MDA5 (Melanoma Differentiation-Associated protein 5) is a RIG-I-like receptordsRNAhelicaseenzyme that in humans is encoded by the IFIH1gene.[1] MDA5 is part of the RIG-I-like receptor (RLR) family, which also includes RIG-I and LGP2, and functions as a pattern recognition receptor (recognizing dsRNA) that is a sensor for viruses. MDA5 typically recognizes dsRNA that is over 2000nts in length.[2] For many viruses, effective MDA5-mediated antiviral responses are dependent on functionally active LGP2.[3] The signaling cascades in MDA5 is initiated via CARD domain.[4]
DEAD box proteins, characterized by the conserved motif Asp-Glu-Ala-Asp (DEAD), are putative RNA helicases. They are implicated in a number of cellular processes involving alteration of RNA secondary structure such as translation initiation, nuclear and mitochondrial splicing, and ribosome and spliceosome assembly. Based on their distribution patterns, some members of this family are believed to be involved in embryogenesis, spermatogenesis, and cellular growth and division. This gene encodes a DEAD box protein that is upregulated in response to treatment with beta-interferon (IFNB) and a protein kinase C-activating compound, mezerein (MEZ). Irreversible reprogramming of melanomas can be achieved by treatment with both these agents; treatment with either agent alone only achieves reversible differentiation.[1]
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Kang DC, Gopalkrishnan RV, Lin L, Randolph A, Valerie K, Pestka S, Fisher PB (March 2004). "Expression analysis and genomic characterization of human melanoma differentiation associated gene-5, mda-5: a novel type I interferon-responsive apoptosis-inducing gene". Oncogene. 23 (9): 1789–800. doi:10.1038/sj.onc.1207300. PMID14676839.
Yoneyama M, Kikuchi M, Matsumoto K, Imaizumi T, Miyagishi M, Taira K, Foy E, Loo YM, Gale M, Akira S, Yonehara S, Kato A, Fujita T (September 2005). "Shared and unique functions of the DExD/H-box helicases RIG-I, MDA5, and LGP2 in antiviral innate immunity". Journal of Immunology. 175 (5): 2851–8. doi:10.4049/jimmunol.175.5.2851. PMID16116171.
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Meylan E, Curran J, Hofmann K, Moradpour D, Binder M, Bartenschlager R, Tschopp J (October 2005). "Cardif is an adaptor protein in the RIG-I antiviral pathway and is targeted by hepatitis C virus". Nature. 437 (7062): 1167–72. doi:10.1038/nature04193. PMID16177806.
Lin L, Su Z, Lebedeva IV, Gupta P, Boukerche H, Rai T, Barber GN, Dent P, Sarkar D, Fisher PB (November 2006). "Activation of Ras/Raf protects cells from melanoma differentiation-associated gene-5-induced apoptosis". Cell Death and Differentiation. 13 (11): 1982–93. doi:10.1038/sj.cdd.4401899. PMID16575407.
Smyth DJ, Cooper JD, Bailey R, Field S, Burren O, Smink LJ, Guja C, Ionescu-Tirgoviste C, Widmer B, Dunger DB, Savage DA, Walker NM, Clayton DG, Todd JA (June 2006). "A genome-wide association study of nonsynonymous SNPs identifies a type 1 diabetes locus in the interferon-induced helicase (IFIH1) region". Nature Genetics. 38 (6): 617–9. doi:10.1038/ng1800. PMID16699517.
Berghäll H, Sirén J, Sarkar D, Julkunen I, Fisher PB, Vainionpää R, Matikainen S (July 2006). "The interferon-inducible RNA helicase, mda-5, is involved in measles virus-induced expression of antiviral cytokines". Microbes and Infection. 8 (8): 2138–44. doi:10.1016/j.micinf.2006.04.005. PMID16782388.
Sirén J, Imaizumi T, Sarkar D, Pietilä T, Noah DL, Lin R, Hiscott J, Krug RM, Fisher PB, Julkunen I, Matikainen S (July 2006). "Retinoic acid inducible gene-I and mda-5 are involved in influenza A virus-induced expression of antiviral cytokines". Microbes and Infection. 8 (8): 2013–20. doi:10.1016/j.micinf.2006.02.028. PMID16797201.
Sutherland A, Davies J, Owen CJ, Vaikkakara S, Walker C, Cheetham TD, James RA, Perros P, Donaldson PT, Cordell HJ, Quinton R, Pearce SH (August 2007). "Genomic polymorphism at the interferon-induced helicase (IFIH1) locus contributes to Graves' disease susceptibility". The Journal of Clinical Endocrinology and Metabolism. 92 (8): 3338–41. doi:10.1210/jc.2007-0173. PMID17535987.
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