ZNF365 promotes stability of fragile sites and telomeres

Critically short telomeres activate cellular senescence or apoptosis, as mediated by the tumor suppressor p53, but in the absence of this checkpoint response, telomere dysfunction engenders chromosomal aberrations and cancer. Here, analysis of p53-regulated genes activated in the setting of telomere dysfunction identified Zfp365 (ZNF365 in humans) as a direct p53 target that promotes genome stability. Germline polymorphisms in the ZNF365 locus are associated with increased cancer risk, including those associated with telomere dysfunction. On the mechanistic level, ZNF365 suppresses expression of a subset of common fragile sites (CFS) including telomeres. In the absence of ZNF365, defective telomeres engage in aberrant recombination of telomere ends, leading to increased telomere sister chromatid exchange (T-SCE) and formation of anaphase DNA bridges, including ultra-fine DNA bridges (UFB), and ultimately increased cytokinesis failure and aneuploidy. Thus, the p53-ZNF365 axis contributes to genomic stability in the setting of telomere dysfunction. We expressed an inducible p53 allele encoding a p53-estrogen receptor fusion protein (p53ER) that becomes functional upon addition of 4-hydroxytamoxifen (4-OHT) in TKO cells. We chose a time point of 4 hours post-4-OHT induction to catalog potential direct targets.