Proteasomal Degradation of Eukaryotic Elongation Factor-2 Kinase (EF2K) Is Regulated by cAMP-PKA Signaling and the SCFβTRCP Ubiquitin E3 Ligase
| Autor: | Clive Palfrey, Angus C. Nairn, Shari L. Wiseman, Yoshio Shimizu |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Elongation Factor 2 Kinase
Proteasome Endopeptidase Complex Adenosine Adenosine A2 Receptor Agonists Primary Cell Culture PC12 Cells Second Messenger Systems Biochemistry chemistry.chemical_compound Ubiquitin Phenethylamines MG132 Cyclic AMP Protein biosynthesis Animals Humans Insulin-Like Growth Factor I education Protein kinase A Molecular Biology Neurons education.field_of_study SKP Cullin F-Box Protein Ligases biology Protein Stability Brain-Derived Neurotrophic Factor Colforsin HEK 293 cells Ubiquitination Cell Biology Cullin Proteins Cyclic AMP-Dependent Protein Kinases Rats Ubiquitin ligase Cell biology HEK293 Cells chemistry Protein Synthesis and Degradation Proteolysis biology.protein CUL1 Elongation Factor-2 Kinase Protein Binding |
| Zdroj: | Journal of Biological Chemistry. 288:17803-17811 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m113.477182 |
| Popis: | 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 Ca2+/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. Background: Eukaryotic elongation factor-2 kinase (EF2K) inhibits the elongation phase of protein translation. Results: EF2K degradation by the ubiquitin-proteasome system (UPS) is regulated by cAMP-PKA signaling and SCFβTRCP. Conclusion: Degradation of EF2K enables coordination of UPS function and translational control. Significance: This coordination may be important for achieving proper protein expression to effect cellular adaptations, including synaptic plasticity. |
| Databáze: | OpenAIRE |
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