Feline mucopolysaccharidosis type VI. Characterization of recombinant N-acetylgalactosamine 4-sulfatase and identification of a mutation causing the disease.
Mucopolysaccharidosis type VI (MPS VI) is an autosomal recessive disease caused by a deficiency of N-acetylgalactosamine 4-sulfatase (4S) leading to the lysosomal accumulation and urinary excretion of dermatan sulfate. MPS VI has also been described in the Siamese cat. As an initial step toward enzyme replacement therapy with recombinant feline 4S (rf4S) in MPS VI cats, the feline 4S cDNA was isolated and expressed in CHO-KI cells and rf4S was immunopurified from the culture medium. SDS-polyacrylamide gel electrophoresis analysis showed that the precursor form of immunopurified rf4S was a 66-kDa polypeptide that underwent maturation to a 43-44-kDa polypeptide. Endocytosis of rf4S by cultured feline MPS VI myoblasts was predominantly mediated by a mannose 6-phosphate receptor and resulted in the correction of dermatan sulfate storage. The mutation causing feline MPS VI was identified as a base substitution at codon 476, altering a leucine codon to a proline (L476P). The L476P allele displayed no detectable 4S activity when expressed in CHO-KI cells and was observed only as a "precursor" polypeptide that was not secreted into the medium. Identification of the mutation has allowed the development of a rapid PCR-based screening method to genotype individuals within the cat colony.
Lysosomal Diseases Research Unit, Department of Chemical Pathology, Women's and Children's Hospital, 72 King William Road, North Adelaide, 5006 South Australia, Australia.
G
G
Yogalingam
T
T
Litjens
J
J
Bielicki
A C
AC
Crawley
V
V
Muller
D S
DS
Anson
J J
JJ
Hopwood
D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002371:Cat Diseases; D002415:Cats; D002478:Cells, Cultured; D003001:Cloning, Molecular; D006224:Cricetinae; D017931:DNA Primers; D006580:Genetic Carrier Screening; D007700:Kinetics; D008247:Lysosomes / Q000378:metabolism; D008969:Molecular Sequence Data; D009087:Mucopolysaccharidosis VI / Q000201:enzymology / Q000235:genetics / Q000662:veterinary*; D020051:N-Acetylgalactosamine-4-Sulfatase; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D013429:Sulfatases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D014162:Transfection
D017931:DNA Primers; D017527:Receptor, IGF Type 2; D011994:Recombinant Proteins; D013429:Sulfatases; D020051:N-Acetylgalactosamine-4-Sulfatase