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Proteomic Analysis of the Impact of Nicotine and THC on Extracellular Vesicle Signaling

Christie Fowler, University of California, Irvine
This project seeks to define the actions of nicotine and THC on extracellular vesicle signaling in the brain and periphery. We have previously found that nicotine and THC induce the release of extracellular vesicles from cellular subpopulations in the brain. When isolated from the cerebrospinal fluid (CSF), these vesicles have been found to contain various proteins and RNA transcripts. Since these signaling factors are transferred between cells in the brain, extracellular vesicle cargo is thus hypothesized to alter protein expression in target brain regions. For this project, our first aim is to determine the specific proteomic changes occurring in the medial habenula during nicotine intake. We have found that the choroid plexus releases extracellular vesicles containing miRNAs and proteins into the CSF during intravenous nicotine self-administration, a model of drug reinforcement/dependence. We have further shown that extracellular vesicles in the CSF integrate into habenular neurons, and choroid plexus-derived miRNAs are enriched in the habenula. Given that the habenula has been shown to mediate an aversion signal that controls drug reinforcement, altered habenular neuronal function due to protein modulation may underlie drug intake and/or serve as a novel target for therapeutic development. Thus, these studies are focused on elucidating the functional significance of drug-mediated effects on extracellular vesicle signaling in vivo. Our second aim is to determine the specific proteomic changes occurring in circulating extracellular vesicles following nicotine and/or THC consumption. We will first examine which proteins become differentially expressed in circulating extracellular vesicles in the CSF following drug use. These findings may thereby link altered neural signaling to extracellular vesicle cargo that integrate into neuronal populations from the CSF. Further, by correlating findings between the CSF and blood, we may further identify markers of brain-specific EVs that have infiltrated into the blood, to provide a foundation for further studies examining brain changes along the drug use trajectory through analysis of this readily accessible peripheral biofluid. In sum, this project has high relevance to the Center’s theme, “Proteomics of Altered Signaling in Addiction”, as it seeks to analyze neuronal signal transduction mechanisms and the adaptive changes in these processes that occur in response to nicotine and THC.