Berberine Increases Glucose Uptake and Intracellular ROS Levels by Promoting Sirtuin 3 Ubiquitination

Objective: Berberine improves insulin sensitivity and ovulation function in PCOS patients. However, the mechanism by which berberine initiates glucose metabolism-related signaling pathways in ovarian cells remains unknown. This study unveiled a new mechanism by which berberine promotes ovarian cell glucose uptake, and demonstrated that SIRT3 ubiquitination is involved in the insulin sensitizing effect of berberine.

Methods: Berberine was used at different concentrations to treat cultured KGN cells. Then, cell viability, cell apoptosis, intracellular ROS levels, mitochondrial depolarization and activation of related signaling pathways were evaluated.

Results: Berberine administration led to mitochondrial depolarization and AMP accumulation by promoting SIRT3 ubiquitination. We confirmed that AMP accumulation activated AMPK signaling and further promoted glucose uptake. Meanwhile, berberine reduced the activity of mitochondrial complex I in a dose-depended manner, but not that of mitochondrial complex II. Furthermore, intracellular ROS levels and the expression of mitochondrial apoptosis pathway related factors increased with berberine concentration. Berberine caused significant SIRT3 ubiquitination and degradation by activating the AMPK pathway and increasing intracellular ROS levels. Interestingly, berberine induced ubiquitination paralleled the increased FOXO3a phosphorylation and FOXO3a/Parkin pathway activation.

Conclusions: Berberine promotes glucose uptake and inhibits mitochondrial function by promoting SIRT3 ubiquitination, and is likely to regulate autophagy related function in ovarian cells by activating the AMPK pathway. These findings may provide novel insights into the development of drugs for the treatment of abnormal reproductive functions of the ovary.