E47 activates the Ig-heavy chain and TdT loci in non-B cells.
The E2A proteins, E12 and E47, are basic helix-loop-helix (bHLH) proteins essential for the B-cell lineage. Initially identified as immunoglobulin enhancer-binding proteins, they have also been shown to activate immunoglobulin enhancer-based reporters in transient transfection assays. Here, we examine the relationship between E2A DNA binding activity and activation of the endogenous, chromosomal immunoglobulin heavy chain (IgH) locus. Using sterile I(mu) transcription as an indicator of IgH enhancer activity, we see a direct correlation between E2A DNA binding activity and I(mu) transcription in stable BxT hybrids. We also observe a 1000-fold stimulation of endogenous I(mu) transcription in fibroblasts that express high levels of E47 and less stimulation in cells that express E12. By contrast, none of the other IgH enhancer-binding proteins tested (E2-2, Pu.1, Oct-2, OCA-B, TFE3 and USF) were able to activate I(mu) transcription. E47 overexpression also resulted in transcriptional activation of the endogenous gene encoding TdT, indicating that it, too, is a target of E2A proteins early in the B-cell lineage. Our results indicate that E2A proteins have the distinctive property of activating silent, chromatin-embedded B-cell-specific genes, underscoring their crucial role in B-cell development.
Choi
J K
JK
Department of Genetics and Pathology, University of Pennsylvania School of Medicine, Philadelphia 19104-6145, USA.
Shen
C P
CP
Radomska
H S
HS
Eckhardt
L A
LA
Kadesch
T
T
D016475:3T3 Cells; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D004253:DNA Nucleotidylexotransferase / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D018257:Helix-Loop-Helix Motifs; D007143:Immunoglobulin Heavy Chains / Q000378:metabolism*; D051379:Mice; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000378:metabolism; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D007143:Immunoglobulin Heavy Chains; D051820:TCF Transcription Factors; C544913:Tcf7l1 protein, mouse; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; D004247:DNA; D004253:DNA Nucleotidylexotransferase