title: MicroRNA-145 post-transcriptionally regulates the expression and function of P-glycoprotein in intestinal epithelial cells.
abstract: 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.
authors.affiliation: College of Pharmacy, Kinjo Gakuin University, Nagoya, Aichi, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ikemura
authors.forename: Misato
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Saori
authors.initials: S
authors.lastname: Miyazaki
authors.forename: Hideki
authors.initials: H
authors.lastname: Mizutani
authors.forename: Takuya
authors.initials: T
authors.lastname: Iwamoto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okuda
mesh_terms: D020413:3' Untranslated Regions; D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics / Q000378:metabolism; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D018938:Caco-2 Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D015536:Down-Regulation; D004847:Epithelial Cells / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000502:physiology*; D008099:Liver / Q000378:metabolism / Q000502:physiology; D008297:Male; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000235:genetics / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; C541010:MIRN145 microRNA, human; C542511:MIRN145 microRNA, rat; D035683:MicroRNAs; D012333:RNA, Messenger; C095122:multidrug resistance protein 3