DYRK1A phosphorylates caspase 9 at an inhibitory site and is potently inhibited in human cells by harmine

Anne Seifert, Lindsey A. Allan, Paul R. Clarke (Lead / Corresponding author)

    Research output: Contribution to journalArticle

    90 Citations (Scopus)

    Abstract

    DYRK1A is a member of the dual-specificity tyrosine-phosphorylation-regulated protein kinase family and is implicated in Down's syndrome. Here, we identify the cysteine aspartyl protease caspase 9, a critical component of the intrinsic apoptotic pathway, as a substrate of DYRK1A. Depletion of DYRK1A from human cells by short interfering RNA inhibits the basal phosphorylation of caspase 9 at an inhibitory site, Thr125. DYRK1A-dependent phosphorylation of Thr125 is also blocked by harmine, confirming the use of this beta-carboline alkaloid as a potent inhibitor of DYRK1A in cells. We show that harmine not only inhibits the protein-serine/threonine kinase activity of mature DYRK1A, but also its autophosphorylation on tyrosine during translation, indicating that harmine prevents formation of the active enzyme. When co-expressed in cells, DYRK1A interacts with caspase 9, strongly induces Thr125 phosphorylation and inhibits caspase 9 auto-processing. Phosphorylation of caspase 9 by DYRK1A involves co-localization to the nucleus. These results indicate that DYRK1A sets a threshold for the activation of caspase 9 through basal inhibitory phosphorylation of this protease. Regulation of apoptosis through inhibitory phosphorylation of caspase 9 may play a role in the function of DYRK1A during development and in pathogenesis.

    Original languageEnglish
    Pages (from-to)6268-6280
    Number of pages13
    JournalFEBS Journal
    Volume275
    Issue number24
    DOIs
    Publication statusPublished - Dec 2008

    Keywords

    • apoptosis
    • caspase
    • DYRK
    • harmine
    • protein kinase
    • PROTEIN-KINASE DYRK1A
    • DUAL-SPECIFICITY
    • DOWN-SYNDROME
    • ACTIVATION-LOOP
    • CRITICAL REGION
    • HUMAN HOMOLOG
    • CYTOCHROME-C
    • IN-VIVO
    • FAMILY
    • APOPTOSIS

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