Suprachiasmatic nuclei (SCN) is the master circadian pacemaker that generates coordinated rhythms and drives oscillations in other peripheral tissues. Extracellular vesicles (exosomes) have been implicated in cell-to-cell communication and the regulation of circadian clock. However, mammalian clock-derived exosomes have not been characterized. This thesis examine the contents of exosome released from SCN2.2 cells in vitro using a combination of proteomics, next-generation sequencing, and bioinformatic analyses. SCN2.2 cells-derived exosomes, that carry unique microRNAs and proteins, could be taken up by fibroblast cells in vitro. Interestingly, several unique microRNAs and proteins found in SCN2.2 cells-derived exosomes have shown circadian rhythmicity in other cells. In addition, differential expressed microRNAs secreted by SCN cells were also observed outside of exosomes. Taken together, these studies demonstrate that exosomes, containing small RNAs, RNAs and proteins, are released from SCN2.2 cells and likely have a biological role in circadian regulation of metabolism in downstream cells.