title: Laforin, a dual-specificity phosphatase involved in Lafora disease, is phosphorylated at Ser25 by AMP-activated protein kinase.
abstract: Lafora progressive myoclonus epilepsy [LD (Lafora disease)] is a fatal autosomal recessive neurodegenerative disorder caused by loss-of-function mutations in either the EPM2A gene, encoding the dual-specificity phosphatase laforin, or the EPM2B gene, encoding the E3-ubiquitin ligase malin. Previously, we and others showed that laforin and malin form a functional complex that regulates multiple aspects of glycogen metabolism, and that the interaction between laforin and malin is enhanced by conditions activating AMPK (AMP-activated protein kinase). In the present study, we demonstrate that laforin is a phosphoprotein, as indicated by two-dimensional electrophoresis, and we identify Ser(25) as the residue involved in this modification. We also show that Ser(25) is phosphorylated both in vitro and in vivo by AMPK. Lastly, we demonstrate that this residue plays a critical role for both the phosphatase activity and the ability of laforin to interact with itself and with previously established binding partners. The results of the present study suggest that phosphorylation of laforin-Ser(25) by AMPK provides a mechanism to modulate the interaction between laforin and malin. Regulation of this complex is necessary to maintain normal glycogen metabolism. Importantly, Ser(25) is mutated in some LD patients (S25P), and our results begin to elucidate the mechanism of disease in these patients.
authors: Instituto de Biomedicina de Valencia, CSIC and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Jaime Roig 11, 46010 Valencia, Spain.
authors: Carlos
authors: C
authors: Romá-Mateo
authors: Maria Del Carmen
authors: Mdel C
authors: Solaz-Fuster
authors: José Vicente
authors: JV
authors: Gimeno-Alcañiz
authors: Vikas V
authors: VV
authors: Dukhande
authors: Jordi
authors: J
authors: Donderis
authors: Carolyn A
authors: CA
authors: Worby
authors: Alberto
authors: A
authors: Marina
authors: Olga
authors: O
authors: Criado
authors: Antonius
authors: A
authors: Koller
authors: Santiago
authors: S
authors: Rodriguez De Cordoba
authors: Matthew S
authors: MS
authors: Gentry
authors: Pascual
authors: P
authors: Sanz
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D020192:Lafora Disease / Q000201:enzymology*; D008958:Models, Molecular; D010766:Phosphorylation; D011487:Protein Conformation; D054558:Protein Tyrosine Phosphatases, Non-Receptor / Q000737:chemistry / Q000378:metabolism*; D012694:Serine / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D012694:Serine; D055372:AMP-Activated Protein Kinases; D054558:Protein Tyrosine Phosphatases, Non-Receptor; C114990:EPM2A protein, human