PEA-15 Binding to ERK1/2 MAPKs Is Required for Its Modulation of Integrin Activation

• Published in: The Journal of biological chemistry Vol. 278; no. 52; pp. 52587 - 52597
• Main Authors: Chou, Fan-Li, Hill, Justine M., Hsieh, Jyh-Cheng, Pouyssegur, Jacques, Brunet, Anne, Glading, Angela, Überall, Florian, Ramos, Joe W., Werner, Milton H., Ginsberg, Mark H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 26.12.2003; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Motifs; Animals; Biochemistry, Molecular Biology; Cancer; Cell Membrane; Cell Membrane - metabolism; Cell Separation; CHO Cells; Cricetinae; DNA, Complementary; DNA, Complementary - metabolism; Electrophoresis, Polyacrylamide Gel; Flow Cytometry; Green Fluorescent Proteins; Immunoblotting; Integrins; Integrins - metabolism; Life Sciences; Ligands; Luminescent Proteins; Luminescent Proteins - metabolism; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Mitogen-Activated Protein Kinases - metabolism; Models, Genetic; Models, Molecular; Mutagenesis, Site-Directed; Mutation; p38 Mitogen-Activated Protein Kinases; Phosphoproteins; Phosphoproteins - chemistry; Phosphoproteins - genetics; Phosphoproteins - metabolism; Point Mutation; Protein Binding; Protein Structure, Tertiary; Recombinant Fusion Proteins; Recombinant Fusion Proteins - metabolism; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M309322200

Activation of Raf-1 suppresses integrin activation, potentially through the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2). However, bulk ERK1/2 activation does not correlate with suppression. PEA-15 reverses suppression of integrin activation and binds ERK1/2. Here we report that PEA-15 reversal of integrin suppression depends on its capacity to bind ERK1/2, indicating that ERK1/2 function is indeed required for suppression. Mutations in either the death effector domain or C-terminal tail of PEA-15 that block ERK1/2 binding abrogated the reversal of integrin suppression. Furthermore, we used ERK/p38 chimeras and site-directed mutagenesis to identify ERK1/2 residues required for binding PEA-15. Mutations of residues that precede the αG helix and within the mitogen-activated protein kinase insert blocked ERK2 binding to PEA-15, but not activation of ERK2. These ERK2 mutants blocked the ability of PEA-15 to reverse suppression of integrin activation. Thus, PEA-15 regulation of integrin activation depends on its binding to ERK1/2. To directly test the role of ERK1/2 localization in suppression, we enforced membrane association of ERK1 and 2 by joining a membrane-targeting CAAX box sequence to them. Both ERK1-CAAX and ERK2-CAAX were membrane-localized and suppressed integrin activation. In contrast to suppression by membrane-targeted Raf-CAAX, suppression by ERK1/2-CAAX was not reversed by PEA-15. Thus, ERK1/2 are the Raf effectors for suppression of integrin activation, and PEA-15 reverses suppression by binding ERK1/2.