title: An efficient proteomics method to identify the cellular targets of protein kinase inhibitors.
abstract: Small molecule inhibitors of protein kinases are widely used in signal transduction research and are emerging as a major class of drugs. Although interpretation of biological results obtained with these reagents critically depends on their selectivity, efficient methods for proteome-wide assessment of kinase inhibitor selectivity have not yet been reported. Here, we address this important issue and describe a method for identifying targets of the widely used p38 kinase inhibitor SB 203580. Immobilization of a suitable SB 203580 analogue and thoroughly optimized biochemical conditions for affinity chromatography permitted the dramatic enrichment and identification of several previously unknown protein kinase targets of SB 203580. In vitro kinase assays showed that cyclin G-associated kinase (GAK) and CK1 were almost as potently inhibited as p38alpha whereas RICK [Rip-like interacting caspase-like apoptosis-regulatory protein (CLARP) kinase/Rip2/CARDIAK] was even more sensitive to inhibition by SB 203580. The cellular kinase activity of RICK, a known signal transducer of inflammatory responses, was already inhibited by submicromolar concentrations of SB 203580 in intact cells. Therefore, our results warrant a reevaluation of the vast amount of data obtained with SB 203580 and might have significant implications on the development of p38 inhibitors as antiinflammatory drugs. Based on the procedures described here, efficient affinity purification techniques can be developed for other protein kinase inhibitors, providing crucial information about their cellular modes of action.
authors.affiliation: Axxima Pharmaceuticals AG, Max-Lebsche-Platz 32, 81377 Munich, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Godl
authors.forename: Josef
authors.initials: J
authors.lastname: Wissing
authors.forename: Alexander
authors.initials: A
authors.lastname: Kurtenbach
authors.forename: Peter
authors.initials: P
authors.lastname: Habenberger
authors.forename: Stephanie
authors.initials: S
authors.lastname: Blencke
authors.forename: Heidrun
authors.initials: H
authors.lastname: Gutbrod
authors.forename: Kostadinos
authors.initials: K
authors.lastname: Salassidis
authors.forename: Matthias
authors.initials: M
authors.lastname: Stein-Gerlach
authors.forename: Andrea
authors.initials: A
authors.lastname: Missio
authors.forename: Matt
authors.initials: M
authors.lastname: Cotten
authors.forename: Henrik
authors.initials: H
authors.lastname: Daub
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D013058:Mass Spectrometry; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000302:isolation & purification; D047428:Protein Kinase Inhibitors; D040901:Proteomics; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D004791:Enzyme Inhibitors; D047428:Protein Kinase Inhibitors; D011994:Recombinant Proteins; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases