title: Spatiotemporal regulation of ERK2 by dual specificity phosphatases.
abstract: Although many stimuli activate extracellular signal-regulated kinases 1 and 2 (ERK1/2), the kinetics and compartmentalization of ERK1/2 signals are stimulus-dependent and dictate physiological consequences. ERKs can be inactivated by dual specificity phosphatases (DUSPs), notably the MAPK phosphatases (MKPs) and atypical DUSPs, that can both dephosphorylate and scaffold ERK1/2. Using a cell imaging model (based on knockdown of endogenous ERKs and add-back of wild-type or mutated ERK2-GFP reporters), we explored possible effects of DUSPs on responses to transient or sustained ERK2 activators (epidermal growth factor and phorbol 12,13-dibutyrate, respectively). For both stimuli, a D319N mutation (which impairs DUSP binding) increased ERK2 activity and reduced nuclear accumulation. These stimuli also increased mRNA levels for eight DUSPs. In a short inhibitory RNA screen, 12 of 16 DUSPs influenced ERK2 responses. These effects were evident among nuclear inducible MKP, cytoplasmic ERK MKP, JNK/p38 MKP, and atypical DUSP subtypes and, with the exception of the nuclear inducible MKPs, were paralleled by corresponding changes in Egr-1 luciferase activation. Simultaneous removal of all JNK/p38 MKPs or nuclear inducible MKPs revealed them as positive and negative regulators of ERK2 signaling, respectively. The effects of JNK/p38 MKP short inhibitory RNAs were not dependent on protein neosynthesis but were reversed in the presence of JNK and p38 kinase inhibitors, indicating DUSP-mediated cross-talk between MAPK pathways. Overall, our data reveal that a large number of DUSPs influence ERK2 signaling. Together with the known tissue-specific expression of DUSPs and the importance of ERK1/2 in cell regulation, our data support the potential value of DUSPs as targets for drug therapy.
authors.affiliation: Laboratory for Integrated Neuroscience and Endocrinology, Department of Clinical Sciences at South Bristol, University of Bristol, Whitson Street, Bristol BS1 3NY, United Kingdom.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Caunt
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Armstrong
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Rivers
authors.forename: Michael R
authors.initials: MR
authors.lastname: Norman
authors.forename: Craig A
authors.initials: CA
authors.lastname: McArdle
mesh_terms: D019943:Amino Acid Substitution; D002467:Cell Nucleus / Q000201:enzymology*; D054637:Dual-Specificity Phosphatases / Q000235:genetics / Q000378:metabolism*; D020536:Enzyme Activators / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008856:Microscopy, Fluorescence / Q000379:methods; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D020125:Mutation, Missense; D010766:Phosphorylation / Q000187:drug effects
chemical_list: D020536:Enzyme Activators; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D054637:Dual-Specificity Phosphatases