The roles of nuclear factor of activated T cells and ying-yang 1 in activation-induced expression of the interferon-gamma promoter in T cells.
Nuclear factor of activated T cells (NFAT) plays an important role in expression of many cytokine genes including interleukin-2 and interleukin-4. However, its role in interferon-gamma (IFN-gamma) expression is not well understood. In the current studies, two strong NFAT-binding sites in the IFN-gamma promoter were identified by DNase I footprint analysis at positions -280 to -270 and -163 to -155. NFATp bound independently to both sites and was required for the formation of a composite element with AP-1 spanning position -163 to -147. In Jurkat T cells and primary lymphocytes, activation-induced expression of IFN-gamma reporter constructs containing point mutations in either NFAT site or the AP-1 component of the composite site was decreased by approximately 40-65%. Despite elimination of both strong NFAT-binding sites, the IFN-gamma promoter remained completely sensitive to inhibition by cyclosporin. This suggests that other elements in the IFN-gamma promoter, such as the IFN-gamma proximal element, are sufficient for cyclosporin sensitivity of this gene. Ying-Yang 1 (YY1), a potential inhibitor of IFN-gamma expression, binds to sites located between the two NFAT sites. Mutation of the YY1 sites alone had little effect on IFN-gamma promoter activity. However, mutation of both the NFAT and YY1-binding sites abolished activation-induced expression in primary murine splenocytes but not in Jurkat T cells. This suggests that under some conditions, YY1 may play a positive role in activation-induced transcription of IFN-gamma.
Sweetser
M T
MT
Department of Pediatrics, University of Washington, Seattle, Washington 98195, USA. msweet@u.washington.edu
Hoey
T
T
Sun
Y L
YL
Weaver
W M
WM
Price
G A
GA
Wilson
C B
CB
D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000235:genetics; D019169:Jurkat Cells; D051379:Mice; D008957:Models, Genetic; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011994:Recombinant Proteins / Q000096:biosynthesis; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D007371:Interferon-gamma; D016572:Cyclosporine