Compartmentalization of the proteasome-interacting proteins during sperm capacitation

Area of Science:

• Reproductive Biology
• Molecular Biology
• Proteomics

Background:

• Ubiquitination is a key posttranslational modification regulating protein stability and function.
• The ubiquitin-proteasome system (UPS) is crucial for mammalian sperm function, including capacitation and fertilization.
• Previous studies highlighted UPS involvement in human and non-human mammalian sperm, but its role in boar sperm capacitation requires further investigation.

Purpose of the Study:

• To investigate the activity and role of the UPS during in vitro capacitation of boar spermatozoa.
• To identify proteasome-associated proteins and understand their changes during boar sperm capacitation.
• To determine the impact of proteasome inhibition on sperm capacitation and acrosomal membrane remodeling.

Main Methods:

• In vitro capacitation of boar spermatozoa under proteasome-inhibiting and permissive conditions.
• Differential proteomic analysis using 1D PAGE and Mass Spectrometry (MS) to identify protein changes.
• Compartment-specific isolation of sperm proteasome-associated proteins.

Main Results:

• Proteomic analysis revealed differential protein accumulation at specific molecular weights (60, 58, 49, and 35 kDa) during boar sperm capacitation.
• Identified proteins included known proteasome co-purifying proteins and novel proteins, such as P47/lactadherin, ACRBP, ADAM5, and SPINK2.
• Proteasome inhibitors significantly slowed the capacitation-induced reorganization of the outer acrosomal membrane.

Conclusions:

• The UPS plays a significant role in boar sperm capacitation.
• Specific proteins are processed by the proteasome in a capacitation-dependent manner.
• These findings provide new insights into the molecular mechanisms of sperm capacitation and open avenues for future research.