Molecular Mechanism Underlying Alcohol Modulation of Inward Rectifying K+ Channel

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DESCRIPTION (provided by applicant): The major goal of this project is to investigate the molecular mechanisms underlying modulation of ion channels by alcohols. G-protein gated inwardly rectifying potassium (Kir3 or GIRK) channels, which are important for controlling electrical activity of neurons, are activated by ethanol. The mechanism of activation is not well understood. Recently, a binding site for a diol was discovered in a 3D structure of a related inward rectifier, Kir2.1. Since both diol and ethanol are structurally related, this hydrophobic pocket is postulated to be the site of alcohol modulation. The proposed research will assess whether this hydrophobic binding pocket mediates the actions of diols and alcohols on both Kir3 and Kir2 channels. Specifically the aim of the research is to: 1) determine the quantitative structure-activity relationship for diols and alcohols on modulation of related Kir2 channel currents by using patch-clamp techniques; 2) Characterize diol induced activation of Kir3 currents and compare with effects of ethanol modulation of these channel; and 3) Determine whether the diol binding hydrophobic pocket is the site of action of ethanol for Kir3 and Kir2 by domain specific, and site directed mutagenesis. Whole-cell patch-clamp recordings will be used to study the effect of diols and alcohols on Kir channels expressed heterologously in mammalian cells. These experiments will lead to a better understanding of the mechanism of alcohol modulation of ion channels. Alcohol is a major drug of addiction and abuse in the U.S. and worldwide. Consumption of alcohol leads to intoxication which is described as an overall increase in inhibition of the central nervous system. This is mediated by alcohol's effect on ion channels, proteins which are critical in determining how neurons fire. How alcohols directly affect ion channels is poorly understood. The proposed experiments will lead to a better understanding of where alcohols act on a class of ion channels affected by alcohol. This study could also lead to development of pharmaceutical agents designed to prevent or treat addiction and abuse associated with consumption of alcohol.