MicroRNA-145 Post-transcriptionally Regulates the Expression and Function of P-glycoprotein in Intestinal Epithelial Cells

• Published in: Molecular pharmacology 2013-02, Vol.83 (2), p.399-405
• Main Authors: Ikemura, Kenji, Yamamoto, Misato, Miyazaki, Saori, Mizutani, Hideki, Iwamoto, Takuya, Okuda, Masahiro
• Format: Article
• Language: English
• Subjects: 3' Untranslated Regions; Animals; ATP Binding Cassette Transporter, Sub-Family B - genetics; ATP Binding Cassette Transporter, Sub-Family B - metabolism; ATP-Binding Cassette, Sub-Family B, Member 1 - biosynthesis; ATP-Binding Cassette, Sub-Family B, Member 1 - genetics; ATP-Binding Cassette, Sub-Family B, Member 1 - metabolism; Base Sequence; Caco-2 Cells; Cell Line; Cell Line, Tumor; Down-Regulation; Epithelial Cells - metabolism; HEK293 Cells; Humans; Intestines - metabolism; Intestines - physiology; Liver - metabolism; Liver - physiology; Male; MicroRNAs - antagonists & inhibitors; MicroRNAs - genetics; MicroRNAs - metabolism; Molecular Sequence Data; Rats; Rats, Wistar; Reperfusion Injury - genetics; Reperfusion Injury - metabolism; RNA Processing, Post-Transcriptional; RNA, Messenger - genetics
• ISSN: 0026-895X; 1521-0111
• DOI: 10.1124/mol.112.081844

P-glycoprotein (P-gp/MDR1) is a multispecific efflux transporter regulating the pharmacokinetics of various drugs. Although P-gp expression in the small intestine is elevated after liver ischemia-reperfusion (I/R) injury, the regulatory mechanism remains to be clarified. MicroRNAs (miRNAs) play an important role in the post-transcriptional regulation of the expression of drug transporters. Here, we investigated the intestinal expression profile of miRNAs after liver I/R and the role of miRNAs in the post-transcriptional regulation of P-gp in intestinal epithelial cells. Microarray analysis showed that microRNA-145 (miR-145) level was decreased in the small intestine of I/R rats. This downregulation of miR-145 was further confirmed by real-time polymerase chain reaction. In silico analysis revealed that 3′-untranslated regions (UTRs) of rat Mdr1a, mouse Mdr1a, and human MDR1 mRNA retain binding sites for miR-145. Luciferase assays using MDR1 3′-UTR reporter plasmid in HEK293 cells showed that luciferase activity was decreased by the overexpression of miR-145, and the deletion of miR-145 binding site within MDR1 3′-UTR abolished this decreased luciferase activity. The downregulation of miR-145 in Caco-2 cells, an epithelial cell line derived from human colon, increased P-gp expression and efflux activity of rhodamine 123, but not MDR1 mRNA level. These findings demonstrated that miR-145 negatively regulates the expression and function of P-gp through the repression of mRNA by direct interaction on the 3′-UTR of MDR1 mRNA. In addition, the downregulation of miR-145 should significantly contribute to the elevated intestinal P-gp expression after liver I/R. Our results provide new insight into the post-transcriptional regulation of intestinal P-gp.