title: Alterations of myelin-specific proteins and sphingolipids characterize the brains of acid sphingomyelinase-deficient mice, an animal model of Niemann-Pick disease type A.
abstract: Niemann-Pick disease (NPD) type A is a neurodegenerative disorder caused by sphingomyelin (SM) accumulation in lysosomes relying on reduced or absent acid sphingomyelinase (ASM) activity. NPD-A patients develop progressive neurodegeneration including cerebral and cerebellar atrophy, relevant Purkinje cell and myelin deficiency with death within 3 years. ASM'knock-out' (ASMKO) mice, an animal model of NPD-A, develop a phenotype largely mimicking that of NPD-A. The mechanisms underlying myelin formation are poorly documented in ASMKO mice. In this study we determined the content of four myelin-specific proteins, myelin basic protein (MBP), 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP), myelin associated glycoprotein (MAG) and proteolipid protein (PLP), and that of myelin-enriched sphingolipids in the brains of ASMKO and wild-type mice in early stages of post-natal (pn) life. Protein and mRNA analysis revealed that in ASMKO mice beginning from 4 post-natal weeks (wk-pn), the expression levels of MAG, CNP, and MBP were below those observed in wild-type mice and the same applied to PLP at 10 wk-pn. Moreover, at 4 wk-pn the expression of SOX10, one of the transcription factors involved in oligodendrocyte development and maintenance was lower in ASMKO mice. Lipid analysis showed that SM and the gangliosides GM3 and GM2 accumulated in the brains of ASMKO mice, as opposed to galactocerebroside and galactosulfocerebroside that, in parallel with the mRNAs of UDP-galactose ceramide galactosyltransferase and galactose-3-O-sulfotransferase 1, the two transferases involved in their synthesis, decreased. Myelin lipid analysis showed a progressive sphingomyelin accumulation in ASMKO mice; noteworthy, of the two sphingomyelin species known to be resolved by TLC, only that with the lower Rf accumulated. The immunohistochemical analysis showed that the reduced expression of myelin specific proteins in ASMKO mice at 10 wk-pn was not restricted to the Purkinje layer of the cerebellar cortex but involved the cerebral cortex as well. In conclusion, reduced oligodendrocyte metabolic activity is likely to be the chief cause of myelin deficiency in ASMKO mice, thus shedding light on the molecular dysfunctions underlying neurodegeneration in NPD-A.
authors.affiliation: Departments of Medicine and Experimental Oncology, Section of Biochemistry, University of Turin, Turin, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Buccinnà
authors.forename: Marco
authors.initials: M
authors.lastname: Piccinini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Prinetti
authors.forename: Federica
authors.initials: F
authors.lastname: Scandroglio
authors.forename: Simona
authors.initials: S
authors.lastname: Prioni
authors.forename: Manuela
authors.initials: M
authors.lastname: Valsecchi
authors.forename: Barbara
authors.initials: B
authors.lastname: Votta
authors.forename: Silvia
authors.initials: S
authors.lastname: Grifoni
authors.forename: Elisa
authors.initials: E
authors.lastname: Lupino
authors.forename: Cristina
authors.initials: C
authors.lastname: Ramondetti
authors.forename: Edward H
authors.initials: EH
authors.lastname: Schuchman
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Giordana
authors.forename: Sandro
authors.initials: S
authors.lastname: Sonnino
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Rinaudo
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology / Q000378:metabolism*; D004195:Disease Models, Animal; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D009185:Myelin Proteins / Q000235:genetics / Q000378:metabolism*; D052536:Niemann-Pick Disease, Type A / Q000235:genetics / Q000378:metabolism*; D055757:SOXE Transcription Factors / Q000096:biosynthesis / Q000172:deficiency* / Q000235:genetics; D013107:Sphingolipids / Q000235:genetics / Q000378:metabolism*; D013108:Sphingomyelin Phosphodiesterase / Q000172:deficiency* / Q000235:genetics
chemical_list: D009185:Myelin Proteins; D055757:SOXE Transcription Factors; C527924:Sox10 protein, mouse; D013107:Sphingolipids; D013108:Sphingomyelin Phosphodiesterase