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Updated: Apr 26, 2026
Monitoring Activation of the Antiviral Pattern Recognition Receptors RIG-I And PKR By Limited Protease Digestion and Native PAGE
Published on: July 29, 2014
Pattern Recognition and Signaling Mechanisms of RIG-I and MDA5
Stephanie Reikine1, Jennifer B Nguyen1, Yorgo Modis1
1Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, CT , USA.
Abstract:
Most organisms rely on innate immune receptors to recognize conserved molecular structures from invading microbes. Two essential innate immune receptors, RIG-I and MDA5, detect viral double-stranded RNA in the cytoplasm. The inflammatory response triggered by these RIG-I-like receptors (RLRs) is one of the first and most important lines of defense against infection. RIG-I recognizes short RNA ligands with 5'-triphosphate caps. MDA5 recognizes long kilobase-scale genomic RNA and replication intermediates. Ligand binding induces conformational changes and oligomerization of RLRs that activate the signaling partner MAVS on the mitochondrial and peroxisomal membranes. This signaling process is under tight regulation, dependent on post-translational modifications of RIG-I and MDA5, and on regulatory proteins including unanchored ubiquitin chains and a third RLR, LGP2. Here, we review recent advances that have shifted the paradigm of RLR signaling away from the conventional linear signaling cascade. In the emerging RLR signaling model, large multimeric signaling platforms generate a highly cooperative, self-propagating, and context-dependent signal, which varies with the subcellular localization of the signaling platform.
Insights
RIG-I and MDA5 are crucial innate immune receptors detecting viral RNA. Recent findings reveal their signaling forms large, dynamic platforms, not linear cascades, for a robust defense.
Area of Science:
- Immunology
- Molecular Biology
- Virology
Background:
- Innate immunity relies on receptors recognizing microbial structures.
- RIG-I-like receptors (RLRs), including RIG-I and MDA5, detect viral double-stranded RNA in the cytoplasm.
- RLR signaling is a key defense against viral infections.
Purpose of the Study:
- To review recent advances in RIG-I-like receptor (RLR) signaling.
- To present the emerging model of RLR signaling.
- To highlight the shift from linear cascades to multimeric signaling platforms.
Main Methods:
- Literature review of recent research on RLR signaling.
- Analysis of studies on RIG-I and MDA5 ligand recognition and activation.
- Examination of regulatory mechanisms including post-translational modifications and protein interactions.
Main Results:
- RIG-I detects short 5'-triphosphate RNA, while MDA5 detects long dsRNA.
- Ligand binding induces RLR conformational changes and MAVS activation.
- Emerging model: RLRs form large, cooperative, self-propagating signaling platforms.
Conclusions:
- RLR signaling is a complex, regulated process.
- The new model emphasizes dynamic, multimeric platforms over linear cascades.
- Subcellular localization of signaling platforms influences signal output.
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