Rapidly expanding exophthalmos: an unusual presentation of small cell lung cancer.

Abstract

CD1d-restricted invariant natural killer T (iNKT) cells play an important role in the regulation of diverse immune responses. MicroRNAs (miRNAs), a class of 21-25 nt single-stranded non-coding small RNAs, are increasingly being recognized as important regulators of gene expression through the inhibition of effective mRNA translation. We recently reported that miRNAs expressed in iNKT cell lineage are potent regulators of iNKT cell development, maturation, and function. However, the role of specific miRNAs in the iNKT cells has not been addressed so far. Using miRNA arrays, we found that the expression of miR-150 was significantly upregulated in mature iNKT cells compared to immature iNKT cells in the thymus. Interestingly, mice with miR-150 deficiency have a defect in iNKT cell development in the thymus and iNKT cell maturation was blocked at developmental stage 1 and 2, while the peripheral iNKT cells maturated normally. Furthermore, miR-150-deficient peripheral iNKT cells produce more cytokine interferon-gamma compared to that from wild type after PMA/Ionomycin stimulation. Thus, our results suggest that miR-150 controls iNKT cell thymic maturation and regulates iNKT cell function.