Interferon-induced helicase C domain-containing protein 1 (MDA5) (MDA5)

Interferon-induced helicase C domain-containing protein 1 (IFIH1), commonly known as Melanoma Differentiation-Associated protein 5 (MDA5), is a cytosolic pattern recognition receptor that plays a critical role in the innate immune system by sensing long double-stranded RNA (dsRNA) typically associated with viral replication [UniProt Q9BYX4, PubMed: 32047299]. Upon binding to dsRNA, MDA5 undergoes an ATP-dependent conformational change and oligomerization, which triggers the recruitment of the mitochondrial antiviral-signaling protein (MAVS) [PubMed: 24450244, PubMed: 16474402]. This signaling cascade leads to the activation of interferon regulatory factors (IRF3 and IRF7) and NF-κB, resulting in the production of Type I interferons and pro-inflammatory cytokines [PubMed: 16474402, PubMed: 24450244]. Mutations in the IFIH1 gene are linked to various autoimmune conditions, such as Aicardi-Goutières syndrome and Singleton-Merten syndrome, where constitutive activation leads to chronic interferon production [PubMed: 24413737]. Additionally, anti-MDA5 autoantibodies are diagnostic markers for a specific subset of dermatomyositis associated with rapidly progressive interstitial lung disease [PubMed: 16307188]. While there are currently no FDA-approved drugs that directly target MDA5, it is an active area of research for both antiviral therapies (using agonists) and autoimmune treatments (using inhibitors) [PubMed: 30761124, PubMed: 24745623]. Therapeutic challenges include the risk of systemic inflammation when using agonists and increased susceptibility to viral infections when using inhibitors [PubMed: 30761124].

Other names

Melanoma differentiation-associated protein 5IFIH1HelicardCADM-140 autoantigenRH116RIG-I-like receptor 2RLR-2

MDA5 recognizes and binds to long cytosolic double-stranded RNA (dsRNA), triggering ATP-dependent oligomerization and recruitment of the MAVS adapter protein to activate Type I interferon and pro-inflammatory cytokine pathways.