“15% of couples of childbearing age worldwide are experiencing problems of sterility and fertility, and the agents of sterility tend to be male factors (30%) and female factors (30%) to the same percentage. With respect to male sterility, many causes have been identified, yet a high percentage of the problems underlying the cause remain unknown. So the molecular mechanisms of fertility need to be analysed to get to know sterility better and to develop new therapeutic targets,” said Itziar Urizar-Arenaza, a researcher in the UPV/EHU’s Department of Physiology.

“Although we know that the spermatozoon is one of the most specialised cells in the body, in this work we have seen that spermatozoa have certain special, unique molecular mechanisms not displayed by other cells,” said Urizar. This assertion constitutes a huge step forward in better understanding cases of sterility.

So attention has been focussed on the proteome —the set of proteins in every living being— of the more reproductive spermatozoa, and the influence of opioid receptors on the reproductive capacity of spermatozoa has been explored.  In fact, “we believe that the receptors’ association with G-proteins (GPCR) could perform an important function in regulating fertility. However, the responses that could be produced by these receptors in spermatozoa are as yet unknown,” explained Itziar Urizar. “By contrast,” she added, “this work has confirmed that some of the molecular mechanisms induced by these receptors operate only in spermatozoa”.

In addition, “we observed that there are approximately 13 proteins that are only activated or suppressed in spermatozoa. Among these proteins, those of the SPANX-A/D family belong to the Cancer Testis Antigen set of proteins, which, aside from being present in spermatozoa, appear in some cases of cancer. For example, they increase cell growth in skin cancer. So analysing them is crucial in addressing sterility and also for treating cases of skin cancer”, said the UPV/EHU researcher.

The researcher stressed the fact that “conducting the study of these specific molecular mechanisms of spermatozoa is of great interest in helping to better understand the causes of many cases of sterility in men and to develop new therapeutic treatments, and to treat cases of skin cancer, among other things”.

Additional information

This research was conducted within the framework of the PhD thesis by Itziar Urizar-Arenaza (Bilbo, 1989), entitled ‘Proteomic study of sperm-specific molecular mechanisms in human spermatozoa underlying sperm fertility/ Giza esperamtozoideen ahalmen ugalkorra erregulatzen duten mekanismo molekular espezifikoen azterketa proteomikoa’. Her supervisors were Nerea Subiran, lecturer in the Department of Physiology, and Prof Jon Irazusta.