disease with predominantly thromboembolic complications. We have analysed clinical and laboratory data at the time of diagnosis in 328 patients with CBS deficiency from the E-HOD (European network and registry for Homocystinurias and methylation Defects) registry. We developed comprehensive criteria to classify patients into four groups of pyridoxine responsivity: non-responders (NR), partial, full and extreme responders (PR, FR and ER, respectively). All groups showed overlapping concentrations of plasma total homocysteine while pyridoxine responsiveness inversely correlated with plasma/serum methionine concentrations. The FR and ER groups had a later age of onset and diagnosis and a longer diagnostic delay than NR and PR patients. Lens dislocation was common in all groups except ER but the age of dislocation increased with increasing responsiveness. Developmental delay was commonest in the NR group while no ER patient had cognitive impairment. Thromboembolism was the commonest presenting feature in ER patients, whereas it was least likely at presentation in the NR group. This probably is due to the differences in ages at presentation: all groups had a similar number of thromboembolic events per 1000 patient-years. Clinical severity of CBS deficiency depends on the degree of pyridoxine responsiveness. Therefore, a standardised pyridoxine-responsiveness test in newly diagnosed patients and a critical review of previous assessments is indispensable to ensure adequate therapy and to prevent or reduce long-term complications.
- MeSH
- cystathionin-beta-synthasa nedostatek MeSH
- dítě MeSH
- dospělí MeSH
- fenotyp MeSH
- homocystinurie diagnóza farmakoterapie enzymologie MeSH
- kojenec MeSH
- lidé středního věku MeSH
- lidé MeSH
- lineární modely MeSH
- methionin krev MeSH
- mladiství MeSH
- mladý dospělý MeSH
- opožděná diagnóza MeSH
- předškolní dítě MeSH
- pyridoxin terapeutické užití MeSH
- registrace MeSH
- senioři MeSH
- stupeň závažnosti nemoci MeSH
- Check Tag
- dítě MeSH
- dospělí MeSH
- kojenec MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- předškolní dítě MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Evropa MeSH
Závěrečná zpráva o řešení grantu Agentury pro zdravotnický výzkum MZ ČR
Nestr.
Metabolický syndrom je rizikový faktor pro atherosklerózu a diabetes 2.typu a patří mezi populačně významné stavy, naproti tomu homocystinurie s postižením cévního systému patří mezi vzácné genetické nemoci. U obou těchto zdánlivě nesouvisejících chorob však byly nalezeny změny v metabolismu cysteinu i sirovodíku. Ve studii použijeme metody cílené metabolomiky pro stanovení látek souvisejících s metabolismem cysteinu (včetně látek odrážejících syntézu a katabolismus sirovodíku) ve vzorcích plasmy získaných od pacientů s homocystinuriemi, obézních pacientů a kontrol, a dále v kultivovaných lidských buňkách. Pro porozumění orgánově specifickým změnám doplníme výzkum na humánních vzorcích studiem tkání u zvířecích modelů. Řešení tohoto projektu objasní detailně úlohu cysteinu a sirovodíku u dvou skupin nemocí a umožní tak vývoj nových postupů personalizované medicíny zacílených na určitá místa metabolických drah; tyto postupy budou využitelné při léčbě metabolického syndromu či jeho komponent a pro zmírnění komplikací u pacientů s homocystinuriemi.; Metabolic syndrome-a risk factor for arteriosclerosis and diabetes type 2- is one of the major population health burdens while homocystinurias are rare genetic disorders complicated also by vascular disease. These seemingly unrelated conditions, however, have been both linked to disturbed metabolism of sulfur compounds including cysteine and hydrogen sulfide. We will use targeted metabolomics approach for determination of compounds related to cysteine metabolism (including markers of hydrogen sulfide synthesis and catabolism) in plasma samples obtained from patients with homocystinurias, obese patients and controls, and in cultured human cells; to get further insight into organ-specific changes we will complement research in humans by studying tissues from animal models. This project will elucidate the role of cysteine and hydrogen sulfide in selected diseases and will facilitate development of novel personalized approaches to treat metabolic syndrome or its components, and to ameliorate complications in homocystinurias by targeting specific parts of relevant metabolic pathways.
