TMT-based quantitative N-glycoproteomic analysis reveals glycoprotein protection can improve the quality of frozen bovine sperm

Proteomics and metabolomics analyses of mechanism underlying bovine sperm cryoinjury

BACKGROUND

The cryoinjury of semen during cryopreservation reduces sperm motility, constraining the application of artificial insemination (AI) in bovine reproduction. Some fertility markers, related to sperm motility before and after freezing have been identified. However, little is known about the biological mechanism through which freezing reduces sperm motility. This study investigated the selective effects of cryoinjury on high-motility sperm (HMS) and low-motility sperm (LMS) in frozen-thawed from the perspectives of reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and ATP levels. The molecular mechanism of decreased sperm motility caused by cryoinjury was explored through a joint analysis of 4D-label free quantitative proteomics and non-targeted metabolomics.

RESULTS

The results indicate that low levels of ROS and high degrees of MMP and ATP play a critical role in the survival of HMS during the freezing process. The sperm samples from the frozen-thawed HMS and LMS were analysed for proteomics and metabolomics, 2,465 proteins and 4,135 metabolites were detected in bovine sperm samples. In contrast to LMS, HMS have 106 proteins and 106 metabolites with high abundance expression, and 79 proteins and 223 metabolites with low abundance expression. Proteomics and metabolomics data exhibit that highly expressed antioxidant enzymes and metabolites in HMS can maintain sperm motility by regulating the ROS produced during freezing to prevent sperm from oxidative stress and apoptosis. Furthermore, the KEGG analysis of differential proteins and metabolites during the freezing process implies that the significant enrichment of glycolysis and cAMP in HMS can guarantee energy supply.

CONCLUSIONS

The results provided that during the process of bovine sperm freezing, highly expressed antioxidant enzymes can regulate the reactive oxygen species levels to avoid oxidative stress and the glycolysis signalling pathway ensures ATP production can sustain frozen-thawed sperm motility.

An updated review on the application of proteomics to explore sperm cryoinjury mechanisms in livestock animals

This comprehensive review critically examines the application of proteomics in understanding sperm cryoinjury mechanisms in livestock animals, in the context of the widespread use of semen cryopreservation for genetic conservation. Despite its global adoption, cryopreservation often detrimentally affects sperm quality and fertility due to cryoinjuries. These injuries primarily arise from ice crystal formation, osmotic shifts, oxidative stress, and the reorganization of membrane proteins and lipids during freezing and thawing, leading to premature capacitation-like changes. Moreover, the cryopreservation process induces proteome remodeling in mammalian sperm. Although there have been technological advances in semen cryopreservation, the precise mechanisms of mammalian sperm cryoinjury remain elusive. This review offers an in-depth exploration of how recent advancements in proteomic technologies have enabled a detailed investigation into these molecular disruptions. It presents an analysis of protein-level alterations post-thaw and their impact on sperm viability and functionality. Additionally, it discusses the role of proteomics in refining cryopreservation techniques to mitigate cryoinjury and enhance reproductive outcomes in livestock. This work synthesizes current knowledge, highlights gaps, and suggests directions for future research in animal reproductive science and biotechnology.