Nuclear factor of activated T cells and YY1 combine to repress IL-5 expression in a human T-cell line.
BACKGROUND
IL-5 is an inducible T-cell cytokine with the unique ability to induce eosinophilia without increases in other cell compartments. Regulation of IL-5 expression is controlled primarily at the level of transcription. The role of eosinophilia in allergic disorders indicates IL-5 as a target for therapy.


OBJECTIVE
This report aims to increase our understanding of IL-5 gene regulation by identifying distal control elements in the human (h) IL-5 promoter, determining the transcription factors that bind these elements and elucidating their role in control of hIL-5 gene expression.


METHODS
Methods used in this study include deoxyribonuclease I footprint analysis, electrophoretic mobility shift assay, and functional analysis by transfection of PER-117 cells with site-directed mutants of the hIL-5 promoter.


RESULTS
We have identified a protected region in the distal hIL-5 promoter that has sequence homology to the previously identified negative regulatory element within BR3. This protected region has not been previously reported and is shown to contain overlapping binding sites for YY1 and nuclear factor of activated cells. The binding sites exist between positions -447 and -459, and this sequence was named hPRE2-IL5. Substitution mutations that abolish binding of these proteins to hPRE2-IL5 result in a 2- to 3-fold increase in hIL-5 promoter activity in activated human T cells.


CONCLUSIONS
We report the novel combination of YY1 and nuclear factor of activated T cells transcription factors binding to a distal hIL-5 promoter element where both factors are involved in down-regulation of hIL-5 gene expression in human T cell.
Schwenger
G T
GT
Curtin University of Technology, Perth, Australia.
Fournier
R
R
Hall
L M
LM
Sanderson
C J
CJ
Mordvinov
V A
VA
D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D016384:Consensus Sequence; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism*; D050981:Erythroid-Specific DNA-Binding Factors; D005786:Gene Expression Regulation; D006801:Humans; D015848:Interleukin-5 / Q000235:genetics*; D008957:Models, Genetic; D016297:Mutagenesis, Site-Directed; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D013601:T-Lymphocytes / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*; D050986:YY1 Transcription Factor
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D015848:Interleukin-5; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D014157:Transcription Factors; D050986:YY1 Transcription Factor; C494698:YY1 protein, human