Proteomics of THC-mediated changes in Extracellular Vesicle Signaling

This project seeks to define the actions of THC on extracellular vesicle (EV) signaling in the brain. EVs have been emerging as important mediators of cell-to-cell communication throughout the brain and body. All cell types examined thus far (e.g., glia, neurons, epithelial cells, immune cells, adipose) have been found to release EVs. Under the supervision of my laboratory’s PI, Dr. Christie Fowler, we have discovered that nicotine induces the release of extracellular vesicles from cellular subpopulations in the brain. As such, we are now seeking to determine the EV-specific proteomic changes that occur following acute and/or chronic THC exposure. Our preliminary in vitro data has shown that THC administration increases cell activation and CB1 receptor mRNA expression in the choroid plexus. Given that the choroid plexus directly releases EVs into the cerebrospinal fluid (CSF), these findings support a potential interaction between cannabinoids and EV signaling. We have also shown that THC increases the expression of the EV-specific markers NCAM1 and CD63 in the CSF of adolescent male, but not female, rats. Interestingly, the NCAM1 gene encodes for neural cell adhesion molecule 1 (aka, CD56 or NCAM1), a surface marker on EVs. Of note, recent human GWAS studies have implicated allelic variation in the NCAM1 gene with cannabis use, thereby providing potential translational relevance for these studies. While we have shown these changes during adolescence, NCAM1 expression is developmentally regulated and may not be altered in adulthood with THC exposure. Therefore, in these proposed studies, adult male and female rats will be exposed to THC vapor for a single acute exposure or 14 days of chronic exposure. CSF will be collected, and EVs will be extracted for proteomic analysis. Changes in EV protein signatures will be examined, and findings may be indicative of altered release of EVs from cellular subpopulations, altered targeting of EVs to specific recipient cells, and/or altered protein cargo within EVs to induce changes in recipient cells. This project has high relevance to the Center’s theme, “Proteomics of Altered Signaling in Addiction”, as it seeks to analyze neuronal signaling mechanisms and the adaptive changes in these processes that occur in response to THC. Moreover, since EVs remain an understudied signaling mechanism within the brain, these studies will further have the potential to elucidate a novel mechanism impacting neural function that underlies drug use and abuse.