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Journal of Lipid Research, Vol. 43, 1096-1104, July 2002
Copyright © 2002 by Lipid Research, Inc.
Defects in degradation of blood group A and B glycosphingolipids in Schindler and Fabry diseases
Befekadu Asfaw1,*,
Jana Ledvinová*,
Robert Dobrovol y*,
Henk D. Bakker ,
Robert J. Desnick ,
Otto P. van Diggelen**,
Jan G. N. de Jong ,
Tamotsu Kanzaki ,
Amparo Chabas***,
Irene Maire  ,
Ernst Conzelmann  and
Detlev Schindler****
* Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, 128 08 Prague, Czech Republic
Children's Hospital, Academic Medical Centre, NL-1105 AZ Amsterdam, The Netherlands
Department of Human Genetics, Mount Sinai School of Medicine, New York, NY
** Department of Clinical Genetics, Erasmus University, NL-3000 DR Rotterdam, The Netherlands
Laboratory for Pediatrics and Neurology, University Medical Centre Nijmegen, NL-6525 GC Nijmegen, The Netherlands
 Department of Dermatology, Faculty of Medicine, Kagoshima University, Kagoshima, Japan
*** Instituto de Bioquimica Clinica, E-08290 Cerdanyola, Barcelona, Spain
  Laboratoire d'Enzymologie, F- 69322 Lyon, France
  Department of Physiological Chemistry, Biozentrum, University of Wuerzburg, D-97074 Wuerzburg, Germany
**** Department of Human Genetics, Biozentrum, University of Wuerzburg, D-97074 Wuerzburg, Germany
1 To whom correspondence should be addressed. e-mail: basfaw{at}beba.cesnet.cz
Skin fibroblast cultures from patients with inherited lysosomal enzymopathies, -N-acetylgalactosaminidase ( -NAGA) and -galactosidase A deficiencies (Schindler and Fabry disease, respectively), and from normal controls were used to study in situ degradation of blood group A and B glycosphingolipids. Glycosphingolipids A-6-2 (GalNAc ( 1 3)[Fuc 1 2]Gal(ß1 4)GlcNAc(ß1 3)Gal(ß1 4)Glc (ß1 1')Cer, IV2- -fucosyl-IV3- -N-acetylgalactosaminylneolactotetraosylceramide), B-6-2 (Gal( 1 3)[Fuc 1 2] Gal (ß1 4)GlcNAc(ß1 3)Gal(ß1 4)Glc(ß1 1')Cer, IV2- -fucosyl-IV3- -galactosylneolactotetraosylceramide), and globoside (GalNAc(ß1 3)Gal( 1 4)Gal(ß1 4)Glc(ß1 1') Cer, globotetraosylceramide) were tritium labeled in their ceramide moiety and used as natural substrates. The degradation rate of glycolipid A-6-2 was very low in fibroblasts of all the -NAGA-deficient patients (less than 7% of controls), despite very heterogeneous clinical pictures, ruling out different residual enzyme activities as an explanation for the clinical heterogeneity. Strongly elevated urinary excretion of blood group A glycolipids was detected in one patient with blood group A, secretor status (five times higher than upper limit of controls), in support of the notion that blood group A-active glycolipids may contribute as storage compounds in blood group A patients. When glycolipid B-6-2 was fed to -galactosidase A-deficient cells, the degradation rate was surprisingly high (50% of controls), while that of globotriaosylceramide was reduced to less than 15% of control average, presumably reflecting differences in the lysosomal enzymology of polar glycolipids versus less-polar ones.
Relatively high-degree degradation of substrates with -D-Galactosyl moieties hints at a possible contribution of other enzymes.
Abbreviations: A-6-2, blood group glycolipid A-6-2 (GalNAc ( 1 3)[Fuc 1 2]Gal(ß1 4)GlcNAc(ß1 3)Gal(ß1 4)Glc(ß1 1')Cer, IV2- -fucosyl-IV3- -N-acetylgalactosaminylneolactotetraosylceramide); -NAGA, -N-acetylgalactosaminidase; B-6-2, blood group glycolipid B-6-2 (Gal( 1 3)[Fuc 1 2]Gal(ß1 4)GlcNAc(ß1 3) Gal(ß1 4)Glc(ß1 1')Cer, IV2- -fucosyl-IV3- -galactosylneolactotetra- osylceramide); GbOse3Cer (Gal( 1 4)Gal(ß1 4)Glc(ß1 1')Cer, globotriaosylceramide); globoside (GalNAc(ß1 3)Gal( 1 4)Gal(ß1 4)Glc(ß1 1')Cer, globotetraosylceramide); mAb, mouse monoclonal antibody; Supplementary key words -N-acetylgalactosaminidase deficiency -galactosidase A deficiency skin fibroblasts in situ metabolism lysosome targeting blood group glycolipids secretor status

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Copyright © 2002 by the American Society for Biochemistry and Molecular Biology.
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