Collections > Electronic Theses and Dissertations > Characterization of INO80 Chromatin-Remodeling Activity During Germ Cell Development
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The ability to faithfully transmit genetic information across generations via the germ cells is a critical aspect of mammalian reproduction. The process of germ cell development requires a number of large-scale chromatin modifications within the nucleus. One such occasion arises during meiotic recombination, when hundreds of DNA double-strand breaks are induced and subsequently repaired, enabling the transfer of genetic information between homologous chromosomes. The inability to properly repair DNA damage is known to lead to an arrest in the developing germ cells and sterility within the animal. Chromatin-remodeling activity, and in particular the BRG1 subunit of the SWI/SNF complex, has been shown to be required for successful completion of meiosis. In contrast, remodeling complexes of the ISWI and CHD families are required for post-meiotic processes. Little is known regarding the contribution of the INO80 family of chromatin-remodeling complexes, which is a particularly interesting candidate due to its well-described functions during DNA double-strand break repair. Here we show that INO80 is expressed in developing spermatocytes during the early stages of meiotic prophase I. Based on this information, we used a conditional allele to delete the INO80 core ATPase subunit, thereby eliminating INO80 chromatin-remodeling activity in this lineage. The loss of INO80 resulted in sterility of the animal due to the failure to repair DNA damage during meiotic recombination. Specifically, we observed a disruption in the Fanconi Anemia repair pathway, where early elements of the pathway were present on the chromosomal axes while BRCA1 remained absent. From these observations, we propose a model where INO80 activity is required to prepare the chromatin landscape local to the break site, creating the physical space necessary for the localization of downstream DNA repair proteins. In conclusion, this work provides deeper insight in to the critical nature of chromatin-remodeling activity for spermatogenesis, particularly during meiotic recombination, and a foundation for future studies into the genomic functions of the INO80 complex.