Activity of protein phosphatases against initiation factor-2 and elongation factor-2

Redpath, Nicholas T.; Proud, Christopher G.

doi:10.1042/bj2720175

Cited by 79 publications

(53 citation statements)

References 40 publications

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“…Thus, BDNF increased the net amount of active, unphosphorylated eEF2. This alteration in the activity of eEF2 is a consequence of both a decrease in the expression of a kinase that phosphorylates eEF2, eEF2K (38), and an increase in the expression of the PP2A phosphatase, for which eEF2 is a substrate (39,40). The enzymatic activities of eEF2K and PP2A correlated with their expression levels.…”

Section: Discussionmentioning

confidence: 99%

Brain-derived Neurotrophic Factor Enhances the Basal Rate of Protein Synthesis by Increasing Active Eukaryotic Elongation Factor 2 Levels and Promoting Translation Elongation in Cortical Neurons

Takei

Kawamura

Ishizuka

et al. 2009

Journal of Biological Chemistry

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The constitutive and activity-dependent components of protein synthesis are both critical for neural function. Although the mechanisms controlling extracellularly induced protein synthesis are becoming clear, less is understood about the molecular networks that regulate the basal translation rate. Here we describe the effects of chronic treatment with various neurotrophic factors and cytokines on the basal rate of protein synthesis in primary cortical neurons. Among the examined factors, brain-derived neurotrophic factor (BDNF) showed the strongest effect. The rate of protein synthesis increased in the cortical tissues of BDNF transgenic mice, whereas it decreased in BDNF knock-out mice. BDNF specifically increased the level of the active, unphosphorylated form of eukaryotic elongation factor 2 (eEF2). The levels of active eEF2 increased and decreased in BDNF transgenic and BDNF knock-out mice, respectively. BDNF decreased kinase activity and increased phosphatase activity against eEF2 in vitro. Additionally, BDNF shortened the ribosomal transit time, an index of translation elongation. In agreement with these results, overexpression of eEF2 enhanced protein synthesis. Taken together, our results demonstrate that the increased level of active eEF2 induced by chronic BDNF stimulation enhances translational elongation processes and increases the total rate of protein synthesis in neurons.The synthesis and post-translational modification of proteins play key roles in neural development, synaptic plasticity, and cognitive brain functions such as learning and memory (1, 2). Recent studies have revealed that activity-dependent regulation of translation affects neural plasticity (3, 4). Previously, we reported that BDNF, 2 a critical molecule for neural plasticity (5-7), enhances protein synthesis and activates the translational machinery in central nervous system neurons (8). In addition, neurotransmitters such as glutamate (9, 10), dopamine (11), and serotonin (12) are also reported to facilitate translation in neurons. These observations indicate that endogenous molecules can acutely modulate neuronal translation in response to neural activity. Translation of an mRNA molecule comprises three steps: initiation, elongation, and release (or termination) (13). In the first step, mRNA and methionyltRNA i Met are recruited to a ribosome. During elongation, aminoacyl-tRNAs are sequentially recruited and the nascent peptide chain lengthens incrementally as amino acids are covalently attached via peptide bonds. Finally, the polypeptide chain is released from the ribosome. Each step is regulated by a variety of factors. The activities of these regulatory proteins are predominantly controlled by phosphorylation and GTP binding. BDNF activates both initiation and elongation by modulating these processes (8,14,15).In addition to these acute, stimulation-induced changes in the translation rate, the long term regulation of translation plays important roles in developing and mature brains. In fact, recent studies have shown that ge...

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Section: Discussionmentioning

confidence: 99%

Brain-derived Neurotrophic Factor Enhances the Basal Rate of Protein Synthesis by Increasing Active Eukaryotic Elongation Factor 2 Levels and Promoting Translation Elongation in Cortical Neurons

Takei

Kawamura

Ishizuka

et al. 2009

Journal of Biological Chemistry

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“…eEF-2 ancl its kinase were prepared as described previously [21], 2.2. Phosphorylation of eEF-2 eEF-2 (200 ,g) was incubated with eEF-2 kinase in the presence of 20 mM (N-[2-hydro>cyethyll-piperazine-N'-[3-propane-sulphonic acid]) pH 7,6, 125 .aM ATP, 10 mM MgCI2, 10 ~g, ml -~ of calmodulin, 0,15 mM CaClz, and 10 #Ci of [3,-3~PIATP in a final volume of 250 ~1 at 30°C.…”

