Dysregulation of miRNA regulatory networks by chronic ethanol consumption impairs liver regeneration

microRNAs are a class of small, non‐coding RNAs ~21 nucleotides long that regulate numerous cellular processes in a post‐transcriptional manner. Previous research has identified several microRNAs of interest involved in liver regeneration and hepatocellular carcinoma, including miR‐21, which has been shown by our lab and others to be significantly upregulated following liver damage by 70% partial hepatectomy (PHx); miR‐21 is further increased in animals undergoing PHx following ethanol adaptation. Given that different microRNAs can regulate multiple targets in any given pathway, we sought to identify additional microRNAs involved in liver regeneration alongside miR‐21. In order to accomplish this, we knocked down miR‐21 in vivo using a locked nucleic acid (LNA) probe containing a complementary sequence to miR‐21. Whole liver tissue samples were collected from both control‐ and ethanol‐fed Sprague‐Dawley rats at baseline conditions and 24 hours post‐partial hepatectomy. These samples were analyzed for microRNA expression using the NanoString microRNA microarray platform. Analysis of the expression data reveals seven microRNAs that show differential expression in response to miR‐21 knockdown. Of these genes, three show positive correlations with miR‐21 expression while four are negatively correlated. Using target prediction software, we developed a network of putative microRNA‐gene interactions and compared the predicted targets to genes identified as differentially expressed based on Affymetrix microarray analysis. This network of putative targets identifies a number of genes that are potentially regulated by these differentially expressed microRNAs. Gene ontology and pathway analysis reveals that multiple predicted targets are involved in processes relating to cell cycle progression. In conclusion, these studies identified a set of candidate co‐regulatory microRNAs whose dysregulation by chronic ethanol consumption may lead to impaired liver regeneration. Support or Funding Information Research was supported by the National Institutes of Health grants from National Institute on Alcohol Abuse and Alcoholism R01 AA018873, R21 AA022417, and T32 AA007463.