p48/STAT-1alpha-containing complexes play a predominant role in induction of IFN-gamma-inducible protein, 10 kDa (IP-10) by IFN-gamma alone or in synergy with TNF-alpha.
Human IFN-gamma-inducible protein, 10 kDa (hIP-10) and murine IP-10 (mIP-10) genes are induced by IFN-gamma alone, and synergistically induced by TNF-alpha and IFN-gamma. Upstream regions of the human and murine genes contain conserved regulatory motifs, including an IFN-stimulated response element (ISRE), which governs response of the mIP-10 gene to IFN-gamma. Trans-acting factors mediating the IFN-gamma response via ISRE remain incompletely defined. We examined ISRE-binding factors in the regulation of the hIP-10 gene. The requirement of p48 for hIP-10 induction by IFN-gamma, with or without TNF-alpha, was demonstrated using p48-deficient U2A cells. An hIP-10 promoter-reporter mutant (mISRE3) that was relatively deficient for binding a related factor, IFN regulatory factor-1 (IRF-1) but competent for binding p48, was induced as well as the wild-type hIP-10 promoter, supporting the interpretation that p48 played a necessary and sufficient role in hIP-10 transcription. Genomic in vivo footprinting revealed IFN-gamma/TNF-alpha-inducible binding at the ISRE consistent with the presence of p48 and associated factors, but not with IRF-1. Induction of hIP-10 by TNF-alpha/IFN-gamma also required NFkappaB binding sites, which were protected in vivo and bound p65 homodimeric NFkappaB in vitro. These results documented the essential role of p48 (complexed with STAT-1alpha) for induction and sustained transcription of the IP-10 gene, strongly suggesting that IRF-1 is not required for IP-10 induction by these inflammatory cytokines.
Majumder
S
S
Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, OH 44195, USA.
Zhou
L Z
LZ
Chaturvedi
P
P
Babcock
G
G
Aras
S
S
Ransohoff
R M
RM
D001483:Base Sequence; D054357:Chemokine CXCL10; D019743:Chemokines, CXC / Q000096:biosynthesis* / Q000235:genetics; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004357:Drug Synergism; D005354:Fibrosarcoma / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects*; D017930:Genes, Reporter; D006801:Humans; D050856:Interferon Regulatory Factor-1; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D007371:Interferon-gamma / Q000494:pharmacology*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D054357:Chemokine CXCL10; D019743:Chemokines, CXC; D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; C494227:IRF9 protein, human; D050856:Interferon Regulatory Factor-1; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D046911:Macromolecular Substances; D016328:NF-kappa B; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; C079868:gamma interferon activation factor; D007371:Interferon-gamma