Binding and inhibition of the ternary complex factor Elk-4/Sap1 by the adapter protein Dok-4
| Autor: | Victoria Roodman, Erika Hooker, Cindy Baldwin, Serge Lemay, Tomoko Takano, Naajia Nur Isa, Anupam Batra |
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| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
MAPK/ERK pathway animal diseases Immunoblotting Nuclear Localization Signals Active Transport Cell Nucleus Biology Biochemistry Madin Darby Canine Kidney Cells 03 medical and health sciences Transactivation Mice fluids and secretions 0302 clinical medicine Dogs Two-Hybrid System Techniques Animals Humans Amino Acid Sequence ets-Domain Protein Elk-4 Nuclear export signal Molecular Biology Transcription factor Adaptor Proteins Signal Transducing Cell Proliferation Nuclear Export Signals Microscopy Confocal Sequence Homology Amino Acid Signal transducing adaptor protein Cell Biology Molecular biology Cell biology Pleckstrin homology domain 030104 developmental biology HEK293 Cells Protein destabilization Gene Expression Regulation COS Cells RNA Interference 030217 neurology & neurosurgery Nuclear localization sequence Protein Binding |
| Zdroj: | The Biochemical journal. 474(9) |
| ISSN: | 1470-8728 |
| Popis: | The adapter protein Dok-4 (downstream of kinase-4) has been reported as both an activator and inhibitor of Erk and Elk-1, but lack of knowledge about the identity of its partner molecules has precluded any mechanistic insight into these seemingly conflicting properties. We report that Dok-4 interacts with the transactivation domain of Elk-4 through an atypical phosphotyrosine-binding domain-mediated interaction. Dok-4 possesses a nuclear export signal and can relocalize Elk-4 from nucleus to cytosol, whereas Elk-4 possesses two nuclear localization signals that restrict interaction with Dok-4. The Elk-4 protein, unlike Elk-1, is highly unstable in the presence of Dok-4, through both an interaction-dependent mechanism and a pleckstrin homology domain-dependent but interaction-independent mechanism. This is reversed by proteasome inhibition, depletion of endogenous Dok-4 or lysine-to-arginine mutation of putative Elk-4 ubiquitination sites. Finally, Elk-4 transactivation is potently inhibited by Dok-4 overexpression but enhanced by Dok-4 knockdown in MDCK renal tubular cells, which correlates with increased basal and EGF-induced expression of Egr-1, Fos and cylcinD1 mRNA, and cell proliferation despite reduced Erk activation. Thus, Dok-4 can target Elk-4 activity through multiple mechanisms, including binding of the transactivation domain, nuclear exclusion and protein destabilization, without a requirement for inhibition of Erk. |
| Databáze: | OpenAIRE |
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