Bazzoni Flavia, Rossato Marzia, Fabbri Marco, Gaudiosi Daniele, Mirolo Massimiliano, Mori Laura, Tamassia Nicola, Mantovani Alberto, Cassatella Marco A, Locati Massimo
Department of Pathology, Division of General Pathology, University of Verona, Strada le Grazie 8, I-37134 Verona, Italy.
Proc Natl Acad Sci U S A. 2009 Mar 31;106(13):5282-7. doi: 10.1073/pnas.0810909106. Epub 2009 Mar 16.
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.
炎症涉及由正负调控机制控制的一系列协调、有序且自我限制的事件。最近的研究表明，微小RNA（miRNA）是一类进化上保守的内源性22个核苷酸的非编码RNA，通过在转录后水平抑制基因表达来参与炎症调节。在本研究中，我们描述了脂多糖（LPS）在人多形核中性粒细胞（PMN）和单核细胞中诱导的miRNA谱。特别地，我们确定miR-9是（在分析的365个miRNA中）TLR4激活后在两种细胞类型中均上调的唯一miRNA。miR-9也可由TLR2和TLR7/8激动剂以及促炎细胞因子TNF-α和IL-1β诱导，但不能由IFNγ诱导。在人类编码miR-9前体的3个不同基因中，我们发现LPS以依赖MyD88和NF-κB的方式选择性诱导位于CROC4基因座的miR-9-1的转录。在PMN和单核细胞中，LPS在转录和转录后水平调节NFKB1，并且一个保守的miR-9种子序列维持了miR-9对NFKB1转录本的依赖性抑制。总体而言，这些数据表明，TLR4激活的NF-κB迅速增加miR-9的表达，miR-9通过微调NF-κB家族关键成员的表达对NF-κB依赖性反应进行反馈控制。
