Date of Award

2023

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Molecular Biology

Abstract

MicroRNAs are small noncoding RNA molecules that negatively regulate gene expression. Within the intestinal epithelium, miRNAs play a critical role in gut homeostasis and aberrant miRNA expression has been implicated in various disorders associated with intestinal inflammation and barrier disruption. In this study, we sought to profile changes in intestinal epithelial cell miRNA expression after alcohol and burn injury and elucidate their impact on inflammation and barrier integrity. In a more targeted approach, we began by focusing on anti-inflammatory miRNAs that, when downregulated, could exacerbate inflammation and result in intestinal barrier disruption. Using a mouse model of acute ethanol intoxication and burn injury, we found that small intestinal epithelial cell expression of miR-146a is significantly decreased one day following injury. Using in vitro studies, we demonstrate that miR-146a inhibition in small intestinal epithelial cells promotes, while miR-146a overexpression prevents, LPS induced inflammation. Further mechanistic studies revealed that reduced miR-146a promotes intestinal epithelial cell inflammation by promoting p38 MAPK signaling via increased levels of its target TRAF6. Furthermore, we demonstrate that in vivo miR-146a overexpression significantly inhibits intestinal inflammation one day following combined injury and potentially supports intestinal barrier homeostasis. In a secondary approach, we integrated miRNA and mRNA sequencing with miRNA target gene databases as a non-biased approach to generate a network of dysregulated miRNAs of interest after alcohol and burn injury. Our results identify several miRNAs which could promote gut barrier disruption after alcohol and burn injury, including upregulation of miR-98-3p and miR-381-3p, which is associated with reduced proliferation, upregulation of miR-29a-3p, miR-429-3p and miR3535, which can reduce cellular adhesion, and downregulation of Let-7d-5p and miR-130b-5p, which is linked to apoptosis. Overall, this study highlights the important impact that miRNA expression can have the intestinal homeostasis and the valuable potential of harnessing aberrant miRNA expression as a therapeutic target to control intestinal inflammation.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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