Classical homocystinuria (HCU) is the most common inherited disorder of sulfur amino acid metabolism caused by deficiency in cystathionine beta-synthase (CBS) activity and characterized by severe elevation of homocysteine in blood and tissues. Treatment with dietary methionine restriction is not optimal, and poor compliance leads to serious complications. We developed an enzyme replacement therapy (ERT) and studied its efficacy in a severe form of HCU in mouse (the I278T model). Treatment was initiated before or after the onset of clinical symptoms in an effort to prevent or reverse the phenotype. ERT substantially reduced and sustained plasma homocysteine concentration at around 100 μM and normalized plasma cysteine for up to 9 months of treatment. Biochemical balance was also restored in the liver, kidney, and brain. Furthermore, ERT corrected liver glucose and lipid metabolism. The treatment prevented or reversed facial alopecia, fragile and lean phenotype, and low bone mass. In addition, structurally defective ciliary zonules in the eyes of I278T mice contained low density and/or broken fibers, while administration of ERT from birth partially rescued the ocular phenotype. In conclusion, ERT maintained an improved metabolic pattern and ameliorated many of the clinical complications in the I278T mouse model of HCU.

• Klíčová slova
• PEGylation, alopecia, bone density, cystathionine beta-synthase, enzyme replacement, eye defect, homocysteine, inborn error of metabolism, metabolomics, preclinical studies,
• MeSH
• aminokyseliny sírové krev   metabolismus   MeSH
• cystathionin-beta-synthasa aplikace a dávkování   chemie   MeSH
• enzymová substituční terapie * MeSH
• fenotyp * MeSH
• glukosa metabolismus   MeSH
• homocystinurie diagnóza   metabolismus   terapie   MeSH
• játra účinky léků   metabolismus   MeSH
• metabolismus lipidů MeSH
• modely nemocí na zvířatech MeSH
• myši MeSH
• oxidační stres MeSH
• polyethylenglykoly chemie   MeSH
• preklinické hodnocení léčiv MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• aminokyseliny sírové MeSH
• cystathionin-beta-synthasa MeSH
• glukosa MeSH
• polyethylenglykoly MeSH

Cystathionine beta-synthase (CBS) deficiency is a rare inherited disorder in the methionine catabolic pathway, in which the impaired synthesis of cystathionine leads to accumulation of homocysteine. Patients can present to many different specialists and diagnosis is often delayed. Severely affected patients usually present in childhood with ectopia lentis, learning difficulties and skeletal abnormalities. These patients generally require treatment with a low-methionine diet and/or betaine. In contrast, mildly affected patients are likely to present as adults with thromboembolism and to respond to treatment with pyridoxine. In this article, we present recommendations for the diagnosis and management of CBS deficiency, based on a systematic review of the literature. Unfortunately, the quality of the evidence is poor, as it often is for rare diseases. We strongly recommend measuring the plasma total homocysteine concentrations in any patient whose clinical features suggest the diagnosis. Our recommendations may help to standardise testing for pyridoxine responsiveness. Current evidence suggests that patients are unlikely to develop complications if the plasma total homocysteine concentration is maintained below 120 μmol/L. Nevertheless, we recommend keeping the concentration below 100 μmol/L because levels fluctuate and the complications associated with high levels are so serious.

• MeSH
• betain metabolismus   MeSH
• cystathionin-beta-synthasa nedostatek   MeSH
• homocystein metabolismus   MeSH
• homocystinurie dietoterapie   farmakoterapie   MeSH
• lidé MeSH
• methionin metabolismus   MeSH
• pyridoxin terapeutické užití   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• systematický přehled MeSH
• Názvy látek
• betain MeSH
• cystathionin-beta-synthasa MeSH
• homocystein MeSH
• methionin MeSH
• pyridoxin MeSH

Misfolding of mutant enzymes may play an important role in the pathogenesis of cystathionine beta-synthase (CBS) deficiency. We examined properties of a series of 27 mutant variants, which together represent 70% of known alleles observed in patients with homocystinuria due to CBS deficiency. The median amount of SDS-soluble mutant CBS polypeptides in the pellet after centrifugation of bacterial extracts was increased by 50% compared to the wild type. Moreover, mutants formed on average only 12% of tetramers and their median activity reached only 3% of the wild-type enzyme. In contrast to the wild-type CBS about half of mutants were not activated by S-adenosylmethionine. Expression at 18 degrees C substantially increased the activity of five mutants in parallel with increasing the amounts of tetramers. We further analyzed the role of solvent accessibility of mutants as a determinant of their folding and activity. Buried mutations formed on average less tetramers and exhibited 23 times lower activity than the solvent exposed mutations. In summary, our results show that topology of mutations predicts in part the behavior of mutant CBS, and that misfolding may be an important and frequent pathogenic mechanism in CBS deficiency.

• MeSH
• cystathionin-beta-synthasa chemie   nedostatek   genetika   MeSH
• Escherichia coli genetika   MeSH
• homocystinurie enzymologie   genetika   MeSH
• katalytická doména genetika   MeSH
• katalýza MeSH
• kvarterní struktura proteinů MeSH
• lidé MeSH
• molekulární modely MeSH
• multimerizace proteinu MeSH
• mutace * MeSH
• mutantní proteiny chemie   genetika   metabolismus   MeSH
• nízká teplota MeSH
• rozpustnost MeSH
• sbalování proteinů MeSH
• stabilita enzymů MeSH
• terciární struktura proteinů MeSH
• western blotting MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cystathionin-beta-synthasa MeSH
• mutantní proteiny MeSH