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MEK hyperphosphorylation coincides with cell cycle shut down of cultured smooth muscle cells
Author(s) -
Vogel Sabina,
Kubin Thomas,
von der Ahe Dietmar,
Deindl Elisabeth,
Schaper Wolfgang,
Zimmermann René
Publication year - 2006
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.20500
Subject(s) - microbiology and biotechnology , mapk/erk pathway , downregulation and upregulation , phosphorylation , platelet derived growth factor receptor , fibroblast growth factor , cell growth , hyperphosphorylation , cell cycle , growth factor , biology , chemistry , cancer research , cell , biochemistry , receptor , gene
Abstract Smooth muscle cells (SMCs) form the backbone of arteries and their proliferation hallmarks collateral vessel growth, a process termed arteriogenesis, as well as pathogenic responses such as restenosis. Since signaling pathways in SMCs are the main targets for therapeutic interventions, we aimed to determine how and to what extent the activation of the ubiquitous MEK–ERK signaling pathway correlates with important in vivo phenomena such as dedifferentiation, nuclear activation, and proliferation of SMCs. Specificity of this pathway was monitored using MEK inhibitors UO126 and PD98059 in platelet derived growth factor‐AB (PDGF‐AB) and fibroblast growth factor‐2 (FGF‐2)‐stimulated SMCs. PDGF‐AB induced a rapid MEK activation followed by phosphorylation of the MEK substrates ERK1/2, while FGF‐2 showed a less pronounced and delayed activation. Both growth factors triggered a marked phosphorylation of c‐Myc and expression of Egr1. Pretreatment with MEK inhibitors suppressed the activation of the ERK cascade, abolished the downregulation of desmin and led to cell‐cycle arrest. However, the reversibility of p27 Kip1 downregulation by UO126 was mainly observed after PDGF‐AB stimulation, indicating MEK independent p27 Kip1 downregulation by FGF‐2. Surprisingly, treatment of SMCs with UO126 or PD98059 increased the level of MEK phosphorylation in a dose‐dependent manner at serine residues 217/221 in the presence as well as in the absence of both growth factors. Our results strongly imply that depending on the environmental context phosphorylation of serines 217/221 serves as an “on” as well as an “off ” switch. © 2005 Wiley‐Liss, Inc. The original article to which this Erratum refers was published online on 26 May 2005 J Cell Physiol 2005;DOI 10.1002/jcp.20437 .