Glycobiology, 2000, Vol. 10, No. 8 829-835
© 2000 Oxford University Press
Mannose supplementation corrects GDP-mannose deficiency in cultured fibroblasts from some patients with Congenital Disorders of Glycosylation (CDG)
3Department of Biochemistry, A.B.Chandler Medical Center, University of Kentucky College of Medicine, Lexington, KY and 4The Burnham Institute, La Jolla, CA 92037 USA
Congenital Disorders of Glycosylation (CDG) are human deficiencies in glycoprotein biosynthesis. Previous studies showed that 1 mM mannose corrects defective protein N-glycosylation in cultured fibroblasts from some CDG patients. We hypothesized that these CDG cells have limited GDP-mannose (GDP-Man) and that exogenous mannose increases the GDP-Man levels. Using a well established method to measure GDP-Man, we found that normal fibroblasts had an average of 23.5 pmol GDP-Man/106 cells, whereas phosphomannomutase (PMM)-deficient fibroblasts had only 2.3–2.7 pmol/106 cells. Adding 1 mM mannose to the culture medium increased the GDP-Man level in PMM-deficient cells to approximately 15.5 pmol/106 cells, but had no significant effect on GDP-Man levels in normal fibroblasts. Similarly, mannose supplementation increased GDP-Man from 4.6 pmol/106 cells to 24.6 pmol/106 cells in phosphomannose isomerase (PMI)-deficient fibroblasts. Based on the specific activity of the GDP-[3H]Man pool present in [2-3H]mannose labeled cells, mannose supplementation also partially corrected the impaired synthesis of mannosylphosphoryldolichol (Man-P-Dol) and Glc0-3Man9GlcNAc2-P-P-Dol. These results confirm directly that deficiencies in PMM and PMI result in lowered cellular GDP-Man levels that are corrected by the addition of mannose. In contrast to these results, GDP-Man levels in fibroblasts from a CDG-Ie patient, who is deficient in Man-P-Dol synthase, were normal and unaffected by mannose supplementation even though mannose addition was found to correct abnormal lipid intermediate synthesis in another study (Kim et al. [2000] J. Clin. Invest., 105, 191–198). The mechanism by which mannose supplementation corrects abnormal protein N-glycosylation in Man-P-Dol synthase deficient cells is unknown, but this observation suggests that the regulation of Man-P-Dol synthesis and utilization may be more complex than is currently understood.
1 Present address: Glycobiology Research and Training Center, University of California San Diego School of Medicine, La Jolla, CA 92093
2 To whom correspondence should be addressed at: The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M. A Lehrman Teaching dolichol-linked oligosaccharides more tricks with alternatives to metabolic radiolabeling Glycobiology, August 1, 2007; 17(8): 75R - 85R. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Thiel, T. Lubke, G. Matthijs, K. von Figura, and C. Korner Targeted Disruption of the Mouse Phosphomannomutase 2 Gene Causes Early Embryonic Lethality Mol. Cell. Biol., August 1, 2006; 26(15): 5615 - 5620. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Lamani, R. B. Mewbourne, D. S. Fletcher, S. D. Maltsev, L. L. Danilov, V. V. Veselovsky, A. V. Lozanova, N. Ya. Grigorieva, O. A. Pinsker, J. Xing, et al. Structural studies and mechanism of Saccharomyces cerevisiae dolichyl-phosphate-mannose synthase: insights into the initial step of synthesis of dolichyl-phosphate-linked oligosaccharide chains in membranes of endoplasmic reticulum Glycobiology, July 1, 2006; 16(7): 666 - 678. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Gao, J. Shang, and M. A. Lehrman Analysis of Glycosylation in CDG-Ia Fibroblasts by Fluorophore-assisted Carbohydrate Electrophoresis: IMPLICATIONS FOR EXTRACELLULAR GLUCOSE AND INTRACELLULAR MANNOSE 6-PHOSPHATE J. Biol. Chem., May 6, 2005; 280(18): 17901 - 17909. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Shang and M. A. Lehrman Metformin-stimulated Mannose Transport in Dermal Fibroblasts J. Biol. Chem., March 12, 2004; 279(11): 9703 - 9712. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Gao and M. A. Lehrman Analyses of dolichol pyrophosphate-linked oligosaccharides in cell cultures and tissues by fluorophore-assisted carbohydrate electrophoresis Glycobiology, May 1, 2002; 12(5): 353 - 360. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. H. Freeze Update and perspectives on congenital disorders of glycosylation Glycobiology, December 1, 2001; 11(12): 129R - 143R. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Westphal, S. Murch, S. Kim, G. Srikrishna, B. Winchester, R. Day, and H. H. Freeze Reduced Heparan Sulfate Accumulation in Enterocytes Contributes to Protein-Losing Enteropathy in a Congenital Disorder of Glycosylation Am. J. Pathol., December 1, 2000; 157(6): 1917 - 1925. [Abstract] [Full Text] [PDF]
|
|