MiRNA-223 Inhibits MouseGallstone Formation by Targeting Key Transporters in Hepatobiliary Cholesterol Secretion Pathway

Abstract

Backgroud: MiRNA-223 has previously been reported to play an essential role in hepatic cholesterol homeostasis by suppressing cholesterol synthesis, attenuating cholesterol uptake by hepatocyte from and promoting cholesterol efflux into the blood. However, its role in regulation of biliary cholesterol secretion and gallstone formation remains unknown. Methods: Mice with conventional knockout (KO), hepatocyte-specific knockout (ΔHepa) / knockdown (KD) or gain expression of miRNA-223 were included in the study and were subjected to lithogenic diet (LD) for various weeks. The gallbladders were harvested and subjected to cholesterol crystal imaging and gallstone mass measurement. Liver tissues were collected for western blotting, RT-qPCR, and immunohistochemistry staining. Levels of cholesterol, bile salt, phospholipids, and triglyceride were determined in serum, liver tissues, and bile by enzyme color reactive assays. 3' UTR reporter gene assays were used to verify the direct target genes for miRNA-223. Results: LD-induced gallstone formation was remarkably accelerated in miRNA-223 KO, ΔHepa, and KD mice with concurrent enhancement in total cholesterol levels in liver tissue and bile. Key biliary cholesterol transporters ABCG5 and ABCG8 were identified as direct targets of miRNA-223. Reversely, AAV-mediated hepatocyte-specific miRNA-223 overexpression prevented gallstone progression with reduced targets protein expression. Conclusion: The present study demonstrates a novel role of miRNA-223 in the regulation of hepatic bile cholesterol secretion pathway and gallstone formation by targeting ABCG5 and ABCG8 expression. Therefore, elevating miRNA-223 would be a potentially novel approach to overcome the sternness of cholesterol gallstone disease. Key words: miRNA-223; gallstone; ABCG5 and ABCG8