The human body is developed from one egg. Cell divisions and growth start from this single egg after an event called fertilization in which a sperm meets the egg. So fertilization is the most important event that forms our body. During 2 years of my EMBO fellowship I analysed how fertilisation signals start eggs cell division using frog (Xenopus laevis) eggs as a model system.
I found that a protein phosphatase, called Calcineurin, was crucial for this step. Protein phosphatase is an enzyme which removes phosphate groups from other proteins to change its function/structure. A 50-fold increase of Calcineurin activity was observed after the addition of calcium ion which was normally induced by a sperm. If Calcineurin was inhibited by a specific inhibitor, many proteins remained phosphorylated and cell division cycle was consequently disturbed, indicating its importance for proper development. I also found another protein phosphatase activity which fluctuated synchronously with cell division, suggesting its role in controlling this process. Control of cell division is important in regard to cancer predisposition because disturbance of the control of cell division could cause loss and/or gain of information on DNA. It is anticipated that these and future results would benefit a broad range of medical fields including regeneration, sterility and cancer.
