Tyrosine Phosphorylation of the Kv2.1 Channel Contributes to Injury in Brain Ischemia

Abstract

In brain ischemia, oxidative stress induces neuronal apoptosis, which is mediated by increased activity of the voltage-gated K+ channel Kv2.1 and results in an efflux of intracellular K+. The molecular mechanisms underlying the regulation of Kv2.1 and its activity during brain ischemia are not yet fully understood. Here this study provides evidence that oxidant-induced apoptosis resulting from brain ischemia promotes rapid tyrosine phosphorylation of Kv2.1. When the tyrosine phosphorylation sites Y124, Y686, and Y810 on the Kv2.1 channel are mutated to non-phosphorylatable residues, PARP-1 cleavage levels decrease, indicating suppression of neuronal cell death. The tyrosine residue Y810 on Kv2.1 was a major phosphorylation site. In fact, cells mutated Y810 were more viable in our study than were wild-type cells, suggesting an important role for this site during ischemic neuronal injury. In an animal model, tyrosine phosphorylation of Kv2.1 increased after ischemic brain injury, with an observable sustained increase for at least 2 h after reperfusion. These results demonstrate that tyrosine phosphorylation of the Kv2.1 channel in the brain may play a critical role in regulating neuronal ischemia and is therefore a potential therapeutic target in patients with brain ischemia.

Discovery of 2-Ethoxy-5-isobutyramido-N-1-substituted Benzamide Derivatives as Selective Kv2.1 Inhibitors with In Vivo Neuroprotective Effects

“…A characteristic hallmark of neuronal injury after cerebral ischemia is excitotoxic damage and delayed neuronal apoptosis in ischemic penumbra . It was demonstrated that the ischemic insult would activate voltage-gated potassium channel, leading to the enhanced K + efflux in injured neurons and facilitating the execution of cell death cascades. − Kv2.1 is a delayed rectifier voltage-gated potassium channel, which is highly expressed in hippocampus and cortical neurons of the brain. , Kv2.1 plays an important role in regulating neuronal excitability and neuronal cell apoptosis. , The Kv2.1 mediated excessive outflow of potassium ions, and massive loss of intracellular potassium ions is one of the mechanisms that cause cerebral ischemia cell injury and apoptosis. − Recently, it has been demonstrated that disrupting Kv2.1-syntaxin interaction and Kv2.1-VAPA association are able to reduce the outflow of potassium ions, consequently achieving neuroprotective effect in cerebral ischemia animal model. , Thus, disrupting the function of Kv2.1 was a potentially intriguing strategy to deal with the ischemic stroke.…”