MiR-9 regulation of beta-catenin mediated alcohol tolerance and EtOH consumption

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PROJECT SUMMARY miRNA regulation of Wnt/beta-catenin triggers BK channel alcohol tolerance and facilitated consumption Research has identified the large conductance voltage- and calcium-activated channel (BK) as a key regulator of neuronal excitability genetically associated to behavioral alcohol tolerance in invertebrates. Similarly in mammals, decreasing BK channel alcohol sensitivity by knocking out its ß4 subunit leads to increased alcohol voluntary consumption in mice. Sensitivity to ethanol at the molecular level is characterized by acute potentiation of channel activity. However, different isoforms of the BK channel show variations in alcohol sensitivity and are differentially distributed on the plasma membrane surface in response to prolonged exposure, also known as persistent alcohol tolerance (PMT). miRNA targeting of alcohol-sensitive isoforms coupled with active internalization of BK channels in response to ethanol are believed to be key in establishing homeostatic adaptations that produce persistent changes within the striatum. These mechanisms may operate independently, with the same end point of increasing the representation of alcohol insensitive BK channels or interact to orchestrate and optimize these persistent adaptive changes at the translational and trafficking level of regulation. Results from our current project have identified the Wnt/β-catenin signaling pathway as a key regulator of BK channel surface redistribution in response to 6hr ethanol exposure. We have characterized this as a form of long-term neuronal plasticity, which requires protein synthesis resulting in increased ß-catenin expression and persistence, past 24hr withdrawal. Activation of ß-catenin signaling has been linked to miR-9 upregulation in human cancer cells, as well as, miRNA expression in depression-resilient mice. Notably, miR-9 upregulated expression in the striatum is a key event in PMT mediating acute EtOH desensitization of BK channels. Thus, the overarching hypothesis of this proposal is that a single “binge-like” 6hr exposure persistently alters BK channel surface distribution within the NAc via miRNA regulated Wnt/β-catenin signaling, impacting subsequent alcohol consumption. We will use electrophysiology, molecular biology, behavioral assays and imaging techniques to determine the role of Wnt/ß-catenin signaling in both BK trafficking and miRNA regulation within the striatum with the goal of identifying novel therapeutic targets involved in preventing the transition from initial to compulsive drinking behavior.