The Role of Chtf18 in Sister Chromatid Cohesion and Post-Replicative Genome Maintenance

Abstract

Mitosis is a critical process that all living cells undergo to produce two identical daughter cells. To ensure that each daughter cell contains the same requisite genetic material, cohesion must be established and maintained between sister chromatids. Chromosome Transmission Fidelity factor 18 (CTF18), a protein subunit of the Replication Factor C-like complex (CTF18-RLC), has functions in DNA replication and also helps to establish cohesion between sister chromatids in yeast. Previously, we demonstrated a function for CHTF18 (the mouse ortholog) in meiotic recombination that is consistent with a role in chromosome cohesion during mammalian meiosis. We used Chtf18−/− and wild type murine embryonic fibroblasts (MEFs) to investigate a possible function for CHTF18 in sister chromatid cohesion and post-replicative genome maintenance. Cultured Chtf18−/− MEFs ceased proliferating after the 6th population doubling compared to wild type MEFs, which continued to proliferate until the 11th doubling. Immunofluorescence staining with 53BP1 antibody, a marker of DNA double strand breaks (DSBs) showed that DSBs are increased in Chtf18−/− MEFs. These findings suggest that defects in cellular proliferation of Chtf18−/− MEFs are due to DNA damage. Analysis of chromosome spreads reveals that Chtf18−/− MEFs may have a propensity for increased sister chromatid separation and breakage. Together, our data indicate a role for CHTF18 in sister chromatid cohesion and post-replicative genome maintenance.M.S., Biochemistry -- Drexel University, 201