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Effect of cysteamine on mutant ASL proteins with cysteine for arginine substitutions


Inauen, Corinne; Rüfenacht, Véronique; Pandey, Amit V; Hu, Liyan; Blom, Henk; Nuoffer, Jean-Marc; Häberle, Johannes (2016). Effect of cysteamine on mutant ASL proteins with cysteine for arginine substitutions. Molecular Diagnosis & Therapy, 20(2):125-133.

Abstract

INTRODUCTION Cysteamine is used to treat cystinosis via the modification of cysteine residues substituting arginine in mutant proteins.
OBJECTIVES We investigated the effect of cysteamine on mutant argininosuccinate lyase (ASL), the second most common defect in the urea cycle.
METHODS In an established mammalian expression system, 293T cell lysates were produced after transfection with all known cysteine for arginine mutations in the ASL gene (p.Arg94Cys, p.Arg95Cys, p.Arg168Cys, p.Arg379Cys, and p.Arg385Cys), allowing testing of the effect of cysteamine over 48 h in the culture medium as well as for 1 h immediately prior to the enzyme assay.
RESULTS Cysteamine at low concentrations showed no effect on 293T cell viability, ASL protein expression, or ASL activity when applied during cell culture. However, incubation of transfected cells with 0.05 mM cysteamine immediately before the enzyme assay resulted in increased ASL activity of p.Arg94Cys, p.Arg379Cys, and p.Arg385Cys by 64, 20, and 197 %, respectively, and this result was significant (p < 0.01). Cell lysates carrying p.Arg385Cys and treated with cysteamine recover enzyme activity that is similar to the untreated designed mutation p.Arg385Lys, providing circumstantial evidence for the assumed cysteamine-induced change of a cysteine to a lysine analogue.
CONCLUSION Since 12 % of all known genotypes in ASL deficiency are affected by a cysteine for arginine mutation, we conclude that the potential of cysteamine or of related substances as remedy for this disease should be investigated further.

Abstract

INTRODUCTION Cysteamine is used to treat cystinosis via the modification of cysteine residues substituting arginine in mutant proteins.
OBJECTIVES We investigated the effect of cysteamine on mutant argininosuccinate lyase (ASL), the second most common defect in the urea cycle.
METHODS In an established mammalian expression system, 293T cell lysates were produced after transfection with all known cysteine for arginine mutations in the ASL gene (p.Arg94Cys, p.Arg95Cys, p.Arg168Cys, p.Arg379Cys, and p.Arg385Cys), allowing testing of the effect of cysteamine over 48 h in the culture medium as well as for 1 h immediately prior to the enzyme assay.
RESULTS Cysteamine at low concentrations showed no effect on 293T cell viability, ASL protein expression, or ASL activity when applied during cell culture. However, incubation of transfected cells with 0.05 mM cysteamine immediately before the enzyme assay resulted in increased ASL activity of p.Arg94Cys, p.Arg379Cys, and p.Arg385Cys by 64, 20, and 197 %, respectively, and this result was significant (p < 0.01). Cell lysates carrying p.Arg385Cys and treated with cysteamine recover enzyme activity that is similar to the untreated designed mutation p.Arg385Lys, providing circumstantial evidence for the assumed cysteamine-induced change of a cysteine to a lysine analogue.
CONCLUSION Since 12 % of all known genotypes in ASL deficiency are affected by a cysteine for arginine mutation, we conclude that the potential of cysteamine or of related substances as remedy for this disease should be investigated further.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Children's Hospital Zurich > Medical Clinic
04 Faculty of Medicine > Center for Integrative Human Physiology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:April 2016
Deposited On:23 Jan 2017 13:51
Last Modified:23 Jan 2017 13:51
Publisher:Adis International Ltd.
ISSN:1177-1062
Publisher DOI:https://doi.org/10.1007/s40291-015-0182-z
PubMed ID:26745957

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