Abstract 309: ATM phosphorylation of NRF2 promotes DNA damage repair

Abstract

Abstract Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor that responds to cellular and oxidative stress by promoting the transcription of antioxidant response element-containing genes. In an unstressed cellular environment, NRF2 is bound by Kelch-like ECH-associated protein 1 (KEAP1) and tagged for proteasomal degradation. In many cancers, the interaction between NRF2 and KEAP1 is interrupted due to mutations in either protein. Previous work has suggested that NRF2 can promote DNA damage repair, and our preliminary data demonstrates that NRF2 is phosphorylated at Serine-40 by the DNA damage response kinase, Ataxia Telangiectasia Mutated (ATM) in response to DNA damage. To create a system to better study the relationship between NRF2 Serine-40 phosphorylation and DNA damage, we modified the mouse Nfe2l2 locus to generate a mouse model in which Nrf2 Serine-40 is mutated to Alanine on a C57BL/6 background. Utilizing this model, we administered 7.5 Gy of total body irradiation and found that Nrf2S40A/S40A mice had significantly shortened survival compared to Nrf2WT mice. Immunohistochemical analysis of radiation-sensitive tissues including bone marrow and spleen revealed a prolonged persistence of the DNA damage marker γH2AX following irradiation in the Nrf2S40A/S40A group compared to Nrf2WT. We also observed a significantly higher level of cell death in the Nrf2S40A/S40A splenic tissue compared with Nrf2WT as indicated by the marker of apoptotic cell death, Cleaved Caspase-3. Our findings indicate that phosphorylation of Nrf2 at Serine-40 in response to DNA damage promotes DNA damage repair. Our ongoing work is focused on examining these phenotypes in cellular systems to determine the specific mechanisms by which NRF2 promotes DNA damage repair. Future work will include incorporating the systems generated thus far into non-small cell lung cancer (NSCLC) and liver cancer mouse models to further investigate the impact of this phosphorylation site on tumorigenesis and radio-resistance. Citation Format: Cheyenne A. Schneider, Tin-Yu Lin, Aimee Falzone, Samantha Caldwell, Jared L. Johnson, Gina M. DeNicola. ATM phosphorylation of NRF2 promotes DNA damage repair [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 309.