Induction and regulatory function of miR-9 in human monocytes and neutrophils exposed to proinflammatory signals

Flavia Bazzoni, Marzia Rossato, Marco Fabbri, Daniele Gaudiosi, Massimiliano Mirolo, Laura Mori, Nicola Tamassia, Alberto Mantovani, Marco A. Cassatella, Massimo Locati

Research output: Contribution to journalArticle


Inflammation involves a coordinated, sequential, and self limiting sequence of events controlled by positive and negative regulatory mechanisms. Recent studies have shown that microRNAs (miRNAs), an evolutionary conserved class of endogenous 22-nucleotide noncoding RNAs, contribute to the regulation of inflammation by repressing gene expression at the posttranscriptional level. In this study, we characterize the profile of miRNAs induced by LPS in human polymorphonuclear neutrophils (PMN) and monocytes. In particular, we identify miR-9 as the only miRNA (among 365 analyzed) up-regulated in both cell types after TLR4 activation. miR-9 is also induced by TLR2 and TLR7/8 agonists and by the proinflammatory cytokines TNF-α and IL-1β, but not by IFNγ. Among the 3 different genes encoding miR-9 precursors in humans, we show that LPS selectively induces the transcription of miR-9-1 located in the CROC4 locus, in a MyD88- and NF-κB-dependent manner. In PMN and monocytes, LPS regulates NFKB1 at both the transcriptional and posttranscriptional levels, and a conserved miR-9 seed sustained a miR-9-dependent inhibition of the NFKB1 transcript. Overall, these data suggest that TLR4-activated NF-κB rapidly increases the expression of miR-9 that operates a feedback control of the NF-κB-dependent responses by fine tuning the expression of a key member of the NF-κB family.

Original languageEnglish
Pages (from-to)5282-5287
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number13
Publication statusPublished - Mar 31 2009



  • Cytokines
  • Inflammation
  • Innate immunity
  • NFKB1
  • Toll-like receptors

ASJC Scopus subject areas

  • General

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