14-3-3 cooperates with LKB1 to regulate the activity and localization of QSK and SIK

Abdallah K. Al-Hakim (Lead / Corresponding author), Olga Göransson, Maria Deak, Rachel Toth, David G. Campbell, Nick A. Morrice, Alan R. Prescott, Dario R. Alessi

    Research output: Contribution to journalArticlepeer-review

    78 Citations (Scopus)

    Abstract

    The LKB1 tumour suppressor kinase phosphorylates and activates a number of protein kinases belonging to the AMP-activated protein kinase (AMPK) subfamily. We have used a modified tandem affinity purification strategy to identify proteins that interact with AMPKα, as well as the twelve AMPK-related kinases that are activated by LKB1. The AMPKβ and AMPKγ regulatory subunits were associated with AMPKα but not with any of the AMPK-related kinases, explaining why AMP does not influence the activity of these enzymes. In addition, we identified novel binding partners that interacted with one or more of the AMPK subfamily enzymes, including fat facets/ubiquitin specific protease-9 (USP9), AAA-ATPase-p97, adenine nucleotide translocase, protein phosphatase 2A holoenzyme and isoforms of the phospho-protein binding adaptor 14-3-3. Interestingly, the 14-3-3 isoforms bound directly to the T-loop Thr residue of QSK and SIK, after these were phosphorylated by LKB1. Consistent with this, the 14-3-3 isoforms failed to interact with non-phosphorylated QSK and SIK, in LKB1 knockout muscle or in HeLa cells in which LKB1 is not expressed. Moreover, mutation of the T-loop Thr phosphorylated by LKB1, prevented QSK and SIK from interacting with 14-3-3 in vitro. Binding of 14-3-3 to QSK and SIK, enhanced catalytic activity towards the TORC2 protein and the AMARA peptide, and was required for the cytoplasmic localization of SIK and for localization of QSK to punctate structures within the cytoplasm. To our knowledge, this study provides the first example of 14-3-3 binding directly to the T-loop of a protein kinase and influencing its catalytic activity and cellular localization.

    Original languageEnglish
    Pages (from-to)5661-5673
    Number of pages13
    JournalJournal of Cell Science
    Volume118
    Issue number23
    DOIs
    Publication statusPublished - 1 Dec 2005

    Keywords

    • AMPK
    • Cell polarity
    • MARK/Par1
    • Mass spectrometry
    • Tandem affinity purification

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