Thiopental Inhibits Global Protein Synthesis by Repression of Eukaryotic Elongation Factor 2 and Protects from Hypoxic Neuronal Cell Death

Eukaryotic Elongation Factor-2 Kinase (eEF2K) acts as a negative regulator of protein synthesis, translation, and cell growth. As a structurally unique member of the alpha-kinase family, eEF2K is essential to cell survival under stressful conditions, as it contributes to both cell viability and proliferation. Known as the modulator of the global rate of protein translation, eEF2K inhibits eEF2 (eukaryotic Elongation Factor 2) and decreases translation elongation when active. eEF2K is regulated by various mechanisms, including phosphorylation through residues and autophosphorylation. Specifically, this protein kinase is downregulated through the phosphorylation of multiple sites via mTOR signaling and upregulated via the AMPK pathway. eEF2K plays important roles in numerous biological systems, including neurology, cardiology, myology, and immunology. This review provides further insights into the current roles of eEF2K and its potential to be explored as a therapeutic target for drug development.

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Regulation and roles of elongation factor 2 kinase

Biochemical Society Transactions ◽

10.1042/bst20140323 ◽

2015 ◽

Vol 43 (3) ◽

pp. 328-332 ◽

Cited By ~ 43

Author(s):

Christopher G. Proud

Keyword(s):

Protein Synthesis ◽

Elongation Factor ◽

Mrna Translation ◽

Inhibit Protein Synthesis ◽

Potential Therapeutic Target ◽

Elongation Factor 2 ◽

Eukaryotic Elongation Factor 2 ◽

Eukaryotic Elongation Factor ◽

Nutrient Consumption ◽

Almost All

Eukaryotic elongation factor 2 kinase (eEF2K) belongs to the small family of atypical protein kinases termed α-kinases, and is the only calcium/calmodulin (Ca/CaM)-dependent member of that group. It phosphorylates and inactivates eEF2, to slow down the rate of elongation, the stage in mRNA translation that consumes almost all the energy and amino acids consumed by protein synthesis. In addition to activation by Ca/CaM, eEF2K is also regulated by an array of other regulatory inputs, which include inhibition by the nutrient- and growth-factor activated signalling pathways. Recent evidence shows that eEF2K plays an important role in learning and memory, processes that require the synthesis of new proteins and involve Ca-mediated signalling. eEF2K is activated under conditions of nutrient and energy depletion. In cancer cells, or certain tumours, eEF2K exerts cytoprotective effects, which probably reflect its ability to inhibit protein synthesis, and nutrient consumption, under starvation conditions. eEF2K is being evaluated as a potential therapeutic target in cancer.

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De Novo Protein Synthesis Mediated by the Eukaryotic Elongation Factor 2 Is Required for the Anxiolytic Effect of Oxytocin

Biological Psychiatry ◽

10.1016/j.biopsych.2019.01.010 ◽

2019 ◽

Vol 85 (10) ◽

pp. 802-811 ◽

Cited By ~ 7

Author(s):

Stefanie Martinetz ◽

Carl-Philipp Meinung ◽

Benjamin Jurek ◽

David von Schack ◽

Erwin H. van den Burg ◽

...

Keyword(s):

Protein Synthesis ◽

De Novo ◽

Elongation Factor ◽

Anxiolytic Effect ◽

Elongation Factor 2 ◽

Eukaryotic Elongation Factor 2 ◽

Eukaryotic Elongation Factor ◽

De Novo Protein Synthesis

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Abstract 204: Protective Roles of Eukaryotic Elongation Factor 2 Kinase on Rat Cardiomyoblast Death Under Glucose-deprived Condition

Circulation Research ◽

10.1161/res.121.suppl_1.204 ◽

2017 ◽

Vol 121 (suppl_1) ◽

Author(s):

Satoshi Kameshima ◽

Muneyoshi Okada ◽

Hideyuki Yamawaki

Keyword(s):

Cell Death ◽

Protein Kinase ◽

Caspase 3 ◽

Elongation Factor ◽

H9c2 Cell ◽

H9c2 Cells ◽

Nuclear Condensation ◽

Elongation Factor 2 ◽

Eukaryotic Elongation Factor 2 ◽

Eukaryotic Elongation Factor

Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K; also known as calmodulin-dependent protein kinase III) has both active and inactive phosphorylation sites. An intracellular energy sensor, AMP-activated protein kinase (AMPK) was reported to activate eEF2K via increasing dephosphorylation at Ser366 (inactive site). Activated eEF2K phosphorylates and inactivates a specific substrate, eEF2, which results in the inhibition of protein translation consuming high energy. Glucose depletion (GD) is one of the primary causes for cardiomyocyte death in the developed cardiac hypertrophy. We have recently found that the expression and dephosphorylation of eEF2K (Ser366) and eEF2 phosphorylation were significantly increased in left ventricle of several cardiac hypertrophy models. However, it is almost unknown whether eEF2K/eEF2 signals affect GD-induced cardiomyocyte death. The aim of this study was to explore it. GD was induced by incubating H9c2 cells in a glucose-free medium. H9c2 cell viability, apoptotic-like nuclear condensation or protein expression was examined using a cell counting assay, DAPI staining or Western blotting, respectively. GD induced H9c2 cell death (p<0.01, n=6) and caspase-3 fragmentation (p<0.05, n=10-12). In addition, GD significantly increased phosphorylation of AMPK (p<0.05, n=6-8) and eEF2 (p<0.01, n=4-8) as well as eEF2K dephosphorylation at Ser366 (p<0.01, n=4-8). eEF2K gene knockdown (eEF2K KD) by siRNA transfection significantly increased GD-induced H9c2 cell death (p<0.05, n=7) and caspase-3 fragmentation (p<0.01, n=9). Moreover, eEF2K KD significantly facilitated GD-induced increase of nuclear condensation (44.0±3.3%, eEF2K siRNA vs. 30.9±2.4%, control siRNA p<0.01, n=5). AMPK KD did not affect GD-induced H9c2 cell death and eEF2K dephosphorylation. In conclusion, we for the first time revealed in H9c2 cells that activated eEF2K might play protective roles in GD-induced apoptosis via the inhibition of caspase-3 fragmentation, whereas AMPK activation is not directly related to the regulation of eEF2K/eEF2 signals in GD condition. The present results suggest eEF2K as a novel pharmacotherapeutic target for cardiac dysfunction.

