Characterization of deregulated microRNA in microgliai activation by endotoxin stimulation

Microglial cells are the hematopoietic originated immune cells of the central nervous system (CNS). They are resident macrophages of CNS. In CNS, they play a role in inflammation mechanism of most neurodegenerative diseases. MicroRNAs (miRNAs) are the non-coding small regulatory RNAs playing role in post-transcriptional regulation. In this study, neuro-inflammation related miRNAs and their targets were aimed to be determined.In this study, N9 murine microglial and 293T human embryonic kidney cell lines were used. In the experiment, N9 cells were treated with 10-1000ng/ml doses of Lipopolysaccharide (LPS). In preliminary study, by using 100 ng/ml LPS, miRNA expression changes were determined by microarray. Of microarray-characterized miRNAs, miR-125b-3p, miR-132, miR-146a and miR-155 were further analyzed by quantitative PCR (qPCR). Of verified miRNAs, miRNA target genes were determined by bioinformatic analysis and targetes were validated by luciferase assay.According to miRNA array analysis, 30 mostly changed miRNAs are detected. As a result of qPCR analyses, miR-125-3p expression was reduced while miR-146a and miR-155 expressions were increased. Target validation experiments verified the bioinformatically determined miRNA target genes (TNF-?, IL-1ß, IL-6, IRAK1, TRAF6 and MyD88).This study helped the characterization of the miRNAs related to microglial activation. Of these microRNAs, it was shown that miR-125b targets TNF-? and IL-1ß mRNAs, miR-132 targets IL-6 mRNA, miR-146a targets IRAK1 and TRAF6 mRNAs and miR-155 targets MyD88 mRNA.