Studies on the participation of epididymal sperm protein DE/CRISP-1 in egg activation
Busso, D.; Cohen, D.J.; Da Ros, V.; Fissore, R.; Cuasnicú, P.S.
Cellular and Molecular Biology 49(3): 407-412
2003
ISSN/ISBN: 0145-5680 PMID: 12887093 Document Number: 553317
In order to investigate whether the binding of Protein DE (32kDa) to its egg complementary sites triggers egg activation, zona-free eggs were incubated in the presence of purified protein DE at 50, 250 and 500 micro g/ml, and intracellular Ca2+ responses were measured individually for each egg. As a control, a group of zona-free eggs were inseminated with capacitated sperm. While inseminated eggs showed fertilization induced spikes, eggs incubated with protein DE did not show modifications in their Ca2+ levels even at concentrations of DE higher than those known to produce maximum inhibition of egg penetration (200 micro g/ml). With regards to the ability of DE to regulate intracellular calcium channels, eggs were individually microinjected with 200 pg of protein DE, and intracellular Ca2+ release was monitored for each egg. Results showed however, that Ca2+ levels remained unaffected after DE microinjection. This findings contribute to a better understanding of the function of DE during mammalian fertilization, arguing against the participation of DE in the initiation or modulation of Ca2+ oscillations that are responsible for egg activation, and restricting the activity of this sperm protein and its binding sites to the process of gamete fusion.