Neuroimmune Gene Expression in Alcohol Use Disorder

Alcohol use disorder (AUD) is a debilitating psychiatric condition that impacts millions of people in the United States. Chronic alcohol exposure induces a number of molecular and biological changes, including increasing neuroinflammation and transcriptomic alterations. While much of the focus to date has been on protein coding genes when characterizing genetic changes associated with AUD, interest has begun to shift to long noncoding RNAs (lncRNAs). LncRNAs are now widely recognized as active molecules regulating processes from cell proliferation and neuroinflammation to behavior. With this knowledge, the work presented here aimed to characterize neuroinflammatory-related transcriptomic changes following ethanol exposure and begin to understand how these changes contribute to AUD. To begin, extracellular vesicles were isolated from ethanol exposed brains and the RNA content was examined. Due to their role in neuroinflammation, I next moved into primary astrocyte cultures and characterized transcriptomic changes following ethanol exposure in both males and females. Finally, I focused my interest in lncRNA on metastasis associated lung adenocarcinoma transcript 1 (Malat1), which is increased in the brain following ethanol exposure. Changes in the glial transcriptome, as well as alternative splicing, were characterized following Malat1 knockdown with and without ethanol exposure. Then, using both a global knockout mouse and a global, inducible knockout mouse line, the impact of Malat1 knockout was assessed on ethanol consumption and preference, among other ethanol-related behaviors such as tolerance and anxiety-like behavior. Overall, ethanol exposure induced significant and sex-dependent changes in the RNA content of extracellular vesicles and in primary astrocyte cultures, which corresponded with biological processes such as neuroinflammation, extracellular matrix organization, and cell proliferation. Malat1 knockout in glial cultures also revealed distinct sex-dependent mechanisms, wherein female cultures demonstrated significant changes in inflammatory responses not found in male cultures. Finally, Malat1 knockout in vivo led to female-specific decreases in ethanol consumption and preference in both mouse lines. Together, these findings highlight the transcriptome as an integral part of controlling the effects of chronic ethanol exposure and highlight the importance studying biological sex in the study of AUD. These studies also establish Malat1 as a key regulator of neuroinflammation and ethanol consumption in females.