Data di Pubblicazione:
2003
Citazione:
Ganglioside/glycosphingolipid turnover : new concepts / G. Tettamanti. - In: GLYCOCONJUGATE JOURNAL. - ISSN 0282-0080. - 20:5(2003 Jun), pp. 301-317.
Abstract:
In this review focus is given to the metabolic turnover of gangliosides/glycosphingolipids. The metabolism and accompanying
intracellular trafficking of gangliosides/glycosphingolipids is illustrated with particular attention to the following events: (a) the de novo biosynthesis in the endoplasmic reticulum and Golgi apparatus, followed by vesicular sorting to the plasma membrane; (b) the enzyme-assisted chemical modifications occurring at the plasma membrane level; (c) the internalization via endocytosis and recycling to the plasma membrane; (d) the direct glycosylations taking place after
sorting from endosomes to the Golgi apparatus; (e) the degradation at the late endosomal/lysosomal level with formation
of fragments of sugar (glucose, galactose, hexosamine, sialic acid) and lipid (ceramide, sphingosine, fatty acid) nature;
(f) the metabolic recycling of these fragments for biosynthetic purposes (salvage pathways); and (g) further degradation
of fragments to waste products. Noteworthy, the correct course of ganglioside/glycosphingolipid metabolism requires the presence of the vimentin intracellular filament net work, likely to assist intracellular transport of sphingoid molecules. Out of the above events those that can be quantitatively evaluated with acceptable reliability are the processes of
de novo biosynthesis, metabolic salvage and direct glycosylation. Depending on the cultured cells employed, the percentage
of distribution of de novo biosynthesis, salvage pathways, and direct glycosylation, over total metabolism were
reported to be: 35% (range: 10–90%) for de novo biosynthesis, 7% (range: 5–10%) for direct glycosylation, and 58% (range: 10–90%) for salvage pathways. The attempts made to calculate the half-life of overall ganglioside turnover provided
data of unsure reliability, especially because in many studies salvage pathways were not taken into consideration.
The values of half-life range from 2 to 6.5 h to 3 days depending on the cells used. Available evidence for changes of
ganglioside/glycosphingolipid turnover, due to extracellular stimuli, is also considered and discussed.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
ganglioside metabolism ; ganglioside turnover ; glycosphingolipid salvage pathways ; glycosphingolipid signalling
Elenco autori:
G. Tettamanti
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