Molecular mechanisms of sperm-egg fusion

The life of every sexually reproducing organism begins with the fusion of two specialized cells: the sperm and the egg. Despite decades of research in this field, it is still unclear how this process is achieved. Understanding the details of how fertilization works at a molecular level is important since it can lead to the identification of new contraceptive targets or the development of infertility treatments. So far, we have discovered that the sperm is able to interact with the egg through a molecular key that is made of three parts. These key parts are molecules that are called IZUMO1, SPACA6 and TMEM81. This key is present in almost all vertebrates, suggesting a conserved way for sperm to interact with the egg. Interestingly, the lock on the egg differs in fish versus mammals. This discovery has changed the way scientists think about fertilization since it suggests that molecules need to come together in the sperm to be able to recognize and interact with the egg. Future work will focus on characterizing this key and lock mechanism further. What is the role in fertilization? How does it work together with other molecules on the sperm and egg surface? We will use zebrafish, mice and human cells to study this process and learn more about fertilization.