Functions and gene expression alterations of phospholipase C in gametes

Phospholipases hydrolyze ester bonds of phospholipids and are clustered into four groups: A (PLA), B (PLB), C (PLC), and D (PLD). Phospholipase Cs are classified into six families: beta (PLCβ), delta (PLCδ), epsilon (PLCɛ), gamma (PLCγ), zeta (PLCζ), and eta (PLCη). In sperm, PLCβ and PLCγ have been found to be involved in sperm capacitation and acrosome reaction. The most studied group, however, is PLCζ, a sperm-specific protein that plays a crucial role in oocyte activation, the process through which, upon gamete fusion, fertilized oocytes are alleviated from metaphase-II arrest and begin embryogenesis. Mutations in the coding sequence of PLCZ1 result in total fertilization failure or subfertility. In oocytes, PLCβ1 appears to be involved in oocyte maturation, and PLCγ1 is related to aging and apoptosis. While the research conducted in the field is scarce, the mechanisms in which PLCs participate also involve other phospholipases, such as PLA2 and PLD, in both sperm and oocytes. This Chapter aims to summarize the evidence collected thus far, particularly the transduction pathways involving PLCs, and the main physiological events that seem to play a major role. In addition, how alterations in these proteins result in dysfunctional mechanisms is also discussed.