- MeSH
- cystein metabolismus MeSH
- homocystinurie etiologie metabolismus MeSH
- kultivované buňky MeSH
- lidé MeSH
- metabolický syndrom etiologie metabolismus MeSH
- metabolomika MeSH
- modely nemocí na zvířatech MeSH
- sulfan metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Konspekt
- Patologie. Klinická medicína
- NLK Obory
- vnitřní lékařství
- neurologie
- NLK Publikační typ
- závěrečné zprávy o řešení grantu AZV MZ ČR
PURPOSE OF REVIEW: Metabolism of sulfur amino acids (SAA) provides compounds important for many cellular functions. Inherited disorders of SAA metabolism are typically severe multisystemic diseases affecting brain, liver, connective tissue, or vasculature. The review summarizes the present therapeutic approaches and advances in identifying novel treatment targets, and provides an overview of new therapies. RECENT FINDINGS: Current treatments of genetic disorders of SAA metabolism are primarily based on modulation of affected pathways by dietary measures and provision of lacking products or scavenging of toxic molecules. Recent studies identified additional therapeutic targets distant from the primary defects and explored ideas envisioning novel treatments, such as chaperone and gene therapy. Recombinant protein production and engineering resulted in development and clinical testing of enzyme therapies for cystathionine β-synthase deficiency, the most common inborn error of SAA metabolism. SUMMARY: Complex regulation of pathways involved in SAA metabolism and cellular consequences of genetic defects in SAA metabolism are only partially understood. There is a pressing need to increase substantially our knowledge of the disease mechanisms to develop more effective therapies for patients suffering from these rare disorders.
- MeSH
- aminokyseliny sírové * MeSH
- dieta MeSH
- homocystinurie * MeSH
- játra MeSH
- lidé MeSH
- mozek MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
The metabolism of sulfur-containing amino acids (SAAs) requires an orchestrated interplay among several dozen enzymes and transporters, and an adequate dietary intake of methionine (Met), cysteine (Cys), and B vitamins. Known human genetic disorders are due to defects in Met demethylation, homocysteine (Hcy) remethylation, or cobalamin and folate metabolism, in Hcy transsulfuration, and Cys and hydrogen sulfide (H2S) catabolism. These disorders may manifest between the newborn period and late adulthood by a combination of neuropsychiatric abnormalities, thromboembolism, megaloblastic anemia, hepatopathy, myopathy, and bone and connective tissue abnormalities. Biochemical features include metabolite deficiencies (e.g. Met, S-adenosylmethionine (AdoMet), intermediates in 1-carbon metabolism, Cys, or glutathione) and/or their accumulation (e.g. S-adenosylhomocysteine, Hcy, H2S, or sulfite). Treatment should be started as early as possible and may include a low-protein/low-Met diet with Cys-enriched amino acid supplements, pharmacological doses of B vitamins, betaine to stimulate Hcy remethylation, the provision of N-acetylcysteine or AdoMet, or experimental approaches such as liver transplantation or enzyme replacement therapy. In several disorders, patients are exposed to long-term markedly elevated Met concentrations. Although these conditions may inform on Met toxicity, interpretation is difficult due to the presence of additional metabolic changes. Two disorders seem to exhibit Met-associated toxicity in the brain. An increased risk of demyelination in patients with Met adenosyltransferase I/III (MATI/III) deficiency due to biallelic mutations in the MATIA gene has been attributed to very high blood Met concentrations (typically >800 μmol/L) and possibly also to decreased liver AdoMet synthesis. An excessively high Met concentration in some patients with cystathionine β-synthase deficiency has been associated with encephalopathy and brain edema, and direct toxicity of Met has been postulated. In summary, studies in patients with various disorders of SAA metabolism showed complex metabolic changes with distant cellular consequences, most of which are not attributable to direct Met toxicity.
