Role of astroglial Kir4.1 channels in the pathogenesis and treatment of epilepsy

Abstract

The inwardly rectifying potassium (Kir) channel subunit Kir4.1 is specifically expressed in brain astrocytes and Kir4.1-containing channels (Kir4.1 channels) mediate astroglial spatial potassium (K + ) buffering. Recent advances in Kir4.1 research revealed that Kir4.1 channels can serve as a novel therapeutic target for epilepsy. Specifically, reduced expression or dysfunction of Kir4.1 channels seems to be involved in generation of generalized tonic-clonic seizures (GTCS) in animal models of epilepsy and patients with temporal lobe epilepsy. In addition, recent clinical studies showed that loss-of-function mutations of human gene ( KCNJ10 ) encoding Kir4.1 elicit “EAST” or “SeSAME” syndrome which manifests as GTCS and ataxia. Although the precise mechanisms remain to be clarified, it is suggested that dysfunction of Kir4.1 channels disrupts spatial K + buffering by astrocytes, elevates extracellular levels of K + and/or glutamate and causes abnormal excitation of neurons in the limbic regions and neocortex. All these findings suggest that agents that activate or up-regulate astroglial Kir4.1 channels would be effective for epilepsy. In addition, docking simulation analysis using the Kir4.1 homology model provides important information for designing new Kir4.1 ligands. Discovery of such agents that activate or up-regulate Kir4.1 channels would be a novel approach for the treatment of epilepsy.