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PMID:17908927

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Citation

Cheng, A, Zhang, M, Gentry, MS, Worby, CA, Dixon, JE and Saltiel, AR (2007) A role for AGL ubiquitination in the glycogen storage disorders of Lafora and Cori's disease. Genes Dev. 21:2399-409

Abstract

Cori's disease is a glycogen storage disorder characterized by a deficiency in the glycogen debranching enzyme, amylo-1,6-glucosidase,4-alpha-glucanotransferase (AGL). Here, we demonstrate that the G1448R genetic variant of AGL is unable to bind to glycogen and displays decreased stability that is rescued by proteasomal inhibition. AGL G1448R is more highly ubiquitinated than its wild-type counterpart and forms aggresomes upon proteasome impairment. Furthermore, the E3 ubiquitin ligase Malin interacts with and promotes the ubiquitination of AGL. Malin is known to be mutated in Lafora disease, an autosomal recessive disorder clinically characterized by the accumulation of polyglucosan bodies resembling poorly branched glycogen. Transfection studies in HepG2 cells demonstrate that AGL is cytoplasmic whereas Malin is predominately nuclear. However, after depletion of glycogen stores for 4 h, approximately 90% of transfected cells exhibit partial nuclear staining for AGL. Furthermore, stimulation of cells with agents that elevate cAMP increases Malin levels and Malin/AGL complex formation. Refeeding mice for 2 h after an overnight fast causes a reduction in hepatic AGL levels by 48%. Taken together, these results indicate that binding to glycogen crucially regulates the stability of AGL and, further, that its ubiquitination may play an important role in the pathophysiology of both Lafora and Cori's disease.

Links

PubMed PMC1993871 Online version:10.1101/gad.1553207

Keywords

Animals; Binding Sites; Carrier Proteins/genetics; Carrier Proteins/metabolism; Cell Line; Glucans/metabolism; Glycogen/metabolism; Glycogen Debranching Enzyme System/analysis; Glycogen Debranching Enzyme System/genetics; Glycogen Debranching Enzyme System/metabolism; Glycogen Storage Disease/enzymology; Glycogen Storage Disease/etiology; Glycogen Storage Disease Type III/enzymology; Glycogen Storage Disease Type III/etiology; Humans; Lafora Disease/enzymology; Lafora Disease/etiology; Mice; Ubiquitin/metabolism

Significance

Annotations

Gene product Qualifier GO ID GO term name Evidence Code with/from Aspect Notes Status


See also

References

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