Gaucher disease mouse models: point mutations at the acid β-glucosidase locus combined with low-level prosaposin expression lead to disease variants

Abstract

Gaucher disease is a common lysosomal storage disease caused by a defect of acid ␤ -glucosidase (GCase). The optimal in vitro hydrolase activity of GCase requires saposin C, an activator protein that derives from a precursor, prosaposin. To develop additional models of Gaucher disease and to test in vivo effects of saposin deficiencies, mice expressing low levels (4-45% of wild type) of prosaposin and saposins (PS-NA) were backcrossed into mice with specific point mutations (V394L/V394L or D409H/D409H) of GCase. The resultant mice were designated 4L/PS-NA and 9H/PS-NA, respectively. In contrast to PS-NA mice, the 4L/PS-NA and 9H/PS-NA mice displayed large numbers of engorged macrophages and nearly exclusive glucosylceramide (GC) accumulation in the liver, lung, spleen, thymus, and brain. Electron microscopy of the storage cells showed the characteristic tubular storage material of Gaucher cells. Compared with V394L/V394L mice, 4L/PS-NA mice that expressed 4-6% of wild-type prosaposin levels had ‫ف‬ 25-75% decreases in GCase activity and protein in liver, spleen, and fibroblasts. These results imply that reduced saposin levels increased the instability of V394L or D409H GCases and that these additional decreases led to large accumulations of GC in all tissues. These models mimic a more severe Gaucher disease phenotype and could be useful for therapeutic intervention studies. -Sun, Y., B. Quinn, D. P. Witte, and G. A. Grabowski. Gaucher disease mouse models: point mutations at the acid ␤ -glucosidase locus combined with low-level prosaposin expression lead to disease variants. J. Lipid Res. 2005. 46: 2102-2113.

Ex Vivo and in Vivo Effects of Isofagomine on Acid β-Glucosidase Variants and Substrate Levels in Gaucher Disease

“…Mouse Models and IFG Treatment-Mice homozygous for Gba1 encoding V394L (4L), D409V (9V), and D409H (9H) GCases (11) and 4L/PS-NA (PS-NA;V394L/V394L) mice were as described (13). The 4L/PS-NA mice contain a hypomorphic prosaposin cDNA against a prosaposin knock-out (PSϪ/Ϫ) background that also had the Gba1 encoding homozygous V394L (13).…”

“…Mouse fibroblast cells with the designated genotypes were established from newborn pups (11,13). The cells were incubated for 5 days in the medium containing IFG at the indicated concentrations.…”

“…Homozygosity for V394L or D409H leads to defective GCase activity, but mice survive to ϳ24 months with only minor visceral abnormalities (11). More extensive involvement in such mouse models was developed by cross-breeding of V394L or D409H with a hypomorphic prosaposin-deficient mouse, termed 4L/PS-NA or 9H/PS-NA, respectively (13). Such mice show numerous engorged macrophages and large GC accumulations.…”

The biodegradability of electrospun Dextran/PLGA scaffold in a fibroblast/macrophage co-culture

“…α-glucosidase and β-glucosidase are lysosomal enzymes with important roles in carbohydrate metabolism [25]. Dextran could be metabolized into glucose, and thus is a potential substrate for these two enzymes.…”

Downregulation of neurotrophic factors in the brain of a mouse model of Gaucher disease: implications for neuronal loss in Gaucher disease

“…In vivo approaches to understanding the pathophysiology of Gaucher disease and the development of new therapeutic strategies to address it have previously been hindered by the lack of a viable animal model (Tybulewicz et al, 1992;Liu et al, 1998). However, the generation of viable mouse models of Gaucher disease has recently been reported (Xu et al, 2003;Sun et al, 2005), and these mouse models will be useful in elucidating the pathogenesis of Gaucher disease.…”