GATA-1 modulates the chromatin structure and activity of the chicken alpha-globin 3' enhancer.
Long-distance regulatory elements and local chromatin structure are critical for proper regulation of gene expression. Here we characterize the chromatin conformation of the chicken alpha-globin silencer-enhancer elements located 3' of the domain. We found a characteristic and erythrocyte-specific structure between the previously defined silencer and the enhancer, defined by two nuclease hypersensitive sites, which appear when the enhancer is active during erythroid differentiation. Fine mapping of these sites demonstrates the absence of a positioned nucleosome and the association of GATA-1. Functional analyses of episomal vectors, as well as stably integrated constructs, revealed that GATA-1 plays a major role in defining both the chromatin structure and the enhancer activity. We detected a progressive enrichment of histone acetylation on critical enhancer nuclear factor binding sites, in correlation with the formation of an apparent nucleosome-free region. On the basis of these results, we propose that the local chromatin structure of the chicken alpha-globin enhancer plays a central role in its capacity to differentially regulate alpha-globin gene expression during erythroid differentiation and development.
Escamilla-Del-Arenal
Martín
M
Instituto de Fisiología Celular, Departamento de Genética Molecular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, México D.F. 04510, México. .
Recillas-Targa
Félix
F
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002645:Chickens / Q000235:genetics*; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D003850:Deoxyribonuclease I / Q000378:metabolism; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D041905:Erythroid Cells / Q000166:cytology / Q000378:metabolism; D050982:GATA1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D005914:Globins / Q000235:genetics*; D006657:Histones / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009707:Nucleosomes / Q000235:genetics; D011485:Protein Binding; D011499:Protein Processing, Post-Translational
D048868:Adaptor Proteins, Signal Transducing; D002843:Chromatin; D050982:GATA1 Transcription Factor; D006657:Histones; D009707:Nucleosomes; D005914:Globins; D003850:Deoxyribonuclease I