Circular RNA, ciR-02852, a novel epigenetic inhibitor of ovarian cell functions

The presence of the circular RNA ciR-02852 in ovarian tissue has been documented, but its role in controlling ovarian functions remains unknown. To evaluate its role, we examined the effects from both increasing (via an overexpressing vector) and decreasing (via a shRNA vector) the expression of this circRNA on the basic functions of cultured porcine ovarian granulosa cells. We assessed the relative expression levels of ciR-02852; cell viability; proliferation (measured by the accumulation of PCNA and cyclin B1, which are markers of the S and G phases of mitosis); the cytoplasm (assessed via the accumulation of bax and caspase-3); and nuclear (DNA fragmentation) apoptosis and the release of progesterone, testosterone, estradiol, IGF-I, and oxytocin. The transfection of cells with ciR-02852 resulted in significant increases in cell viability, proliferation, and progesterone, testosterone, estradiol, and oxytocin outputs but decreases in both cytoplasmic and nuclear apoptosis rates. Suppression of ciR-02852 by shRNA had the opposite effects. These observations demonstrated that ciR-02852 may be a physiological inhibitor of basic porcine ovarian cell functions and that regulators of ciR-02852 might be potentially useful for both the downregulation and upregulation of female reproductive processes.