Characterization of the E3 Ubiquitin ligase EEL-1 in DNA Damage-induced Germ Line Apoptosis in C. elegans

E3 ubiquitin ligases are important regulators of several cellular processes, including apoptosis. To determine the extent to which E3 ligases regulate DNA damage-induced apoptotic signalling in C. elegans, a high-throughput RNAi screen was performed in our laboratory. We identified the E3 ubiquitin ligase EEL-1 as a positive regulator of DNA damage-induced germ cell apoptosis. ARF-BP1, the mammalian EEL-1 ortholog, negatively regulates both the tumour suppressor protein p53 and the anti-apoptotic protein Mcl-1. In C. elegans, we found that eel-1 regulates DNA damage-induced germ cell apoptosis by a mechanism downstream of cep-1/p53 and upstream of ced-9/mcl-1. My results show that unlike ARF-BP1, EEL-1 does not regulate CED-9/Mcl-1 protein levels, suggesting a novel mechanism of apoptosis regulation in C. elegans for this E3 ligase. Unexpectedly, eel-1 causes synthetic sterility in ced-9 loss-of-function mutants that is suppressed by ablation of the Apaf-1 orthologue ced-4, suggesting an additional role for these genes in oogenesis.MAS