title: Increased globotriaosylceramide on plasma membranes of synchronized familial dysautonomia cells. Verotoxin binding studies.
abstract: Familial dysautonomia is an autosomal recessive genetic disease found almost exclusively among Ashkenazi Jews, characterized by deficits in autonomic, sensory, and central functions. Although the gene has been localized to chromosome 9, the biochemical defect remains elusive. We previously reported an increase in globotriaosylceramide in dysautonomic fibroblasts and lymphoblasts, and unusual fibroblast growth patterns suggesting plasma membrane abnormalities. Globotriaosylceramide is a plasma membrane component, and the natural receptor for verotoxin derived from E. coli. In Vero and HeLa cells, which are susceptible to verotoxin, the expression of globotriaosylceramide on the cell surface is maximal at the G1/S boundary of the cell cycle. Measurement of toxin binding at 0 degrees C at this boundary is indicative of the amount of globotriaosylceramide exposed on the cell surface. Above 0 degrees C, verotoxin enters, and is toxic to, the cell. We analyzed verotoxin-globotriaosylceramide interactions in synchronized FD and normal cells at this boundary. 125I-toxin binding was much more marked to lymphoblasts from patients than from controls. When cells were grown in the presence of verotoxin, at 10(-2)-10(-7) micrograms/mL, 70% of dysautonomic lymphoblasts died, compared to 25% of controls. The CD50 was 10 ng/mL for dysautonomic fibroblasts vs 450 for controls. These results may be exploited to create a biological assay to differentiate between FD and normal cells.
authors.affiliation: Department of Microbiology, Hospital for Sick Children, Toronto, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Pereira
authors.forename: B
authors.initials: B
authors.lastname: Boyd
authors.forename: J
authors.initials: J
authors.lastname: Newbigging
authors.forename: C
authors.initials: C
authors.lastname: Lingwood
authors.forename: P M
authors.initials: PM
authors.lastname: Strasberg
mesh_terms: D001342:Autonomic Nervous System Diseases / Q000378:metabolism*; D001427:Bacterial Toxins; D001665:Binding Sites; D002452:Cell Count; D002462:Cell Membrane / Q000187:drug effects*; D002470:Cell Survival; D002478:Cells, Cultured / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D008214:Lymphocytes; D022622:Shiga Toxin 1; D014281:Trihexosylceramides / Q000494:pharmacology*
chemical_list: D001427:Bacterial Toxins; D022622:Shiga Toxin 1; D014281:Trihexosylceramides; C018549:globotriaosylceramide