A Fine-Tune Role of Mir-125a-5p on During Age-Associated Changes in the Thymus.

Decline of transcription factor , which predominantly regulates thymic epithelial cell (TEC) differentiation and homeostasis lifelong, is demonstrated to be casually related to age-related thymic involution. Whereas, a global role of microRNAs (miRNAs) has also been demonstrated to control and maintain TEC-constituting thymic microenvironment and to be changed in expression profile in the aged thymus. Therefore, it is urgently necessary to build knowledge regarding whether and which miRNAs regulate gene in the aged thymus. We primarily compared changes in miRNA expression profile between young and aged murine TECs with miRBase-V20 arrays (containing 1892 unique probes), and clearly identified and validated that at least one miRNA, miR-125a-5p, was increased in aged thymus. Applying miR-125a-5p mimics was able to inhibit 3'UTR luciferase activity in a 293T cell line and to suppress FoxN1 expression in murine TEC Z210 cells. Since a single miRNA can play a fine-tuning role to regulate expression of multiple genes and a single gene can be regulated by multiple miRNAs, our result adds a single miRNA, miR-125a-5p, into the panel of -regulating miRNAs associated with thymic aging.