Comparative proteomic and transcriptomic analysis of testicular tissue of yaks with or without cryptorchidism.

Yak is a large plateau mammal with low reproduction rate, while cryptorchidism is a major reproductive disorder associated with infertility in highland yaks. To better understand the occurrence of cryptorchidism and its regulatory mechanisms in yaks, we conducted a multi-omic analysis, and screened a total of 4456 differentially expressed genes (DEGs) and 332 differentially expressed proteins (DEPs) between normal and unilateral cryptorchid testes of yaks using high-throughput transcriptome sequencing (RNA-seq) and Tandem Mass Tag (TMT)-based proteomics techniques, with testes from yaks with cryptorchidism as the target. Enrichment analysis revealed that the DEGs were associated with cell growth, sperm motility, immune regulation, and intercellular tight junctions, and were mainly enriched in pathways related to cell differentiation; amino acid, sugar, and lipid metabolism; cell adhesion, and hypoxia tolerance. The results of protein interactions network analyses indicated tight interactions between the differential proteins CCT2, CCT4, CCT5, FZR1, and PSMA8. In conclusion. This expression of these differential genes and proteins dysregulation may lead to the obstruction of the testicular descent process or the abnormal development of the testis, potentially leading to cryptorchidism. The results of this study laid a foundation for the screening of key candidate genes and proteins for cryptorchidism in yak, and also provided a theoretical basis for the research molecular mechanism of reproductive system diseases in yak and plateau animals.