Fertilizome Project: Proteomics of Fertilization Signaling - The Biological Bridge Between Gametogenesis and Embryogenesis

Fertilization is the biological bridge between gametogenesis and embryogenesis, by which sperm and eggs grow and mature, mate, and fuse with each other to give rise to the birth of a new individual(s). In this review, we address the current status of the knowledge in the field of fertilization, with a special focus on the role of maternal and paternal protein molecules such as tyrosine kinases, phospholipase C, and inositol trisphosphate receptor / Ca2+ channels in the establishment of intracellular Ca 2+ release, block to polyspermy, transition from meiotic to mitotic cell cycle, and nuclear fusion that are collectively called “sperm-induced egg activation”. We then discuss some proteomics approaches to analyze signaling events associated with sperm-induced egg activation. Protein profiling of subcellular microdomains and its differential display before and after fertilization, screening of fertilization-specific antigens by using a subtractive immunization scheme, and in vitro reconstitution of egg activation events using cell-free systems are now under investigation in our research team. These new experimental approaches, collectively termed “fertilizome project”, will be useful to understand the complexity of fertilization signaling, and will also be necessary for understanding and improving assisted reproduction and reproductive cloning techniques.