High Frequency of Matrix Attachment Regions and Cut-Like Protein x/CCAAT-Displacement Protein and B Cell Regulator of IgH Transcription Binding Sites Flanking Ig V Region Genes

Goebel, Peter; Montalbano, Alina P.; Ayers, Neil; Kompfner, Elizabeth; Dickinson, Liliane A.; Webb, Carol F.; Feeney, Ann J.

doi:10.4049/jimmunol.169.5.2477

Cited by 33 publications

(33 citation statements)

References 73 publications

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“…These data support the findings from the in vitro model system and suggest that endogenous Bright and Btk can be inhibited by dominant negative forms of TFII-I. However, it is not clear whether TFII-I/Bright/Btk complexes are important for the transcription of all immunoglobulin heavy-chain genes, as some V H promoter-flanking regions do not contain obvious Bright binding sites (14). Nonetheless, a model for Bright-enhanced activation of at least some Ig genes involving Bright DNA-binding activity-interaction of Bright with TFII-I/Btk and subsequent phosphorylation of TFII-I by Btk-can be envisioned.…”

Section: Discussionsupporting

confidence: 77%

Induction of Immunoglobulin Heavy-Chain Transcription through the Transcription Factor Bright Requires TFII-I

Rajaiya

Nixon

Ayers

et al. 2006

Molecular and Cellular Biology

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Bright/ARID3a/Dril1, a member of the ARID family of transcription factors, is expressed in a highly regulated fashion in B lymphocytes, where it enhances immunoglobulin transcription three-to sixfold. Recent publications from our lab indicated that functional, but not kinase-inactive, Bruton's tyrosine kinase (Btk) is critical for Bright activity in an in vitro model system, yet Bright itself is not appreciably tyrosine phosphorylated. These data suggested that a third protein, and Btk substrate, must contribute to Bright-enhanced immunoglobulin transcription. The ubiquitously expressed transcription factor TFII-I was identified as a substrate for Btk several years ago. In this work, we show that TFII-I directly interacts with human Bright through amino acids in Bright's protein interaction domain and that specific tyrosine residues of TFII-I are essential for Bright-induced activity of an immunoglobulin reporter gene. Moreover, inhibition of TFII-I function in a B-cell line resulted in decreased heavy-chain transcript levels. These data suggest that Bright functions as a three-component protein complex in the immunoglobulin locus and tie together previous data indicating important roles for Btk and TFII-I in B lymphocytes.The transcription factor Bright (B-cell regulator of immunoglobulin H [IgH] transcription)/ARID3a/Dril1 is a B-cellspecific protein first discovered in a mature mouse B-cell line, BCg3R1-d, as a mobility-shifted protein complex that caused three-to sixfold increases in heavy-chain mRNA levels in response to stimulation with a T-dependent antigen and interleukin-5 (42, 43). Bright binds to AϩT-rich regions of the intronic heavy-chain enhancer previously identified as matrix association regions and to regions 5Ј of some variable heavychain (V H ) promoters, including the V1 S107 family gene (15,43). The cDNA for Bright was isolated in 1995, and the protein was shown to interact with DNA as a multimeric complex that included multiple copies of Bright (15). The Bright protein structure consists of an acidic N-terminal domain of unknown function, a DNA-binding AϩT-rich interaction domain (ARID), a putative transactivation domain, a protein interaction domain containing a helix-turn-helix region, and a small carboxyl-terminal domain with no assigned function.Earlier studies indicated that Bruton's tyrosine kinase (Btk), the defective enzyme in X-linked immunodeficiency disease in both mice and humans, is a component of the Bright DNAbinding complex (28, 44). X-linked immunodeficiency disease in mice, or X-linked agammaglobulinemia (XLA) in humans, results in blocks in B-lymphocyte development that ultimately lead to a deficient production of serum antibodies (9,33,40). Patients with XLA are unable to fight normal bacterial infections without frequent intravenous Ig treatments. Although Btk was identified as the genetic defect in XLA many years ago, the mechanism by which Btk deficiencies lead to early blocks at the pro-B-to pre-B-lymphocyte stages in humans remains unclear.Recently, an in vitro mode...

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Section: Discussionsupporting

confidence: 77%

Induction of Immunoglobulin Heavy-Chain Transcription through the Transcription Factor Bright Requires TFII-I

Rajaiya

Nixon

Ayers

et al. 2006

Molecular and Cellular Biology

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“…As with other MAR binding proteins, Bright binds to ATC-rich sequences within MARs and, as such, became the founding member of the 15-membered (in humans and mice) ARID (AT-Rich Interacting Domain) family (reviewed in reference 42). However, while most ARID members bind AT-rich DNA relatively nonspecifically (28), Bright and its other ARID3 paralogue, Bright Dri-like protein (Bdp), show highly restricted specificity for an extended ATC-rich consensus found in promoter-associated MARs of some but not all variable region (V H ) gene segments (13,16) and within the MARs flanking the intronic enhancer (16). This specificity is engendered, at least in part, by the ability of ARID3 proteins to homo-oligomerize through a region conserved only in ARID3 termed the REKLES domain (reviewed in reference 41).…”

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confidence: 99%

A Regulated Nucleocytoplasmic Shuttle Contributes to Bright's Function as a Transcriptional Activator of Immunoglobulin Genes

