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A (GATA) 7 motif located in the 5′ boundary area of the human β‐globin locus control region exhibits silencer activity in erythroid cells
Author(s) -
Ramchandran Ramani,
Bengra Chikh,
Whitney Barry,
Lanclos Kenneth,
Tuan Dorothy
Publication year - 2000
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/1096-8652(200009)65:1<14::aid-ajh3>3.0.co;2-f
Subject(s) - locus control region , enhancer , microbiology and biotechnology , biology , repressor , mutant , globin , chloramphenicol acetyltransferase , gene , transfection , reporter gene , genetics , gene expression
A 40‐bp DNA, consisting of seven tandem GATA repeats, is located near the HS5 site in the 5′ boundary area of the locus control region (LCR) of human β‐globin gene. This (GATA) 7 motif, named 5a, exhibits silencer activity in erythroid cells. In transfected, recombinant plasmids containing the chloramphenicol acetyltransferase (CAT) reporter gene, 5a repressed the activity of the cis ‐linked housekeeping phosphoglycerate kinase (pgk) promoter; 5a also repressed the activity of the cis ‐linked HS2 enhancer regardless of whether the CAT gene was driven by the pgk or the ϵ‐globin promoter. Repression by 5a was most severe when 5a was spliced upstream of HS2 at a distance of less than 200 bases from the HS2 enhancer core. The silencer activity of 5a was independent of whether the component GATA motifs were in head to tail orientation as in the wild type 5a or in head to head or tail to tail orientation as in a mutant 5a. Band shift experiments show that the GATA‐1 protein binds to both 5a and the mutant 5a and forms a large protein complex. Together, the results suggest that GATA‐1 bound at 5a is a strong, proximal repressor of HS2 enhancer activity. Am. J. Hematol. 65:14–24, 2000. © 2000 Wiley‐Liss, Inc.