The results of a recently-conducted study may produce certain significant insights into the changes that occur within sperm after it enters the female reproductive tract.
Mark Platt, an assistant professor of Chemistry and Chemical Biology at Rensselaer Polytechnic Institute, says that his findings provide important clues into the still-mysterious process of capacitation, the process by which sperm acquire the ability to fertilize an egg, including why some otherwise healthy males might encounter fertility issues.
He says that his work may have implications for the development of entirely new contraceptive, even a male version of the birth control pill.
"Much has been done to understand capacitation, but with the tools that we have within the lab we can now identify how specific sites on individual proteins are modified during this process. With this knowledge we can develop a deeper understanding of the molecular mechanisms required to provide sperm with fertilizing competence...Based upon some of our additional work, a few of these sites appear to be essential to carrying out the process of capacitation," he says.
Platt's findings suggest that phosphorylation may be thought of as a light switch, which can be used to turn on or turn off a step in the chain of reactions, known as a signal transduction cascade, that leads to capacitation.
The researcher says that phosphorylation provides the initial trigger that moves a cellular signal through the cell that turns "on" its ability to fertilize an egg.
He believes that interfering with a just a single site of phosphorylation could entirely switch off the fertilization process.
It is this ability that has the strongest potential for the development of a novel contraceptive, he adds.
"If phosphorylation on a particular amino acid is absolutely required for sperm capacitation, a drug could be developed which prevents phosphorylation from occurring at that specific site, thereby preventing the entire capacitation process," says Platt, adding that this turning off of the phosphorylation switch could then prevent fertilization entirely.
"These applications are currently hypothetical at this point, but the implications for contraceptives resulting from this research are promising," the researcher adds.
Platt says that there may be a number of options that may be developed using this and future research, including a drug for males that specifically targets the individual sites of protein phosphorylation in the developing sperm or a novel spermicide that prevents capacitation from occurring in sperm residing in the female reproductive tract.
His study also provides important insight into male infertility.
"Certain types of male infertility could be caused by a mutation of a single amino acid on a critical protein that prevents the sperm from ever undergoing the capacitation process. If you could correct that specific mutation or design a drug which mimics phosphorylation on that particular amino acid, for example, you might be able to improve fertility," he says.
A research article on the study has been published in the Journal of Proteome Research.