A novel enhancer in the immunoglobulin lambda locus is duplicated and functionally independent of NF kappa B.

Hagman, James; Rudin, Charles M.; Haasch, Deanna L.; Chaplin, David; Storb, Ursula

doi:10.1101/gad.4.6.978

Cited by 104 publications

(71 citation statements)

References 80 publications

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“…We speculate that the reason for the differential requirement of PU.1 and/or Spi-B for the Ig vs the Ig and IgH genes might be the nature of the enhancers present in these loci. The Ig locus contains two enhancers that are nearly identical, and are believed to have arisen by gene duplication (57). Both of these enhancers contain PU.1-IRF-4 composite binding sites and therefore the cumulative effect of loss of PU.1 and/or Spi-B activity may be significant impairment of enhancer function (26).…”

Section: Discussionmentioning

confidence: 99%

Analysis of Gene Expression and Ig Transcription in PU.1/Spi-B-Deficient Progenitor B Cell Lines

Schweitzer

DeKoter

2004

The Journal of Immunology

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A number of presumptive target genes for the Ets-family transcription factor PU.1 have been identified in the B cell lineage. However, the precise function of PU.1 in B cells has not been studied because targeted null mutation of the PU.1 gene results in a block to lymphomyeloid development at an early developmental stage. In this study, we take advantage of recently developed PU.1−/−Spi-B−/− IL-7 and stromal cell-dependent progenitor B (pro-B) cell lines to analyze the function of PU.1 and Spi-B in B cell development. We show that contrary to previously published expectations, PU.1 and/or Spi-B are not required for Ig H chain (IgH) gene transcription in pro-B cells. In fact, PU.1−/−Spi-B−/− pro-B cells have increased levels of IgH transcription compared with wild-type pro-B cells. In addition, high levels of Igκ transcription are induced after IL-7 withdrawal of wild-type or PU.1−/−Spi-B−/− pro-B cells. In contrast, we found that Igλ transcription is reduced in PU.1−/−Spi-B−/− pro-B cells relative to wild-type pro-B cells after IL-7 withdrawal. These results suggest that Igλ, but not IgH or Igκ, transcription, is dependent on PU.1 and/or Spi-B. The PU.1−/−Spi-B−/− pro-B cells have other phenotypic changes relative to wild-type pro-B cells including increased proliferation, increased CD25 expression, decreased c-Kit expression, and decreased RAG-1 expression. Taken together, our observations suggest that reduction of PU.1 and/or Spi-B activity in pro-B cells promotes their differentiation to a stage intermediate between late pro-B cells and large pre-B cells.

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Section: Discussionmentioning

confidence: 99%

Analysis of Gene Expression and Ig Transcription in PU.1/Spi-B-Deficient Progenitor B Cell Lines

Schweitzer

DeKoter

2004

The Journal of Immunology

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“…Ig light-chain gene transcription and recombination are dependent on the activity of several enhancer elements (Hagman et al 1990;Gorman et al 1996;Xu et al 1996;Inlay et al 2002). The locus has two distinct enhancers (Ei and E3Ј ), whereas the locus has two duplicated enhancers (E 2-4, E 3-1).…”

Section: Irf-48 −/− Pre-b Cells Are Impaired For Light-chain Gene Trmentioning

confidence: 99%

IRF-4,8 orchestrate the pre-B-to-B transition in lymphocyte development

Lu¹,

Medina²,

Lancki³

et al. 2003

Genes Dev.

