Abnormal IL-4 gene expression by atopic dermatitis T lymphocytes is reflected in altered nuclear protein interactions with IL-4 transcriptional regulatory element.
Among the atopic disease, atopic dermatitis is characterized by the highest levels of serum IgE and by increased peripheral blood T-cell interleukin-4 (IL-4) production. IL-4 promotes IgE synthesis by B cells and stimulates the growth of IL-4-producing T cells and may contribute to the pathogenesis of this disease. In this study, in situ hybridization established that atopic dermatitis patients have a higher frequency of IL-4-producing peripheral blood T cell when compared to normal subjects. These in vivo-derived T cells were used to examine the signaling requirements of IL-4 production and the nuclear factors that associate with a critical IL-4 transcriptional regulatory element between -88 and -60 relative to the IL-4 transcription initiation site, the activation responsive element. We demonstrate that, as in T-cell lines, proteins belonging to the NF-AT and AP-1 family of transcription factors are present in stimulated cell extracts and specifically associate with the activation responsive element. Dysregulated IL-4 production is reflected in the nuclear proteins that associated this element. Using gel shift assays, we found that 12 of 12 nuclear extracts from stimulated atopic T cells formed the activation-dependent protein-DNA complex, compared to only 2 of 12 normal T-cell extracts. Activation complex formation correlated with the relative level of IL-4 mRNA and protein produced in stimulated T cells, suggesting that abnormal IL-4 gene expression in atopic disease may be linked to alterations in nuclear protein interactions with these promoter elements.
Chan
S C
SC
Department of Medicine, Oregon Health Sciences University, Portland 97201-3098, USA.
Brown
M A
MA
Willcox
T M
TM
Li
S H
SH
Stevens
S R
SR
Tara
D
D
Hanifin
J M
JM
D001483:Base Sequence; D001665:Binding Sites; D003876:Dermatitis, Atopic / Q000276:immunology*; D006801:Humans; D015847:Interleukin-4 / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D013601:T-Lymphocytes / Q000378:metabolism*
D009687:Nuclear Proteins; D015847:Interleukin-4