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J Biol Chem. 2013 Sep 13;288(37):26898-907. doi: 10.1074/jbc.M113.464503. Epub 2013 Jul 23.

Basal autophagy is required for the efficient catabolism of sialyloligosaccharides.

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From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN Max Planck Joint Research Center, RIKEN Global Research Cluster, Saitama 351-0198, Japan.


Macroautophagy is an essential, homeostatic process involving degradation of a cell's own components; it plays a role in catabolizing cellular components, such as protein or lipids, and damaged or excess organelles. Here, we show that in Atg5(-/-) cells, sialyloligosaccharides specifically accumulated in the cytosol. Accumulation of these glycans was observed under non-starved conditions, suggesting that non-induced, basal autophagy is essential for their catabolism. Interestingly, once accumulated in the cytosol, sialylglycans cannot be efficiently catabolized by resumption of the autophagic process, suggesting that functional autophagy is important for preventing sialyloligosaccharides from accumulating in the cytosol. Moreover, knockdown of sialin, a lysosomal transporter of sialic acids, resulted in a significant reduction of sialyloligosaccharides, implying that autophagy affects the substrate specificity of this transporter. This study thus provides a surprising link between basal autophagy and catabolism of N-linked glycans.


Autophagy; Glycan Catabolism; Glycoprotein; Lysosomal Glycoproteins; Lysosomes; Oligosaccharide; Sialic Acid; Sialin; Sialyloligosaccharides

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