Jiao-tai-wan and its component coptisine attenuate PCOS by regulating mitochondrial cholesterol import through suppression of SIRT1 ubiquitination

Polycystic ovary syndrome (PCOS) has emerged as a common endocrine disorder that impacts female reproductive health. The traditional herbal formulation, Jiao-tai-wan (JTW), exhibits multiple biological activities, including improving insulin resistance, reducing oxidative stress, and mitigating inflammation. The clinical efficacy of JTW against PCOS has been reported, however, mechanistic studies remain absent. To clarify the mechanisms behind the therapeutic efficacy of JTW in PCOS. The PCOS rat model was established by injection of DHEA. The in vivo study consisted of two parts: Part 1 included control, PCOS, low-dose JTW, high-dose JTW, and metformin groups; Part 2 included control, PCOS, and coptisine groups. The in vitro study utilized primary theca cells. The effects of JTW on ameliorating PCOS phenotypes were assessed. Key pathways were identified via RNA sequencing, and the primary constituents of JTW were identified using UPLC fingerprinting. Further mechanistic investigations were conducted using techniques including network pharmacology, cell transfection, transmission electron microscopy imaging, confocal imaging, co-immunoprecipitation, CETSA, and SPR. JTW attenuated abnormal ovulation, sex hormone imbalance, ​​glycolipid metabolism disorders​, and oxidative stress in PCOS rats. RNA sequencing revealed that JTW regulated the ovarian steroidogenesis pathway. Furthermore, JTW regulated mitochondrial dynamics and inhibited ​​StAR localization to the outer mitochondrial membrane in the ovarian theca cells. SIRT1 was identified as the key target of JTW. Coptisine, a component of JTW, reversed abnormal mitochondrial dynamics in theca cells by upregulating SIRT1 expression, which in turn suppressed mitochondrial cholesterol import, thereby alleviating LH-induced aberrant steroidogenesis. Coptisine intervention produced effects similar to SIRT1 overexpression, but SIRT1 knockdown blocked these effects. Notably, coptisine did not alter SIRT1 mRNA levels but enhanced SIRT1 protein expression by suppressing ubiquitination-mediated degradation. Coptisine weakened the interaction between the E3 ubiquitin ligase SMURF2 and SIRT1. Additionally, coptisine exhibited high affinity for SIRT1 (K D = 5.71 μM). Finally, coptisine demonstrated therapeutic effects in PCOS rats. JTW and its component, coptisine, modulate mitochondrial dynamics by inhibiting SIRT1 ubiquitination to restrict StAR-mediated mitochondrial cholesterol import, thereby normalizing abnormal ovarian steroidogenesis and attenuating PCOS. Furthermore, this study provides novel evidence that coptisine functions as a natural stabilizer of SIRT1 protein.