Researchers from Japan and the U.K. have
identified a new male fertility gene that may help with the development of
future fertility treatments in humans.
Experts
from Durham University in the U.K. and Osaka University in Japan have
identified a new gene that may help with the development of future fertility
treatments.
In a
study published in the journal, Proceedings of the National Academy of
Sciences, they discovered that this gene, which makes a protein called
PDILT, enables sperm to bind to an egg, a process essential to fertilization.
When
the gene was ‘switched off’ in male mice, the team found that less than three
percent of females’ eggs were fertilized compared to more than 80 percent in
mice when the gene was left switched on.
The
researchers also found that the cumulus cells, 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.
“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 fertilization
process,” said Dr. Adam Benham from Durham University in the U.K.
The
researchers found the gene a few years ago through a database search for new
genes 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. ADAM3 then helps the sperm swim past the uterus,
ascend the oviduct, and get through the sticky outer layers of an egg.
The
team honed in on the role of the PDILT protein by switching it off in mice and
tracking the ability of sperm to bind to and fertilize eggs in petri dishes and
in mice. They noticed that sperm from mice with the PDILT gene switched off
will not bind to a bare egg, but will bind to an egg surrounded by cumulus
cells.
“This
protein is essential for sperm to migrate successfully and is required for
fertility. The next step is to see how this protein works with other proteins
to control the sperm binding and fusion process,” said Dr. Masahito Ikawa from
Osaka University.
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. They also hope
that their research may lead to new in vitro fertility
treaments. Similarly, new contraceptive techniques could be developed that
deactivate the PDILT gene and prevent sperm from fertilizing the egg.
The
article can be found at: Tokuhiro K et al. (2012) Protein disulfide
isomerase homolog PDILT is required for quality control of sperm membrane
protein ADAM3 and male fertility.
Source: Durham
University.
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