title: Interaction with MEK causes nuclear export and downregulation of peroxisome proliferator-activated receptor gamma.
abstract: The mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) cascade plays a central role in intracellular signaling by many extracellular stimuli. One target of the ERK cascade is peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear receptor that promotes differentiation and apoptosis. It was previously demonstrated that PPARgamma activity is attenuated upon mitogenic stimulation due to phosphorylation of its Ser84 by ERKs. Here we show that stimulation by tetradecanoyl phorbol acetate (TPA) attenuates PPARgamma's activity in a MEK-dependent manner, even when Ser84 is mutated to Ala. To elucidate the mechanism of attenuation, we found that PPARgamma directly interacts with MEKs, which are the activators of ERKs, but not with ERKs themselves, both in vivo and in vitro. This interaction is facilitated by MEKs' phosphorylation and is mediated by the basic D domain of MEK1 and the AF2 domain of PPARgamma. Immunofluorescence microscopy and subcellular fractionation revealed that MEK1 exports PPARgamma from the nucleus, and this finding was supported by small interfering RNA knockdown of MEK1 and use of a cell-permeable interaction-blocking peptide, which prevented TPA-induced export of PPARgamma from the nucleus. Thus, we show here a novel mode of downregulation of PPARgamma by its MEK-dependent redistribution from the nucleus to the cytosol. This unanticipated role for the stimulation-induced nuclear shuttling of MEKs shows that MEKs can regulate additional signaling components besides the ERK cascade.
authors.affiliation: Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Elke
authors.initials: E
authors.lastname: Burgermeister
authors.forename: Dana
authors.initials: D
authors.lastname: Chuderland
authors.forename: Tamar
authors.initials: T
authors.lastname: Hanoch
authors.forename: Markus
authors.initials: M
authors.lastname: Meyer
authors.forename: Mordechai
authors.initials: M
authors.lastname: Liscovitch
authors.forename: Rony
authors.initials: R
authors.lastname: Seger
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D042962:Acyl-CoA Oxidase / Q000235:genetics; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D003600:Cytosol / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000378:metabolism*; D048370:MAP Kinase Kinase 2 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D000077154:Rosiglitazone; D012694:Serine / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D045162:Thiazolidinediones / Q000494:pharmacology; D015533:Transcriptional Activation / Q000187:drug effects; D020798:Two-Hybrid System Techniques
chemical_list: D047495:PPAR gamma; D045162:Thiazolidinediones; D000077154:Rosiglitazone; D012694:Serine; D042962:Acyl-CoA Oxidase; C482128:MAP2K2 protein, human; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; D013755:Tetradecanoylphorbol Acetate