The phosphorylation status of eukaryotic elongation factor-2 indicates neural activity in the brain

Abstract

Assessment of neural activity in the specific brain area is critical for understanding the circuit mechanisms underlying altered brain function and behaviors. A number of immediate early genes (IEGs) that are rapidly transcribed in neuronal cells in response to synaptic activity have been used as markers for neuronal activity. However, protein detection of IEGs requires translation, and the amount of newly synthesized gene product is usually insufficient to detect using western blotting, limiting their utility in western blot analysis of brain tissues for comparison of basal activity between control and genetically modified animals. Here, we show that the phosphorylation status of eukaryotic elongation factor-2 (eEF2) rapidly changes in response to synaptic and neural activities. Intraperitoneal injections of the GABA A receptor (GABAAR) antagonist picrotoxin and the glycine receptor antagonist brucine rapidly dephosphorylated eEF2. Conversely, potentiation of GABAARs or inhibition of AMPA receptors (AMPARs) induced rapid phosphorylation of eEF2 in both the hippocampus and forebrain of mice. Chemogenetic suppression of hippocampal principal neuron activity promoted eEF2 phosphorylation. Novel context exploration and acute restraint stress rapidly modified the phosphorylation status of hippocampal eEF2. Furthermore, the hippocampal eEF2 phosphorylation levels under basal conditions were reduced in mice exhibiting epilepsy and abnormally enhanced excitability in CA3 pyramidal neurons. Collectively, the results indicated that eEF2 phosphorylation status is sensitive to neural activity and the ratio of phosphorylated eEF2 to total eEF2 could be a molecular signature for estimating neural activity in a specific brain area.

Neuronal activity rapidly reprograms dendritic translation via eIF4G2:uORF binding

“…To demonstrate the rigor of our experimental findings, we shortened the KCl activation time, relative to previous prolonged depolarizations [83][84][85] , and, notably, replicated our key findings with the glutamate agonist DHPG. Although dephosphorylation followed by increased de novo translation has been observed in behavioral studies 86,87 , our finding that depolarization induces phosphorylation of translation control factors and global translational downregulation agrees with several other analyses [88][89][90][91][92] . The disparity among studies could be attributed to different activation paradigms and experimental strategies or could, in fact, highlight the spatial and temporal complexity of activity-dependent synaptic translational control.…”

Hyperactive GluN2B impairs neuroplasticity and cognition in phenylketonuria

“…injections to rats with the similar concentration (10 mmole/kg) induced, within 1 h, the Phe Brain comparable to those observed in patients with PKU at autopsy 44 . As the phosphorylation status of eukaryotic elongation factor 2 (eEF2) changes rapidly in response to neuronal activity 45 , we examined the effect of L-Phe challenge on the proportion of phosphorylated eEF2 (p-eEF2) in total eEF2. L-Phe (1 mg/g)-treated mice exhibited an increased p-eEF2/eEF2 ratio in both the hippocampus and whole brain compared to vehicle treated mice (Fig.…”