Poster Presentation Australasian Society for Immunology Annual Scientific Meeting 2014

MicroRNA-487b contributes to macrophage homeostasis by targeting interleukin-33 (#263)

Yang Xiang 1 2 , Fiona Eyers 1 , Paul Foster 1 , Ming Yang 1
  1. University of Newcastle, Newcaslte, NSW, Australia
  2. Department of Physiology, Central South University, Changsha, HUNAN, P.R.CHINA
MicroRNAs (miRNAs) are non-coding and regulate broad biological processes including immune responses. MiRNAs fine-tune gene expression post-transcriptionally by inhibiting translation or inducing degradation of target mRNAs. Their contributions to the function of specific immune cells still remain largely unknown. MiR-487b was initially discovered in human neuroblastoma and it plays critical role in cell growth, however its function in immunity remain unclear. In this study, we report that miR-487b can suppress both mRNA and protein levels of IL-33 during the differentiation of bone-marrow derived macrophages (BMDM), thus suppressing IL-33-enhanced expression of antigen presenting and co-stimulatory molecules and inflammatory mediators. Luciferase assay showed that miR-487b could bind to the IL-33 untranslated region. We also confirmed that IL-33 promotes the activation of BMDM by increasing the expression of MHC -I and –II, CD80, CD86 and inducible nitric oxide synthase (iNOS) in a dose-dependent manner. LPS, a typical TLR4 ligand, decreases miR-487b expression, increases IL-33 expression and promotes BMDM activation. Inhibition of miR-487b resulted in the elevated IL-33 expression, thus augmenting the expression of inflammatory factors of LPS-stimulated BMDM. Therefore, miR-487b plays an important role in the regulation of homeostasis and the activation of macrophages by targeting IL-33 transcripts. Our results provide an important link for triggering macrophage’s inflammatory response.