title: Proteasomal degradation of eukaryotic elongation factor-2 kinase (EF2K) is regulated by cAMP-PKA signaling and the SCFβTRCP ubiquitin E3 ligase.
abstract: Protein translation and degradation are critical for proper protein homeostasis, yet it remains unclear how these processes are dynamically regulated, or how they may directly balance or synergize with each other. An important translational control mechanism is the Ca(2+)/calmodulin-dependent phosphorylation of eukaryotic elongation factor-2 (eEF-2) by eukaryotic elongation factor-2 kinase (EF2K), which inhibits elongation of nascent polypeptide chains during translation. We previously described a reduction of EF2K activity in PC12 cells treated with NGF or forskolin. Here, we show that both forskolin- and IGF-1-mediated reductions of EF2K activity in PC12 cells are due to decreased EF2K protein levels, and this is attenuated by application of the proteasome inhibitor, MG132. We further demonstrate that proteasome-mediated degradation of EF2K occurs in response to A2A-type adenosine receptor stimulation, and that activation of protein kinase A (PKA) or phospho-mimetic mutation of the previously characterized PKA site, Ser-499, were sufficient to induce EF2K turnover in PC12 cells. A similar EF2K degradation mechanism was observed in primary neurons and HEK cells. Expression of a dominant-negative form of Cul1 in HEK cells demonstrated that EF2K levels are regulated by an SCF-type ubiquitin E3 ligase. Specifically, EF2K binds to the F-box proteins, βTRCP1 and βTRCP2, and βTRCP regulates EF2K levels and polyubiquitylation. We propose that the proteasomal degradation of EF2K provides a mechanistic link between activity-dependent protein synthesis and degradation.
authors: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508, USA.
authors: Shari L
authors: SL
authors: Wiseman
authors: Yoshio
authors: Y
authors: Shimizu
authors: Clive
authors: C
authors: Palfrey
authors: Angus C
authors: AC
authors: Nairn
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D058908:Adenosine A2 Receptor Agonists / Q000494:pharmacology; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D044842:Cullin Proteins / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D054736:Elongation Factor 2 Kinase / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D016716:PC12 Cells; D010627:Phenethylamines / Q000494:pharmacology; D061251:Primary Cell Culture; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D055550:Protein Stability; D059748:Proteolysis; D051381:Rats; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism*; D015290:Second Messenger Systems; D054875:Ubiquitination
chemical_list: D058908:Adenosine A2 Receptor Agonists; D019208:Brain-Derived Neurotrophic Factor; C100318:Cullin 1; D044842:Cullin Proteins; D010627:Phenethylamines; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D005576:Colforsin; D007334:Insulin-Like Growth Factor I; D000242:Cyclic AMP; D044843:SKP Cullin F-Box Protein Ligases; C517691:Eef2k protein, rat; D017868:Cyclic AMP-Dependent Protein Kinases; D054736:Elongation Factor 2 Kinase; D046988:Proteasome Endopeptidase Complex; D000241:Adenosine
keywords: Cyclic AMP (cAMP); E3 Ubiquitin Ligase; Proteasome; Translation Control; Translation Elongation Factors; eEF-2; eEF-2 Kinase; βTRCP
references: Nat Neurosci. 2000 Mar;3(3):211-6
references: 10700251
references: Eur J Neurosci. 2008 Jun;27(11):3009-19
references: 18588539
references: Genes Dev. 1999 Feb 1;13(3):270-83
references: 9990852
references: Neuron. 2006 Oct 19;52(2):239-45
references: 17046687
references: EMBO J. 2001 Aug 15;20(16):4370-9
references: 11500364
references: Eur J Neurosci. 2001 Dec;14(11):1820-6
references: 11860477
references: J Biol Chem. 1992 Jun 25;267(18):12742-52
references: 1377674
references: Genes Dev. 2003 Dec 15;17(24):3062-74
references: 14681206
references: Neuron. 2008 Jul 10;59(1):70-83
references: 18614030
references: Neuron. 2007 Aug 16;55(4):648-61
references: 17698016
references: Mol Cell. 2011 Oct 21;44(2):290-303
references: 22017875
references: Biochem J. 2001 Feb 1;353(Pt 3):621-6
references: 11171059
references: J Biol Chem. 1987 Jul 15;262(20):9785-92
references: 3496338
references: Mol Cell. 2011 Oct 21;44(2):304-16
references: 22017876
references: Psychol Bull. 1984 Nov;96(3):518-59
references: 6096908
references: Cell. 2006 Jan 13;124(1):191-205
references: 16413491
references: J Biol Chem. 1989 Jan 25;264(3):1748-53
references: 2536373
references: Science. 2006 Oct 20;314(5798):467-71
references: 17053147
references: Nat Rev Mol Cell Biol. 2004 Sep;5(9):739-51
references: 15340381
references: J Neurosci. 1997 May 15;17(10):3445-54
references: 9133370
references: Prog Mol Subcell Biol. 2001;27:91-129
references: 11575162
references: J Neurosci. 2006 May 3;26(18):4949-55
references: 16672670
references: Sci Signal. 2012 Jun 05;5(227):ra40
references: 22669845
references: Mol Cell. 2011 Oct 21;44(2):317-24
references: 22017877
references: Neuron. 2009 Jan 15;61(1):10-26
references: 19146809
references: Cancer Res. 2005 May 1;65(9):3806-10
references: 15867377
references: J Biol Chem. 2004 Mar 26;279(13):12220-31
references: 14709557
references: Neuron. 2009 Dec 24;64(6):871-84
references: 20064393
references: J Neurochem. 1990 Mar;54(3):1034-9
references: 1689374
references: J Biol Chem. 1993 Jun 25;268(18):13422-33
references: 8514778
references: Biochem J. 1993 Jul 1;293 ( Pt 1):31-4
references: 8328970
references: EMBO J. 2002 Sep 16;21(18):4875-84
references: 12234927
references: Proc Natl Acad Sci U S A. 2007 Nov 13;104(46):18001-6
references: 17986610
references: J Biol Chem. 2005 Jul 22;280(29):26863-72
references: 15917222
references: J Biol Chem. 1987 Oct 15;262(29):14265-72
references: 2443502
references: Neuron. 2006 Aug 17;51(4):441-54
references: 16908410
references: Nat Neurosci. 2003 Mar;6(3):231-42
references: 12577062
references: Nat Rev Mol Cell Biol. 2005 Jan;6(1):9-20
references: 15688063