Kim

Tucker

2006

Molecular and Cellular Biology

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Bright/ARID3a has been implicated in mitogen-and growth factor-induced up-regulation of immunoglobulin heavy-chain (IgH) genes and in E2F1-dependent G 1 /S cell cycle progression. For IgH transactivation, Bright binds to nuclear matrix association regions upstream of certain variable region promoters and flanking the IgH intronic enhancer. While Bright protein was previously shown to reside within the nuclear matrix, we show here that a significant amount of Bright resides in the cytoplasm of normal and transformed B cells. Leptomycin B, chromosome region maintenance 1 (CRM1) overexpression, and heterokaryon experiments indicate that Bright actively shuttles between the nucleus and the cytoplasm in a CRM1-dependent manner. We mapped the functional nuclear localization signal to the N-terminal region of REKLES, a domain conserved within ARID3 paralogues. Residues within the C terminus of REKLES contain its nuclear export signal, whose regulation is primarily responsible for Bright shuttling. Growth factor depletion and cell synchronization experiments indicated that Bright shuttling during S phase of the cell cycle leads to an increase in its nuclear abundance. Finally, we show that shuttle-incompetent Bright point mutants, even if sequestered within the nucleus, are incapable of transactivating an IgH reporter gene. Therefore, regulation of Bright's cellular localization appears to be required for its function.Confinement of biomolecules within compartments is an important feature of eukaryotic cells, because each compartment has its own specific functions (8,20,45). For all transcription factors, translocation to the nucleus is an essential process. Transport into or out of the nucleus takes place through large multiprotein structures, termed nuclear pores, that span the nuclear envelope. Small proteins (less than 40 to 60 kDa) can enter the nucleus by passive diffusion following a concentration gradient, although notable exceptions include histones (45). In most cases, molecules of more than 40 to 60 kDa are actively transported across nuclear pore complexes. Nuclear import of a protein is mediated by a nuclear localization signal (NLS), and the best known NLS is a stretch of basic amino acids, such as that found in the simian virus 40 (SV40) large T-antigen NLS (4). However, not all proteins that carry an NLS motif are nuclear (9), and conversely, noncanonical NLSs have been reported (17,30,36). Proteins exported from the nucleus to the cytoplasm require a nuclear export signal (NES). The most common type of NES is a leucine-rich hydrophobic amino acid stretch, such as LX 1-3 LX 2-4 LXL, which is recognized and bound by the export receptor, chromosome region maintenance 1 (CRM1)/exportin 1 (6, 34). Covalent binding of CRM1 by the antibiotic leptomycin B (LMB) inhibits CRM1-dependent nuclear export of NES-containing proteins (11), resulting in their nuclear accumulation. Therefore, LMB has been used extensively to examine the existence of CRM1-dependent NES activity.Bright is a transcription factor discovered ...

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“…As part of a potential novel 5Ј Igh regulatory region, HS2 could thus protect neighboring sequences from recombination events or accessibility changes associated with these events. Sequence analysis of HS3a revealed binding motifs for cut-like protein x/CCAAT-displacement proteins (Cux/CDP) and special ATrich sequence binding protein (SATB1), both factors frequently colocalized with matrix attachment regions (80). An intriguing possibility is that HS3a has a role in defining chromatin borders necessary for V(D)J recombination and Igh expression.…”

Section: Discussionmentioning

confidence: 99%

Identification of a Candidate Regulatory Element within the 5′ Flanking Region of the MouseIghLocus Defined by Pro-B Cell-Specific Hypersensitivity Associated with Binding of PU.1, Pax5, and E2A

Pawlitzky

Angeles

Siegel

et al. 2006

The Journal of Immunology

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The Igh locus is controlled by cis-acting elements, including Eμ and the 3′ IgH regulatory region which flank the C region genes within the well-studied 3′ part of the locus. Although the presence of additional control elements has been postulated to regulate rearrangements of the VH gene array that extends to the 5′ end of the locus, the 5′ border of Igh and its flanking region have not been characterized. To facilitate the analysis of this unexplored region and to identify potential novel control elements, we physically mapped the most D-distal VH segments and scanned 46 kb of the immediate 5′ flanking region for DNase I hypersensitive sites. Our studies revealed a cluster of hypersensitive sites 30 kb upstream of the most 5′ VH gene. Detection of one site, HS1, is restricted to pro-B cell lines and HS1 is accessible to restriction enzyme digestion exclusively in normal pro-B cells, the stage defined by actively rearranging Igh-V loci. Sequence motifs within HS1 for PU.1, Pax5, and E2A bind these proteins in vitro and these factors are recruited to HS1 sequence only in pro-B cells. Transient transfection assays indicate that the Pax5 binding site is required for the repression of transcriptional activity of HS1-containing constructs. Thus, our characterization of the region 5′ of the VH gene cluster demonstrated the presence of a single cluster of DNase I hypersensitive sites within the 5′ flanking region, and identified a candidate Igh regulatory region defined by pro-B cell-specific hypersensitivity and interaction with factors implicated in regulating V(D)J recombination.

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High Frequency of Matrix Attachment Regions and Cut-Like Protein x/CCAAT-Displacement Protein and B Cell Regulator of IgH Transcription Binding Sites Flanking Ig V Region Genes

Cited by 33 publications

References 73 publications

Induction of Immunoglobulin Heavy-Chain Transcription through the Transcription Factor Bright Requires TFII-I

Induction of Immunoglobulin Heavy-Chain Transcription through the Transcription Factor Bright Requires TFII-I

A Regulated Nucleocytoplasmic Shuttle Contributes to Bright's Function as a Transcriptional Activator of Immunoglobulin Genes

Identification of a Candidate Regulatory Element within the 5′ Flanking Region of the MouseIghLocus Defined by Pro-B Cell-Specific Hypersensitivity Associated with Binding of PU.1, Pax5, and E2A

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