title: Induction and regulatory function of miR-9 in human monocytes and neutrophils exposed to proinflammatory signals.
abstract: 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 evolutionarily 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-alpha and IL-1beta, but not by IFNgamma. 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-kappaB-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-kappaB rapidly increases the expression of miR-9 that operates a feedback control of the NF-kappaB-dependent responses by fine tuning the expression of a key member of the NF-kappaB family.
authors.affiliation: Department of Pathology, Division of General Pathology, University of Verona, Strada le Grazie 8, I-37134 Verona, Italy.
authors.forename: Flavia
authors.initials: F
authors.lastname: Bazzoni
authors.forename: Marzia
authors.initials: M
authors.lastname: Rossato
authors.forename: Marco
authors.initials: M
authors.lastname: Fabbri
authors.forename: Daniele
authors.initials: D
authors.lastname: Gaudiosi
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Mirolo
authors.forename: Laura
authors.initials: L
authors.lastname: Mori
authors.forename: Nicola
authors.initials: N
authors.lastname: Tamassia
authors.forename: Alberto
authors.initials: A
authors.lastname: Mantovani
authors.forename: Marco A
authors.initials: MA
authors.lastname: Cassatella
authors.forename: Massimo
authors.initials: M
authors.lastname: Locati
mesh_terms: D016207:Cytokines / Q000096:biosynthesis; D020869:Gene Expression Profiling; D006801:Humans; D007249:Inflammation; D018836:Inflammation Mediators / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D035683:MicroRNAs / Q000235:genetics*; D009000:Monocytes / Q000276:immunology*; D016328:NF-kappa B / Q000378:metabolism*; D009504:Neutrophils / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D051193:Toll-Like Receptors / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D035683:MicroRNAs; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors