title: Proteome-wide identification of cellular targets affected by bisindolylmaleimide-type protein kinase C inhibitors.
abstract: Bisindolylmaleimide compounds such as GF109203X are potent inhibitors of protein kinase C (PKC) activity. Although bisindolylmaleimides are not entirely selective for PKC and are known to inhibit a few other protein kinases, these reagents have been extensively used to study the functional roles of PKC family enzymes in cellular signal transduction for more than a decade. Here, we establish a proteomics approach to gain further insights into the cellular effects of this compound class. Functional immobilization of suitable bisindolylmaleimide analogues in combination with the specific purification of cellular binding proteins by affinity chromatography led to the identification of several known and previously unknown enzyme targets. Subsequent in vitro binding and activity assays confirmed the protein kinases Ste20-related kinase and cyclin-dependent kinase 2 (CDK2) and the non-protein kinases adenosine kinase and quinone reductase type 2 as novel targets of bisindolylmaleimide inhibitors. As observed specifically for CDK2, minor chemical variation of the ligand by immobilizing the closely related bisindolylmaleimides III, VIII, and X dramatically affected target binding. These observed changes in affinity correlated with both the measured IC(50) values for in vitro CDK2 inhibition and results from molecular docking into the CDK2 crystal structure. Moreover, the conditions for affinity purification could be adapted in a way that immobilized bisindolylmaleimide III selectively interacted with either PKC alpha or ribosomal S6 protein kinase 1 only after activation of these kinases. Thus, we have established an efficient technique for the rapid identification of cellular bisindolylmaleimide targets and further demonstrate the comparative selectivity profiling of closely related kinase inhibitors within a cellular proteome.
authors.affiliation: Axxima Pharmaceuticals AG, Max-Lebsche-Platz 32, 81377 Munich, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Brehmer
authors.forename: Klaus
authors.initials: K
authors.lastname: Godl
authors.forename: Birgit
authors.initials: B
authors.lastname: Zech
authors.forename: Josef
authors.initials: J
authors.lastname: Wissing
authors.forename: Henrik
authors.initials: H
authors.lastname: Daub
mesh_terms: D000818:Animals; D042846:CDC2-CDC28 Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D002846:Chromatography, Affinity; D051357:Cyclin-Dependent Kinase 2; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008301:Maleimides / Q000494:pharmacology*; D008958:Models, Molecular; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D040901:Proteomics; D011808:Quinone Reductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D047428:Protein Kinase Inhibitors; D011808:Quinone Reductases; D011494:Protein Kinases; C069329:RPS6KA1 protein, human; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C496628:PRKCA protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; C088060:bisindolylmaleimide