Chromatin remodeling of the interleukin-2 gene: distinct alterations in the proximal versus distal enhancer regions.
Known transcription factor-DNA interactions in the minimal enhancer of the murine interleukin-2 gene (IL-2) do not easily explain the T cell specificity of IL-2 regulation. To seek additional determinants of cell type specificity, in vivo methodologies were employed to examine chromatin structure 5' and 3' of the 300 bp IL-2 proximal promoter/enhancer region. Restriction enzyme accessibility revealed that until stimulation the IL-2 proximal promoter/enhancer exists in a closed conformation in resting T and non-T cells alike. Within this promoter region, DMS and DNase I genomic footprinting also showed no tissue-specific differences prior to stimulation. However, DNase I footprinting of the distal -600 to -300 bp region revealed multiple tissue-specific and stimulation-independent DNase I hypersensitive sites. Gel shift assays detected T cell-specific complexes binding within this region, which include TCF/LEF or HMG family and probable Oct family components. Upon stimulation, new DNase I hypersensitive sites appeared in both the proximal and distal enhancer regions, implying that there may be a functional interaction between these two domains. These studies indicate that a region outside the established IL-2 minimal enhancer may serve as a stable nucleation site for tissue-specific factors and as a potential initiation site for activation-dependent chromatin remodeling.
Ward
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SB
Division of Biology MC156-29, California Institute of Technology, Pasadena, CA 91125, USA.
Hernandez-Hoyos
G
G
Chen
F
F
Waterman
M
M
Reeves
R
R
Rothenberg
E V
EV
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002843:Chromatin / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D018983:DNA Footprinting / Q000379:methods; D004268:DNA-Binding Proteins / Q000378:metabolism; D003850:Deoxyribonuclease I; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005796:Genes / Q000276:immunology; D006609:High Mobility Group Proteins / Q000378:metabolism; D007376:Interleukin-2 / Q000235:genetics* / Q000276:immunology; D008213:Lymphocyte Activation; D051821:Lymphoid Enhancer-Binding Factor 1; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D013601:T-Lymphocytes / Q000276:immunology*; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics / Q000276:immunology*
D002843:Chromatin; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D007376:Interleukin-2; D051821:Lymphoid Enhancer-Binding Factor 1; D014157:Transcription Factors; D004247:DNA; D003850:Deoxyribonuclease I