title: Correction of cystathionine β-synthase deficiency in mice by treatment with proteasome inhibitors.
abstract: Cystathionine beta-synthase (CBS) deficiency is an inborn error of metabolism characterized by extremely elevated levels of plasma total homocysteine. The vast majority of CBS-deficient patients have missense mutations located in the CBS gene that result in the production of either misfolded or unstable protein. Here, we examine the effect of proteasome inhibitors on mutant CBS function using two different mouse models of CBS deficiency. These mice lack mouse CBS and express a missense mutant human CBS enzyme (either p.I278T or p.S466L) that has less than 5% of normal liver CBS activity, resulting in a 10-30-fold elevation in plasma homocysteine levels. We show that treatment of these mice with two different proteasome inhibitors can induce liver Hsp70, Hsp40, and Hsp27, increase levels of active CBS, and lower plasma homocysteine levels to within the normal range. However, response rates varied, with 100% (8/8) of the p.S466L animals showing correction, but only 38% (10/26) of the p.I278T animals. In total, our data show that treatment with proteostasis modulators can restore significant enzymatic activity to mutant misfolded CBS enzymes and suggests that they may be useful in treating certain types of genetic diseases caused by missense mutations.
authors.affiliation: Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
authors.forename: Sapna
authors.initials: S
authors.lastname: Gupta
authors.forename: Liqun
authors.initials: L
authors.lastname: Wang
authors.forename: Janet
authors.initials: J
authors.lastname: Anderl
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Slifker
authors.forename: Christopher
authors.initials: C
authors.lastname: Kirk
authors.forename: Warren D
authors.initials: WD
authors.lastname: Kruger
mesh_terms: D000818:Animals; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D003541:Cystathionine beta-Synthase / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D006712:Homocystinuria / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020125:Mutation, Missense; D009842:Oligopeptides / Q000494:pharmacology*; D061988:Proteasome Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D017510:Protein Folding / Q000187:drug effects; D011719:Pyrazines / Q000494:pharmacology*
chemical_list: D001897:Boronic Acids; C554738:ONX 0912; D009842:Oligopeptides; D061988:Proteasome Inhibitors; D011719:Pyrazines; D000069286:Bortezomib; D003541:Cystathionine beta-Synthase
keywords: aminoaciduria; chaperone; genetic disease; inborn error; missense mutation