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E2F1 sumoylation as a protective cellular mechanism in oxidative stress response.

ABSTRACT: Oxidative stress is a ubiquitous threat to all aerobic organisms and has been implicated in numerous pathological conditions such as cancer. Here we demonstrate a pivotal role for E2F1, a cell cycle regulatory transcription factor, in cell tolerance of oxidative stress. Cells lacking E2F1 are hypersensitive to oxidative stress due to the defects in cell cycle arrest. Oxidative stress inhibits E2F1 transcriptional activity, independent of changes in association with Rb and without decreasing its DNA-binding activity. Upon oxidative insult, SUMO2 is extensively conjugated to E2F1 mainly at lysine 266 residue, which specifically modulates E2F1 transcriptional activity to enhance cell cycle arrest for cell survival. We identify SENP3, a desumoylating enzyme, as an E2F1-interacting partner. Oxidative stress inhibits the interaction between E2F1 and SENP3, which leads to accumulation of sumoylated E2F1. SENP3-deficient cells exhibit hypersumoylation of E2F1 and are resistant to oxidative insult. High levels of SENP3 in breast cancer are associated with elevated levels of E2F targets, high tumor grade, and poor survival. Given the prevalence of elevated levels of SENP3 across numerous cancer types, the SENP3-E2F1 axis may serve as an avenue for therapeutic intervention in cancer.

SUBMITTER: Graves JD

PROVIDER: S-EPMC7334650 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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E2F1 sumoylation as a protective cellular mechanism in oxidative stress response.

Graves Joshua D JD Lee Yu-Ju YJ Liu Kang K Li Gang G Lin Fang-Tsyr FT Lin Weei-Chin WC

Proceedings of the National Academy of Sciences of the United States of America 20200615 26

Oxidative stress is a ubiquitous threat to all aerobic organisms and has been implicated in numerous pathological conditions such as cancer. Here we demonstrate a pivotal role for E2F1, a cell cycle regulatory transcription factor, in cell tolerance of oxidative stress. Cells lacking E2F1 are hypersensitive to oxidative stress due to the defects in cell cycle arrest. Oxidative stress inhibits E2F1 transcriptional activity, independent of changes in association with Rb and without decreasing its ...[more]

PMID: 32541040

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Project description:Various environmental insults including diseases, heat and oxidative stress could lead to abnormal growth, functions and apoptosis in granulosa cells during ovarian follicle growth and oocyte maturation. Despite the fact that cells exposed to oxidative stress are responding transcriptionally, the potential release of transcripts associated with oxidative stress response into extracellular space through exosomes is not yet determined. Therefore, here we aimed to investigate the effect of oxidative stress in bovine granulosa cells in vitro on the cellular and exosome mediated defense mechanisms. Bovine granulosa cells were aspirated from ovarian follicles and cultured in DMEM/F-12 Ham culture medium supplemented with 10% exosome-depleted fetal bovine serum. In the first experiment sub-confluent cells were treated with 5 ?M H2O2 for 40 min to induce oxidative stress. Thereafter, cells were subjected to ROS and mitochondrial staining, cell proliferation and cell cycle assays. Furthermore, gene and protein expression analysis were performed in H2O2-challenged versus control group 24 hr post-treatment using qRT-PCR and immune blotting or immunocytochemistry assay, respectively. Moreover, exosomes were isolated from spent media using ultracentrifugation procedure, and subsequently used for RNA isolation and qRT-PCR. In the second experiment, exosomes released by granulosa cells under oxidative stress (StressExo) or those released by granulosa cells without oxidative stress (NormalExo) were co-incubated with bovine granulosa cells in vitro to proof the potential horizontal transfer of defense molecules from exosomes to granulosa cells and investigate any phenotype changes. Exposure of bovine granulosa cells to H2O2 induced the accumulation of ROS, reduced mitochondrial activity, increased expression of Nrf2 and its downstream antioxidant genes (both mRNA and protein), altered the cell cycle transitions and induced cellular apoptosis. Granulosa cells exposed to oxidative stress released exosomes enriched with mRNA of Nrf2 and candidate antioxidants. Subsequent co-incubation of StressExo with cultured granulosa cells could alter the relative abundance of cellular oxidative stress response molecules including Nrf2 and antioxidants CAT, PRDX1 and TXN1. The present study provide evidences that granulosa cells exposed to oxidative stress conditions react to stress by activating cascades of cellular antioxidant molecules which can also be released into extracellular environment through exosomes.

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E2F1 sumoylation as a protective cellular mechanism in oxidative stress response.

Publications

E2F1 sumoylation as a protective cellular mechanism in oxidative stress response.

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