- MeSH
- aminokyseliny sírové metabolismus MeSH
- cystein metabolismus MeSH
- glutathion metabolismus MeSH
- homocystein metabolismus MeSH
- homocystinurie etiologie metabolismus MeSH
- játra metabolismus MeSH
- lidé MeSH
- metabolické nemoci genetika metabolismus patologie terapie MeSH
- methionin metabolismus MeSH
- methioninadenosyltransferasa metabolismus MeSH
- metylace MeSH
- nemoci mozku etiologie metabolismus MeSH
- S-adenosylmethionin metabolismus MeSH
- síra metabolismus MeSH
- siřičitany metabolismus MeSH
- sloučeniny síry metabolismus MeSH
- sulfan metabolismus MeSH
- vrozené poruchy metabolismu patologie terapie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
BACKGROUND AND PURPOSE: Homocystinurias are rare genetic defects characterized by altered fluxes of sulfur compounds including homocysteine and cysteine. We explored whether the severely perturbed sulfur amino acid metabolism in patients with homocystinurias affects the metabolism of hydrogen sulfide. EXPERIMENTAL APPROACH: We studied 10 treated patients with a block in the conversion of homocysteine to cysteine due to cystathionine β-synthase deficiency (CBSD) and six treated patients with remethylation defects (RMD) and an enhanced flux of sulfur metabolites via transsulfuration. Control groups for CBSD and RMD patients consisted of 22 patients with phenylketonuria on a low-protein diet and of 12 healthy controls respectively. Plasma and urine concentrations of selected sulfur compounds were analysed by HPLC and LC-MS/MS. KEY RESULTS: Patients with CBSD exhibited plasma concentrations of monobromobimane-detected sulfide similar to appropriate controls. Urinary homolanthionine and thiosulfate in CBSD were increased significantly 1.9 and 3 times suggesting higher hydrogen sulfide synthesis by γ-cystathionase and detoxification respectively. Surprisingly, patients with RMD had significantly lower plasma sulfide levels (53 and 64% of controls) with lower sulfite concentrations, and higher taurine and thiosulfate levels suggesting enhanced cysteine oxidation and hydrogen sulfide catabolism respectively. CONCLUSION AND IMPLICATIONS: The results from this study suggest that severe inherited defects in sulfur amino acid metabolism may be accompanied by only moderately perturbed hydrogen sulfide metabolism and lends support to the hypothesis that enzymes in the transsulfuration pathway may not be the major contributors to the endogenous hydrogen sulfide pool. LINKED ARTICLES: This article is part of a themed section on Chemical Biology of Reactive Sulfur Species. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.4/issuetoc.
- MeSH
- dítě MeSH
- dospělí MeSH
- homocystinurie krev metabolismus moč MeSH
- kojenec MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- předškolní dítě MeSH
- sloučeniny síry krev metabolismus moč MeSH
- Check Tag
- dítě MeSH
- dospělí MeSH
- kojenec MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- předškolní dítě MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Two enzymes in the transsulfuration pathway of homocysteine -cystathionine beta-synthase (CBS) and gamma-cystathionase (CTH)-use cysteine and/or homocysteine to produce the important signaling molecule hydrogen sulfide (H2S) and simultaneously the thioethers lanthionine, cystathionine or homolanthionine. In this study we explored whether impaired flux of substrates for H2S synthesis and/or deficient enzyme activities alter production of hydrogen sulfide in patients with homocystinurias. As an indirect measure of H2S synthesis we determined by LC-MS/MS concentrations of thioethers in plasma samples from 33 patients with different types of homocystinurias, in 8 patient derived fibroblast cell lines, and as reaction products of seven purified mutant CBS enzymes. Since chaperoned recombinant mutant CBS enzymes retained capacity of H2S synthesis in vitro it can be stipulated that deficient CBS activity in vivo may impair H2S production. Indeed, in patients with classical homocystinuria we observed significantly decreased cystathionine and lanthionine concentrations in plasma (46% and 74% of median control levels, respectively) and significantly lower cystathionine in fibroblasts (8% of median control concentrations) indicating that H2S production from cysteine and homocysteine may be also impaired. In contrast, the grossly elevated plasma levels of homolanthionine in CBS deficient patients (32-times elevation compared to median of controls) clearly demonstrates a simultaneous overproduction of H2S from homocysteine by CTH. In the remethylation defects the accumulation of homocysteine and the increased flux of metabolites through the transsulfuration pathway resulted in elevation of cystathionine and homolanthionine (857% and 400% of median control values, respectively) indicating a possibility of an increased biosynthesis of H2S by both CBS and CTH. This study shows clearly disturbed thioether concentrations in homocystinurias, and modeling using these data indicates that H2S synthesis may be increased in these conditions. Further studies are needed to confirm our findings and to explore the possible implications for pathophysiology of these disorders.
- MeSH
- alanin analogy a deriváty metabolismus MeSH
- cystathionin-beta-synthasa metabolismus MeSH
- cystathionin metabolismus MeSH
- fibroblasty metabolismus patologie MeSH
- homocystinurie metabolismus patologie MeSH
- kultivované buňky MeSH
- lidé MeSH
- sulfan metabolismus MeSH
- sulfidy metabolismus MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
