Figure 2. miR-126 is highly and specifically expressed by plasmacytoid DCs.
(a) Measurement of miR-126 expression in TLR7 and TLR9 expressing immune cells. Splenic B cells, CD8+ T cells, CD4+ T cells, macrophages, CD4+ DCs, CD8+ DCs and plasmacytoid DCs (pDCs) were sorted by flow cytometry. Small RNA was extracted and miR-126-3p, miR-21 and miR-16 were measured by quantitative PCR (qPCR). miR-126 abundance was normalized to miR-16 and miR-21, and calibrated across samples relative to expression in B cells (lowest value). Results are shown as mean ± s.d. (n = 4). **P < 0.01. (b) Profile of 365 miRNAs in mouse DCs. CD4+ DCs, CD8+ DCs and pDCs from the spleen and CD103+ DCs from the lungs were sorted by flow cytometry, small RNA was extracted, and the expression of 365 miRNAs was measured by qPCR (n = 3-5 replicates per cell type). The data was normalized using array means, and plotted in decreasing order according to the miRNA expression average across the groups. The color scale denotes the relative abundance of each miRNA. (c,d) miR-126 abundance in pDCs and CD4+ DCs. Small RNA was extracted from sorted splenic CD4+ DCs and pDCs and subjected to deep-sequencing. The relative frequency of each miRNA in pDCs is shown (c), as well as the read density across the miR-126 gene for pDCs and CD4+ DCs, and across the Mir142 gene, as a comparison. (e) miR-126 expression in human DCs. Human pDCs and conventional DCs (cDCs) were isolated from blood, small RNA was extracted, and qPCR analysis was performed to measure expression of miR-126 and miR-21. miR-126 abundance was normalized to miR-21 and calibrated relative to that expressed in cDCs. Results are shown as the mean ± s.d. (n = 3). *P <0.05 vs cDCs.