Identification and Characterization of TF1phox, a DNA-binding Protein That Increases Expression of gp91phox in PLB985 Myeloid Leukemia Cells

Abstract

The CYBB gene encodes gp91 phox , the heavy chain of the phagocyte-specific NADPH oxidase. CYBB is transcriptionally inactive until the promyelocyte stage of myelopoiesis, and in mature phagocytes, expression of gp91 phox is further increased by interferon-␥ (IFN-␥) and other inflammatory mediators. The CYBB promoter region contains several lineage-specific cis-elements involved in the IFN-␥ response. We screened a leukocyte cDNA expression library for proteins able to bind to one of these cis-elements (؊214 to ؊262 base pairs) and identified TF1 phox , a protein with sequence-specific binding to the CYBB promoter. Electrophoretic mobility shift assay with nuclear proteins from a variety of cell lines demonstrated binding of a protein to the CYBB promoter that was cross-immunoreactive with TF1 phox . DNA binding of this protein was increased by IFN-␥ treatment in the myeloid cell line PLB985, but not in the non-myeloid cell line HeLa. Overexpression of recombinant TF1 phox in PLB985 cells increased endogenous gp91 phox message abundance, but did not lead to cellular differentiation. Overexpression of TF1 phox in myeloid leukemia cell lines increased reporter gene expression from artificial promoter constructs containing CYBB promoter sequence. These data suggested that TF1 phox increased expression of gp91 phox .

GCN5 Regulates the Superoxide-Generating System in Leukocytes Via Controlling gp91-phox Gene Expression

“…The gp91-phox gene is exclusively expressed in phagocytes and B lymphocytes, and its expression is regulated by cell/tissue-typeand/or development stage-specific mechanisms in hematopoietic cells (15). It is known that the gp91-phox gene expression is regulated via activation of its promoter by several transcriptional factors [i.e., CCAAT-displacement protein (16)(17)(18)(19), CCAATbinding protein-1 (16,18,(20)(21)(22), YY1 (23), IFN regulatory factor-1, IFN regulatory factor-2 (18,20,21), hematopoieticassociated factor-1 (24)(25)(26), PU.1 (25)(26)(27)(28)(29), HOXA9 (30), and NF-kB (31)]. However, the involvement of epigenetic regulation including acetylation levels of core histones in the gp91-phox gene expression remains to be resolved.…”

“…IFN-g enhances interaction of GCN5 with gp91-phox gene promoter and acetylation levels of H2BK16 and H3K9 residues surrounding the promoter Many transcription factors are involved in regulation of the gp91-phox gene expression through their interaction with its promoter region (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). As is well known, HATs play critical roles in modulation of chromatin topology and thereby regulation of gene expression through acetylation of core histones.…”

Eosinophil-specific Regulation of gp91 Gene Expression by Transcription Factors GATA-1 and GATA-2

“…However, these factors may work after bound CDPs are released because their binding sites overlap with sites for CDP (10,11). Interferon regulatory factor-2 may have dual functions as a transcriptional activator and repressor depending on binding sites in gp91 phox gene expression (12,13). TF1 phox , a component of BID-2, displaces CDP and interferon regulatory factor-2, resulting in increased expression of the gp91 phox gene in the myeloid cell lines (13).…”

“…Interferon regulatory factor-2 may have dual functions as a transcriptional activator and repressor depending on binding sites in gp91 phox gene expression (12,13). TF1 phox , a component of BID-2, displaces CDP and interferon regulatory factor-2, resulting in increased expression of the gp91 phox gene in the myeloid cell lines (13). We have shown that PU.1 is an essential activator for the expression of the gp91 phox gene in human neutrophils, monocytes, and B-lymphocytes (14).…”

YY1 Binds Five cis-Elements and Trans-activates the Myeloid Cell-restricted gp91 Promoter

“…Data base searching with the four putative BID-binding sites revealed no common consensus binding sites for known transcription factors. Eklund and Kakar (13) reported the cloning of a novel component of the BID complex (denoted TF1 phox in that report). However, data from Yamit-Hezi et al (14) demonstrate that this clone is a bacterial contaminant present in some commercially available libraries.…”