Pompe disease is an autosomal recessive lysosomal storage disorder (LSD) caused by deficiency of the lysosomal enzyme acid alpha glucosidase (GAA). Many disease-causing mutated GAA retain enzymatic ...activity, but are not translocated from endoplasmic reticulum (ER) to lysosomes. Enzyme replacement therapy (ERT) is the only treatment for Pompe disease, but remains expensive, inconvenient and does not reverse all disease manifestations. It was postulated that small molecules which aid in protein folding and translocation to lysosomes could provide an alternate to ERT. Previously, several iminosugars have been proposed as small-molecule chaperones for specific LSDs. Here we identified a novel series of non-iminosugar chaperones for GAA. These moderate GAA inhibitors are shown to bind and thermo-stabilize GAA, and increase GAA translocation to lysosomes in both wild-type and Pompe fibroblasts. AMDE and physical properties studies indicate that this series is a promising lead for further pharmacokinetic evaluation and testing in Pompe disease models.
Pompe disease is a lysosomal storage disease (LSD) caused by a deficiency in the lysosomal enzyme acid alpha-glucosidase. In several LSDs, enzyme inhibitors have been used as small molecule ...chaperones to facilitate and increase the translocation of mutant protein from the endoplasmic reticulum to the lysosome. Enzyme activators with chaperone activity would be even more desirable as they would not inhibit the enzyme after translocation and might potentiate the activity of the enzyme that is successfully translocated. Herein we report our initial findings of a new series of acid alpha-glucosidase activators.
Compound
1 and analogues are able to activate acid alpha-glucosidase's hydrolysis of resorufin α-
d-glucopyranoside and 4-methylumbelliferyl-α-
d-glucopyranoside in a selective and dose-dependent manner.
Display omitted
To comprehensively describe the ophthalmic characteristics of patients with mucolipidosis type IV.
Prospective natural history study.
Twenty-two patients with confirmed mucolipidosis type IV. METHODS ...OR TESTING: External and slit-lamp examination with dilated funduscopy, photography of corneal and retinal lesions, and exfoliative conjunctival cytology were performed.
Grading of corneal, optic nerve, retinal vasculature, and pigmentary abnormalities.
All patients exhibited some degree of corneal epithelial haze, optic nerve pallor, retinal vascular attenuation, and retinal pigment epithelial changes. The associated ocular findings observed in decreasing order of frequency were strabismus, corneal erosion, cataract, corneal abnormalities, fundus abnormalities, and ptosis. The older patients were significantly more likely to demonstrate severe optic nerve pallor, retinal vascular attenuation, and corneal epithelial haze. Conjunctival cytologic studies showed characteristic lysosomal inclusions on light and electron microscopy.
Patients with mucolipidosis type IV have characteristic ophthalmic features, most of which have a progressive course. Conjunctival cytologic studies help confirm the diagnosis of this disorder.
Alpha-galactosidase A hydrolyzes the terminal alpha-galactosyl moieties from glycolipids and glycoproteins in lysosomes. Mutations in α-galactosidase cause lysosomal accumulation of the ...glycosphingolipid, globotriaosylceramide, which leads to Fabry disease. Small-molecule chaperones that bind to mutant enzyme proteins and correct their misfolding and mistrafficking have emerged as a potential therapy for Fabry disease. We have synthesized a red fluorogenic substrate, resorufinyl α-d-galactopyranoside, for a new α-galactosidase enzyme assay. This assay can be measured continuously at lower pH values, without the addition of a stop solution, due to the relatively low pK a of resorufin (~6). In addition, the assay emits red fluorescence, which can significantly reduce interferences due to compound fluorescence and dust/lint as compared to blue fluorescence. Therefore, this new red fluorogenic substrate and the resulting enzyme assay can be used in high-throughput screening to identify small-molecule chaperones for Fabry disease.
PDF
