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MicroRNA-145 post-transcriptionally regulates the expression and function of P-glycoprotein in intestinal epithelial

Kenji Ikemura1, Misato Yamamoto, Saori Miyazaki

  • 1College of Pharmacy, Kinjo Gakuin University, Nagoya, Aichi, Japan.

Molecular Pharmacology
|November 21, 2012
PubMed

Insights

Liver ischemia-reperfusion injury decreases microRNA-145 (miR-145) levels, leading to increased P-glycoprotein (P-gp) expression in the intestine. This study reveals miR-145 as a key regulator of intestinal P-gp post-transcriptionally.

Area of Science:

  • Pharmacology
  • Molecular Biology
  • Gastroenterology

Background:

  • P-glycoprotein (P-gp/MDR1) is a crucial drug efflux transporter affecting drug pharmacokinetics.
  • Intestinal P-gp expression increases after liver ischemia-reperfusion (I/R) injury, but regulatory mechanisms are unclear.
  • MicroRNAs (miRNAs) are known regulators of drug transporter expression.

Purpose of the Study:

  • To investigate intestinal miRNA expression changes following liver I/R injury.
  • To elucidate the role of miRNAs in the post-transcriptional regulation of intestinal P-gp.
  • To identify specific miRNAs involved in modulating P-gp expression after liver I/R.

Main Methods:

  • Microarray analysis and real-time PCR to profile intestinal miRNA expression in I/R rats.
  • In silico analysis to predict miRNA binding sites on Mdr1 mRNA 3'-UTRs.
  • Luciferase reporter assays in HEK293 cells to validate miR-145 interaction with MDR1 3'-UTR.
  • Experiments in Caco-2 cells to assess the impact of miR-145 modulation on P-gp expression and function.

Main Results:

  • MicroRNA-145 (miR-145) levels were significantly downregulated in the small intestine of I/R rats.
  • In silico and luciferase assays confirmed direct binding of miR-145 to the 3'-UTR of MDR1 mRNA.
  • Downregulation of miR-145 in Caco-2 cells increased P-gp expression and efflux activity, without altering MDR1 mRNA levels.
  • These findings indicate miR-145 negatively regulates P-gp expression and function.

Conclusions:

  • miR-145 directly represses P-gp expression and function via interaction with the MDR1 mRNA 3'-UTR.
  • The observed downregulation of miR-145 contributes to elevated intestinal P-gp expression post-liver I/R.
  • This study provides novel insights into the post-transcriptional regulation of intestinal P-gp by miRNAs.

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