RNF34 functions in immunity and selective mitophagy by targeting MAVS for autophagic degradation

Area of Science:

• Immunology
• Cell Biology
• Virology

Background:

• Viral infections activate mitochondrial antiviral signaling protein (MAVS) aggregates, crucial for immune signaling.
• Autophagy regulates MAVS-mediated antiviral responses, but its precise degradation mechanism is unknown.

Purpose of the Study:

• To investigate the mechanism of RNF34 in regulating immunity and mitophagy by targeting MAVS.
• To elucidate how RNF34 controls MAVS ubiquitination and subsequent autophagic degradation.

Main Methods:

• Co-immunoprecipitation to detect RNF34-MAVS binding.
• Ubiquitination assays to identify MAVS ubiquitination sites and types.
• Autophagy-related protein (NDP52) interaction studies.
• Mitochondrial clearance assays post-viral infection.

Main Results:

• RNF34 binds MAVS in mitochondria post-viral infection, inhibiting RIG-I-like receptor (RLR) signaling.
• RNF34 catalyzes K27-/K29-linked ubiquitination of MAVS, marking it for NDP52-dependent autophagy.
• RNF34 facilitates the K63- to K27-linked ubiquitination switch on MAVS, promoting its degradation.
• RNF34 is essential for clearing damaged mitochondria during viral infections.

Conclusions:

• RNF34-mediated MAVS degradation is a key mechanism regulating innate immunity.
• This process is critical for maintaining mitochondrial homeostasis and controlling viral infections.
• RNF34 links ubiquitination, autophagy, and mitophagy in antiviral defense.