Secret of the egg revealed: new hope for treating infertility?
This discovery could lead to improved treatment of infertility or the development of new contraceptives, say the researchers.
Secret of the egg revealed: new hope for treating infertility?
This discovery could lead to improved treatment of infertility or the development of new contraceptives, say the researchers.
For fertilization to occur, the egg and sperm must dock with each other.
This reciprocal recognition and their ability to attach to each other, the first step towards their fusion and the formation of the embryo, depend on the presence of proteins and their interaction.
In 2005, Japanese researchers discovered the protein involved in the spermatozoon, named Izumo (after a Japanese shrine celebrating marriage), but its counterpart in the egg remained a mystery. It has just been lifted. A huge step for egg donation proccesses.
Indeed, researchers from the Wellcome Trust Sanger (Great Britain) report the discovery of the protein located on the membrane of the ovum, which they nicknamed Juno, after the goddess of fertility.
Male mice, whose sperm do not carry Izumo, are infertile.
Female mice lacking the Juno receptor protein are also infertile, as their deficient eggs are unable to fuse with normal sperm to form an egg, according to the study by Gavin Wright and colleagues.
The observations indicate that the interaction between Juno and Izumo is essential for normal fertilization in mammals.
The researchers further suggest that the Juno protein, which disappears quickly after anchoring, plays a role in the blockage that prevents fusion with an additional sperm.
"Like other advances in biology, this discovery raises questions and creates new leads," notes specialist Paul Wassarman (Mount Sinai Medical School, New York) in an editorial in the journal. He stresses that it remains to be determined what part, if any, the protein's malfunctioning plays in female infertility. Just like inducing egg development in infertile women, it gets to an ethics question.
Izumo has proven to be a good candidate for the development of a contraceptive vaccine, he says. But, he adds, detailed knowledge of the three-dimensional structure of the Juno and Izumo complex would facilitate the development of small molecules that could prevent their attachment for contraceptive purposes.
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