236

229

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IRF-4,8 are two specialized members of the interferon regulatory factor (IRF) family that have been implicated in regulating immunoglobulin (Ig) light-chain gene transcription during B-lymphocyte development (Pongubala et al. 1992;Eisenbeis et al. 1995;Shaffer et al. 1997;Brass et al. 1999; Muljo and Schlissel 2002). They are more highly related to one another than to other IRFs and are selectively expressed in the lymphoid and myeloid lineages of the immune system (for review, see Taniguchi et al. 2001). IRF-4,8 bind very weakly to DNA-containing IRF sites, but are recruited to their binding sites via interactions with other transcription factors. In particular, the related Ets family transcription factors PU.1 and Spi-B have been shown to recruit IRF-4 or IRF-8 to Ets-IRF composite elements (EICE) in Ig 3Ј and enhancers (Pongubala et al. 1992;Eisenbeis et al. 1995;Brass et al. 1999;Escalante et al. 2002). These heterodimeric protein complexes have been implicated in the control of Ig light-chain gene transcription. PU.1 is required for early B-cell development and Spi-B is important for B-cell activation (Scott et al. 1994;Su et al. 1997). It remains to be determined whether PU.1/Spi-B regulate Ig light-chain gene expression during the pre-B-to-B transition. IRF-4 −/− mutant mice exhibit profound defects in B-and T-cell activation that are manifested in the failure to mount antibody, cytotoxic, or antitumor responses (Mittrucker et al. 1997;Rengarajan et al. 2002). IRF-8 −/− mutant mice are impaired in macrophage development, highly susceptible to viral infections, and manifest a chronic myelogenous leukemia-like syndrome (Holtschke et al. 1996). Loss of either IRF-4 or IRF-8 does not block the generation of B lymphocytes. Given their structural relatedness and similar molecular properties, we sought to examine whether they function redundantly to regulate Ig lightchain gene expression and the pre-B-to-B transition. (Fig. 1A). Strikingly, the double mutant mice lacked sIgM + peripheral B lymphocytes (Fig. 1B). In contrast, splenic T lymphocytes, (CD4 + or CD8 + ) were present in the double mutant mice, albeit with reduced numbers (Fig. 1C). We note that loss of IRF-4 and IRF-8 does not impair T-cell development in the thymus (data not shown). We next examined B-cell generation in the bone marrow. Immature IgM + B cells were absent in the IRF-4,8 −/− bone marrow (Fig. 1D). These results establish that the combined loss of IRF-4,8 causes a lineage-specific block to B-cell development. It should be noted that as is the case for IRF-8 −/− mice, there was an increase in the numbers of myeloid cells Fig. 2A). The levels of HSA expression on the mutant B220 + , CD43 + , BP-1 + , B-lineage cells were particularly high, suggesting that they represent transitional pre-B cells, which are a subset of fraction C cells in the nomenclature of Hardy et al. (1991). The disproportionate increase in the percentage fraction C cells in the IRF-4,8 −/− bone marrow ( Fig. 2A) was also reflected in a substantial increase in their a...

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“…Subsequently, one-third of the transfected cells were cultured at the permissive temperature, and the remaining two-thirds were incubated at the nonpermissive temperature for 22 h. Firefly and Renilla luciferase activities were measured in protein extracts (25 g) with a dual assay kit (Promega). The pV and pVE constructs contain the V2 promoter alone (14) or together with E2-4 (14) in the BamHI site of the pGL2 basic plasmid (Promega). The 6xB plasmid contains six B binding sites located upstream of a minimal thymidine kinase promoter in pGL2-basic plasmid (18).…”

Section: Reporter Gene Assaysmentioning

confidence: 99%

“…Two nearly identical Ig enhancers (E3-1 and E2-4), which are active in mature B and plasma cells, require binding by the PU.1/IFN regulatory factor-4 transcription factor complex (13). Importantly, E3-1 and E2-4 function in an NF-B-independent manner in these late-stage cells (14).…”

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confidence: 99%

Transcription Factor NF-κB Regulates Igλ Light Chain Gene Rearrangement

Bendall

Sikes

Oltz

2001

The Journal of Immunology

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The tissue- and stage-specific assembly of Ig and TCR genes is mediated by a common V(D)J recombinase complex in precursor lymphocytes. Directed alterations in the accessibility of V, D, and J gene segments target the recombinase to specific Ag receptor loci. Accessibility within a given locus is regulated by the functional interaction of transcription factors with cognate enhancer elements and correlates with the transcriptional activity of unrearranged gene segments. As demonstrated in our prior studies, rearrangement of the Igκ locus is regulated by the inducible transcription factor NF-κB. In contrast to the Igκ locus, known transcriptional control elements in the Igλ locus lack functional NF-κB binding sites. Consistent with this observation, the expression of assembled Igλ genes in mature B cells has been shown to be NF-κB independent. Nonetheless, we now show that specific repression of NF-κB inhibits germline transcription and recombination of Igλ gene segments in precursor B cells. Molecular analyses indicate that the block in NF-κB impairs Igλ rearrangement at the level of recombinase accessibility. In contrast, the activities of known Igλ promoter and enhancer elements are unaffected in the same cellular background. These findings expand the range of NF-κB action in precursor B cells beyond Igκ to include the control of recombinational accessibility at both L chain loci. Moreover, our results strongly suggest the existence of a novel Igλ regulatory element that is either directly or indirectly activated by NF-κB during the early stages of B cell development.

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A novel enhancer in the immunoglobulin lambda locus is duplicated and functionally independent of NF kappa B.

Cited by 104 publications

References 80 publications

Analysis of Gene Expression and Ig Transcription in PU.1/Spi-B-Deficient Progenitor B Cell Lines

Analysis of Gene Expression and Ig Transcription in PU.1/Spi-B-Deficient Progenitor B Cell Lines

IRF-4,8 orchestrate the pre-B-to-B transition in lymphocyte development

Transcription Factor NF-κB Regulates Igλ Light Chain Gene Rearrangement

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