Chromosome structure and homologous recombination in meiosis


Meiosis is a specialized cell division that is essential for sexual reproduction because it gives rise from one diploid cell to haploid cells which will form the gametes. It proceeds through one round of replication followed by two successive divisions, meiosis I and II. To segregate correctly at meiosis I, homologous chromosomes must associate. In most eukaryotes, the programmed formation of DNA double strand breaks (DSBs) and their repair by homologous recombination (HR) in prophase I mediate this association (figure A). Although DSBs are essential for chromosome segregation, it represents an important threat for the cells, which may cause chromosomal rearrangements if they are not properly repaired. Therefore, multiple layers of DSB formation and repair regulation are needed to preserve genome integrity during gametes formation and our team is interested in understanding these regulation processes using mouse as a model organism.
One crucial feature of meiotic HR is that it occurs in the context of an important structural reorganization of the chromosomes (figure B). Our goal is to characterize the function of new structural components in the meiotic chromosome reorganization and to elucidate their contribution in the regulation of DSB formation and HR. In particular, one of our main objectives is to decipher the function of the SMC related complex of condensin, describe as the universal organizer of chromosomes, in this reorganization and in the control of meiotic HR.

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