Small self-RNA generated by RNase L amplifies antiviral innate immunity.

Area of Science:

• Immunology
• Molecular Biology
• Virology

Background:

• Antiviral innate immunity relies on sensing viral RNA to activate interferon (IFN) production.
• Key pattern recognition receptors like RIG-I and MDA5 initiate signaling cascades involving IPS-1.
• The precise origin of RNA molecules initiating these antiviral responses remains unclear.

Purpose of the Study:

• To investigate the role of RNase L in initiating antiviral innate immunity.
• To determine if RNase L-derived RNA fragments can activate IFN production.
• To elucidate the signaling pathway involved in RNase L-mediated antiviral responses.

Main Methods:

• Activation of RNase L with 2',5'-linked oligoadenylate (2-5A).
• Analysis of IFN-beta induction in wild-type and RNase L-deficient mouse embryonic fibroblasts and mice.
• Assessment of RNA cleavage products and their interaction with RIG-I, MDA5, and IPS-1 signaling pathways.

Main Results:

• RNase L activation produces small RNA cleavage products from self-RNA that initiate IFN-beta production.
• RNase L-deficient cells and mice exhibit resistance to IFN-beta induction upon stimulation with 2-5A, dsRNA, or viral infection.
• Signaling involves RIG-I, MDA5, and IPS-1, with RNase L-deficient mice producing significantly less IFN-beta during viral infections.
• In vivo activation of RNase L induces IFN-beta in wild-type but not RNase L-deficient mice.

Conclusions:

• RNase L plays a crucial role in the innate antiviral immune response.
• RNase L activation by 2-5A generates endogenous RNA triggers for IFN production.
• This pathway bypasses the need for direct sensing of non-self RNA, revealing a novel mechanism in antiviral immunity.