title: Reorganization of prion protein membrane environment during low potassium-induced apoptosis in primary rat cerebellar neurons.
abstract: We studied the changes occurring in the membrane environment of prion protein (PrP) during apoptosis induced by low potassium in primary rat cerebellar neurons. Ceramide levels increased during apoptosis-inducing treatment, being doubled with respect to time-matched controls after 24 h. Sphingomyelin levels were parallely decreased, while cholesterol and ganglioside contents were not affected. Changes in ceramide and sphingomyelin composition were exclusively restricted to a detergent-resistant membrane fraction. The pro-apoptotic treatment was accompanied by the down-regulation of PrP and of the non-receptor kinase Fyn. The levels of PrP and Fyn were correspondingly reduced in the detergent-resistant membrane fraction. In control cells, the membrane microenvironment separated by immunoprecipitation with anti-PrP antibody contained 80% of the detergent-resistant PrP and 35% and 38% of the sphingolipids and cholesterol respectively. Upon low potassium treatment, 20% of the PrP originally present in the detergent-resistant fraction was immunoprecipitated, together with 19% of sphingolipids and 22% of cholesterol. Thus, PrP in the immunoprecipitate from apoptotic cells was ninefold less than in control ones, while sphingolipids and cholesterol were about 50% with respect to controls cells. The molar ratio between cholesterol, sphingomyelin and ceramide was 15 : 6 : 1 in the PrP-rich environment from control neurons, and 6 : 2 : 1 in that from apoptotic cells.
authors.affiliation: Center of Excellence on Neurodegenerative Diseases, Study Center for the Biochemistry and Biotechnology of Glycolipids, Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, Milan, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Rivaroli
authors.forename: Simona
authors.initials: S
authors.lastname: Prioni
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Loberto
authors.forename: Arianna
authors.initials: A
authors.lastname: Bettiga
authors.forename: Vanna
authors.initials: V
authors.lastname: Chigorno
authors.forename: Alessandro
authors.initials: A
authors.lastname: Prinetti
authors.forename: Sandro
authors.initials: S
authors.lastname: Sonnino
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D047468:Immunoprecipitation / Q000379:methods; D050356:Lipid Metabolism / Q000187:drug effects; D008715:Methionine / Q000378:metabolism; D009474:Neurons / Q000187:drug effects*; D011188:Potassium / Q000494:pharmacology*; D011328:Prions / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013110:Sphingosine / Q000493:pharmacokinetics; D014316:Tritium / Q000493:pharmacokinetics
chemical_list: D011328:Prions; D014316:Tritium; D008715:Methionine; D013110:Sphingosine; D011188:Potassium