mda-5: An interferon-inducible putative RNA helicase with double-stranded RNA-dependent ATPase activity and melanoma growth-suppressive properties

AUTOR(ES)
FONTE

The National Academy of Sciences

RESUMO

Human melanoma cells can be reprogrammed to terminally differentiate and irreversibly lose proliferative capacity by appropriate pharmacological manipulation. Subtraction hybridization identified melanoma differentiation-associated gene-5 (mda-5) as a gene induced during differentiation, cancer reversion, and programmed cell death (apoptosis). This gene contains both a caspase recruitment domain and putative DExH group RNA helicase domains. Atypical helicase motifs of MDA-5 deviate from consensus sequences but are well conserved in a potentially new group of cloned and hypothetical proteins. mda-5 is an early response gene inducible by IFN and tumor necrosis factor-α, responding predominantly to IFN-β. Protein kinase C activation by mezerein further augments mda-5 expression induced by IFN-β. Expression of mda-5 is controlled transcriptionally by IFN-β, and the MDA-5 protein localizes in the cytoplasm. mda-5 displays RNA-dependent ATPase activity, and ectopic expression of mda-5 in human melanoma cells inhibits colony formation. In these contexts, mda-5 may function as a mediator of IFN-induced growth inhibition and/or apoptosis. MDA-5 is a double-stranded RNA-dependent ATPase that contains both a caspase recruitment domain and RNA helicase motifs, with a confirmed association with growth and differentiation in human melanoma cells.

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