EBF‐regulating Pax5 transcription is enhanced by STAT5 in the early stage of B cells

Abstract

Pax5 is an essential transcription factor for B cell development, and it is reported that Pax5 expression was reduced in the IL-7 receptor (IL-7R) knockout mouse. To investigate whether signals from the IL-7R regulate Pax5 transcription, we searched the consensus sequence of signal transducers and activators of transcription (STAT) in the Pax5 promoter region, since STAT is one of the components of cytokine signal transduction. A STAT-binding motif, termed SBM, was identified at 1,118 bp upstream of the transcriptional start site, and SBM completely overlapped with the binding site for early B cell factor (EBF). STAT5 was phosphorylated in the presence of IL-7 in the IL-7-dependent preB cell line, PreBR1, and phosphorylated-STAT5 as well as EBF was found to bind to the SBM. Moreover, we also revealed STAT5 binding to SBM in PreBR1 cells by chromatin immunoprecipitation assay. Transient co-transfection of reporter genes together with expression vectors of a constitutive active form of STAT5 and EBF into NIH3T3 cells demonstrated that STAT5 enhanced EBFregulating transcription. Our results suggest that STAT5 phosphorylated by IL-7 can directly up-regulate Pax5 transcription in early B cells.

Characterization of Transcription Factor Binding to Human Papillomavirus Type 16 DNA during Cellular Differentiation

“…The Wilms' tumor gene product (WT1) is known to be associated with tumor progression (20), and its interaction with the HPV-16 promoter regions could represent an additional mechanism by which this factor may promote carcinogenesis. TFs such as C-Myb, NFATx, and Pax5 are known to play important roles in development and/or differentiation (18,28,33). Expression of the C-Myb and Pax5 protein was not detectable in the 20863 epithelial cells before differentiation but was induced during differentiation, as shown by Western blot analysis (Fig.…”

Ebf1-mediated down-regulation of Id2 and Id3 is essential for specification of the B cell lineage

“…Observations showing that E2A is present (albeit at reduced levels) in Ebf1 knockout animals (3) and that the Ebf1 promoter is bound by E47 in vivo (11,12) and can be transactivated by overexpression of E47 (13) or E12 (14) in non-B-lineage cell lines, suggest that E2A activity is essential upstream of Ebf1. Similarly, the Pax5 promoter is bound by Ebf1 based on EMSA and Ebf1 can transactivate the Pax5 promoter in transient co-transfection assays (15,16). Ebf1 is also present in Pax5-deficient pro-B cells derived from Pax5 Ϫ/Ϫ adult mice (17), suggesting that Ebf1 may participate in the activation of Pax5 expression.…”

The Survival and Differentiation of Pro-B and Pre-B Cells in the Bone Marrow Is Dependent on IL-7Rα Tyr449

“…PU1 is initially transcribed at the common lymphoid progenitor (CLP) stage, followed by Ebf1 in the Ly6D + CLP (22,23), Pax5 at the pro-B (24), and Irf4/8 at the pre-B cell stage (25). PU1 expression in CLPs initiates IL-7Ra expression, which contributes to B cell lineage specification via STAT5-mediated expression of Ebf1 and Pax5 (26,27). Pro-B cells from either Ebf1 2/2 or Pax5 2/2 mice do not commit to the B cell lineage (10,28).…”