Obesity induced by a high-fat diet regulates the MYC‒PPIL1 network in the mediation of asthenozoospermia

Male infertility, particularly asthenozoospermia (AZS), has become an increasingly severe global public health issue. Obesity induced by a high-fat diet (HFD) is considered a key factor in the development of AZS, although its exact molecular mechanisms remain unclear. This study employs bioinformatics analysis to explore the key genes and potential regulatory mechanisms of HFD-induced obesity in AZS, which were validated by animal experiments. First, on the basis of GEO transcriptomic data, we identified nine common differentially expressed genes (DEGs) between HFD-induced obesity and AZS. Using LASSO regression and support vector machine methods, we subsequently identified C1QBP and PPIL1 as critical genes associated with HFD-induced AZS. Furthermore, a core gene‒transcription factor coexpression network revealed that MYC is likely an upstream transcriptional regulator of these two core genes. According to single-cell RNA-seq data, C1QBP and PPIL1 are predominantly expressed in spermatogonia, whereas MYC is primarily localized in stromal cells and is closely correlated with AZS. Additionally, through genome-wide enrichment analysis, we identified several key pathways regulating both HFD-induced obesity and AZS, including cell proliferation and differentiation (MYC targets and mTOR signalling), energy metabolism, cellular stress and homeostasis, and immune and inflammatory responses. The results of animal experiments demonstrated that HFD-induced obesity significantly impaired sperm motility in male rats, accompanied by decreased testosterone levels and increased oxidative stress. At the molecular level, the expression of MYC and mTOR in the HFD obesity/AZS group was significantly reduced (P < 0.01), whereas PPIL1 expression was significantly increased (P < 0.01). Moreover, L-carnitine partially reversed these changes, indicating potential therapeutic value. In conclusion, our study suggests that HFD-induced obesity may lead to AZS through the upregulation of PPIL1 levels and the inhibition of the MYC and mTOR signalling pathways.