| Summary: | 碩士 === 長庚大學 === 醫學生物技術研究所 === 96 === Reactive oxygen species (ROS) play important roles in regulating cellular functions. Some growth factors, such as PDGF and EGF, have been discovered to signal through ROS and activate the MAP kinase cascades to regulate the expression of transcription factors. Several laboratories have found that ROS could directly regulate the binding of transcription factors, like AP-1, NF-κB and p53, to DNA and thus influence the downstream gene expression. MicroRNAs (miRNAs) are a class of regulatory RNAs of approximately 21~25 nucleotides that post-transcriptionally regulate gene expression by directing mRNA cleavage or translational inhibition. The relationship between oxidative stress and miRNAs has not been clearly defined. Toward this end, we used A549 as a cell model to explore the effect of oxidative stress on miRNA expression. Cells were exposed to 500 μM H2O2 for 1hr and the expression levels of 270 human miRNAs were determined by quantitative RT-PCR. H2O2 treatment caused a 5-fold increase in the level of has-miR-200C. Analysis of putative miR-200c targets revealed that three target mRNAs, PCAF, COL4A3, TFAP2A, showed an inverse correlation to the level of miR-200c. The biological significance of miR-200c up-regulation in response to oxidative stress should be clearly defined.
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