In vitro activation of a transcription factor by gamma interferon requires a membrane-associated tyrosine kinase and is mimicked by vanadate.
Gamma interferon (IFN-gamma) activates the formation of a DNA-binding protein complex (FcRF gamma) that recognizes the gamma response region (GRR) of the promoter for the human high-affinity Fc gamma receptor. In a membrane-enriched fraction prepared from human peripheral blood monocytes, IFN-gamma activation of FcRF gamma occurred within 1 min and was ATP dependent. Activation of FcRF gamma required a tyrosine kinase activity, and recognition of the GRR sequence by FcRF gamma could be abrogated by treatment with a tyrosine-specific protein phosphatase. Treatment of cells with vanadate alone resulted in the formation of FcRF gamma without the need for IFN-gamma. UV cross-linking and antibody competition experiments demonstrated that the FcRF gamma complex was composed of at least two components: the 91-kDa protein of the IFN-alpha-induced transcription complex ISGF3 and a 43-kDa component that bound directly to the GRR. Therefore, specificity for IFN-induced transcriptional activation of early response genes requires at least two events: (i) ligand-induced activation of membrane-associated protein by tyrosine phosphorylation and (ii) formation of a complex composed of an activated membrane protein(s) and a sequence-specific DNA-binding component.
Igarashi
K
K
Division of Cytokine Biology, Food and Drug Administration, Bethesda, Maryland 20892.
David
M
M
Larner
A C
AC
Finbloom
D S
DS
D001483:Base Sequence; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D004247:DNA; D005786:Gene Expression Regulation; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D007700:Kinetics; D008969:Molecular Sequence Data; D009000:Monocytes; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011961:Receptors, Fc / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014638:Vanadates / Q000494:pharmacology*
D011961:Receptors, Fc; D014157:Transcription Factors; D014638:Vanadates; D007371:Interferon-gamma; D004247:DNA; D011505:Protein-Tyrosine Kinases