Lack of microRNA miR-150 reduces the capacity of epidermal Langerhans cell cross-presentation.

MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs that repress target genes at post-transcriptional level. Langerhans cells (LCs) are skin-residential dendritic cells (DCs) with a life cycle distinct from other types of DCs. miRNA deficiency interrupts the homoeostasis and function of epidermal LCs, suggesting the critical roles of miRNAs in LC development and function. However, the roles of individual miRNAs in regulating LC development and function remain completely unknown. MiRNA miR-150 is highly expressed in mature lymphocytes and regulates T- and B-cell development and function. Here, we reported that miR-150 is also expressed in epidermal LCs, and its expression is significantly down-regulated during in vitro LC maturation. Using a miR-150 knockout mouse model, we found that lack of miR-150 reduces the capacity of LCs to cross-present a soluble antigen to antigen-specific CD8(+) T cells, but does not disturb the development, maturation, migration and phagocytic capacity of LCs. Thus, our data indicate that miR-150 is required for LC cross-presentation.