Section: I Material Smentioning

confidence: 99%

Identification of the phosphorylation sites in elongation factor‐2 from rabbit reticulocytes

et al. 1991

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The sites in ~ukaryolic elongation factor eEF-2 phosphorylated by the Ca~*tcalmodulin.depcnd¢nt dZF.2 ktnas© in vitro have been identified, The kinase eatalysed the rapid mcorperation of one real ol'phosphate par real cEF.2 .nd the slower incorporation of a second mol. All the phosphorylation sit,:s in eE F-2 are contained in the CN Br fragment ¢orrespondinil to residues 22~ 155. TP/ptie discstion cf phosphorylnted QEF.2 yielded 3 phospkopeptides, one being tlnique to monophosphoryl~ted eF.F.2, The phosphorylation sites w©re identified as threonine residues 56 and 58. tha fona~r bein8 more rapidly phosphorylated, Ala.Gly.Glu-Thr.Phc-Th#*-Asp.Thr'~.Arl~. The same sites are labelled in eEF-2 isolated from reticulocyte lysates,

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“…The stable level of eEF-2 phosphorylation observed from 0.5 to 5 min after glutamate application suggests an equilibrium between the activities of eEF-2 kinase and phosphatase, which is likely to be phosphatase 2A Redpath and Proud, 1990). However, during the first minutes of glutamate treatment, phosphatase activity did not appear to be a limiting factor for eEF-2 phosphorylation because okadaic acid, a nonselective inhibitor of phosphatase 2A at the concentration used in our ex-periments (1 M), did not significantly enhance the phosphorylation of eEF-2 induced by a 2 min exposure to glutamate (112 Ϯ 9% of the glutamate effect, mean Ϯ SEM of densitometric analyses of immunoreactive bands obtained with the anti-phosphoeEF-2 antibody in three independent experiments; see also Fig.…”

Section: Phosphorylation Of Eef-2 In Cortical Neurons Exposed To Glutmentioning

confidence: 99%

Glutamate-Dependent Phosphorylation of Elongation Factor-2 and Inhibition of Protein Synthesis in Neurons

et al. 1997

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Postischemic delayed neuronal death is attributed to excitotoxic activation of glutamate receptors. It is preceded by a persistent inhibition of protein synthesis, the molecular basis of which is not known. Here we have examined in cortical neurons in culture the regulation by glutamate of phosphorylation of eukaryotic elongation factor-2 (eEF-2) by eEF-2 kinase, a Ca 2ϩ / calmodulin-dependent enzyme. Using a phosphorylation statespecific antibody, we show that glutamate, which triggers a large influx of Ca 2ϩ , enhances dramatically the phosphorylation of eEF-2. On the basis of kinetic and pharmacological analysis, we demonstrate a close correlation among the increase in cytosolic Ca 2ϩ concentration, the degree of eEF-2 phosphorylation, and the inhibition of protein synthesis. A 30 min treatment with NMDA induced a transient phosphorylation of eEF-2 and delayed neuronal death. However, pharmacological inhibition of protein translation was not neurotoxic by itself and protected neurons against the toxicity evoked by low concentrations of NMDA. Thus, phosphorylation of eEF-2 and the resulting depression of protein translation may have protective effects against excitotoxicity and open new perspectives for understanding long-term effects of glutamate.

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Activity of protein phosphatases against initiation factor-2 and elongation factor-2

Cited by 79 publications

References 40 publications

Brain-derived Neurotrophic Factor Enhances the Basal Rate of Protein Synthesis by Increasing Active Eukaryotic Elongation Factor 2 Levels and Promoting Translation Elongation in Cortical Neurons

Brain-derived Neurotrophic Factor Enhances the Basal Rate of Protein Synthesis by Increasing Active Eukaryotic Elongation Factor 2 Levels and Promoting Translation Elongation in Cortical Neurons

Identification of the phosphorylation sites in elongation factor‐2 from rabbit reticulocytes

Glutamate-Dependent Phosphorylation of Elongation Factor-2 and Inhibition of Protein Synthesis in Neurons

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