The Laforin-Malin Complex, Involved in Lafora Disease, Promotes the Incorporation of K63-linked Ubiquitin Chains into AMP-activated Protein Kinase beta Subunits

Daniel Moreno, Mhairi C. Towler, D. Grahame Hardie, Erwin Knecht, Pascual Sanz

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    32 Citations (Scopus)

    Abstract

    Lafora progressive myoclonus epilepsy is a fatal neurodegenerative disorder caused by defects in the function of at least two proteins: laforin, a dual-specificity protein phosphatase, and malin, an E3-ubiquitin ligase. In this study, we report that a functional laforin-malin complex promotes the ubiquitination of AMP-activated protein kinase (AMPK), a serine/threonine protein kinase that acts as a sensor of cellular energy status. This reaction occurs when any of the three AMPK subunits (alpha, beta, and gamma) are expressed individually in the cell, and it also occurs on AMPK beta when it is part of a heterotrimeric complex. We also report that the laforin-malin complex promotes the formation of K63-linked ubiquitin chains, which are not involved in proteasome degradation. On the contrary, this modification increases the steady-state levels of at least AMPK beta subunit, possibly because it leads to the accumulation of this protein into inclusion bodies. These results suggest that the modification introduced by the laforin-malin complex could affect the subcellular distribution of AMPK beta subunits.

    Original languageEnglish
    Pages (from-to)2578-2588
    Number of pages11
    JournalMolecular Biology of the Cell
    Volume21
    Issue number15
    DOIs
    Publication statusPublished - 1 Aug 2010

    Keywords

    • PROGRESSIVE MYOCLONUS EPILEPSY
    • CONJUGATING ENZYMES
    • PHOSPHATASE LAFORIN
    • RETICULUM STRESS
    • GLYCOGEN
    • DEGRADATION
    • BINDING
    • MUTATIONS
    • GENE
    • POLYUBIQUITINATION

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