title: Distinct functions of the dual leucine zipper kinase depending on its subcellular localization.
abstract: The dual leucine zipper kinase DLK induces β-cell apoptosis by inhibiting the transcriptional activity conferred by the β-cell protective transcription factor cAMP response element binding protein CREB. This action might contribute to β-cell loss and ultimately diabetes. Within its kinase domain DLK shares high homology with the mixed lineage kinase (MLK) 3, which is activated by tumor necrosis factor (TNF) α and interleukin (IL)-1β, known prediabetic signals. In the present study, the regulation of DLK in β-cells by these cytokines was investigated. Both, TNFα and IL-1β induced the nuclear translocation of DLK. Mutations within a putative nuclear localization signal (NLS) prevented basal and cytokine-induced nuclear localization of DLK and binding to the importin receptor importin α, thereby demonstrating a functional NLS within DLK. DLK NLS mutants were catalytically active as they phosphorylated their down-stream kinase c-Jun N-terminal kinase to the same extent as DLK wild-type but did neither inhibit CREB-dependent gene transcription nor transcription conferred by the promoter of the anti-apoptotic protein BCL-xL. In addition, the β-cell apoptosis-inducing effect of DLK was severely diminished by mutation of its NLS. In a murine model of prediabetes, enhanced nuclear DLK was found. These data demonstrate that DLK exerts distinct functions, depending on its subcellular localization and thus provide a novel level of regulating DLK action. Furthermore, the prevention of the nuclear localization of DLK as induced by prediabetic signals with consecutive suppression of β-cell apoptosis might constitute a novel target in the therapy of diabetes mellitus.
authors.affiliation: Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Wallbach
authors.affiliation: Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
authors.forename: Jorge
authors.initials: J
authors.lastname: Duque Escobar
authors.affiliation: Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany; Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
authors.forename: Rohollah
authors.initials: R
authors.lastname: Babaeikelishomi
authors.affiliation: Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.
authors.forename: Marie-Jeannette
authors.initials: MJ
authors.lastname: Stahnke
authors.affiliation: Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Blume
authors.affiliation: Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Schröder
authors.affiliation: Department of Prothetics, Faculty of Medicine, Georg-August-University, GZMB, Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
authors.forename: Jenny
authors.initials: J
authors.lastname: Kruegel
authors.affiliation: Center for Biomolecular Interactions Bremen, Leobener Str. Im NW2, 28359 Bremen, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Maedler
authors.affiliation: German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kluth
authors.affiliation: Department of Molecular Biology, Faculty of Medicine, Georg-August-University, GZMB, Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
authors.forename: Ralph H
authors.initials: RH
authors.lastname: Kehlenbach
authors.affiliation: Department of Prothetics, Faculty of Medicine, Georg-August-University, GZMB, Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
authors.forename: Nicolai
authors.initials: N
authors.lastname: Miosge
authors.affiliation: Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany; Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg Eppendorf, Martinistr. 52, 20246 Hamburg, Germany; Institute of Pharmacy, University of Hamburg, Bundesstr. 45, 20146 Hamburg, Germany. Electronic address: e.oetjen@uke.uni-hamburg.de.
authors.forename: Elke
authors.initials: E
authors.lastname: Oetjen
mesh_terms: D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology* / Q000235:genetics; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology* / Q000235:genetics; D050417:Insulin-Secreting Cells / Q000201:enzymology* / Q000473:pathology; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D021381:Protein Transport / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D053583:Interleukin-1beta; D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D014409:Tumor Necrosis Factor-alpha; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11; C492004:Creb1 protein, mouse; C587672:IL1B protein, mouse; C090757:mitogen-activated protein kinase kinase kinase 12
keywords: CREB; Diabetes; Dual leucine zipper kinase; Nuclear localization signal; β-Cell apoptosis