Influence of the Season and Region Factor on Phosphoproteome of Stallion Epididymal Sperm

Katarzyna Dyrda,Joanna Ner-Kluza,Paweł Wysocki,Aleksandra Orzołek

doi:10.3390/ani11123487

Abstract

Simple SummaryPhosphorylation and dephosphorylation of proteins are considered to be the most important processes in sperm maturation during the epididymal transit. We demonstrated that 27 proteins underwent phosphorylation both in and out of the breeding season. Differences in the phosphorylation status were demonstrated in the case of endoplasmic reticulum chaperone BiP, albumin, protein disulfide-isomerase A3, nesprin-1, peroxiredoxin-5, and protein bicaudal D homolog.Epididymal maturation can be defined as a scope of changes occurring during epididymal transit that prepare spermatozoa to undergo capacitation. One of the most common post-translational modifications involved in the sperm maturation process and their ability to fertilise an oocyte is the phosphorylation of sperm proteins. The aim of this study was to compare tyrosine, serine, and threonine phosphorylation patterns of sperm proteins isolated from three subsequent segments of the stallion epididymis, during and out of the breeding season. Intensities of phosphorylation signals and phosphoproteins profiles varied in consecutive regions of the epididymis. However, significant differences in the phosphorylation status were demonstrated in case of endoplasmic reticulum chaperone BiP (75 and 32 kDa), protein disulfide-isomerase A3 (50 kDa), nesprin-1 (23 kDa), peroxiredoxin-5 (17 kDa), and protein bicaudal D homolog (15 kDa) for season x type of phosphorylated residues variables. Significant differences in the phosphorylation status were also demonstrated in case of endoplasmic reticulum chaperone BiP and albumin (61 kDa), protein disulfide-isomerase A3 (50 kDa), and protein bicaudal D homolog (15 kDa) for region x type of phosphorylated residues variables.

Highlights

Mammalian spermatozoa leave the testes as immobile and functionally immature reproductive cells
Electrophoretic profiles of separated sperm proteins and phosphoproteins showed the highest number of fractions in the caput and corpus segments, both in (Figure 2 and Figure 4A) and out of the breeding season (Figures 3 and 4B)
We observed 27 proteins fractions whose presence was differentiated among segments of the epididymis and individuals (Figure 4)

Summary

Introduction

Mammalian spermatozoa leave the testes as immobile and functionally immature reproductive cells. It is well known that maturation of epididymal spermatozoa is associated with the activation of a cAMP-induced tyrosine phosphorylation cascade. The level of sperm’s intracellular cAMP gradually increases from the corpus to the cauda, and so does the metabolic capacity and ATP production [3] These changes are associated with the subsequent phenomena as hyperactivation of the motility and acrosomal exocytosis of the sperm. By the time gametes will have reached the cauda of the epididymis, they are subjected to phosphorylation within the entire tail, from the neck to the endpiece This particular pattern of phosphorylation is associated with the sperm maturation, a requirement for acquiring competence for fertilisation [1]. Phosphorylation may trigger the transition between conformations and lead to the activation or deactivation of a chosen protein [10]

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