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Protein-DNA interactions upstream from the human A gamma globin gene
D O'Neill1, J Kaysen, M Donovan-Peluso
1Department of Genetics, Columbia University, New York, NY 10032.
Nucleic Acids Research
|April 25, 1990
Summary
Researchers studied proteins binding to the human A gamma globin gene promoter. They found that OTF-1 may repress gamma globin transcription by competing with NFE-1 for a key binding site.
Area of Science:
- Molecular Biology
- Genetics
- Gene Regulation
Background:
- The human A gamma globin gene plays a crucial role in fetal hemoglobin production.
- Understanding the regulation of gamma globin gene expression is vital for studying hemoglobinopathies like hereditary persistence of fetal hemoglobin.
Purpose of the Study:
- To identify and characterize proteins that bind to promoter elements of the human A gamma globin gene.
- To investigate the roles of specific transcription factors, OTF-1 and NFE-1, in gamma globin gene regulation.
Main Methods:
- DNAase I footprinting assay to map protein-binding sites on the DNA.
- Gel mobility shift assay to study protein-DNA interactions.
- Analysis of nuclear extracts from both erythroid and nonerythroid cells.
Main Results:
- Identified three protein-binding sites between -140 and -382 upstream of the A gamma globin gene.
- Discovered an erythroid-specific footprint between -194 and -189.
- Demonstrated that OTF-1 and NFE-1 bind to the -194 to -172 region, with overlapping footprints.
- Showed that a mutation at -175, linked to hereditary persistence of fetal hemoglobin, reduces OTF-1 binding.
Conclusions:
- OTF-1 and NFE-1 are key transcription factors binding to the A gamma globin gene promoter.
- OTF-1 may compete with NFE-1 for the -175 binding site.
- OTF-1 might function as a repressor of gamma globin transcription, potentially explaining its role in hereditary persistence of fetal hemoglobin.