Transcriptome analysis of murine thymic epithelial cells reveals age-associated changes in microRNA expression

Age-related thymic involution is accompanied by a decrease in thymopoiesis and, thus, a deficiency in T cell-mediated immunity in the elderly. A number of events involved in thymic involution have been discovered; however, it remains unclear as to whether they are causes or consequences of thymic involution. These events include the degeneration of T cell progenitors, as well as the deterioration of the thymic stroma, which is a characteristic of thymic epithelial cell loss due to increased apoptosis and decreased cell proliferation. MicroRNAs (miRNAs) are believed to play important roles in the regulation of cell death and proliferation during the aging process. In the present study, we compared the transcriptional levels of various miRNAs in TECs from young and aged mice using microarray analysis. Quantitative PCR was performed to confirm the changes in the expression of miRNAs in the different age groups. Possible downstream targets and pathways of these miRNAs were predicted by performing bioinformatics analysis. To the best of our knowledge, this is the first study to systematically analyze the expression of miRNAs in mouse TECs and to demonstrate that miRNA expression is altered with thymic aging.