Comparative iTRAQ proteomics revealed proteins associated with spermatogenic arrest of cattleyak.

Male infertility of cattleyak due to spermatogenic arrest greatly restricts their effective utilization in yak breeding. Although much work has been done to investigate the mechanisms of spermatogenic arrest, there is no information regarding the differences of protein composition between cattleyak and yak testis. Comparative investigation of testis proteomes between cattleyak and yak using iTRAQ proteomics identified 256 differentially abundant proteins with fold change values higher than ±1.5. Most of the differentially abundant proteins were involved in extracellular matrix organization, response to stimulus, metabolic and cellular process, in which a large number of the cattleyak predominant proteins were associated with various stresses, cell adhesion and germ cell migration. Such upregulated proteins as integrins and their ligands in the extracellular matrix involved in ECM-receptor interaction pathway may help germ cells to endure pulling forces and impede their migration. In contrast, down-regulated proteins in cattleyak were associated with defects in various metabolic processes and cellular processes during spermatogenesis. Such Downregulated proteins as the subunits of mitochondrial cytochrome Bc1 complex involved in the Alzheimer's disease and oxidative phosphorylation pathways may lead to mitochondrial dysfunction and cell death in cattleyak testis.