High dietary fructose induces the senescence of granulosa cells by enhancing O-GlcNAcylation

Granulosa cells play a pivotal role in follicle initiation and development. Metabolic disorders can inflict damage on granulosa cells, ultimately leading to abnormal ovarian function. It is well established that a high dietary intake of fructose can induce a range of metabolic diseases, such as insulin resistance and non-alcoholic fatty liver disease. However, the underlying mechanism by which fructose affects ovarian function remains unclear. In this study, we subjected wild-type mice to a 30% fructose solution in their drinking water for 16 weeks to establish high-fructose animal models. The results obtained showed that in mice exposed to high fructose, hormone levels and estrous cycles were abnormal, and the number of atretic follicles increased. Simultaneously, senescence and apoptosis of granulosa cells were also observed in high-fructose mice, and the level of cellular protein O-GlcNAcylation significantly increased. Treatment of granulosa cells with the O-GlcNAcylation activator Thiamet G and inhibitor OSMI-1 demonstrated that elevated O-GlcNAcylation induces granulosa cell senescence and promotes apoptosis. We utilized immunoprecipitation-mass spectrometry to investigate O-GlcNAcylated proteins in the ovaries of high-fructose mice and the results indicated that numerous proteins had significantly elevated O-GlcNAcylation levels, mainly centered on the chromatin "remodeling" and "nucleocytoplasmic transport" pathways. Among them, increases in the O-GlcNAcylation levels of nucleoporin 54 and glucose-regulated protein 78 were confirmed by co-immunopreciptitation. These results uncover a new mechanism of fructose-induced ovarian function impairment, providing potential targets for the treatment of diet-related fertility disorders.