Bull Sperm Capacitation Is Accompanied by Redox Modifications of Proteins

Abstract

The ability to fertilise an egg is acquired by the mammalian sperm during the complex biochemical process called capacitation. Capacitation is accompanied by the production of reactive oxygen species (ROS), but the mechanism of redox regulation during capacitation has not been elucidated. This study aimed to verify whether capacitation coincides with reversible oxidative post-translational modifications of proteins (oxPTMs). Flow cytometry, fluorescence microscopy and Western blot analyses were used to verify the sperm capacitation process. A fluorescent gel-based redox proteomic approach allowed us to observe changes in the level of reversible oxPTMs manifested by the reduction or oxidation of susceptible cysteines in sperm proteins. Sperm capacitation was accompanied with redox modifications of 48 protein spots corresponding to 22 proteins involved in the production of ROS (SOD, DLD), playing a role in downstream redox signal transfer (GAPDHS and GST) related to the cAMP/PKA pathway (ROPN1L, SPA17), acrosome exocytosis (ACRB, sperm acrosome associated protein 9, IZUMO4), actin polymerisation (CAPZB) and hyperactivation (TUBB4B, TUB1A). The results demonstrated that sperm capacitation is accompanied by altered levels of oxPTMs of a group of redox responsive proteins, filling gaps in our knowledge concerning sperm capacitation.

In Vitro versus Cryo-Induced Capacitation of Bovine Spermatozoa, Part 2: Changes in the Expression Patterns of Selected Transmembrane Channels and Protein Kinase A

“…Biochemical changes in the plasma membrane and other subcellular compartments have been linked to sperm capacitation [ 20 ]. Major molecular events associated with the capacitation process involve, among others, the activation of calcium channels with a subsequent alkalinization of the sperm cell, reactive oxygen species (ROS) generation (particularly superoxide and hydrogen peroxide) [ 8 , 21 ], cAMP synthesis and the activation of protein kinases, accompanied by cholesterol efflux from the sperm plasma membrane [ 22 ].…”

The sperm-interacting proteome in the bovine isthmus and ampulla during the periovulatory period

“…The reported roles of the most abundant SIPs in sperm physiology and fertilization are indicated in Table 1. Sperm capacitation is a timed process starting with an elevation of intracellular calcium and includes phospholipid remodeling, protein tyrosine phosphorylation, and hyperactivated motility, allowing sperm to cross the cumulus cells and the zona pellucida and eventually fuse with the oocyte [61]. After 3 h of co-incubation, OF from the ampulla increased sperm membrane fluidity compared to OF from the isthmus.…”

The sperm-interacting proteome in bovine oviduct fluid: temporal and spatial resolution

“…The reported roles of the most abundant SIPs in sperm physiology and fertilization are indicated in Table 1. Sperm capacitation is a timed process starting with an elevation of intracellular calcium and includes phospholipid remodeling, protein tyrosine phosphorylation, and hyperactivated motility, allowing sperm to cross the cumulus cells and the zona pellucida and eventually fuse with the oocyte [57]. Though the contribution of SIPs to the acquisition of hyperactivated motility remains to be explored, the enrichment analysis of SIPs highlighted functions such as cytoskeletal motor activity and microtubule motor activity, which are all needed for agellar movements [58].…”