Ethanol-induced impairment in the biosynthesis of N-linked glycosylation.
- Welti M Institute of Physiology, University of Zürich, Zürich, Switzerland.
- Hülsmeier AJ
- 2013-11-19
Published in:
- Journal of cellular biochemistry. - 2014
ALCOHOLIC LIVER DISEASE
CONGENITAL DISORDER OF GLYCOSYLATION
DOLICHOL
DOLICHOL-LINKED OLIGOSACCHARIDES
N-LINKED GLYCOSYLATION
Alcohol Dehydrogenase
Carbohydrate Conformation
Cells, Cultured
Cytochrome P-450 CYP2E1
Dolichol Phosphates
Dolichols
Ethanol
Gene Expression Regulation
Glycosylation
Hepatocytes
Hexosyltransferases
Humans
Inactivation, Metabolic
Mannosyltransferases
Oligosaccharides
Polysaccharides
Proteasome Endopeptidase Complex
Transferrin
English
Deficiency in N-linked protein glycosylation is a long-known characteristic of alcoholic liver disease and congenital disorders of glycosylation. Previous investigations of ethanol-induced glycosylation deficiency demonstrated perturbations in the early steps of substrate synthesis and in the final steps of capping N-linked glycans in the Golgi. The significance of the biosynthesis of N-glycan precursors in the endoplasmic reticulum, however, has not yet been addressed in alcoholic liver disease. Ethanol-metabolizing hepatoma cells were treated with increasing concentrations of ethanol. Transcript analysis of genes involved in the biosynthesis of N-glycans, activity assays of related enzymes, dolichol-phosphate quantification, and analysis of dolichol-linked oligosaccharides were performed. Upon treatment of cells with ethanol, we found a decrease in the final N-glycan precursor Dol-PP-GlcNAc(2) Man(9) Glc(3) and in C95- and C100-dolichol-phosphate levels. Transcript analysis of genes involved in N-glycosylation showed a 17% decrease in expression levels of DPM1, a subunit of the dolichol-phosphate-mannose synthase, and an 8% increase in RPN2, a subunit of the oligosaccharyl transferase. Ethanol treatment decreases the biosynthesis of dolichol-phosphate. Consequently, the formation of N-glycan precursors is affected, resulting in an aberrant precursor assembly. Messenger RNA levels of genes involved in N-glycan biosynthesis are slightly affected by ethanol treatment, indicating that the assembly of N-glycan precursors is not regulated at the transcriptional level. This study confirms that ethanol impairs N-linked glycosylation by affecting dolichol biosynthesis leading to impaired dolichol-linked oligosaccharide assembly. Together our data help to explain the underglycosylation phenotype observed in alcoholic liver disease and congenital disorders of glycosylation.
- Language
-
- English
- Open access status
- green
- Identifiers
-
- DOI 10.1002/jcb.24713
- PMID 24243557
- Persistent URL
- https://sonar.ch/global/documents/121103
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