Enzyme replacement with PEGylated cystathionine β-synthase ameliorates homocystinuria in murine model

Bublil, Erez M.; Majtán, Tomáš; Park, Insun; Carrillo, Richard S.; Hůlková, Helena; Krijt, Jakub; Kožich, Viktor; Kraus, Jan P.

doi:10.1172/jci85396

Cited by 39 publications

(82 citation statements)

References 37 publications

(41 reference statements)

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“…Previous microscopic evaluation of liver sections from KO mice showed severe steatosis with hepatocellular necrosis (5,6,8,18). These observations were confirmed in this study in the untreated KO mice.…”

Section: Discussionsupporting

confidence: 90%

Enzyme replacement prevents neonatal death, liver damage, and osteoporosis in murine homocystinuria

et al. 2017

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Classical homocystinuria (HCU) is an inborn error of sulfur amino acid metabolism caused by deficient activity of cystathionine β-synthase (CBS), resulting in an accumulation of homocysteine and a concomitant decrease of cystathionine and cysteine in blood and tissues. In mice, the complete lack of CBS is neonatally lethal. In this study, newborn CBS-knockout (KO) mice were treated with recombinant polyethyleneglycolylated human truncated CBS (PEG-CBS). Full survival of the treated KO mice, along with a positive impact on metabolite levels in plasma, liver, brain, and kidneys, was observed. The PEG-CBS treatment prevented an otherwise fatal liver disease characterized by steatosis, death of hepatocytes, and ultrastructural abnormalities of endoplasmic reticulum and mitochondria. Furthermore, treatment of the KO mice for 5 mo maintained the plasma metabolite balance and completely prevented osteoporosis and changes in body composition that characterize both the KO model and human patients. These findings argue that early treatment of patients with HCU with PEG-CBS may prevent clinical symptoms of the disease possibly without the need of dietary protein restriction.-Majtan, T., Hůlková, H., Park, I., Krijt, J., Kožich, V., Bublil, E. M., Kraus, J. P. Enzyme replacement prevents neonatal death, liver damage, and osteoporosis in murine homocystinuria.

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Section: Discussionsupporting

confidence: 90%

Enzyme replacement prevents neonatal death, liver damage, and osteoporosis in murine homocystinuria

et al. 2017

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“…Different treatment approaches, such as gene therapy or CBS enzyme replacement therapy (Bublil et al., ), could be more promising than the chemical chaperone approach for treating Qatari patients. Other treatment options include the use of protein stabilizers or proteasome inhibitors.…”

Section: Discussionmentioning

confidence: 99%

In silico and in vivo models for Qatari-specific classical homocystinuria as basis for development of novel therapies

et al. 2018

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Homocystinuria is a rare inborn error of methionine metabolism caused by cystathionine β‐synthase (CBS) deficiency. The prevalence of homocystinuria in Qatar is 1:1,800 births, mainly due to a founder Qatari missense mutation, c.1006C>T; p.R336C (p.Arg336Cys). We characterized the structure–function relationship of the p.R336C‐mutant protein and investigated the effect of different chemical chaperones to restore p.R336C‐CBS activity using three models: in silico, ΔCBS yeast, and CRISPR/Cas9 p.R336C knock‐in HEK293T and HepG2 cell lines. Protein modeling suggested that the p.R336C induces severe conformational and structural changes, perhaps influencing CBS activity. Wild‐type CBS, but not the p.R336C mutant, was able to restore the yeast growth in ΔCBS‐deficient yeast in a complementation assay. The p.R336C knock‐in HEK293T and HepG2 cells decreased the level of CBS expression and reduced its structural stability; however, treatment of the p.R336C knock‐in HEK293T cells with betaine, a chemical chaperone, restored the stability and tetrameric conformation of CBS, but not its activity. Collectively, these results indicate that the p.R336C mutation has a deleterious effect on CBS structure, stability, and activity, and using the chemical chaperones approach for treatment could be ineffective in restoring p.R336C CBS activity.

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“…Human truncated CBS carrying the p.Cys15Ser mutation (htCBS C15S) was expressed and purified as described elsewhere (Bublil et al., ). The purified enzyme was formulated and concentrated using Labscale TFF system (Merck Millipore, Burlington, MA, USA) equipped with Pellicon XL 50 Ultracel 30 cartridge (regenerated cellulose 30 kDa MWCO membrane) into 100 mM sodium phosphate pH 7.2.…”

Section: Methodsmentioning

confidence: 99%

“…We have recently introduced an enzyme replacement therapy (ERT) for HCU and showed that the administration of polyethylene glycol (PEG)‐modified truncated human CBS lacking the C‐terminal regulatory domain (PEG–CBS) to HO mice resulted in ∼75% decrease of Hcy and normalization of Cys in plasma (Bublil et al., ). In addition, this improved plasma metabolite profile was accompanied in KO mice by increased survival and decreased liver disease.…”

Section: Introductionmentioning

confidence: 99%

Enzyme replacement therapy prevents loss of bone and fat mass in murine homocystinuria

Majtán

Park

Bublil³

et al. 2017

Human Mutation

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Skeletal and connective tissue defects are the most striking symptoms in patients suffering from classical homocystinuria (HCU). Here, we determined body composition and bone mass in three mouse models of HCU and assessed whether a long-term administration of enzyme replacement therapy (ERT) corrected the phenotype. The mouse models of HCU were analyzed using dual-energy X-ray absorptiometry and the data were complemented by plasma biochemical profiles. Both the mouse model lacking CBS (KO) and the one expressing human CBS mutant transgene on a mouse CBS null background (I278T) showed marked bone loss and decreased weight mostly due to a lower fat content compared with negative controls. In contrast, the HO mouse expressing the human CBS WT transgene on a mouse CBS null background showed no such phenotype despite similar plasma biochemical profile to the KO and I278T mice. More importantly, administration of ERT rescued bone mass and changes in body composition in the KO mice treated since birth and reversed bone loss and improved fat content in the I278T mice injected after the development of clinical symptoms. Our study suggests that ERT for HCU may represent an effective way of preventing the skeletal problems in patients without a restricted dietary regime.

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Enzyme replacement with PEGylated cystathionine β-synthase ameliorates homocystinuria in murine model

Cited by 39 publications

References 37 publications

Enzyme replacement prevents neonatal death, liver damage, and osteoporosis in murine homocystinuria

Enzyme replacement prevents neonatal death, liver damage, and osteoporosis in murine homocystinuria

In silico and in vivo models for Qatari-specific classical homocystinuria as basis for development of novel therapies

Enzyme replacement therapy prevents loss of bone and fat mass in murine homocystinuria

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