title: Age-related increase in activity of specific lysosomal enzymes in the human retinal pigment epithelium.
abstract: Age related changes in the activity of lysosomal enzymes have been studied in the cultured human retinal pigment epithelium cells collected from 26-85 year old donors. Among four such enzymes studied, activities of cathepsin D and beta-glucuronidase increased with the age of the donors while no notable change in activity of arylsulfatase B and alpha-mannosidase was observed. Kinetic parameters of beta-glucuronidase was measured in retinal pigment epithelium cells isolated from donors of different ages. Similar kinetic parameters for beta-glucuronidase at different ages suggest that the observed increase in the activity of the enzyme with age is not due to post-translational modification of the enzyme. Western blot analysis provides evidence for increased synthesis of beta-glucuronidase with aging. Relative proportions of glycosaminoglycans, the natural substrates of beta-glucuronidase and arylsulfatase B, in the retinal pigment epithelium altered with the age of the donors. A significant decrease of dermatan sulfate levels with aging correlates well with the observed increase in the level of beta-glucuronidase activity.
authors.affiliation: James A. Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Verdugo
authors.forename: J
authors.initials: J
authors.lastname: Ray
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D015153:Blotting, Western; D002402:Cathepsin D / Q000378:metabolism*; D002478:Cells, Cultured; D003871:Dermatan Sulfate / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D005966:Glucuronidase / Q000378:metabolism*; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000201:enzymology*
chemical_list: D006025:Glycosaminoglycans; D003871:Dermatan Sulfate; D005966:Glucuronidase; D002402:Cathepsin D