title: Regulation of Sperm Capacitation by the 26S Proteasome: An Emerging New Paradigm in Spermatology.
abstract: The ubiquitin proteasome system (UPS) participates in many biological processes ranging from cell cycle and antigen processing to cellular defense and signaling. Work of the last decade has made it evident that the UPS is involved in many sperm-related processes leading up to and as part of fertilization. The current knowledge of UPS involvement and changes during sperm capacitation are reviewed together with a list of known proteasome-associated sperm proteins and a discussion of the relationships between these proteins and the proteasome. Proteasomal inhibitors such as MG-132 and epoxomicin significantly alter capacitation and prevent acrosome reaction. The 26S proteasome degrades AKAP3, an A-kinase anchoring protein, partially regulating the release of protein-kinase A (PKA), a vital component necessary for the steps leading up to capacitation. Further, changes occur in 20S core subunit localization and abundance throughout capacitation. Proteasome-interacting valosine-containing protein (VCP) undergoes tyrosine phosphorylation; however, its physiological roles in capacitation and fertilization remain unknown. The E1-type ubiquitin-activating enzyme (UBA1) inhibitor PYR-41 also alters acrosomal membrane remodeling during capacitation. Furthermore, after capacitation, the acrosomal proteasomes facilitate the degradation of zona pellucida glycoproteins leading up to fertilization. Methods to modulate the sperm proteasome activity during sperm storage and capacitation may translate to increased reproductive efficiency in livestock animals. Human male infertility diagnostics may benefit from incorporation of research outcomes built upon relationships between UPS and capacitation. Altogether, the studies reviewed here support the involvement of UPS in sperm capacitation and present opportunities for new discoveries.
authors.affiliation: Division of Animal Sciences, University of Missouri, Columbia, Missouri.
authors.forename: Karl
authors.initials: K
authors.lastname: Kerns
authors.affiliation: Department of Biomedicine, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile Instituto Antofagasta, Antofagasta, Chile.
authors.forename: Patricio
authors.initials: P
authors.lastname: Morales
authors.affiliation: Division of Animal Sciences, University of Missouri, Columbia, Missouri Department of Obstetrics, Gynecology and Women's Health, University of Missouri, Columbia, Missouri SutovskyP@missouri.edu.
authors.forename: Peter
authors.initials: P
authors.lastname: Sutovsky
mesh_terms: D000818:Animals; D005306:Fertilization / Q000502:physiology; D006801:Humans; D008297:Male; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism / Q000502:physiology*; D013075:Sperm Capacitation / Q000502:physiology*; D013076:Sperm Count; D013094:Spermatozoa / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism; D044764:Ubiquitin-Activating Enzymes / Q000378:metabolism
chemical_list: D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex; D044764:Ubiquitin-Activating Enzymes
keywords: capacitation; fertilization; proteasome; sperm; ubiquitin