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Abstract 274: Expression and Phosphorylation States of Eukaryotic Elongation Factor 2 (EEF2) and EEF2 Kinase in Cardiomyocytes From Hypertrophy Models

Circulation Research ◽

10.1161/res.119.suppl_1.274 ◽

2016 ◽

Vol 119 (suppl_1) ◽

Author(s):

Satoshi Kameshima ◽

Muneyoshi Okada ◽

Shiro Ikeda ◽

Yuki Watanabe ◽

Hideyuki Yamawaki

Keyword(s):

Protein Synthesis ◽

Cardiac Hypertrophy ◽

Elongation Factor ◽

Protein Translation ◽

Cardiomyocyte Hypertrophy ◽

Specific Substrate ◽

Elongation Factor 2 ◽

Eukaryotic Elongation Factor 2 ◽

Eukaryotic Elongation Factor ◽

Eef2 Kinase

Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K, also known as calmodulin (CaM)-dependent protein kinase III) is regulated by both CaM-dependent and -independent mechanisms. Activated eEF2K phosphorylates and inactivates a specific substrate, eEF2. eEF2 activation facilitates protein translation. It is recognized that increased protein synthesis is one of the primary factors for cardiomyocyte hypertrophy. In fact, angiotensin II, which induces cardiomyocyte hypertrophy, was reported to facilitate eEF2 dephosphorylation (activation) and protein synthesis in rat isolated cardiomyocytes. We have previously demonstrated that protein expression of eEF2K was increased specifically in left ventricles (LV) of spontaneously hypertensive rats (SHR). However, expression and phosphorylation states of eEF2K and eEF2 in LV of other cardiac hypertrophy models are unknown. The aim of this study was to explore it. Male C57BL/6NJcl mice and Wistar rats received transverse aortic constriction (TAC) and isoproterenol (5 mg/kg; ISO) injection, respectively, which induced cardiac hypertrophy. After 3 and 28 days from TAC operation and 7 days from ISO injection, LV were isolated and used for Western blotting (WB) and immunohistochemistry (IHC). Echocardiography was done in TAC mice before LV isolation. In TAC-induced hypertrophied LV (3 days), eEF2K expression was significantly increased (p<0.01 vs. SHAM) and its phosphorylation at Ser366 was significantly decreased (p<0.05 vs. SHAM). Consistently, eEF2 phosphorylation was significantly increased (p<0.01 vs. SHAM). In LV from ISO rats, eEF2K phosphorylation at Ser366 was significantly decreased as determined by WB (p<0.01 vs. control). In addition, eEF2K- and phosphorylated eEF2-positive cardiomyocytes were increased as determined by IHC. These changes were also confirmed in LV from SHR. At 28 days after TAC, fractional shortening was significantly decreased (from 56.6±1.6% to 44.4±2.3%, p<0.01). Interestingly, eEF2 phosphorylation in LV was significantly decreased (p<0.05 vs. SHAM). The present results suggest the potential role of eEF2K/eEF2 signals in the pathogenesis of cardiac hypertrophy/failure.

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Eukaryotic elongation factor 2 (eEF2) kinase/eEF2 plays protective roles against glucose deprivation-induced cell death in H9c2 cardiomyoblasts

APOPTOSIS ◽

10.1007/s10495-019-01525-z ◽

2019 ◽

Vol 24 (3-4) ◽

pp. 359-368 ◽

Cited By ~ 4

Author(s):

Satoshi Kameshima ◽

Muneyoshi Okada ◽

Hideyuki Yamawaki

Keyword(s):

Cell Death ◽

Elongation Factor ◽

Glucose Deprivation ◽

Elongation Factor 2 ◽

Eukaryotic Elongation Factor 2 ◽

Eukaryotic Elongation Factor ◽

H9c2 Cardiomyoblasts ◽

Eef2 Kinase

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Eukaryotic elongation factor 2 kinase regulates the cold stress response by slowing translation elongation

Biochemical Journal ◽

10.1042/bj20141014 ◽

2015 ◽

Vol 465 (2) ◽

pp. 227-238 ◽

Cited By ~ 23

Author(s):

John R. P. Knight ◽

Amandine Bastide ◽

Anne Roobol ◽

Jo Roobol ◽

Thomas J. Jackson ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Protein Synthesis ◽

Stress Response ◽

Cold Stress ◽

Elongation Factor ◽

Translation Elongation ◽

Elongation Factor 2 ◽

Eukaryotic Elongation Factor 2 ◽

Eukaryotic Elongation Factor

Modulation of translation elongation rates, and not initiation, is responsible for the reduction of protein synthesis in response to cold-stress induced in mild hypothermic conditions. This is mediated by release of Ca2+ ions from the endoplasmic reticulum (ER) and activation of eEF2K (eukaryotic elongation factor 2 kinase).

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