MicroRNAs in normal and malignant lymphocytes

MicroRNAs (miRNAs) are 20-22 nucleotide non-coding RNAs that can play important roles in developmental transitions by post-transcriptional regulation of mRNA translation and stability. We profiled miRNA expression in mouse thymocytes, mature T cells, and activated T cells, and identified distinctive patterns of miRNA expression during development, maturation, and activation of T cells. The miR-128 and miR-181 miRNA families are expressed at significantly higher levels in thymocytes. Examining the expression levels of these microRNAs in more detail, we observed that the expression pattern of these microRNA families distinguishes cells committed to lymphoid lineages from cells committed to myeloid lineages during normal mouse hematopoiesis. Extending this work to human malignancies, we determine that high miR-128 expression distinguishes lymphoid precursor derived malignancies from myeloid precursor derived malignancies.