title: Negative and positive regulation of MAPK phosphatase 3 controls platelet-derived growth factor-induced Erk activation.
abstract: MAPK phosphatases (MKPs) are dual specificity phosphatases that dephosphorylate and thereby inactivate MAPKs. In the present study, we provide evidence that platelet-derived growth factor BB (PDGF-BB) regulates MKP3 (DUSP6), which is considered to be a phosphatase highly selective for Erk. Intriguingly, we observed that Mek is positively regulated by MKP3, whereas Erk itself is negatively regulated. In addition, we found that activation of PDGF receptor alpha or beta leads to a rapid proteasomal degradation of MKP3 in a manner that requires Mek activation; this feed-forward mechanism was found to be essential for efficient Erk phosphorylation. We could also demonstrate that PDGF-BB stimulation induces phosphorylation of MKP3 at Ser-174 and Ser-300; phosphorylation of Ser-174 is involved in PDGF-induced MKP3 degradation, since mutation of this site stabilized MKP3. Moreover, activated Erk induces mkp3 expression, leading to restoration of MKP3 levels after 1-2 h and a concomitant dephosphorylation of Erk in cells with activated PDGFRalpha. Reducing the MKP3 level by small interfering RNA leads to an increased Erk activation and mitogenic response to PDGF-BB. In conclusion, MKP3 is an important regulator of PDGF-induced Erk phosphorylation acting in both a rapid positive feed-forward and a later negative feed-back loop.
authors.affiliation: Ludwig Institute for Cancer Research, Uppsala University, Box 595, SE-751 24 Uppsala, Sweden.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Jurek
authors.forename: Kenichi
authors.initials: K
authors.lastname: Amagasaki
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Gembarska
authors.forename: Carl-Henrik
authors.initials: CH
authors.lastname: Heldin
authors.forename: Johan
authors.initials: J
authors.lastname: Lennartsson
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D000077214:Becaplermin; D002460:Cell Line; D054642:Dual Specificity Phosphatase 6 / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D010982:Platelet-Derived Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics / Q000378:metabolism*; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D013552:Swine; D013997:Time Factors
chemical_list: D043925:Angiogenesis Inducing Agents; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D000077214:Becaplermin; D020796:Receptor, Platelet-Derived Growth Factor alpha; D020797:Receptor, Platelet-Derived Growth Factor beta; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; C517035:DUSP6 protein, human; D054642:Dual Specificity Phosphatase 6; D046988:Proteasome Endopeptidase Complex