MicroRNA transcriptomes of distinct human NK cell populations identify miR-362-5p as an essential regulator of NK cell function.

Natural killer (NK) cells are critical effectors in the immune response against malignancy and infection, and microRNAs (miRNAs) play important roles in NK cell biology. Here we examined miRNA profiles of human NK cells from different cell compartments (peripheral blood, cord blood, and uterine deciduas) and of NKT and T cells from peripheral blood, and we identified a novel miRNA, miR-362-5p, that is highly expressed in human peripheral blood NK (pNK) cells. We also demonstrated that CYLD, a negative regulator of NF-κB signaling, was a target of miR-362-5p in NK cells. Furthermore, we showed that the over-expression of miR-362-5p enhanced the expression of IFN-γ, perforin, granzyme-B, and CD107a in human primary NK cells, and we found that silencing CYLD with a small interfering RNA (siRNA) mirrored the effect of miR-362-5p over-expression. In contrast, the inhibition of miR-362-5p had the opposite effect in NK cells, which was abrogated by CYLD siRNA, suggesting that miR-362-5p promotes NK-cell function, at least in part, by the down-regulation of CYLD. These results provide a resource for studying the roles of miRNAs in human NK cell biology and contribute to a better understanding of the physiologic significance of miRNAs in the regulation of NK cell function.