Regulation of glycogen synthesis by the laforin-malin complex is modulated by the AMP-activated protein kinase pathway.
Lafora progressive myoclonus epilepsy (LD) is a fatal autosomal recessive neurodegenerative disorder characterized by the presence of glycogen-like intracellular inclusions called Lafora bodies. LD is caused by mutations in two genes, EPM2A and EPM2B, encoding respectively laforin, a dual-specificity protein phosphatase, and malin, an E3 ubiquitin ligase. Previously, we and others have suggested that the interactions between laforin and PTG (a regulatory subunit of type 1 protein phosphatase) and between laforin and malin are critical in the pathogenesis of LD. Here, we show that the laforin-malin complex downregulates PTG-induced glycogen synthesis in FTO2B hepatoma cells through a mechanism involving ubiquitination and degradation of PTG. Furthermore, we demonstrate that the interaction between laforin and malin is a regulated process that is modulated by the AMP-activated protein kinase (AMPK). These findings provide further insights into the critical role of the laforin-malin complex in the control of glycogen metabolism and unravel a novel link between the energy sensor AMPK and glycogen metabolism. These data advance our understanding of the functional role of laforin and malin, which hopefully will facilitate the development of appropriate LD therapies.
Solaz-Fuster
Maria Carmen
MC
Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas, and CIBERER-ISCIII, Jaime Roig 11, Valencia 46010, Spain.
Gimeno-Alcañiz
José Vicente
JV
Ros
Susana
S
Fernandez-Sanchez
Maria Elena
ME
Garcia-Fojeda
Belen
B
Criado Garcia
Olga
O
Vilchez
David
D
Dominguez
Jorge
J
Garcia-Rocha
Mar
M
Sanchez-Piris
Maribel
M
Aguado
Carmen
C
Knecht
Erwin
E
Serratosa
Jose
J
Guinovart
Joan Josep
JJ
Sanz
Pascual
P
Rodriguez de Córdoba
Santiago
S
D055372:AMP-Activated Protein Kinases; D000256:Adenoviridae / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002468:Cell Physiological Phenomena; D004926:Escherichia coli / Q000235:genetics; D006003:Glycogen / Q000032:analysis / Q000096:biosynthesis*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000166:cytology; D008954:Models, Biological; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism*; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D054558:Protein Tyrosine Phosphatases, Non-Receptor / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D013223:Statistics as Topic; D014162:Transfection; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases; D054875:Ubiquitination
D002352:Carrier Proteins; D009097:Multienzyme Complexes; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D006003:Glycogen; C478960:NHLRC1 protein, human; D044767:Ubiquitin-Protein Ligases; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; D054558:Protein Tyrosine Phosphatases, Non-Receptor; C114990:EPM2A protein, human