The role of ubiquitin–proteasome pathway in the regulation of activity of two sperm surface proteins the aqn1 spermadhesin And the acrosin inhibitor in boar fertilization

0394633 - BTÚ 2014 RIV CZ eng A - Abstract
Jonáková, Věra - Postlerová, Pavla - Yi, Y.J. - Sutovsky, P. - Pěknicová, Jana
The role of ubiquitin–proteasome pathway in the regulation of activity of two sperm surface proteins the aqn1 spermadhesin And the acrosin inhibitor in boar fertilization.
Book of abstracts. Praha: Biotechnologický ústav, 2013 - (Pěknicová, J.). s. 17-18
[XIX. Symposium imunologie a biologie reprodukce s mezinárodní účastí. 23.05.2013-25.05.2013, Třešť]
R&D Projects: GA ČR GAP503/12/1834
Institutional research plan: CEZ:AV0Z50520701
Keywords : Ubiquitin-proteasome pathway * Sperm surface protein * Spermadhesin * Fertilization * Acrosin
Subject RIV: CE - Biochemistry

Problem. The AQN1 spermadhesin and acrosin inhibitor (AI) bind to the sperm plasma membrane at ejaculation. AQN1 has been implicated in sperm binding to zona pellucida (ZP) of the ovum as well as in sperm interactions with oviductal sperm reservoir. The AI protects sperm from proteolytic degradation. The 26S proteasome is a multi-subunit protease specific to ubiquitinated substrate proteins. It is composed of a 20S proteasomal core with substrate degradation activity, and a 19S regulatory complex that acts in substrate recognition, deubiquitination, priming and transport to the 20S core. This study examined the role of two components of the 19S complex with, the ubiquitin C-hydrolase UCHL3 and PSMD8, in the AQN1-mediated boar sperm binding to ZP. Interaction of subunit PSMD4 with AI was detected. Results. Interaction of PSMD4 with AI provides evidence for the presence of cell proteasomes on the surface of male gametes. Detection of the ubiquitinated forms of AI supported the hypothesis that AI activity is controlled by the ubiquitin proteasome pathway (UPP). We found that the activity and turnover of the porcine AQN1 sperm plasma membrane protein (and thus the efficiency of the sperm-ovum recognition process) may be controlled by surface-bound UPP, in particular by UCHL3, and by subunit PSMD8 of the 19S complex. The UCH inhibitor ubiquitin aldehyde and the antibodies against UCHL3 or PSMD8 increased the rate of sperm-ZP penetration and polyspermy during porcine in vitro fertilization (IVF). In contrast, the addition of recombinant UCHL3 into fertilization medium significantly reduced polyspermy rates while maintaining a satisfactory monospermic fertilization rate of approx. 50%. Conclusion. These results are of practical significance. They suggest that the high level of polyspermy (~50%), currently observed during porcine IVF for commercial embryo transfer, might be efficiently reduced e.g. by the modulation of the UCHL3 and/or PSMD8 activity.
Permanent Link: http://hdl.handle.net/11104/0223163