The binding of PCBP2 to IGF2 mRNA restores mitochondrial function in granulosa cells to ameliorate ovarian function in premature ovarian insufficiency mice

Abstract

Background

Premature ovarian insufficiency (POI) is characterized by early ovarian dysfunction, which has a profound impact on female fertility. Insulin-like Growth Factor 2 (IGF2) is believed to maintain ovarian function, yet the mechanisms and specific roles of IGF2 in POI remain unclear. This study explores the roles of IGF2 and its binding protein PCBP2 in POI, with a particular focus on their effects on mitochondrial function in granulosa cells and ovarian function.

Methods

A POI mouse model was induced by cyclophosphamide (CTX), and ovarian function and IGF2 levels were evaluated using ELISA, RT-qPCR, Western blot, and histology. Human granulosa cells (KGN) were treated with CTX. IGF2 and PCBP2 were overexpressed or knocked down, and CCCP (a mitochondrial uncoupling agent) was applied to evaluate their effects on apoptosis, mitochondrial function, and mitochondrial fission proteins. RIP and RNA pull down assays were utilized to verify the binding of PCBP2 to IGF2 mRNA and IGF2 mRNA stability was assessed using actinomycin D. To further investigate the therapeutic potential of PCBP2 in POI, PCBP2 was overexpressed in the animal model to evaluate its effects on ameliorating ovarian function in POI mice.

Results

IGF2 expression was reduced in POI mouse ovaries, characterized by disrupted estrous cycles, hormonal imbalances, and decreased follicle numbers. IGF2 overexpression inhibited CTX-induced apoptosis in KGN cells, restored mitochondrial function, and downregulated mitochondrial fission proteins. These effects were reversed by CCCP pre-treatment. PCBP2 expression was downregulated in POI mice and CTX-treated KGN cells. PCBP2 stabilized IGF2 mRNA, thereby promoting its expression. Knocking down IGF2 reversed PCBP2's protective effects. In animal experiments, PCBP2 overexpression improved hormone levels, increased ovarian weight and follicle numbers, and significantly alleviated granulosa cell apoptosis and mitochondrial damage in POI mice.

Conclusions

PCBP2 promoted IGF2 expression by stabilizing IGF2 mRNA, thereby inhibiting granulosa cell apoptosis, restoring mitochondrial function, and ameliorating ovarian function in POI mice. This study highlights the significant function of the PCBP2/IGF2 axis in POI and suggests it as a promising potential therapeutic target.