Impact of miR-222-3p-mediated downregulation of arylacetamide deacetylase on drug hydrolysis and lipid accumulation.

Arylacetamide deacetylase (AADAC) is involved in drug hydrolysis and lipid metabolism. In 23 human liver samples, no significant correlation was observed between AADAC mRNA (19.7-fold variation) and protein levels (137.6-fold variation), suggesting a significant contribution of post-transcriptional regulation to AADAC expression. The present study investigated whether AADAC is regulated by microRNA in the human liver and elucidate its biological significance. Computational analysis predicted two potential miR-222-3p recognition elements in the 3'-untranslated region (UTR) of AADAC. Luciferase assay revealed that the miR-222-3p recognition element was functional in downregulating AADAC expression. In HEK293 cells transfected with an AADAC expression plasmid containing 3'-UTR, miR-222-3p overexpression decreased AADAC protein level and activity, whereas miR-222-3p inhibition increased them. Similar results were observed in human hepatoma-derived Huh-1 cells endogenously expressing AADAC and HepaSH cells that are hepatocytes from chimeric mice with humanized livers. In individual human liver samples, AADAC protein levels inversely correlated with miR-222-3p levels. Overexpression of miR-222-3p resulted in increased lipid accumulation in Huh-1 cells, which was reversed by AADAC overexpression. In contrast, miR-222-3p inhibition decreased lipid accumulation, which was reversed by AADAC knockdown. In conclusion, we found that hepatic AADAC was downregulated by miR-222-3p, resulting in decreased drug hydrolysis and increased lipid accumulation.

miR-141-3p commonly regulates human UGT1A isoforms via different mechanisms.

UDP-Glucuronosyltransferase (UGT) 1A enzymes catalyze the glucuronidation of various compounds. Since no correlation was observed between the protein and mRNA expression of some UGT1A isoforms in the human liver, the involvement of post-transcriptional regulation was hypothesized. We examined whether microRNAs (miRNAs) regulate human UGT1A, focusing on the predicted miR-141-3p. A luciferase assay revealed that a miRNA recognition element for miR-141-3p in the 3'-untranslated region of UGT1A mRNA was functional. Overexpression of miR-141-3p in HEK293 cells stably expressing UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A7, or UGT1A9 significantly decreased the protein expression of all UGT1As. The mRNA levels of the UGT1As, except for UGT1A9, were also decreased by miR-141-3p. This indicated that the regulation mechanisms by miR-141-3p were different between UGT1A9 and the other UGT1A isoforms. Overexpression of miR-141-3p in HuH-7 or Caco-2 cells significantly decreased 4-methylumbelliferone O-glucuronosyltransferase activities, suggesting that miR-141-3p down-regulates endogenous UGT1As. No correlation was observed between miR-141-3p and the UGT1A mRNA levels in a panel of human liver samples, suggesting that regulation by other factors could hide the contribution of miR-141-3p to the regulation of UGT1A constitutive expression in the human liver. In conclusion, this study revealed that the miR-141-3p is an additional modulator of human UGT1A expression.

Serum microRNA profiles in patients with chronic hepatitis B, chronic hepatitis C, primary biliary cirrhosis, autoimmune hepatitis, nonalcoholic steatohepatitis, or drug-induced liver injury.

PURPOSE: Some blood biomarkers or histological examination by liver biopsy are used for the diagnosis of liver diseases in clinics. However, conventional blood biomarkers show poor specificity and sensitivity, and liver biopsy is highly invasiveness. Therefore, to overcome such disadvantages, specific/sensitive and noninvasive options are desirable. In recent years, circulating microRNAs (miRNAs) have been acknowledged for their potential as disease markers. Actually, several miRNAs have been reported to be biomarker candidates of liver diseases. However, these earlier studies were performed for one disease. Therefore, the specificity as biomarkers was not guaranteed, because they didn't study for the other types of liver injury. In this study, we examined if circulating miRNA could distinguish different types of liver diseases. METHODS: Serum miRNA profiles in 28 patients with chronic hepatitis B, chronic hepatitis C, primary biliary cirrhosis, autoimmune hepatitis, nonalcoholic steatohepatitis or drug-induced liver injury as well as 4 control subjects were determined by TaqMan MicroRNA Array analysis. Principal component analysis (PCA) of selected miRNAs was performed. RESULTS: We identified 37 miRNAs whose levels were significantly different between any of the groups. Although individual miRNAs could not distinguish different types of liver diseases, probably because of similar liver pathology, their profiling by PCA could classify different liver disease groups. CONCLUSIONS: The profiling of the selected miRNAs can be useful to distinguish different types of liver diseases.