Melanoma differentiation-associated protein 5 (MDA5) (MDA5)

Melanoma differentiation-associated protein 5 (MDA5), encoded by the IFIH1 gene, is a cytosolic pattern recognition receptor and a member of the RIG-I-like receptor (RLR) family [1.1.1, 1.4.1]. It plays a pivotal role in the innate immune system by sensing long double-stranded RNA (dsRNA) molecules, which are characteristic of certain viral infections such as those from the Picornaviridae and Coronaviridae families [1.2.2, 1.2.4]. Upon activation, MDA5 forms filaments along the dsRNA and interacts with the mitochondrial antiviral-signaling protein (MAVS), leading to the production of Type I interferons (IFN-alpha and IFN-beta) and pro-inflammatory cytokines [1.2.1, 1.2.3]. In the context of oncology, MDA5 is a therapeutic target for cancer immunotherapy; synthetic agonists like poly(I:C) and its derivatives are used to induce tumor cell apoptosis and stimulate a robust anti-tumor T-cell response [1.3.1, 1.3.2]. Conversely, dysregulation of the MDA5 pathway is linked to severe autoimmune and autoinflammatory diseases. Gain-of-function mutations in IFIH1 cause Aicardi-Goutières syndrome and Singleton-Merten syndrome, while the presence of anti-MDA5 autoantibodies is a hallmark of a specific subtype of dermatomyositis associated with life-threatening rapidly progressive interstitial lung disease [1.4.1, 1.4.2, 1.1.3]. Management of these conditions often involves the use of JAK inhibitors to dampen the downstream interferon signaling triggered by the pathway [1.1.4, 1.3.4].

Other names

IFIH1Interferon induced with helicase C domain protein 1CADM-140 autoantigenMelanoma differentiation-associated gene 5RIG-I-like receptor 2RLR-2

Agonism via binding to the helicase and C-terminal domains to induce filament formation and MAVS-mediated Type I interferon production, or downstream inhibition of the JAK/STAT signaling pathway to mitigate pathway overactivation.