Candidates for reproductive biomarkers: Protein phosphorylation and acetylation positively related to selected parameters of boar spermatozoa quality

Abstract

Protein post-translational modifications (PTMs) have been reported to be involved in various functions of sperm, yet the exact correlation between PTMs and sperm motility remains unclear. With the goal of contributing to this subject, motility variables were measured by computer-assisted sperm analysis system (CASA), and the amount of PTMs were evaluated using Western blot and immunofluorescence in fresh sperm and liquid stored sperm. Results of the present study indicate that the amount of the phosphorylated substrates of PKA (P-PKAs), protein tyrosine phosphorylation (PTP), global protein acetylation (Pan-Kac) and α-tubulin acetylation (Tub-Kac) was greater in sperm of fresh semen samples with relatively greater motility than in sperm of fresh semen samples with relatively lesser motility. Similarly, the amounts of phosphorylation and acetylation gradually decreased with the reduction in the motility of sperm in liquid stored semen samples. Interestingly, the P-PKAs (r = 0. 634, P < 0. 01) and Pan-Kac (r = 0. 380, P < 0. 05) were positively correlated with sperm motility in fresh semen, whereas only P-PKAs (r = 0.607, P < 0. 01) were positively correlated with sperm motility during liquid storage. Furthermore, it is noteworthy that the amounts of phosphorylation and acetylation were positively correlated with the acrosome integrity and mitochondrial membrane potential of fresh sperm and liquid stored sperm. This study is the first to explore the correlation between PTMs and sperm motility, and it may provide a new reproductive biomarker for evaluating semen quality and predicting sperm capacity for enhancing reproductive performance, which is meaningful for the pig breeding industry.