Lack of glycogenin causes glycogen accumulation and muscle function impairment
Glycogenin is considered essential for glycogen synthesis, as it acts as a primer for the initiation of the polysaccharide chain. Against expectations, glycogenin-deficient mice (Gyg KO) accumulate high amounts of glycogen in striated muscle. Furthermore, this glycogen contains no covalently bound p...
| Authors: | , , , , , , , , , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2017 |
| Country: | España |
| Institution: | Universitat Pompeu Fabra |
| Repository: | Repositorio Digital de la UPF |
| OAI Identifier: | oai:repositori.upf.edu:10230/36843 |
| Online Access: | http://hdl.handle.net/10230/36843 http://dx.doi.org/10.1016/j.cmet.2017.06.008 |
| Access Level: | Open access |
| Keyword: | Glycogenin Glycogen GSD XV Glycogen storage disease XV Glycogenosis Exercise Muscle performance Priming protein Oxidative metabolism Mitochondrial respiration |
| Summary: | Glycogenin is considered essential for glycogen synthesis, as it acts as a primer for the initiation of the polysaccharide chain. Against expectations, glycogenin-deficient mice (Gyg KO) accumulate high amounts of glycogen in striated muscle. Furthermore, this glycogen contains no covalently bound protein, thereby demonstrating that a protein primer is not strictly necessary for the synthesis of the polysaccharide in vivo. Strikingly, in spite of the higher glycogen content, Gyg KO mice showed lower resting energy expenditure and less resistance than control animals when subjected to endurance exercise. These observations can be attributed to a switch of oxidative myofibers toward glycolytic metabolism. Mice overexpressing glycogen synthase in the muscle showed similar alterations, thus indicating that this switch is caused by the excess of glycogen. These results may explain the muscular defects of GSD XV patients, who lack glycogenin-1 and show high glycogen accumulation in muscle. |
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