Quantitative proteomics analysis reveals alterations of lysine acetylation in mouse testis in response to heat shock and X-ray exposure

Environmental stresses are important factors causing male infertility which attracts broad attention. Protein acetylation is a pivotal post-translational modification and modulates diverse physiological processes including spermatogenesis. In this study, we employed quantitative proteomic techniques and bioinformatics tools to analyze the alterations of acetylome profile of mouse testis after heat shock and X-irradiation. Overall, we identified 1139 lysine acetylation sites in 587 proteins in which 1020 lysine acetylation sites were quantified. The Gene Ontology analysis showed that the major acetylated protein groups were involved in generation of precursor metabolites and metabolic processes, and were localized predominantly in cytosolic and mitochondrial. Compared to the control group, 36 sites of 28 acetylated proteins have changed after heat shock, and 49 sites of 43 acetylated proteins for X-ray exposure. Some of the differentially acetylated proteins have been reported to be associated with the progression of spermatogenesis and male fertility. We observed the up-regulated acetylation level change on testis specific histone 2B and heat shock protein upon heat treatment and a sharp decline of acetylation level on histone H2AX under X-ray treatment, suggesting their roles in male germ cells. Notably, the acetylation level on K279 of histone acetyltransferase (Kat7) was down-regulated in both heat and X-ray treatments, indicating that K279 may be a key acetylated site and affect its functions in spermatogenesis. Our results reveal that protein acetylation might add another layer of complexity to the regulation for spermatogenesis, and further functional studies of these proteins will help us elucidate the mechanisms of abnormal spermatogenesis.