Mitochondrial dynamics regulate the RIG-I-like receptor antiviral pathway

Area of Science:

• Immunology
• Cell Biology
• Virology

Background:

• Intracellular retinoic acid-inducible gene I-like receptors (RLRs) detect viral RNA.
• RLRs signal via mitochondrial antiviral signalling (MAVS) to induce type I interferons and cytokines.
• Mitochondrial dynamics play a role in cellular signaling pathways.

Purpose of the Study:

• To investigate the role of RLR activation in mitochondrial network dynamics.
• To determine how mitochondrial morphology affects MAVS-mediated antiviral signaling.
• To explore potential immune evasion strategies employed by viruses targeting this pathway.

Main Methods:

• Studied the effect of RLR activation on mitochondrial network elongation.
• Investigated the impact of mimicking mitochondrial elongation or fragmentation on MAVS signaling.
• Assessed the association between MAVS and mitochondrial fusion proteins.
• Examined the effect of a cytomegalovirus (CMV) protein on MAVS signaling and mitochondrial morphology.

Main Results:

• RLR activation promotes mitochondrial network elongation.
• Mimicking mitochondrial elongation enhances MAVS signaling and MAVS-STING interaction.
• Enforced mitochondrial fragmentation impairs MAVS signaling and MAVS-STING interaction.
• MAVS associates with mitofusin 1, suggesting a role in regulating mitochondrial dynamics.
• CMV's viral mitochondria-localized inhibitor of apoptosis protein fragments mitochondria and inhibits MAVS signaling.

Conclusions:

• Mitochondrial dynamics, specifically elongation, are critical for effective RLR-mediated antiviral signaling.
• MAVS can regulate mitochondrial morphology to facilitate signal transduction.
• CMV utilizes mitochondrial fragmentation as a mechanism to dampen antiviral responses, representing a novel immune evasion strategy.