title: Interaction partners of Dlk/ZIP kinase: co-expression of Dlk/ZIP kinase and Par-4 results in cytoplasmic retention and apoptosis.
abstract: Dlk/ZIP kinase is a newly discovered serine/threonine kinase which, due to its homology to DAP kinase, was named DAP like kinase, Dlk. This kinase is tightly associated with nuclear structures, it undergoes extensive autophosphorylation and phosphorylates myosin light chain and core histones H3, H2A and H4 in vitro. Moreover, it possesses a leucine zipper which mediates interaction with transcription factor ATF-4, therefore it was called ZIP kinase. We employed the yeast two-hybrid system to identify interaction partners of Dlk that might serve as regulators or targets. Besides ATF-4 and others we found Par-4, a modulator of transcription factor WT1 and mediator of apoptosis. Complex formation between Dlk and Par-4 was confirmed by GST pull-down experiments and kinase reactions in vitro and coexpression experiments in vivo. The interaction domain within Dlk was mapped to an arginine-rich region between residues 338 - 417, rather than to the leucine zipper. Strikingly, coexpression of Dlk and Par-4 lead to relocation of Dlk from the nucleus to the cytoplasm, particularly to actin filaments. These interactions provoked a dramatic reorganization of the cytoskeleton and morphological symptoms of apoptosis, thus suggesting a functional relationship between Dlk and Par-4 in the control of apoptosis.
authors.affiliation: Institute of Genetics, University of Bonn, Roemerstr. 164, D-53117 Bonn, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Page
authors.forename: D
authors.initials: D
authors.lastname: Kögel
authors.forename: V
authors.initials: V
authors.lastname: Rangnekar
authors.forename: K H
authors.initials: KH
authors.lastname: Scheidtmann
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D003593:Cytoplasm / Q000502:physiology; D064550:Death-Associated Protein Kinases; D004926:Escherichia coli; D005786:Gene Expression Regulation; D047908:Intracellular Signaling Peptides and Proteins; D016350:Leucine Zippers; D020930:MAP Kinase Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D017468:Receptors, Fibroblast Growth Factor; C101296:prostate apoptosis response-4 protein; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020930:MAP Kinase Kinase Kinases; C090757:mitogen-activated protein kinase kinase kinase 12