Identification and partial characterization of FRAG-6, a novel interferon-stimulated gene that is expressed in an IRF-1-INDEPENDENT manner.
In order to identify new interferon-stimulated genes that could help in the better understanding of the mechanism of action of interferons (IFNs), we decided to compare, by differential display RT-PCR (DDRT-PCR), the pattern of gene expression between IFN-alpha treated and untreated mouse embryonic fibroblasts (MEFs). Here we describe the initial characterization of a new cDNA fragment, named FRAG-6, that is expressed only upon IFN stimulation. The IFN-induced expression of this new gene can be observed in both wild-type and IRF-1-deficient MEF. FRAG-6 cDNA hybridizes with an mRNA of 6-9 kb that is induced by IFNs in a time-dependent manner. Analysis of the cloned nucleotide sequence revealed a 174 amino acid (aa) open reading frame (ORF) contained within the 576 bp. No significant homology with known nucleotide or protein sequences was observed. FRAG-6 is induced in vitro upon treatment of wild type or IRF-1-null cells with IFN-alpha or -gamma, but not with TNF or IL-1. Treatment of mice with imiquimod, a potent inducer of IFN, led to induced expression of FRAG-6 mRNA in various organs from wild type or IRF-1-deficient mice, but not from STAT-1 or type I IFN receptor deficient animals. Our results demonstrate that FRAG-6 mRNA induction by interferons is IRF-1-independent and it is likely to be activated by the JAK/STAT pathway. Further characterization of FRAG-6 will help us in the understanding of the mechanism of action of IFNs.
Silva
A M
AM
Instituto de Ciências Biológicas, Federal University of Minas Gerais, Belo Horizonte, MG, 31270-901, Brazil.
Bottrel
R L
RL
Reis
L F
LF
D000595:Amino Acid Sequence; D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000172:deficiency* / Q000235:genetics; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D000077271:Imiquimod; D007369:Interferon Inducers / Q000494:pharmacology; D050856:Interferon Regulatory Factor-1; D007372:Interferons / Q000494:pharmacology*; D007375:Interleukin-1 / Q000494:pharmacology; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000172:deficiency* / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000172:deficiency; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050794:STAT1 Transcription Factor; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D015534:Trans-Activators / Q000172:deficiency; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000634:Aminoquinolines; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C403316:FRAG-6 protein, mouse; D007369:Interferon Inducers; D050856:Interferon Regulatory Factor-1; D007375:Interleukin-1; C494258:Irf1 protein, mouse; D008565:Membrane Proteins; D010750:Phosphoproteins; D011506:Proteins; D012333:RNA, Messenger; D017471:Receptors, Interferon; D050794:STAT1 Transcription Factor; C494080:Stat1 protein, mouse; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D053633:Receptor, Interferon alpha-beta; D007372:Interferons; D000077271:Imiquimod