p62-mediated Selective autophagy endows virus-transformed cells with insusceptibility to DNA damage under oxidative stress
| Autor: | Shunbin Ning, Jonathan P. Moorman, Caroline Hawkins, Ayrianna Sparks-Wallace, Zhi Q. Yao, Mary E. A. Howell, Carissa Kohne, Kenton Hall, Ling Wang, Camri A. Nicksic |
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| Rok vydání: | 2019 |
| Předmět: |
Epstein-Barr Virus Infections
Herpesvirus 4 Human DNA Repair medicine.disease_cause Biochemistry Small hairpin RNA chemistry.chemical_compound Spectrum Analysis Techniques Ubiquitin MG132 Biology (General) Post-Translational Modification Pathology and laboratory medicine 0303 health sciences Kelch-Like ECH-Associated Protein 1 Cell Death biology Chemistry 030302 biochemistry & molecular biology RNA-Binding Proteins Medical microbiology Flow Cytometry Burkitt Lymphoma Chromatin Virus Latency Viral Persistence and Latency Cell biology Nucleic acids Cell Processes Spectrophotometry Viruses Cytophotometry Pathogens Signal Transduction Research Article Proteasome Endopeptidase Complex Herpesviruses Programmed cell death QH301-705.5 NF-E2-Related Factor 2 DNA damage DNA repair Autophagic Cell Death Immunoblotting Immunology Molecular Probe Techniques Research and Analysis Methods Microbiology 03 medical and health sciences Virology Autophagy medicine Genetics Humans Epstein-Barr virus Molecular Biology Techniques Molecular Biology 030304 developmental biology Medicine and health sciences Ubiquitination Organisms Viral pathogens Biology and Life Sciences Proteins Cell Biology DNA RC581-607 Cell Transformation Viral Microbial pathogens Oxidative Stress biology.protein Parasitology Immunologic diseases. Allergy Reactive Oxygen Species DNA viruses Carcinogenesis |
| Zdroj: | PLoS Pathogens PLoS Pathogens, Vol 15, Iss 4, p e1007541 (2019) |
| ISSN: | 1553-7374 |
| DOI: | 10.1371/journal.ppat.1007541 |
| Popis: | DNA damage response (DDR) and selective autophagy both can be activated by reactive oxygen/nitrogen species (ROS/RNS), and both are of paramount importance in cancer development. The selective autophagy receptor and ubiquitin (Ub) sensor p62 plays a key role in their crosstalk. ROS production has been well documented in latent infection of oncogenic viruses including Epstein-Barr Virus (EBV). However, p62-mediated selective autophagy and its interplay with DDR have not been investigated in these settings. In this study, we provide evidence that considerable levels of p62-mediated selective autophagy are spontaneously induced, and correlate with ROS-Keap1-NRF2 pathway activity, in virus-transformed cells. Inhibition of autophagy results in p62 accumulation in the nucleus, and promotes ROS-induced DNA damage and cell death, as well as downregulates the DNA repair proteins CHK1 and RAD51. In contrast, MG132-mediated proteasome inhibition, which induces rigorous autophagy, promotes p62 degradation but accumulation of the DNA repair proteins CHK1 and RAD51. However, pretreatment with an autophagy inhibitor offsets the effects of MG132 on CHK1 and RAD51 levels. These findings imply that p62 accumulation in the nucleus in response to autophagy inhibition promotes proteasome-mediated CHK1 and RAD51 protein instability. This claim is further supported by the findings that transient expression of a p62 mutant, which is constitutively localized in the nucleus, in B cell lines with low endogenous p62 levels recaptures the effects of autophagy inhibition on CHK1 and RAD51 protein stability. These results indicate that proteasomal degradation of RAD51 and CHK1 is dependent on p62 accumulation in the nucleus. However, small hairpin RNA (shRNA)-mediated p62 depletion in EBV-transformed lymphoblastic cell lines (LCLs) had no apparent effects on the protein levels of CHK1 and RAD51, likely due to the constitutive localization of p62 in the cytoplasm and incomplete knockdown is insufficient to manifest its nuclear effects on these proteins. Rather, shRNA-mediated p62 depletion in EBV-transformed LCLs results in significant increases of endogenous RNF168-γH2AX damage foci and chromatin ubiquitination, indicative of activation of RNF168-mediated DNA repair mechanisms. Our results have unveiled a pivotal role for p62-mediated selective autophagy that governs DDR in the setting of oncogenic virus latent infection, and provide a novel insight into virus-mediated oncogenesis. Author summary Reactive oxygen/nitrogen species (ROS/RNS) can induce both DNA damage response (DDR) and selective autophagy, which play crucial roles in cancer development. The selective autophagy receptor and ubiquitin (Ub) sensor p62 links their crosstalk. However, p62-mediated selective autophagy and its interplay with DDR have not been investigated in latent infection of oncogenic viruses including Epstein-Barr Virus (EBV). In this study, we provide evidence that p62-mediated selective autophagy is constitutively induced in virus-transformed cells, and that its inhibition exacerbates ROS-induced DNA damage, and promotes proteasomal degradation of CHK1 and RAD51 in a manner depending on p62 accumulation in the nucleus. However, rigorous autophagy induction results in accumulation of DNA repair proteins CHK1 and RAD51, and p62 degradation. Further, transient expression of a constitutive nucleus-localizing mutant of p62 recaptures the effects of autophagy inhibition on CHK1 and RAD51 protein stability. These findings support the claim that p62 accumulation in the nucleus in response to autophagy inhibition promotes proteasome-mediated CHK1 and RAD51 protein instability. However, small hairpin RNA (shRNA)-mediated p62 depletion did not affect CHK1 and RAD51 protein levels; rather, shRNA-mediated p62 depletion activates RNF168-dependent DNA repair mechanisms. Our results have unveiled a pivotal role for p62-mediated selective autophagy in regulation of DDR by overriding traditional DDR mechanisms in the setting of oncogenic virus latent infection, and provide a novel insight into the etiology of viral cancers. |
| Databáze: | OpenAIRE |
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