title: SCL assembles a multifactorial complex that determines glycophorin A expression.
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.
authors.affiliation: Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada.
authors.forename: Rachid
authors.initials: R
authors.lastname: Lahlil
authors.forename: Eric
authors.initials: E
authors.lastname: Lécuyer
authors.forename: Sabine
authors.initials: S
authors.lastname: Herblot
authors.forename: Trang
authors.initials: T
authors.lastname: Hoang
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; D005786:Gene Expression Regulation; D006021:Glycophorins / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D060588:LIM Domain Proteins; D046911:Macromolecular Substances; D008667:Metalloproteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D020218:Response Elements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000378:metabolism; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; D006021:Glycophorins; D060588:LIM Domain Proteins; D046911:Macromolecular Substances; D008667:Metalloproteins; D011518:Proto-Oncogene Proteins; D016329:Sp1 Transcription Factor; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; C494689:Gata1 protein, mouse; C486312:LDB1 protein, human; C102084:Ldb1 protein, mouse; C513188:Lmo2 protein, mouse; C544912:TCF7L1 protein, human; C489366:Tal1 protein, mouse; C544913:Tcf7l1 protein, mouse