Involvement of two regulatory elements in interferon-gamma-regulated expression of human indoleamine 2,3-dioxygenase gene.
Interferon (IFN)-gamma-induced expression of indoleamine 2,3-dioxygenase (IDO) gene is implicated in the antimicrobial and antiproliferative effects of IFN-gamma in cell cultures. Earlier studies identified a 96 base pair (bp) regulatory region upstream of the IDO gene that conferred IFN-gamma response to the chloroamphenicol acetyltransferase (CAT) gene linked to herpesvirus thymidine kinase promoter. The IFN-gamma-responsive region was further narrowed to a 67 bp fragment by 3' deletion. This 67 bp fragment contains several sequence elements of potential interest, including a 14 bp sequence homologous to the ISRE sequence found in IFN-alpha-inducible genes and two palindromic sequences (PE I and PE II) homologous to the GAS sequence identified in IFN-gamma-inducible genes. Site-directed mutagenesis studies showed that IFN-gamma-induced expression of IDO-CAT constructs involved cooperation between two elements: the ISRE homolog and the PE II (but not PE I). Either element alone with its flanking sequence was inadequate in conferring an IFN-gamma response to CAT reporter gene. Two IFN-gamma-regulated protein factors interacting with these two elements were identified. The factor binding to the ISRE region was induced with a slower kinetics, required new protein synthesis, and reacted with antibodies to IRF-1. The factor interacting with the PE II region appeared rapidly after treatment with IFN-gamma independently of new protein synthesis, and its binding to DNA probe was blocked by antibodies to p91 factor, reported to bind to GAS element.(ABSTRACT TRUNCATED AT 250 WORDS)
Chon
S Y
SY
Hipple Cancer Research Center, Dayton, OH 45439, USA.
Hassanain
H H
HH
Pine
R
R
Gupta
S L
SL
D016375:Antisense Elements (Genetics); D001483:Base Sequence; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005809:Genes, Regulator; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D007371:Interferon-gamma / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D014162:Transfection; D014366:Tryptophan Oxygenase / Q000235:genetics*
D016375:Antisense Elements (Genetics); D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D007371:Interferon-gamma; D014366:Tryptophan Oxygenase