Carbimazole Is an Inhibitor of Protein Synthesis and Protects from Neuronal Hypoxic Damage In Vitro

Abstract

Oxygen deprivation during ischemic or hemorrhagic stroke results in ATP depletion, loss of ion homeostasis, membrane depolarization, and excitotoxicity. Pharmacologic restoration of cellular energy supply may offer a promising concept to reduce hypoxic cell injury. In this study, we investigated whether carbimazole, a thionamide used to treat hyperthyroidism, reduces neuronal cell damage in oxygen-deprived human SK-N-SH cells or primary cortical neurons. Our results revealed that carbimazole induces an inhibitory phosphorylation of eukaryotic elongation factor 2 (eEF2) that was associated with a marked inhibition of global protein synthesis. Translational inhibition resulted in significant bioenergetic savings, preserving intracellular ATP content in oxygen-deprived neuronal cells and diminishing hypoxic cellular damage. Phosphorylation of eEF2 was mediated by AMP-activated protein kinase and eEF2 kinase. Carbimazole also induced a moderate calcium influx and a transient cAMP increase. To test whether translational inhibition generally diminishes hypoxic cell damage when ATP availability is limiting, the translational repressors cycloheximide and anisomycin were used. Cycloheximide and anisomycin also preserved ATP content in hypoxic SK-N-SH cells and significantly reduced hypoxic neuronal cell damage. Taken together, these data support a causal relation between the pharmacologic inhibition of global protein synthesis and efficient protection of neurons from ischemic damage by preservation of high-energy metabolites in oxygen-deprived cells. Furthermore, our results indicate that carbimazole or other translational inhibitors may be interesting candidates for the development of new organprotective compounds. Their chemical structure may be used for computer-assisted drug design or screening of compounds to find new agents with the potential to diminish neuronal damage under ATP-limited conditions.

Elongation Factor 2 Kinase Is Regulated by Proline Hydroxylation and Protects Cells during Hypoxia

“…10B). These data are consistent with the finding that, in neuronal cells subjected to hypoxia, inhibition of protein synthesis using carbimazole (which induces eEF2 phosphorylation) or other agents preserved the ATP content and prevented cell damage (43). These data underline the importance of eEF2K for resistance to oxygen deprivation.…”

Stress fibers, autophagy and necrosis by persistent exposure to PM2.5 from biomass combustion

“…Since cell-cycle progression depends on availability of cellular energy, we determined the consequences of long-term exposure to PM 2.5 on AMPK which is a crucial regulator of energy homeostasis [20]. We observed a prolonged phosphorylation and therefore activation of AMPK (Fig 4A) which was still present after removing the particles for 24 h (Fig 4A, lane 2).…”

“…This phosphorylation was reduced in the presence of the selective AMPK-inhibitor dorsomorphin, indicating that AMPK is involved in the inactivation of eEF2 (Fig 4C, lane 3). When intracellular energy supply is limited, activation of AMPK and inactivation of eEF2 represent pivotal stress responses, which redirect limited energy sources to pathways necessary for cellular survival [20]. Phosphorylation of eEF2 at threonine 56 is associated with inhibition of global protein synthesis, which might contribute to the observed arrest at multiple cell-cycle checkpoints, as observed in Fig 3B [21].…”

Identification of miRNAs Involved in the Protective Effect of Sevoflurane Preconditioning Against Hypoxic Injury in PC12 Cells

“…Neuronal death is partly a result of cell damage that results from hypoxic stress. Several studies have focused on the development of new strategies to prevent hypoxic injury and to promote recovery, however, with only limited success as they focused on the acute phase of brain damage and neglected that a significant amount of neuronal tissue damage develops progressively after the initial insult (Lehane et al 2013). It was suggested that neuroprotective drugs with the potential to reduce cell hypoxic injury should improve clinical outcome (Heiss and Graf 1994).…”