Molecular Basis of Feline β-Glucuronidase Deficiency: An Animal Model of Mucopolysaccharidosis VII

• Published in: Genomics (San Diego, Calif.) Calif.), 1999-06, Vol.58 (2), p.121-128
• Main Authors: Fyfe, John C., Kurzhals, Rebeccah L., Lassaline, Mary E., Henthorn, Paula S., Alur, Prasad R.K., Wang, Ping, Wolfe, John H., Giger, Urs, Haskins, Mark E., Patterson, Donald F., Sun, Huaichang, Jain, Sanjeev, Yuhki, Naoya
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; animal model; animal models; Animals; beta-glucuronidase; Biological and medical sciences; Carbohydrates (enzymatic deficiencies). Glycogenosis; Cats; complementary DNA; Disease Models, Animal; DNA Mutational Analysis; enzyme deficiencies; Errors of metabolism; genbank/af012423; genbank/af012424; gene expression; Gene Transfer Techniques; Glucuronidase - deficiency; Glycosaminoglycans - urine; Humans; lysosomal storage disease; Male; Medical sciences; messenger RNA; Metabolic diseases; missense mutation; Models, Chemical; Molecular Sequence Data; mucopolysaccharidosis; mucopolysaccharidosis VII; Mucopolysaccharidosis VII - genetics; mutation; nucleotide sequences; Pedigree; Phenotype; Rats; segregation; Sequence Homology, Amino Acid; symptoms; β-glucuronidase
• ISSN: 0888-7543; 1089-8646
• DOI: 10.1006/geno.1999.5825

A family of domestic cats was found that exhibited clinical and biochemical abnormalities consistent with mucopolysaccharidosis VII, an autosomal recessive lysosomal storage disorder caused by β-glucuronidase deficiency. β-Glucuronidase activity was undetectable in affected cat fibroblasts and restored by retroviral gene transfer of rat β-glucuronidase cDNA. β-Glucuronidase mRNA was normal in affected cat testis by Northern blot analysis. Normal feline β-glucuronidase cDNA was cloned and characterized, and amplified from affected cat fibroblasts by reverse transcription coupled polymerase chain reaction. There was a G-to-A transition in the affected cat cDNA that predicted an E351K substitution, destroyed a BssSI site, and eliminated GUSB enzymatic activity in expression studies. Multiple species comparison and the crystal structure of human β-glucuronidase indicated that E351 is a highly conserved residue most likely essential in maintenance of the enzyme's conformation. BssSI digestion of polymerase chain reaction products amplified from genomic DNA indicated that affected cats were homozygous and cats with half-normal β-glucuronidase activity were heterozygous for the missense mutation. Carriers identified in this manner produced affected kittens in prospective breedings, and a feline MPS VII breeding colony has been established.