tailieunhanh - Báo cáo khoa học: Harmine specifically inhibits protein kinase DYRK1A and interferes with neurite formation

DYRK1A is a dual-specificity protein kinase that autophosphorylates a conserved tyrosine residue in the activation loop but phosphorylates exoge-nous substrates only at serine or threonine residues. Tyrosine autophospho-rylation of DYRKs is a one-off event that takes place during translation and induces the activation of the kinase. | Harmine specifically inhibits protein kinase DYRK1A and interferes with neurite formation Nora Gockler1 Guillermo Jofre2 Chrisovalantis Papadopoulos1 Ulf Soppa1 Francisco J. Tejedor2 and Walter Becker1 1 Institute of Pharmacology and Toxicology MedicalFaculty of the RWTH Aachen University Aachen Germany 2 Instituto de Neurociencias Consejo Superior de Investigaciones Cientificas CSIC and Universidad MiguelHernandez Alicante Spain Keywords autophosphorylation DYRK1A harmine kinase inhibitor neurite formation Correspondence W. Becker Institute of Pharmacology and Toxicology RWTH Aachen University Wendlingweg 2 52074 Aachen Germany Fax 49 241 80 82433 Tel 49 241 80 89124 E-mail wbecker@ Received 18 June 2009 revised 16 August 2009 accepted 1 September 2009 doi DYRK1A is a dual-specificity protein kinase that autophosphorylates a conserved tyrosine residue in the activation loop but phosphorylates exogenous substrates only at serine or threonine residues. Tyrosine autophosphorylation of DYRKs is a one-off event that takes place during translation and induces the activation of the kinase. Here we characterize the betacarboline alkaloid harmine as a potent and specific inhibitor of DYRK1A both in vitro and in cultured cells. Comparative in vitro assays of four kinases of the DYRK family showed that harmine inhibited substrate phosphorylation by DYRK1A more potently than it inhibited substrate phosphorylation by the closely related kinase DYRK1B half maximal inhibitory concentrations IC50 of 33 nM versus 166 nM respectively and by the more distant members of the family DYRK2 and DYRK4 pM and 80 pM respectively . Much higher concentrations of harmine were required to suppress tyrosine autophosphorylation of the translational intermediate of DYRK1A in a bacterial in vitro translation system IC50 pM . Importantly harmine inhibited the phosphorylation of a specific substrate by DYRK1A in cultured cells with a potency similar