miR-141 and miR-200a are involved in Th17 cell differentiation by negatively regulating RARB expression

Abstract Background: Among T helper (Th) lineages differentiated from naïve CD4+ T cells, interleukin (IL)-17-producing Th17 cells are highly correlated with the pathogenesis of autoimmune disorders. Although a series of microRNAs (miRs) that modulate autoimmunity progress have been reported, further studies on microRNAs particularly involved in Th17 lineage commitment are still warranted. Results: In this study, to clarify the involvement of miR-141-3p and miR-200a-3p in Th17 cell differentiation, as well as to explore their potential target gene involved, purified human naïve CD4+ T cells were cultured under Th17 cell polarizing condition. Differentiation process was confirmed applying ELISA method to measure IL-17 secretion and RT-qPCR to assess Th17 cell-defining genes expression during differentiation period. miR-141 and miR-200a expression pattern as well as expression alteration of their predicted downstream genes, which were identified via consensus and integration in-silico approach, was then evaluated by RT-qPCR. Finally direct interaction between both microRNAs and their common predicted target sequence was approved by dual-luciferase reporter assay. Highly increased IL-17 secretion and Th17 lineage-specific genes expression confirmed Th17 cell differentiation. Conclusions: Results demonstrated that miR-141 and miR-200a were Th17 cell-associated microRNAs and their expression levels upregulated significantly during Th17 cell induction. We also found that retinoic acid receptor beta (RARB) gene, whose product has been reported as a negative regulator of Th17 cell generation, was a direct target of both microRNAs and its downregulation could affect the transcriptional level of JAK/STAT pathway genes. Overall, our results introduced two novel Th17 lineage-associated microRNAs and provided a rationale to further clarify the RARB-dependent mechanism of miR-141 and miR-200a to promote Th17 cell differentiation and hence Th17-mediated autoimmunity.