Abstract
Micro-RNAs (miRNAs) are short, non-coding RNAs that regulate gene expression post transcriptionally. Several studies have demonstrated the relevance of miRNAs for a wide range of cellular mechanisms, however, the current knowledge on how miRNAs respond to relevant external stimuli, e.g. in disease scenarios is very limited. To generate a descriptive picture of the miRNA network associated to inflammatory responses, we quantified the levels of 330 miRNAs upon stimulation with a panel of pro-inflammatory components such as microbial pattern molecules (flagellin, diacylated lipopeptide lipopolysaccharide, muramyl dipeptide), infection with Listeria monocytogenes and TNF-α as pro-inflammatory control in primary human monocytes using real time PCR. As a result, we found distinct miRNA response clusters for each stimulus used. Additionally, we identified potential target genes of three selected miRNAs miR-129-5p, miR-146a and miR-378 which were part of PAMP-specific response clusters by transfecting THP1 monocytes with the corresponding pre- or anti-miRNAs and microfluidic PCR arrays. The miRNAs induced distinct transcriptomal signatures, e.g. overexpression of miRNA129-5p, which was selectively upregulated by the NOD2-elicitor MDP, led to an upregulation of DEFB1, IRAK1, FBXW7 and IKK γ (Nemo). Our findings on highly co-regulated clusters of miRNAs support the hypothesis that miRNAs act in functional groups. This study indicates that miRNAs play an important role in fine-tuning inflammatory mechanisms. Further investigation in the field of miRNA responses will help to understand their effects on gene expression and may close the regulatory gap between mRNA and protein expression in inflammatory diseases.
Highlights
When micro-RNAs were first discovered in Caenorhabditis elegans [1], they were thought to be an oddity in gene regulation of nematodes
Cells were stimulated with either flagellin (500 ng/ml), diacylated lipopeptide (FSL, 100 ng/ml), LPS (100 ng/ml), living Listeria monocytogenes (MOI = 100), muramyl-dipeptide (MDP) (10 mg/ml) or TNF-a (10 ng/ml) for 0, 1, 2, or 4 hours
Results miRNA response signatures In an initial TaqManH real-time PCR-based approach, quantification of 330 individual miRNAs showed that 133 miRNAs were present (90th percentile of all measurements,36.5 cycles) in at least 50% of the samples
Summary
When micro-RNAs (miRNAs) were first discovered in Caenorhabditis elegans [1], they were thought to be an oddity in gene regulation of nematodes. Further research showed that miRNAs are present in a large number of eukaryotes, from plants to humans. MiRNAs consist of 19–24 nucleotides and are highly conserved across species [2]. More than 5900 miRNAs have been identified and deposited in the miRNA database [3,4,5]. MiRNAs can be encoded anywhere in the genome [6], and current data indicates that only 2% of the human genome encode for 30,000 proteincoding mRNAs, whereas 60–70% of our DNA is transcribed into non-coding RNA [7,8]. MiRNAs are being discussed as a new type of post-transcriptional regulatory mechanism [2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
