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Nature. 2015 Apr 23;520(7548):553-7. doi: 10.1038/nature14156. Epub 2015 Feb 2.

Mitochondrial DNA stress primes the antiviral innate immune response.

Author information

  • 1Department of Pathology, Yale School of Medicine, New Haven, Connecticut 06520, USA.
  • 2Department of Immunobiology, Yale School of Medicine, New Haven, Connecticut 06520, USA.
  • 3Li Ka Shing Institute of Virology, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
  • 4Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri 63110, USA.
  • 51] Department of Immunobiology, Yale School of Medicine, New Haven, Connecticut 06520, USA [2] Howard Hughes Medical Institute, Chevy Chase, Maryland 20815-6789, USA.
  • 61] Department of Pathology, Yale School of Medicine, New Haven, Connecticut 06520, USA [2] Department of Genetics, Yale School of Medicine, New Haven, Connecticut 06520, USA.

Abstract

Mitochondrial DNA (mtDNA) is normally present at thousands of copies per cell and is packaged into several hundred higher-order structures termed nucleoids. The abundant mtDNA-binding protein TFAM (transcription factor A, mitochondrial) regulates nucleoid architecture, abundance and segregation. Complete mtDNA depletion profoundly impairs oxidative phosphorylation, triggering calcium-dependent stress signalling and adaptive metabolic responses. However, the cellular responses to mtDNA instability, a physiologically relevant stress observed in many human diseases and ageing, remain poorly defined. Here we show that moderate mtDNA stress elicited by TFAM deficiency engages cytosolic antiviral signalling to enhance the expression of a subset of interferon-stimulated genes. Mechanistically, we find that aberrant mtDNA packaging promotes escape of mtDNA into the cytosol, where it engages the DNA sensor cGAS (also known as MB21D1) and promotes STING (also known as TMEM173)-IRF3-dependent signalling to elevate interferon-stimulated gene expression, potentiate type I interferon responses and confer broad viral resistance. Furthermore, we demonstrate that herpesviruses induce mtDNA stress, which enhances antiviral signalling and type I interferon responses during infection. Our results further demonstrate that mitochondria are central participants in innate immunity, identify mtDNA stress as a cell-intrinsic trigger of antiviral signalling and suggest that cellular monitoring of mtDNA homeostasis cooperates with canonical virus sensing mechanisms to fully engage antiviral innate immunity.

PMID:
25642965
[PubMed - indexed for MEDLINE]
PMCID:
PMC4409480
Free PMC Article

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