title: Expression analysis and genomic characterization of human melanoma differentiation associated gene-5, mda-5: a novel type I interferon-responsive apoptosis-inducing gene.
abstract: Melanoma differentiation associated gene-5 (mda-5) was identified by subtraction hybridization as a novel upregulated gene in HO-1 human melanoma cells induced to terminally differentiate by treatment with IFN-beta+MEZ. Considering its unique structure, consisting of a caspase recruitment domain (CARD) and an RNA helicase domain, it was hypothesized that mda-5 contributes to apoptosis occurring during terminal differentiation. We have currently examined the expression pattern of mda-5 in normal tissues, during induction of terminal differentiation and after treatment with type I IFNs. In addition, we have defined its genomic structure and chromosomal location. IFN-beta, a type I IFN, induces mda-5 expression in a biphasic and dose-dependent manner. Based on its temporal kinetics of induction and lack of requirement for prior protein synthesis mda-5 is an early type I IFN-responsive gene. The level of mda-5 mRNA is in low abundance in normal tissues, whereas expression is induced in a spectrum of normal and cancer cells by IFN-beta. Expression of mda-5 by means of a replication incompetent adenovirus, Ad.mda-5, induces apoptosis in HO-1 cells as confirmed by morphologic, biochemical and molecular assays. Additionally, the combination of Ad.mda-5+MEZ further augments apoptosis as observed in Ad.null or uninfected HO-1 cells induced to terminally differentiate by treatment with IFN-beta+MEZ. The mda-5 gene is located on human chromosome 2q24 and consists of 16 exons, without pseudogenes, and is conserved in the mouse genome. Present data documents that mda-5 is a novel type I IFN-inducible gene, which may contribute to apoptosis induction during terminal differentiation and during IFN treatment. The conserved genomic and protein structure of mda-5 in human and mouse will permit analysis of the evolution and developmental aspects of this gene.
authors.affiliation: Department of Pathology, Herbert Irving Comprehensive Cancer Center, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
authors.forename: Dong-Chul
authors.initials: DC
authors.lastname: Kang
authors.forename: Rahul V
authors.initials: RV
authors.lastname: Gopalkrishnan
authors.forename: Lin
authors.initials: L
authors.lastname: Lin
authors.forename: Aaron
authors.initials: A
authors.lastname: Randolph
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Valerie
authors.forename: Sidney
authors.initials: S
authors.lastname: Pestka
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fisher
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division; D045744:Cell Line, Tumor; D002470:Cell Survival; D002889:Chromosomes, Human, Pair 2 / Q000235:genetics; D053487:DEAD-box RNA Helicases; D004790:Enzyme Induction / Q000187:drug effects; D005091:Exons / Q000235:genetics; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D023281:Genomics; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology*; D000072640:Interferon-Induced Helicase, IFIH1; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D017434:Protein Structure, Tertiary; D020365:RNA Helicases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D007370:Interferon Type I; D012333:RNA, Messenger; C452815:IFIH1 protein, human; D053487:DEAD-box RNA Helicases; D000072640:Interferon-Induced Helicase, IFIH1; D020365:RNA Helicases