Visinin-like protein-1 modulation of nicotinic receptors

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ABSTRACT. Tobacco use is the world’s leading cause of preventable death, according to the World Health Organization. Within the US, cigarette smoking cases approximately one in five deaths, accounting for more than 480K deaths each year. Tobacco users who strive to quit usually relapse. In 2018, approximately 55% of adults in the US who smoked tobacco had made a quit attempt within the past year; only roughly 8% successfully quit for 6-12 months. Because of this, novel approaches are necessary to improve nicotine cessation success rates. Nicotine, a compound highly involved in nicotine use disorder (NUD), binds to neuronal nicotinic acetylcholine receptors (nAChRs) to activate brain reward and positive reinforcement circuits. Further, nicotine use results in cholinergic tone imbalance caused, in part, by dysregulation of the nAChR α4β2 subtype. The neuronal α4β2 subtype expresses in two isoforms with high and low sensitivity to nicotinic agonist (HS (α4β2)2β2 and LS (α4β2)2α4, respectively). Nicotine upregulates functional α4β2 nAChRs and enriches plasma membrane expression of the HS (α4β2)2β2 isoform. These changes result in hypersensitive brain reward (mesocorticolimbic) circuits while enhancing dopamine levels that reinforce rewarding behavior, contributing to NUD. Restoring the cholinergic tone to be less sensitive and comparable to pre-nicotine levels, is likely to be critical in the development of an efficacious approach to treating NUD. Little is known regarding chaperone protein regulation of α4β2 nAChR isoforms, a key proposal mission, and the ability of chaperone proteins to counteract nicotine-driven α4β2 isoform imbalance. To begin to answer some of these questions, we propose to define the basis of visinin-like protein-1 (VILIP-1) functional effects on receptor physiology, the interaction site, and VILIP-1-driven changes in α4β2 nAChR plasma membrane expression. Our preliminary data consistently show VILIP-1 attenuates α4β2 nAChR function and enhances plasma membrane expression. These underlying findings led us to our hypothesis that leveraging the interactions between VILIP-1 and α4β2 nAChRs by a small molecule may be a novel approach to treating NUD. Defining the VILIP-1/α4β2 nAChR interaction site, as proposed here, will remove critical barriers that stymie scientific and clinical NUD work, in addition to other conditions affected by α4β2 nAChR dysregulation. We will pursue the aims of this proposal by combining electrophysiology studies of receptor function with live cell confocal microscopy. Funding of this application will provide foundational support for PI Weltzin’s progress towards becoming an independent and established researcher by demonstrating project fundability and feasibility, assay advancement, preliminary data generation, and senior-author publications. Her mentorship team includes Drs. Miwa and Whiteaker, established nAChR experts. In addition, the proposal will provide hands-on research support for underrepresented students in biomedical science. Activities supported by this proposal will sustenance and enrich the research environment at the University of Alaska Fairbanks.