title: Eukaryotic elongation factor 2 kinase activity is controlled by multiple inputs from oncogenic signaling.
abstract: Eukaryotic elongation factor 2 kinase (eEF2K), an atypical calmodulin-dependent protein kinase, phosphorylates and inhibits eEF2, slowing down translation elongation. eEF2K contains an N-terminal catalytic domain, a C-terminal α-helical region and a linker containing several regulatory phosphorylation sites. eEF2K is expressed at high levels in certain cancers, where it may act to help cell survival, e.g., during nutrient starvation. However, it is a negative regulator of protein synthesis and thus cell growth, suggesting that cancer cells may possess mechanisms to inhibit eEF2K under good growth conditions, to allow protein synthesis to proceed. We show here that the mTORC1 pathway and the oncogenic Ras/Raf/MEK/extracellular signal-regulated kinase (ERK) pathway cooperate to restrict eEF2K activity. We identify multiple sites in eEF2K whose phosphorylation is regulated by mTORC1 and/or ERK, including new ones in the linker region. We demonstrate that certain sites are phosphorylated directly by mTOR or ERK. Our data reveal that glycogen synthase kinase 3 signaling also regulates eEF2 phosphorylation. In addition, we show that phosphorylation sites remote from the N-terminal calmodulin-binding motif regulate the phosphorylation of N-terminal sites that control CaM binding. Mutations in the former sites, which occur in cancer cells, cause the activation of eEF2K. eEF2K is thus regulated by a network of oncogenic signaling pathways.
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Xuemin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Sergio
authors.initials: S
authors.lastname: Regufe da Mota
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Moore
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Jianling
authors.initials: J
authors.lastname: Xie
authors.affiliation: University of Manchester, Manchester, United Kingdom.
authors.forename: Francesco
authors.initials: F
authors.lastname: Lanucara
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Usha
authors.initials: U
authors.lastname: Agarwala
authors.affiliation: Université catholique de Louvain, Brussels, Belgium.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Pyr Dit Ruys
authors.affiliation: Université catholique de Louvain, Brussels, Belgium.
authors.forename: Didier
authors.initials: D
authors.lastname: Vertommen
authors.affiliation: Université catholique de Louvain, Brussels, Belgium.
authors.forename: Mark H
authors.initials: MH
authors.lastname: Rider
authors.affiliation: University of Manchester, Manchester, United Kingdom.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Eyers
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom christopher.proud@sahmri.com.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Proud
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D054736:Elongation Factor 2 Kinase / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D046912:Multiprotein Complexes / Q000378:metabolism*; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017354:Point Mutation; D051381:Rats; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D048490:raf Kinases / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
chemical_list: D046912:Multiprotein Complexes; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D048490:raf Kinases; D054736:Elongation Factor 2 Kinase; D048049:Extracellular Signal-Regulated MAP Kinases; D018631:ras Proteins