Abstract
Long-range interactions between distant regulatory elements, such as enhancers, and their target genes underlie the specificity of gene expression in many developmentally regulated gene families. NLI/Ldb1, a widely expressed nuclear factor, is a potential mediator of long-range interactions. Here, we show that NLI/Ldb1 and erythroid-binding partners GATA-1/SCL/LMO2 bind in vivo to the beta-globin locus control region (LCR). The C-terminal LIM interaction domain of NLI is required for formation of the complex on chromatin. Loss of the LIM domain converts NLI into a dominant-negative inhibitor of globin gene expression, and knockdown of NLI by using shRNA results in failure to activate beta-globin expression. Kinetic studies reveal that the NLI/GATA-1/SCL/LMO2 complex is detected at the beta-globin promoter coincident with RNA Pol II recruitment, beta-globin transcription, and chromatin loop formation during erythroid differentiation, providing evidence that NLI facilitates long-range gene activation.
Publication types
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Research Support, N.I.H., Intramural
MeSH terms
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Adaptor Proteins, Signal Transducing
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Basic Helix-Loop-Helix Transcription Factors / genetics
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Basic Helix-Loop-Helix Transcription Factors / metabolism
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Cell Differentiation
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Chromatin / metabolism
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Chromatin Immunoprecipitation
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DNA-Binding Proteins / antagonists & inhibitors
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DNA-Binding Proteins / genetics*
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DNA-Binding Proteins / metabolism
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Erythroid Cells / metabolism
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GATA1 Transcription Factor / genetics
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GATA1 Transcription Factor / metabolism
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Gene Expression Regulation*
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Globins / genetics*
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Globins / metabolism
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Humans
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Immunoblotting
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Immunoprecipitation
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Kinetics
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LIM Domain Proteins
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Locus Control Region*
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Metalloproteins / genetics
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Metalloproteins / metabolism
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Promoter Regions, Genetic
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism
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RNA Polymerase II / metabolism
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RNA, Small Interfering / pharmacology
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Regulatory Sequences, Nucleic Acid
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T-Cell Acute Lymphocytic Leukemia Protein 1
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Transcription Factors
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Transcription, Genetic
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Transcriptional Activation
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Tumor Cells, Cultured
Substances
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Adaptor Proteins, Signal Transducing
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Basic Helix-Loop-Helix Transcription Factors
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Chromatin
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DNA-Binding Proteins
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GATA1 Transcription Factor
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GATA1 protein, human
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LDB1 protein, human
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LIM Domain Proteins
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LMO2 protein, human
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Metalloproteins
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Proto-Oncogene Proteins
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RNA, Small Interfering
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T-Cell Acute Lymphocytic Leukemia Protein 1
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Transcription Factors
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TAL1 protein, human
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Globins
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RNA Polymerase II