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microRNA-192 suppresses the expression of the farnesoid X receptor

Regina Krattinger, Adrian Boström, Helgi B. Schiöth, Wolfgang E. Thasler, Jessica Mwinyi, Gerd A. Kullak-Ublick
2016 American Journal of Physiology - Gastrointestinal and Liver Physiology  
Farnesoid X receptor (FXR, NR1H4) plays an important role in the regulation of bile acid homeostasis in liver and intestine and may exert protective effects against certain forms of cancer such as colon carcinoma. However, the role of FXR in cell growth regulation, apoptosis, and carcinogenesis is still controversial. Similar to FXR, is mainly expressed in the liver and colon and plays an important role in the pathogenesis of colon carcinoma. In this study, we investigated the extent to which
more » ... e extent to which FXR is regulated by miR-192. Two in silico-predicted binding sites for miR-192-3p within the NR1H4-3' untranslated region (UTR) were examined in vitro by luciferase reporter assays. Wildtype and mutated forms of the NR1H4-3'UTR were subcloned into a pmirGLO vector and cotransfected into Huh-7 cells with miR-192-3p. To study the effects of miR-192 on the expression of FXR, FXR target genes and cell proliferation, Huh-7 and Caco-2 cells were transfected with miR-192-5p and -3p mimics or antagomirs. In addition, the correlation between FXR and miR-192 expression was studied by linear regression analyses in colonic adenocarcinoma tissue from 27 patients. MiR-192-3p bound specifically to the NR1H4-3'UTR and significantly decreased luciferase activity. Transfection with miR-192 led to significant decreases in NR1H4 mRNA and protein levels as well as the mRNA levels of the FXR-inducible bile acid transporters OST-OST and OATP1B3. Significant inverse correlations were detected in colonic adenocarcinoma between NR1H4 mRNA and miR-192-3p expression. In summary, microRNA-192 suppresses the expression of FXR and FXR target genes in vitro and in vivo. ABSTRACT 1 Farnesoid X receptor (FXR, NR1H4) plays an important role in the regulation of bile acid 2 homeostasis in liver and intestine, and may exert protective effects against certain forms of 3 cancer such as colon carcinoma. However, the role of FXR in cell growth regulation, 4 apoptosis and carcinogenesis is still controversial. Similar to FXR, 5 is mainly expressed in the liver and colon, and plays an important role in the pathogenesis of 6 colon carcinoma. In this study, we investigated the extent to which FXR is regulated by miR-7 192. Two in silico-predicted binding sites for miR-192-3p within the NR1H4-3′ untranslated 8 region (UTR) were examined in vitro by luciferase reporter assays. Wild-type and mutated 9 forms of the NR1H4-3′UTR were subcloned into a pmirGlo vector and co-transfected into 10 Huh-7 cells with miR-192-3p. To study the effects of miR-192 on the expression of FXR, 11 FXR target genes and cell proliferation, Huh-7 and Caco-2 cells were transfected with miR-12 192-5p and -3p mimics or antagomirs. In addition, the correlation between FXR and miR-192 13 expression was studied by linear regression analyses in colonic adenocarcinoma tissue from 14 27 patients. MiR-192-3p bound specifically to the NR1H4-3′UTR and significantly decreased 15 luciferase activity. Transfection with miR-192 led to significant decreases in NR1H4 mRNA 16 and protein levels as well as the mRNA levels of the FXR-inducible bile acid transporters 17 OSTα-OSTβ and OATP1B3. Significant inverse correlations were detected in colonic 18 adenocarcinoma between NR1H4 mRNA and miR-192-3p expression. In summary, 19 microRNA-192 suppresses the expression of FXR and FXR target genes in vitro and in vivo. 20 21 KEYWORDS 22 miR-192 -farnesoid X receptor -bile-acid transporters -drug-induced liver injury -colonic 23 adenocarcinoma 24 372 Andersen CL, and Dobbelstein M. p53-Responsive micrornas 192 and 215 are 373 capable of inducing cell cycle arrest.
doi:10.1152/ajpgi.00297.2015 pmid:27079614 fatcat:xqdpp7wm75ehrpgb5m2isfr53a