title: NF-κB and IRF1 Induce Endogenous Retrovirus K Expression via Interferon-Stimulated Response Elements in Its 5' Long Terminal Repeat.
abstract: Thousands of endogenous retroviruses (ERV), viral fossils of ancient germ line infections, reside within the human genome. Evidence of ERV activity has been observed widely in both health and disease. While this is most often cited as a bystander effect of cell culture or disease states, it is unclear which signals control ERV transcription. Bioinformatic analysis suggests that the viral promoter of endogenous retrovirus K (ERVK) is responsive to inflammatory transcription factors. Here we show that one reason for ERVK upregulation in amyotrophic lateral sclerosis (ALS) is the presence of functional interferon-stimulated response elements (ISREs) in the viral promoter. Transcription factor overexpression assays revealed independent and synergistic upregulation of ERVK by interferon regulatory factor 1 (IRF1) and NF-κB isoforms. Tumor necrosis factor alpha (TNF-α) and LIGHT cytokine treatments of human astrocytes and neurons enhanced ERVK transcription and protein levels through IRF1 and NF-κB binding to the ISREs. We further show that in ALS brain tissue, neuronal ERVK reactivation is associated with the nuclear translocation of IRF1 and NF-κB isoforms p50 and p65. ERVK overexpression can cause motor neuron pathology in murine models. Our results implicate neuroinflammation as a key trigger of ERVK provirus reactivation in ALS. These molecular mechanisms may also extend to the pathobiology of other ERVK-associated inflammatory diseases, such as cancers, HIV infection, rheumatoid arthritis, and schizophrenia.
  
  
  
  It has been well established that inflammatory signaling pathways in ALS converge at NF-κB to promote neuronal damage. Our findings suggest that inflammation-driven IRF1 and NF-κB activity promotes ERVK reactivation in neurons of the motor cortex in ALS. Thus, quenching ERVK activity through antiretroviral or immunomodulatory regimens may hinder virus-mediated neuropathology and improve the symptoms of ALS or other ERVK-associated diseases.
authors: Department of Biology, University of Winnipeg, Winnipeg, Manitoba, Canada.
authors: Mamneet
authors: M
authors: Manghera
authors: Department of Biology, University of Winnipeg, Winnipeg, Manitoba, Canada.
authors: Jennifer
authors: J
authors: Ferguson-Parry
authors: Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec, Canada.
authors: Rongtuan
authors: R
authors: Lin
authors: Department of Biology, University of Winnipeg, Winnipeg, Manitoba, Canada Department of Immunology, University of Manitoba, Winnipeg, Manitoba, Canada r.douville@uwinnipeg.ca.
authors: Renée N
authors: RN
authors: Douville
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002478:Cells, Cultured; D020077:Endogenous Retroviruses / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000821:virology; D050856:Interferon Regulatory Factor-1 / Q000378:metabolism*; D007371:Interferon-gamma / Q000378:metabolism; D007372:Interferons / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D020218:Response Elements / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics; D020079:Terminal Repeat Sequences / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D007372:Interferons