MDA5

Innate immune receptor which acts as a cytoplasmic sensor of viral nucleic acids and plays a major role in sensing viral infection and in the activation of a cascade of antiviral responses including the induction of type I interferons and pro-inflammatory cytokines (PubMed:28594402, PubMed:32169843, PubMed:33727702). Its ligands include mRNA lacking 2'-O-methylation at their 5' cap and long-dsRNA (>1 kb in length) (PubMed:22160685). Upon ligand binding it associates with mitochondria antiviral signaling protein (MAVS/IPS1) which activates the IKK-related kinases: TBK1 and IKBKE which phosphorylate interferon regulatory factors: IRF3 and IRF7 which in turn activate transcription of antiviral immunological genes, including interferons (IFNs); IFN-alpha and IFN-beta. Responsible for detecting the Picornaviridae family members such as encephalomyocarditis virus (EMCV), mengo encephalomyocarditis virus (ENMG), and rhinovirus (PubMed:28606988). Detects coronavirus SARS-CoV-2 (PubMed:33440148, PubMed:33514628). Can also detect other viruses such as dengue virus (DENV), west Nile virus (WNV), and reovirus. Also involved in antiviral signaling in response to viruses containing a dsDNA genome, such as vaccinia virus. Plays an important role in amplifying innate immune signaling through recognition of RNA metabolites that are produced during virus infection by ribonuclease L (RNase L). May play an important role in enhancing natural killer cell function and may be involved in growth inhibition and apoptosis in several tumor cell lines.

Type 1 diabetes mellitus 19

T1D19

A multifactorial disorder of glucose homeostasis that is characterized by susceptibility to ketoacidosis in the absence of insulin therapy. Clinical features are polydipsia, polyphagia and polyuria which result from hyperglycemia-induced osmotic diuresis and secondary thirst. These derangements result in long-term complications that affect the eyes, kidneys, nerves, and blood vessels.

None

Disease susceptibility may be associated with variants affecting the gene represented in this entry.

IFIH1 is the CADM-140 autoantigen, involved in clinically amyopathic dermatomyositis (CADM). This is a chronic inflammatory disorder that shows typical skin manifestations of dermatomyositis but has no or little evidence of clinical myositis. Anti-CADM-140 antibodies appear to be specific to dermatomyositis, especially CADM. Patients with anti-CADM-140 antibodies frequently develop life-threatening acute progressive interstitial lung disease (ILD).

Aicardi-Goutieres syndrome 7

AGS7

A form of Aicardi-Goutieres syndrome, a genetically heterogeneous disease characterized by cerebral atrophy, leukoencephalopathy, intracranial calcifications, chronic cerebrospinal fluid (CSF) lymphocytosis, increased CSF alpha-interferon, and negative serologic investigations for common prenatal infection. Clinical features as thrombocytopenia, hepatosplenomegaly and elevated hepatic transaminases along with intermittent fever may erroneously suggest an infective process. Severe neurological dysfunctions manifest in infancy as progressive microcephaly, spasticity, dystonic posturing and profound psychomotor retardation. Death often occurs in early childhood.

None

The disease is caused by variants affecting the gene represented in this entry.

Singleton-Merten syndrome 1

SGMRT1

An autosomal dominant disorder with variable expression. Core features are marked aortic calcification, dental anomalies, osteopenia, acro-osteolysis, and to a lesser extent glaucoma, psoriasis, muscle weakness, and joint laxity. Dental anomalies include delayed eruption and immature root formation of anterior permanent teeth, early loss of permanent teeth due to short roots, acute root resorption, high caries, and aggressive alveolar bone loss. Additional clinical manifestations include particular facial characteristics and abnormal joint and muscle ligaments.

None

The disease is caused by variants affecting the gene represented in this entry.

Immunodeficiency 95

IMD95

An autosomal recessive disorder characterized by the onset of recurrent and severe viral respiratory infections in infancy or early childhood, and impaired interferon production during viral infection.

None

The disease is caused by variants affecting the gene represented in this entry.

Sumoylated. Sumoylation positively regulates its role in type I interferon induction and is enhanced by PIAS2-beta.

Ubiquitinated by RNF125, leading to its degradation by the proteasome (PubMed:17460044). USP17/UPS17L2-dependent deubiquitination positively regulates the receptor (PubMed:20368735). Ubiquitinated by TRIM25 via 'Lys-63'-linked ubiquitination, promoting activation of IFIH1/MDA5 (PubMed:30193849). Ubiquitinated by TRIM40 via 'Lys-48'-linked ubiquitination; leading to proteasomal degradation (PubMed:29117565). Ubiquitinated by TRIM65 via 'Lys-63'-linked ubiquitination, promoting activation of IFIH1/MDA5 (PubMed:28594402).

ISGylated by ISG15. ISGylation increases upon infection with dengue (DENV) or Zika (ZIKV) viruses. ISGylation at Lys-23 and Lys-43 is dependent of dephosphorylation at Ser-88, regulates mitochondrial translocation and oligomerization. Essential for IFIH1/MDA5-mediated cytokine responses and restriction of virus replication.

Phosphorylated at Ser-88 (PubMed:23499489, PubMed:33727702). Dephosphorylated by phosphatases PPP11CA/PPP11CC; dephosphorylation precedes and is required for ISGylation (PubMed:23499489, PubMed:33727702).

During apoptosis, processed into 3 cleavage products. The helicase-containing fragment, once liberated from the CARD domains, translocate from the cytoplasm to the nucleus. The processed protein significantly sensitizes cells to DNA degradation.

(Microbial infection) Cleaved and inactivated by the protease 2A of coxsackievirus B3, poliovirus and enterovirus 71 allowing the virus to disrupt the host type I interferon production.

Belongs to the helicase family. RLR subfamily.

Widely expressed, at a low level. Expression is detected at slightly highest levels in placenta, pancreas and spleen and at barely levels in detectable brain, testis and lung.

• Cytoplasm
• Nucleus
• Mitochondrion
• Upon viral RNA stimulation and ISGylation, translocates from cytosol to mitochondrion. May be found in the nucleus, during apoptosis.

MDA5, RH116, IFIH1, Interferon-induced helicase C domain-containing protein 1, Clinically amyopathic dermatomyositis autoantigen 140 kDa, Helicase with 2 CARD domains, Interferon-induced with helicase C domain protein 1, Melanoma differentiation-associated protein 5, Murabutide down-regulated protein, RIG-I-like receptor 2, RNA helicase-DEAD box protein 116, CADM-140 autoantigen, Helicard, MDA-5, RLR-2

• entrezGene:64135
• omim:606951
• swissprot:Q9BYX4

Proteins

Immunology & Infectious Disease

116689Da