title: The PHD domain of MEKK1 acts as an E3 ubiquitin ligase and mediates ubiquitination and degradation of ERK1/2.
abstract: ERK1/2 MAP kinases are important regulators in cellular signaling, whose activity is normally reversibly regulated by threonine-tyrosine phosphorylation. In contrast, we have found that stress-induced ERK1/2 activity is downregulated by ubiquitin/proteasome-mediated degradation of ERK1/2. The PHD domain of MEKK1, a RING finger-like structure, exhibited E3 ubiquitin ligase activity toward ERK2 in vitro and in vivo. Moreover, both MEKK1 kinase activity and the docking motif on ERK1/2 were involved in ERK1/2 ubiquitination. Significantly, cells expressing ERK2 with the docking motif mutation were resistant to sorbitol-induced apoptosis. Therefore, MEKK1 functions not only as an upstream activator of the ERK and JNK through its kinase domain, but also as an E3 ligase through its PHD domain, providing a negative regulatory mechanism for decreasing ERK1/2 activity.
authors.affiliation: Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Lu
authors.forename: Shuichan
authors.initials: S
authors.lastname: Xu
authors.forename: Claudio
authors.initials: C
authors.lastname: Joazeiro
authors.forename: Melanie H
authors.initials: MH
authors.lastname: Cobb
authors.forename: Tony
authors.initials: T
authors.lastname: Hunter
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001769:Blood; D003546:Cysteine Endopeptidases / Q000378:metabolism; D015536:Down-Regulation; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism; D006801:Humans; D008025:Ligases / Q000378:metabolism*; D048728:MAP Kinase Kinase Kinase 1; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D013012:Sorbitol / Q000378:metabolism; D013329:Structure-Activity Relationship; D014162:Transfection; D014407:Tumor Cells, Cultured; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: D009097:Multienzyme Complexes; D014452:Ubiquitins; D013012:Sorbitol; D004815:Epidermal Growth Factor; D044767:Ubiquitin-Protein Ligases; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; C482578:Map3k1 protein, mouse; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D008025:Ligases