Induction of a unique isoform of the NCOA7 oxidation resistance gene by interferon β-1b.

We demonstrate that interferon (IFN)-β-1b induces an alternative-start transcript containing the C-terminal TLDc domain of nuclear receptor coactivator protein 7 (NCOA7), a member of the OXR family of oxidation resistance proteins. IFN-β-1b induces NCOA7-AS (alternative start) expression in peripheral blood mononuclear cells (PBMCs) obtained from healthy individuals and multiple sclerosis patients and human fetal brain cells, astrocytoma, neuroblastoma, and fibrosarcoma cells. NCOA7-AS is a previously undocumented IFN-β-inducible gene that contains only the last 5 exons of full-length NCOA7 plus a unique first exon (exon 10a) that is not found in longer forms of NCOA7. This exon encodes a domain closely related to an important class of bacterial aldo-keto oxido-reductase proteins that play a critical role in regulating redox activity. We demonstrate that NCOA7-AS is induced by IFN and LPS, but not by oxidative stress and exhibits, independently, oxidation resistance activity. We further demonstrate that induction of NCOA7-AS by IFN is dependent on IFN-receptor activation, the Janus kinase-signal transducers and activators of transcription (JAK-STAT) signaling pathway, and a canonical IFN-stimulated response element regulatory sequence upstream of exon 10a. We describe a new role for IFN-βs involving a mechanism of action that leads to an increase in resistance to inflammation-mediated oxidative stress.