miR-147, a microRNA that is induced upon Toll-like receptor stimulation, regulates murine macrophage inflammatory responses

Proc Natl Acad Sci U S A. 2009 Sep 15;106(37):15819-24. doi: 10.1073/pnas.0901216106. Epub 2009 Aug 31.

Abstract

Toll-like receptors (TLRs) are major receptors that enable inflammatory cells to recognize invading microbial pathogens. MicroRNAs are small non-coding RNAs that play important regulatory roles in a variety of biological processes. In this study, we found that a microRNA, miR-147, was induced upon stimulation of multiple TLRs and functioned as a negative regulator of TLR-associated signaling events in murine macrophages. We first demonstrated that the NMES1 transcript was a functional primary miR-147. miR-147 was induced in LPS-stimulated mouse macrophages and under in vivo conditions in the lungs of LPS-treated mice. Expression of miR-147 was greater after cellular activation by TLR4 than after engagement of either TLR2 or TLR3, suggesting that maximal induction of miR-147 required activation of both NF-kappaB and IRF3. TLR4-induced miR-147 expression was both MyD88- and TRIF-dependent. The miR-147 promoter was responsive to TLR4 stimulation and both NF-kappaB and STAT1alpha bound to the miR-147 promoter. miR-147 mimics or induced expression of miR-147 decreased, whereas miR-147 knockdown increased inflammatory cytokine expression in macrophages stimulated with ligands to TLR2, TLR3, and TLR4. These data demonstrate a negative-feedback loop in which TLR stimulation induces miR-147 to prevent excessive inflammatory responses.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Line
  • Feedback, Physiological
  • Humans
  • Inflammation / genetics
  • Inflammation / immunology*
  • Inflammation / metabolism
  • Lipopolysaccharides / pharmacology
  • Macrophages / drug effects
  • Macrophages / immunology*
  • Macrophages / metabolism
  • Macrophages, Alveolar / drug effects
  • Macrophages, Alveolar / immunology
  • Macrophages, Alveolar / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • MicroRNAs / biosynthesis
  • MicroRNAs / genetics
  • MicroRNAs / immunology*
  • Promoter Regions, Genetic / drug effects
  • Toll-Like Receptor 4 / metabolism
  • Toll-Like Receptors / metabolism*
  • Up-Regulation / drug effects

Substances

  • Lipopolysaccharides
  • MicroRNAs
  • Mirn147 microRNA, mouse
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4
  • Toll-Like Receptors