Abstract
SCL/TAL1 is a hematopoietic-specific transcription factor of the basic helix-loop-helix (bHLH) family that is essential for erythropoiesis. Here we identify the erythroid cell-specific glycophorin A gene (GPA) as a target of SCL in primary hematopoietic cells and show that SCL occupies the GPA locus in vivo. GPA promoter activation is dependent on the assembly of a multifactorial complex containing SCL as well as ubiquitous (E47, Sp1, and Ldb1) and tissue-specific (LMO2 and GATA-1) transcription factors. In addition, our observations suggest functional specialization within this complex, as SCL provides its HLH protein interaction motif, GATA-1 exerts a DNA-tethering function through its binding to a critical GATA element in the GPA promoter, and E47 requires its N-terminal moiety (most likely entailing a transactivation function). Finally, endogenous GPA expression is disrupted in hematopoietic cells through the dominant-inhibitory effect of a truncated form of E47 (E47-bHLH) on E-protein activity or of FOG (Friend of GATA) on GATA activity or when LMO2 or Ldb-1 protein levels are decreased. Together, these observations reveal the functional complementarities of transcription factors within the SCL complex and the essential role of SCL as a nucleation factor within a higher-order complex required to activate gene GPA expression.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing
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Animals
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Base Sequence
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Basic Helix-Loop-Helix Transcription Factors
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Binding Sites
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Cell Line
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / metabolism*
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Electrophoretic Mobility Shift Assay
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Erythroid-Specific DNA-Binding Factors
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GATA1 Transcription Factor
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Gene Expression Regulation*
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Glycophorins / genetics*
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Hematopoietic Stem Cells / metabolism
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LIM Domain Proteins
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Macromolecular Substances
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Metalloproteins / metabolism
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Mice
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Molecular Sequence Data
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Promoter Regions, Genetic / genetics
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Protein Binding
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Protein Structure, Tertiary
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Proto-Oncogene Proteins / chemistry
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Proto-Oncogene Proteins / metabolism*
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Response Elements
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Reverse Transcriptase Polymerase Chain Reaction
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Sp1 Transcription Factor / metabolism
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T-Cell Acute Lymphocytic Leukemia Protein 1
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TCF Transcription Factors
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Transcription Factor 7-Like 1 Protein
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Transcription Factors / chemistry
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Transcription Factors / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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Basic Helix-Loop-Helix Transcription Factors
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DNA-Binding Proteins
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Erythroid-Specific DNA-Binding Factors
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GATA1 Transcription Factor
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Gata1 protein, mouse
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Glycophorins
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LDB1 protein, human
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LIM Domain Proteins
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Ldb1 protein, mouse
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Lmo2 protein, mouse
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Macromolecular Substances
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Metalloproteins
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Proto-Oncogene Proteins
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Sp1 Transcription Factor
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T-Cell Acute Lymphocytic Leukemia Protein 1
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TCF Transcription Factors
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TCF7L1 protein, human
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Tal1 protein, mouse
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Tcf7l1 protein, mouse
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Transcription Factor 7-Like 1 Protein
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Transcription Factors