Progress of sperm Izumo relocation during spontaneous acrosome reaction

0394645 - BTÚ 2014 CA eng A - Abstract
Děd, Lukáš - Šebková, N. - Veselá, K. - Dvořáková-Hortová, K. - Pěknicová, Jana
Progress of sperm Izumo relocation during spontaneous acrosome reaction.
Abstracts. Montréal: Society for the Study of Reproduction, 2013 - (Suarez, S.). s. 167-168
[SSR 46th Annual Meeteing. Reproduction Health: Nano to Global. 22.07.2013-26.07.2013, Montréal]
R&D Projects: GA ČR(CZ) GAP503/12/1834
Institutional research plan: CEZ:AV0Z50520701
Keywords : Izumo * Acrosome reaction * Sperm capacitation
Subject RIV: EC - Immunology

It has been recently shown in mice that sperm undergo acrosome reaction (AR) by passing through cumulus cells, furthermore the acrosome-reacted sperm can bind to zona pellucida, and consequently fertilize the egg. During AR, the relocation of the primary fusion protein Izumo into the equatorial segment is crucial for sperm-egg fusion. There is a high rate of spontaneous acrosomal reaction in rodents, with up to 60% in promiscuous species. The aim was to find out, whether the relocation of Izumo happens during the physiological spontaneous AR, or whether it occurs only in sperm with induced AR with further correlation to species-specific mating behaviour. Immunofluorescent detection of Izumo protein dynamics during the process of in vitro capacitation, spontaneous, calcium ionophore and progesterone induced AR was monitored. Our results show that during spontaneous AR there is a clear Izumo relocation from the acrosomal cap to the equatorial segment and further on to the whole sperm head. Additionally, there is positive tail tyrosine phosphorylation associated with hyperactive motility. Therefore, spontaneously acrosome reacted sperm have the same fertilizing potential as those after induced AR. Moreover, the beginning and progress of Izumo relocation and tail tyrosine phosphorylation positively correlates with the level of promiscuity and the acrosome instability in Apodemus species. The findings that crucial molecular changes essential for sperm-egg fusion represented by dynamic movements of Izumo also happen during spontaneous AR are vital for novel understanding of fertilization in mice. Moreover, this may represent a unique mechanism of accelerating the fertilizing process in a highly promiscuous environment under selective pressure of intra-specific sperm competition.
Permanent Link: http://hdl.handle.net/11104/0223157