Recent evidence has suggested that microRNAs (miRNAs) may play a significant role in the pathogenesis of inflammatory skin conditions such as atopic dermatitis (AD). The aim of the present study was to evaluate the potential functions of miRNAs in AD and to identify the underlying mechanisms. We firstly analyzed miRNA expression in the skin lesions of patients with AD using microarray analysis. Validation analysis was performed in skin biopsy specimens and in serum using quantitative reverse transcription PCR (qRT-PCR). The relationship between microRNA-29b (miR-29b) and development of AD was further explored. Subsequently, gain- and loss-of-function studies were performed to determine the functions of miR-29b in interferon-γ (IFN-d)-induced keratinocytes (KCs) apoptosis. Further bioinformatics analysis and luciferase reporter assays were performed to predict its target genes, then the effects of miR-29b on the expression of BCL2-like2 (Bcl2L2) were investigated using qRT-PCR and western blot analysis. Finally, KCs were transfected with miR-29b mimics or Bcl2L2 siRNA (si-Bcl2L2) to explore the mechanism by which miR-29b plays in the pro-apoptotic roles in IFN-γ-treated keratinocytes. The miR-29b was found to be one of the most significantly up-regulated miRNAs in the skin lesions of patients with AD, as compared with healthy control and its expression was statistically associated with the development of AD. We, therefore, selected miR-29b as a candidate miRNA and investigated its function. Our in vitro data showed that the keratinocytes apoptosis induced by IFN-duced by IFN-ptosis induced by IFN-vestigated its function. Our stically associated with the deve particular, we identified Bcl2L2 as a direct target of miR-29b. More importantly, siRNA-induced knockdown of Bcl2L2 attenuated the protective effects of miR-29b inhibition on keratinocytes apoptosis. These results suggested that miR-29b knockdown may play an important role in preventing cell apoptosis in IFN-cktreated keratinocytes, and these effects might be partially through regulation of Bcl2L2. These findings revealed that the miR-29b/Bcl2L2 regulatory axis was involved in the pathogenesis of AD and suggested that knockdown of miR-29b might be a novel therapeutic target for AD.
Keywords: Atopic dermatitis; IFN-optosis; apoptosis; keratinocyte; microRNA-29b.
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