Gene involved in sperm-to-egg binding is key to fertility in mammals

Experts from Durham University have identified a new gene that could help the development of fertility treatments in humans in the future.

Scientists from Durham University, UK, and Osaka University, Japan, looking at fertility in mice, have discovered for the first time that the gene, which makes a protein called PDILT, enables to bind to an egg, a process essential to fertilisation.

The team found that when the gene was 'switched off' in male mice, less than three per cent of females' eggs were fertilised compared to more than 80 per cent in mice when the gene was left switched on.

It is the first time that a gene of this type has been linked to fertility.

The researchers also found that the , a cluster of cells surrounding and protecting an egg, play an important role in fertility - their presence enables sperm to bind properly to an egg.

Although the research and findings are at an early stage, the researchers now hope to look at how the gene affects sperm-to-egg binding in humans. The findings are published in the journal PNAS, Proceedings of the National Academy of Sciences.

This video is not supported by your browser at this time.

The discoveries could pave the way for the development of new fertility treatments for humans that could help to reduce the cost and improve the effectiveness of in vitro fertilisation (IVF). They could also assist research into new contraceptive techniques that deactivate the gene and prevent sperm reaching an egg and binding to it.

Dr Adam Benham, School of Biological and , Durham University, said: "The protein is an essential part of the navigation system of sperm. It helps sperm swim through the oviduct to the egg and without it sperm get stuck. Our results show that navigating the oviduct is an important part of the fertilisation process.

"Like any navigation system, you have to programme where it is that you want to go and this protein plays an essential role in getting sperm to the right destination, in good shape, and in good time."

The researchers found the gene a few years ago through a database search for new of the PDI family. Following extensive research, they established that the gene made an important protein in the testes.

The PDILT gene, part of the PDI family, helps another gene product called ADAM3 to form and assemble correctly, and then to reach the surface of a sperm, thereby equipping it with the right tools and machinery to navigate and make contact with an egg.

The new findings show the importance of PDILT in the process of sperm-to-egg binding and in enabling sperm to swim past the uterus, ascend the oviduct and to get through the sticky outer layers of an egg.

The team honed in on the role of the protein by switching it off in mice and tracking the ability of sperm to bind to and fertilise eggs in Petri dishes and in mice. They noticed that sperm from mice with the gene switched off will not bind to a bare egg, but will bind to an egg surrounded by cumulous cells.

Dr Benham said: "We now hope to discover how the PDILT protein affects fertility in humans. Mutations in the gene may be responsible for unexplained male fertility problems and further research may aid more effective IVF treatment."

Dr Masahito Ikawa from Osaka University, Japan, added: "This protein is essential for sperm to migrate successfully and is required for fertility. The next step is to see how this works with other proteins to control the sperm binding and fusion process."

More information: PNAS March 6, 2012 vol. 109 doi: 10.1073/pnas.1117963109

Related Stories

Rodent sperm work together for better results

Jan 24, 2007

Although, sperm are inseminated in millions each sperm goes it alone. However, under some circumstances it might be advantageous for sperm to cooperate with one another. This is especially likely to be the case when females ...

New requirements for male fertility

Apr 26, 2010

Two independent groups of researchers have identified distinct roles for two proteins in a family of proteins known as PLA2s as crucial for sperm function and fertility in mice. These data identify proteins that could underlie ...

Researchers Develop Test to Identify 'Best' Sperm

May 20, 2010

(PhysOrg.com) -- Researchers at Yale School of Medicine have discovered a method to select sperm with the highest DNA integrity in a bid to improve male fertility. The method is comparable to that of the egg’s ...

Recommended for you

Leeches help save woman's ear after pit bull mauling

2 hours ago

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

New pain relief targets discovered

14 hours ago

Scientists have identified new pain relief targets that could be used to provide relief from chemotherapy-induced pain. BBSRC-funded researchers at King's College London made the discovery when researching ...

Building 'smart' cell-based therapies

15 hours ago

A Northwestern University synthetic biology team has created a new technology for modifying human cells to create programmable therapeutics that could travel the body and selectively target cancer and other ...

User comments