Glycogen lysosomal degradation

Glycogen may be degraded by an a-glucosidase located in lysosomes. -Lysosomal degradation is not necessary for maintaining normal blood glucose levels. 

Generalized glycogenosis typie II, also called Pompe s disease (J.C. PoMPE, 1932), is caused by a deficiency of lysosomal acidic al,4 glucosidase. This enzyme is responsible for the degradation of glycogen and maltose within the lysosomes. Glycogen is accumulated in all organs, particularly in the heart, but also in the liver. The disease may occur in the newborn (death due to heart failure, often within the first 12 months of life), but may also become manifest in infants and adults. Clinical symptoms include weakened skeletal... 

Some degradation of glycogen also occurs within lysosomes when glycogen particles become surrounded by membranes that then fuse with the lysosomal membranes. A lysosomal glucosidase hydrolyzes this glycogen to glucose. 

An examination of the catabolism of glycogen by an acid a-l,4-glucosidase present in cultured skin fibroblasts of normal cells and in those derived from patients with Cori Type II glycogen-storage disease has indicated the presence of an extra-lysosomal glycogen that is more amenable to degradation. ... 

Furthermore, when castanospermine is fed to mice over 4 5 days, it inhibits lysosomal a-glucosidase and causes the accumulation of partially degraded glycogen within the lysosomal structures [55]. This accumulation resembles the accumulation of glycogen particles in the lysosomal storage disease, Pompe s disease, where individuals lack the lysosomal a-glucosidase [56]. 

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