IFIH1 is a protein that ifih1 is a critical cytoplasmic rna sensor:. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.
| Protein Name | IFIH1 (Melanoma Differentiation-Associated protein 5, MDA5) |
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| Gene | [IFIH1](/genes/ifih1) |
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| UniProt ID | Q9Q5Y5 |
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| PDB Structure | 4GL2, 5G43 |
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| Molecular Weight | ~130 kDa |
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| Subcellular Localization | Cytoplasm |
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| Protein Family | RIG-I-like receptor (RLR) family |
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IFIH1/MDA5 is a large cytoplasmic receptor with multiple domains:
- N-terminal CARD Domains: Two caspase recruitment domains for downstream signaling
- Helicase Domain: Central SF1 helicase domain that binds RNA
- C-terminal Domain (CTD): Regulatory domain that recognizes dsRNA
- Resting State: In auto-inhibited conformation in the absence of RNA
IFIH1 is a critical cytoplasmic RNA sensor:
- Viral RNA Detection: Recognizes long double-stranded RNA from viral infections
- Type I Interferon Induction: Activates MAVS signaling to induce IFN-β and other interferons
- Antiviral Defense: Essential for clearance of picornaviruses and other RNA viruses
- Immunomodulation: Regulates adaptive immune responses
IFIH1 mutations cause AGS, a genetic interferonopathy:
- Type I Interferon Signature: Elevated IFN-α activity in cerebrospinal fluid and blood
- Clinical Features: Early-onset encephalopathy, calcifications, leukoencephalopathy
- Neurological Manifestations: Developmental regression, seizures, movement disorders
- Immune Dysregulation: Autoimmune phenomena and immune cell activation
- Amyotrophic Lateral Sclerosis: IFIH1 variants modify ALS risk and progression
- Systemic Lupus Erythematosus: IFIH1 polymorphisms associated with lupus risk
- Type 1 Diabetes: IFIH1 variants affect diabetes susceptibility
¶ Viral Infections and Neurodegeneration
- Herpes Simplex Encephalitis: IFIH1 mutations increase susceptibility
- Post-infectious Neurodegeneration: Dysregulated IFIH1 responses may contribute
Therapeutic approaches include:
- JAK Inhibitors: Ruxolitinib, baricitinib to block IFN signaling
- Type I Interferon Receptor Antibodies: Anti-IFNAR therapy
- Antiviral Therapy: For acute viral infections in susceptible individuals
- Immunomodulation: Targeting IFIH1 signaling pathway components
- IFIH1 mutations cause AGS (2014)
- MDA5 structure and mechanism (2012)
- Type I interferon in neurodegeneration (2017)
- JAK inhibition for AGS (2019)
- IFIH1 in ALS (2020)