Protein discovered that could shed light on cases of sine causa infertility

Fertility is a complex puzzle .. There are in fact a very high number of factors that influence fertility (and consequently infertility) and one of the most important junctions of the entire process is represented by the encounter between the egg cell, the female gamete. , and the sperm, the male gamete. And today, thanks to the discovery that comes from a team of international researchers, we know something more about how it happens. In fact, a protein has just been identified that helps the two gametes to fuse.

The "divine" name

The protein in question is not by chance called Maia (like the ancient goddess fertility) and was found through a curious experiment, in which the spermatozoa were placed in contact with fake oocytes. These fake oocytes were nothing more than mini spheres, comparable in size to their natural counterparts (i.e. around 100 micrometers in diameter), each covered with many and different peptides, pieces of proteins, coming from a peptide library. The purpose of the experiment was to put the spheres in contact with the spermatozoa and to observe which spheres bind and why, or what type of peptide they had on their surface to bind the spermatozoa.

Find the bound spheres. it was quite simple - they were the ones that moved, say, thanks to the motility conferred by the spermatozoa, the authors write in Science Advances - and after identifying them, the associated peptides were sequenced. It was in this way that the researchers unearthed Maia, a protein that forms a stable complex with IZUMO1 / JUNO (proteins on the sperm and oocyte, respectively), effectively contributing to the fusion of gametes, the researchers explain. This is also confirmed by experiments in which researchers have transferred the Maia gene into some human cells, observing the ability to bind spermatozoa.

The implications of the discovery

Without fusion and therefore fertilization - which leads to the formation of the zygote and then the embryo - reproduction cannot be started (although, perhaps it is superfluous to say it , many other things must work until birth). The discovery of this protein therefore adds an important piece to the fertility puzzle, which could also help to understand some reasons for infertility, as explained Harry Moore of the University of Sheffield, head of the study. Especially in light of the difficulties of research in the field: “Infertility is inexplicable in over half of those who have difficulty conceiving naturally. What we know about human fertility has been somewhat limited by ethical issues and the lack of eggs for research. The ingenious artificial fertilization technique that enabled us to identify the Maya protein will not only allow scientists to better understand the mechanisms of human fertility, but will also pave the way for new ways of treating infertility and revolutionize the development of new contraceptives. in the future ".

What is fertility influenced by

The next lines of research to be followed will aim at understanding whether different types of sperm bind the protein differently, confirming the theory or not incompatibility between gametes, explains a note from Sheffield University. Only a couple of years ago, in fact, a study invited us to consider that ova and spermatozoa could actually be differently compatible, or rather, more or less attracted to each other. The meeting between the gametes, however, is only one of the aspects that regulate fertility, however important it is. In fact, we know that fertility - dangerously steep in recent years according to some - is influenced by a large number of factors. Age, for example, undermines the quality and quantity of oocytes, as well as that of spermatozoa, but also smoking, obesity, alcohol, diseases such as endometriosis, polycystic ovary syndrome, varicocele, stress and thyroid dysfunction, exposure to pesticides can contribute infertility.

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In Italy it is estimated that infertility - absence of conception after 12 months or more of intercourse is not protected - affects about 15% of couples, a value in line with the global one.