RNF144B negatively regulates antiviral immunity by targeting MDA5 for autophagic degradation

Area of Science:

• Immunology
• Molecular Biology
• Virology

Background:

• MDA5 is a RIG-I-like receptor crucial for sensing double-stranded RNA and initiating antiviral type I interferon responses.
• Dysregulation of MDA5 signaling can impact innate immunity and viral pathogenesis.

Purpose of the Study:

• To investigate the role of RNF144B in the regulation of MDA5-mediated innate antiviral immunity.
• To elucidate the molecular mechanism by which RNF144B affects MDA5 function and stability.

Main Methods:

• Co-immunoprecipitation assays to confirm RNF144B-MDA5 interaction.
• Ubiquitination assays to identify ubiquitination sites and linkage types on MDA5.
• Western blotting and immunofluorescence to assess MDA5 protein levels and localization.
• Autophagy assays to evaluate the role of p62 in MDA5 degradation.
• In vivo studies using Rnf144b knockout mice and EMCV infection models to assess antiviral responses and survival rates.

Main Results:

• RNF144B specifically interacts with MDA5.
• RNF144B promotes K27/K33-linked polyubiquitination of MDA5 at Lys23 and Lys43.
• RNF144B facilitates p62-mediated autophagic degradation of MDA5.
• Rnf144b deficiency enhances type I interferon production and inhibits EMCV replication in vivo.
• Rnf144b knockout mice exhibit increased survival rates upon EMCV infection.

Conclusions:

• RNF144B acts as a negative regulator of the innate antiviral immune response.
• RNF144B targets the CARDs of MDA5, promoting its autophagic degradation.
• Inhibition of RNF144B enhances antiviral immunity and improves survival during viral infections.