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Trafficking of mitochondrial double-stranded RNA from mitochondria to the cytosol

Matthew R Krieger1, Melania Abrahamian1, Kevin L He1

  • 1Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA, USA.

Life Science Alliance
|July 2, 2024
PubMed

Insights

Mitochondria export double-stranded RNA (mtdsRNA) via specific channels, activating cellular stress responses. This mitochondrial RNA export is relevant in cancer biology and may represent a new damage-associated molecular pattern.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Immunology

Background:

  • Mitochondria are known to export mitochondrial DNA, but mechanisms for mitochondrial double-stranded RNA (mtdsRNA) export remain unclear.
  • Specific protein channels facilitating mtdsRNA transport from the mitochondrial matrix to the cytosol have not been identified.

Purpose of the Study:

  • To identify and characterize potential protein channels involved in the export of mtdsRNA from mitochondria.
  • To investigate the functional role of specific mitochondrial proteins in regulating mtdsRNA export.

Main Methods:

  • Gene silencing (down-regulation) of SUV3 and PNPase to observe mtdsRNA localization.
  • Protein targeting experiments to determine PNPase localization.
  • Strand-specific sequencing to confirm RNA origin.
  • Inhibition/down-regulation of outer and inner mitochondrial membrane proteins (VDAC1/2, BAK/BAX, PHB1/2).
  • Analysis of cytosolic mtdsRNA localization and downstream effects on stress response pathways.

Main Results:

  • Down-regulation of SUV3 caused mtdsRNA accumulation in the mitochondrial matrix.
  • Down-regulation of PNPase led to mtdsRNA export into the cytosol.
  • Mitochondrial membrane proteins (VDAC1/2, BAK/BAX, PHB1/2) are crucial for mtdsRNA export.
  • Cytosolic mtdsRNAs formed granules with TIA-1 and activated the type 1 interferon pathway.
  • Increased mtdsRNA levels were found in glycolytic non-small-cell lung cancer cells.

Conclusions:

  • mtdsRNA is exported from mitochondria through a regulated process involving specific protein channels.
  • This export mechanism is linked to cellular stress responses and innate immunity.
  • mtdsRNA functions as a novel damage-associated molecular pattern with implications in cancer biology.

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