CORRECTION OF MURINE MUCOPOLYSACCHARIDOSIS-VII BY A HUMAN BETA-GLUCURONIDASE TRANSGENE

We recently described a murine model for mucopolysaccharidosis VII in mice that have an inherited deficiency of β-glucuronidase (β-D-glucuronoside glucuronosohydrolase, EC 3.2.1.31). Affected mice, of genotype gus (mps)/gus(mps), present clinical manifestations similar to those of humans with mucopolysaccharidosis VII (Sly syndrome) and are shown here to have secondary elevations of other lysosomal enzymes. The mucopolysaccharidosis VII phenotype in both species includes dwarfism, skeletal deformities, and premature death. Lysosome storage is visualized within enlarged vesicles and correlates biochemically with accumulation of undergraded and partially degraded glycosaminoglycans. In this report we describe the consequences of introducing the human β-glucuronidase gene, GUSB gus(mps)/gus(mps) mice that produce virtually no murine β-glucuronidase. Transgenic mice homozygous for the mucopolysaccharidoses VII mutation expressed high levels of human β-glucuronidase activity in all tissues examined and were phenotypically normal. Biochemically, both intralysosomal storage of glycosaminoglycans and the secondary elevation of other acid hydrolases were corrected. These findings demonstrate that the GUSB transgene is expressed in gus(mps)/gus(mps) mice and that human β-glucuronidase corrects the murine mucopolysaccharidosis storage disease.