How is cohesin regulated during meiotic prophase?
Though cohesin is required for crossover formation in all model organisms so far tested, its precise role in the process is not understood. Even when crossovers are successfully created, sister chromatid cohesion distal to the crossover sites remains essential for the maintenance of such crossovers. This is particularly important in human oogenesis, because female germ cells undergo homologous recombination during fetal development before birth and homologous chromosome segregation after puberty, indicating that crossovers must be maintained for approximately 10-40 years. Interestingly, cohesin is not replenished after DNA replication in an unchallenged yeast cell cycle. Is this also true for mammalian oogenesis? In addition, how oocytes maintain the cell cycle arrest for such a long time is also an interesting question. We are studying genetically modified mice to address these questions.
