How is the cell cycle regulated in the transition from unfertilized egg to developing embryo?
At fertilization, the calcium rise is absolutely required to re-initiate the cell cycle and launch the newly fertilized egg into the developmental program. Understanding how cells are thrust out of a quiescent (arrested) Go state and into an active cell cycle is key to our understanding of a number of fundamental biological phenomena including cancer, stem cell biology and fertilization biology. We are engaged in experiments designed to evaluate the mechanism of entry from Go into the first S phase of the mitotic cell cycle. Fertilization causes arrested oocytes to undergo rapid and precisely regulated mobilization of a myriad of cell activities. A key aspect of oocyte cell cycle regulation is the Extracellular signal Regulated Kinase/Mitogen Activated Protein Kinase (ERK/MAPK) signaling module. Interestingly, in contrast to the typical role it plays in somatic cells, active MAPK signaling in oocytes acts as a repressor rather than activator of cell cycle progression. Most oocytes must
