Abnormal glycosylation with hypersialylated O-glycans in patients with Sialuria.
until further notice
SourceBiochimica et Biophysica Acta. Molecular Basis of Disease, 1762, 6, (2006), pp. 598-607
Article / Letter to editor
Display more detailsDisplay less details
Biochimica et Biophysica Acta. Molecular Basis of Disease
SubjectDCN 1: Perception and Action; DCN 3: Neuroinformatics; IGMD 3: Genomic disorders and inherited multi-system disorders; IGMD 4: Glycostation disorders; IGMD 8: Mitochondrial medicine; NCMLS 4: Energy and redox metabolism; UMCN 3.1: Neuromuscular development and genetic disorders; UMCN 5.1: Genetic defects of metabolism
Sialuria is an inborn error of metabolism characterized by coarse face, hepatomegaly and recurrent respiratory tract infections. The genetic defect in this disorder results in a loss of feedback control of UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine-kinase by CMP-N-acetylneuraminic acid (CMP-NeuAc) resulting in a substantial overproduction of cytoplasmic free sialic acid. This study addresses fibroblast CMP-NeuAc levels and N- and O-glycan sialylation of serum proteins from Sialuria patients. CMP-NeuAc levels were measured with HPLC in fibroblasts. Isoelectric focusing (IEF) of serum transferrin and of apolipoprotein C-III (apoC-III) was performed on serum of three Sialuria patients. Isoforms of these proteins can be used as specific markers for the biosynthesis of N- and core 1 O-glycans. Furthermore, total N- and O-linked glycans from serum proteins were analyzed by HPLC. HPLC showed a clear overproduction of CMP-NeuAc in fibroblasts of a Sialuria patient. Minor changes were found for serum N-glycans and hypersialylation was found for core 1 O-glycans on serum apoC-III and on total serum O-glycans in Sialuria patients. HPLC showed an increased ratio of disialylated over monosialylated core 1 O-glycans. The hypersialylation of core 1 O-glycans is due to the increase of NeuAcalpha2,6-containing structures (mainly NeuAcalpha2-3Galbeta1-3[NeuAcalpha2-6]GalNAc). This may relate to KM differences between GalNAc-alpha2,6-sialyltransferase and alpha2,3-sialyltransferases. This is the first study demonstrating that the genetic defect in Sialuria results in a CMP-NeuAc overproduction. Subsequently, increased amounts of alpha2,6-linked NeuAc were found on serum core 1 O-glycans from Sialuria patients. N-glycosylation of serum proteins seems largely unaffected. Sialuria is the first metabolic disorder presenting with hypersialylated O-glycans.
Upload full text
Use your RU credentials (u/z-number and password) to log in with SURFconext to upload a file for processing by the repository team.