Human Molecular Genetics Advance Access originally published online on December 23, 2005
Human Molecular Genetics 2006 15(3):493-500; doi:10.1093/hmg/ddi465
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ß-Mannosidosis mice: a model for the human lysosomal storage disease
1Department of Microbiology and Molecular Genetics, 2Department of Neurology and Ophthalmology and Neuroscience Program, 3Pathobiology and Diagnostic Investigation, College of Veterinary Medicine and 4Department of Pediatrics and Human Development, Michigan State University, East Lansing, Michigan, USA and 5Department of Internal Medicine and Transgenic Animal Model Core, University of Michigan, Ann Arbor, Michigan, USA
* To whom correspondence should be addressed at: Department of Microbiology and Molecular Genetics, 5163 Biomedical Physical Sciences Building, Michigan State University, East Lansing, MI 48824, USA. Tel: +1 5173556463 ext. 1558; Email: frideric{at}msu.edu
Received November 7, 2005; Accepted December 16, 2005
ß-Mannosidase, a lysosomal enzyme which acts exclusively at the last step of oligosaccharide catabolism in glycoprotein degradation, functions to cleave the unique ß-linked mannose sugar found in all N-linked oligosaccharides of glycoproteins. Deficiency of this enzyme results in ß-mannosidosis, a lysosomal storage disease characterized by the cellular accumulation of small oligosaccharides. In human ß-mannosidosis, the clinical presentation is variable and can be mild, even when caused by functionally null mutations. In contrast, two existing ruminant animal models have disease that is consistent and severe. To further explore the molecular pathology of this disease and to investigate potential treatment strategies, we produced a ß-mannosidase knockout mouse. Homozygous mutant mice have undetectable ß-mannosidase activity. General appearance and growth of the knockout mice are similar to the wild-type littermates. At >1 year of age, these mice exhibit no dysmorphology or overt neurological problems. The mutant animals have consistent cytoplasmic vacuolation in the central nervous system and minimal vacuolation in most visceral organs. Thin-layer chromatography demonstrated an accumulation of disaccharide in epididymis and brain. This mouse model closely resembles human ß-mannosidosis and provides a useful tool for studying the phenotypic variation in different species and will facilitate the study of potential therapies for lysosomal storage diseases.