Scientists have identified key molecular events that are believed to play a vital role in the creation of life, and the findings could one day lead to the development of male contraception.
When sperm meets an egg it uses enzymes to help it penetrate through and fuse with its target, the University of Virginia reported. These new findings reveal a specific protein that stays intact at the fusion site, even though other proteins are lost in the fertilization process.
"This report expands our fundamental understanding of the molecular architecture at the site of sperm-egg fusion," said John Herr, of UVA's Center for Research in Contraceptive and Reproductive Health. "Understanding at the molecular level exactly how the sperm is able to bind with and enter the egg opens opportunities to identify molecules that can disrupt or block the fertilization event."
The study shows the protein, ESP1 is stabilized in the region of the sperm head that is believed to initiate the fusion following the exchange of enzymes, which is referred to as the acrosome reaction. This suggests ESP1 plays a major role in the development of a new life.
"We suspect ESP1 is one of the key molecules that helps to stabilize the equatorial segment region of the sperm head," Herr said. "Getting at the molecular components of the fertilization event has a lot of practical applications - as well as intellectual value - because you want to account for all the major components involved in the essential events of the fertilization cascade. You want to know which molecules are located precisely where, and when, as the sperm head becomes remodeled prior to fertilization. Just getting all the molecules defined and dissected and located in their correct subcellular positions is a major challenge, and this report adds to that fund of knowledge."
The researchers' next steps will be to try to figure out what is occurring in sugar molecules believed to be associated with the ESP1 protein. One theory is that the sugar molecules are being depleted before the equatorial segment of the sperm head condenses.
"The fundamental questions are, why does the equatorial segment stay intact after the acrosomal reaction? What molecular interactions contribute to its stability?" Herr said.
The answers to these questions could help researchers develop a way to block the protein's interactions, potentially leading to an effective form of male contraception.
The findings were published in a recent edition of the journal Biology of Reproduction.
