Myc influences embryonic stem cell pluripotency by regulating miRNAs

Previous studies have demonstrated that the c-Myc transcription factor regulates and cooperates with oncogenic miRNAs to accelerate tumorigenesis. Much recent work has shown that Myc plays an important role in stem cell pluripotency. These findings have prompted us to determine whether Myc regulates embryonic stem cell pluripotency through miRNAs. We have employed both miRNA- and expression- profiling to demonstrate that Myc up- or down-regulates a subset of miRNAs, which in turn influence expression of groups of genes involved in lineage differentiation. Chromatin immunoprecipitation analysis indicates that c-Myc binds proximal to the coding regions of these miRNAs in a dose dependent manner. Moreover, introduction of Myc-targeted miRNAs into murine ES cells significantly retards differentiation upon withdrawal of LIF. Our data suggest that at the ES cell stage, c-Myc acts at least in part through a subset of miRNAs to maintain pluripotency. Synthetic microRNAs were transfected into mouse embryonic stem cells, and expression signatures from these cells were compared to mock-transfected cells (transfection reagent in the absence of microRNA). Two individual experiments were performed, one containing 12h and 24h timepoints and one containing only a 24h timepoint. Within each experiment, each individual signature was ratioed to the average of all signatures in the experiment.