Noncatalytic function of ERK1/2 can promote Raf/MEK/ERK-mediated growth arrest signaling. J Biol Chem 2009 Nov 27;284(48):33006-18
Date
10/07/2009Pubmed ID
19805545Pubmed Central ID
PMC2785141DOI
10.1074/jbc.M109.012591Scopus ID
2-s2.0-70450230440 (requires institutional sign-in at Scopus site) 69 CitationsAbstract
Kinase activity is known as the key biochemical property of MAPKs. Here, we report that ERK1/2 also utilizes its noncatalytic function to mediate certain signal transductions. Sustained activation of the Raf/MEK/ERK pathway induces growth arrest, accompanied by changes in cell cycle regulators (decreased retinoblastoma phosphorylation, E2F1 down-regulation, and/or p21(CIP1) up-regulation) and cell type-specific changes in morphology and expression of c-Myc or RET in the human tumor lines LNCaP, U251, and TT. Ablation of ERK1/2 by RNA interference abrogated all these effects. However, active site-disabled ERK mutants (ERK1-K71R, ERK2-K52R, and ERK2-D147A), which competitively inhibit activation of endogenous ERK1/2, could not block Raf/MEK-induced growth arrest as well as changes in the cell cycle regulators, although they effectively blocked phosphorylation of the ERK1/2 catalytic activity readouts, p90(RSK) and ELK1, as well as the cell type-specific changes. Because this indicated a potential noncatalytic ERK1/2 function, we generated stable lines of the tumor cells in which both ERK1 and ERK2 were significantly knocked down, and we further investigated the possibility using rat-derived kinase-deficient ERK mutants (ERK2-K52R and ERK2-T183A/Y185F) that were not targeted by human small hairpin RNA. Indeed, ERK2-K52R selectively restored Raf-induced growth inhibitory signaling in ERK1/2-depleted cells, as manifested by regained cellular ability to undergo growth arrest and to control the cell cycle regulators without affecting c-Myc and morphology. However, ERK2-T183A/Y185F was less effective, indicating the requirement of TEY site phosphorylation. Our study suggests that functions of ERK1/2 other than its "canonical" kinase activity are also involved in the pathway-mediated growth arrest signaling.
Author List
Hong SK, Yoon S, Moelling C, Arthan D, Park JIAuthor
Jong-In Park PhD Professor in the Biochemistry department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
CatalysisCell Cycle
Cell Line
Cell Line, Tumor
Cell Proliferation
Extracellular Signal-Regulated MAP Kinases
Green Fluorescent Proteins
Humans
Immunoblotting
Mitogen-Activated Protein Kinase 1
Mitogen-Activated Protein Kinase 3
Mitogen-Activated Protein Kinase Kinases
Mutation
Phosphorylation
RNA Interference
Signal Transduction
Transfection
raf Kinases