Boar seminal plasma exosomes: effect on sperm function and protein identification by sequencing.

Area of Science:

• Reproductive Biology
• Cell Biology
• Biochemistry

Background:

• Mammalian seminal plasma contains exosomes with complex lipid and protein compositions.
• The physiological role of seminal exosomes in sperm function remains uncertain, with conflicting reports on stabilization and activation effects.
• Understanding exosome-sperm interactions is crucial for elucidating reproductive processes.

Purpose of the Study:

• To investigate the modulatory role of boar seminal exosomes on sperm activity.
• To analyze the effects of exosomes on sperm capacitation and related functional parameters.
• To identify exosome proteins and explore their incorporation into sperm.

Main Methods:

• Boar sperm were incubated under conditions inducing capacitation, characterized by tyrosine phosphorylation, cholesterol loss, and membrane fluidity changes.
• The impact of exosomes on capacitation-dependent parameters and the acrosome reaction was assessed.
• Exosome protein composition was analyzed, and sperm-exosome interactions were confirmed via enzyme activity transfer and protein association.

Main Results:

• Exosomes inhibited capacitation-dependent cholesterol efflux and apical membrane fluidity changes.
• The acrosome reaction was unaffected by exosome presence, but sperm-oocyte zona pellucida binding was reduced when exosomes were present during coincubation.
• Protein transfer from exosomes to sperm was confirmed, with actin identified as a major associated protein.

Conclusions:

• Boar seminal exosomes can inhibit key capacitation-dependent events in sperm, suggesting a stabilizing function.
• Direct interaction between exosomes and sperm occurs via protein transfer, influencing sperm function.
• Exosomes may play a significant role in regulating sperm quality and fertilizing capacity in boars.