Identification of functional aryl hydrocarbon receptor and aryl hydrocarbon receptor nuclear translocator in murine splenocytes

Williams, Courtney E.; Crawford, R. J.; Holsapple, Michael P.; Kaminski, Norbert E.

doi:10.1016/0006-2952(96)00360-7

Cited by 24 publications

(19 citation statements)

References 33 publications

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“…The DNA was recovered by phenol/chloroform extraction and ethanol precipitation. Using qualitative RT-PCR as described previously (Williams et al, 1996), DNA was analyzed for a 150-bp hs4 product containing the DRE motif. Total cellular DNA served as a positive control, and a sample incubated without an antibody during the immunoprecipitation step served as the negative control.…”

Section: Methodsmentioning

confidence: 99%

“…Of these effects, immune suppression is one of the most sensitive consequences of TCDD exposure . Inhibition of IgM secretion and of the antibody forming cell response has been well documented with several studies supporting the involvement of the AhR; however, the specific mechanism remains unclear (Tucker et al, 1986;Dooley and Holsapple, 1988;Luster et al, 1988;Morris and Holsapple, 1991;Morris et al, 1993;Williams et al, 1996;Sulentic et al, 1998Sulentic et al, , 2000Vorderstrasse et al, 2001).…”

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confidence: 99%

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2,3,7,8-Tetrachlorodibenzo-p-dioxin, an Exogenous Modulator of the 3′α Immunoglobulin Heavy Chain Enhancer in the CH12.LX Mouse Cell Line

Sulentic¹,

Zhang²,

Na³

et al. 2004

J Pharmacol Exp Ther

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Transcriptional regulation of the Ig heavy chain gene involves several regulatory elements, including the 3Ј␣ enhancer, which is composed of four distinct regulatory domains. DNA binding sites for several transcription factors, including B cell-specific activator protein, nuclear factor for immunoglobulin chain in B cells, and octamer have been identified within the 3Ј␣ enhancer domains and are believed to be important in regulating 3Ј␣ enhancer activity. We have identified an additional DNA binding motif, the dioxin-responsive element (DRE), which can contribute to 3Ј␣ enhancer regulation. 2,3,7,8-Tetrachlorodibenzo-pdioxin (TCDD), a known disrupter of B cell differentiation (i.e., decreased plasma cell formation, inhibition of heavy chain expression, and suppression of IgM secretion), induces binding of the aryl hydrocarbon receptor (AhR) nuclear complex to DREs. TCDD also induces AhR binding to the hypersensitive (hs)4 domain of the 3Ј␣ enhancer. Interestingly, TCDD enhances LPS-induced activation of the hs4 domain but profoundly inhibits LPS-induced activation of the complete 3Ј␣ enhancer. Furthermore, site-directed mutational analysis demonstrated that a DRE and B element in the hs4 domain is modulated by TCDD in lipopolysaccharide-activated B cells. We propose that the AhR is a novel transcriptional regulator of the 3Ј␣ enhancer, which can mediate, at least in part, the effects of TCDD on the 3Ј␣ enhancer and its domains, putatively contributing to a marked suppression of IgM production.Regulation of the murine immunoglobulin heavy chain (IgH) locus is governed through a complex interaction of several regulatory elements whose activity is B cell-specific and dependent on the state of B cell maturation. The most 5Ј regulatory element is the V H promoter, which lies immediately upstream of each variable region and contributes to B cell-specific activity of the Ig heavy chain locus. Located between the rearranged VDJ segments and the C constant region is the E, which contributes to B cell-specific activity and is involved early in B cell development where it regulates

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

2,3,7,8-Tetrachlorodibenzo-p-dioxin, an Exogenous Modulator of the 3′α Immunoglobulin Heavy Chain Enhancer in the CH12.LX Mouse Cell Line

Sulentic¹,

Zhang²,

Na³

et al. 2004

J Pharmacol Exp Ther

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“…Donkey horseradish peroxidase-conjugated anti-rabbit IgG was purchased from Amersham Pharmacia Biotech. Immunochemical staining was performed as described previously (Williams et al, 1996). Detection was performed using the ECL method (Amersham Pharmacia Biotech).…”

Section: Tcdd Induction Of Socs2 In B Cellsmentioning

confidence: 99%

2,3,7,8-Tetrachlorodibenzo-p-dioxin Induces Suppressor of Cytokine Signaling 2 in Murine B Cells

Boverhof¹,

Tam²,

Harney³

et al. 2004

Mol Pharmacol

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The B cell, a major component of humoral immunity, is a sensitive target for the immunotoxic effects of 2,3,7,8-tetrachlorodibenzop-dioxin (TCDD), possibly by rendering cells less responsive to antigenic or mitogenic stimulation. Potential mechanisms of TCDD action on B cells were examined in murine B cell lymphoma cells (CH12.LX) treated with 3 nM TCDD or dimethyl sulfoxide vehicle using sequence-verified cDNA microarrays. One transcript that was significantly induced by TCDD was suppressor of cytokine signaling 2 (Socs2). Changes in Socs2 mRNA levels paralleled that of Cyp1a1 with a maximal 3-fold induction observed at 4 h, as determined by quantitative real-time polymerase chain reaction. Socs2 induction seems B cell-specific, because no induction was observed in TCDD-responsive mouse hepatoma cells or human breast cancer cells. TCDD-mediated induction of Socs2 mRNA was dose-dependent and exhibited the characteristic structureactivity relationships observed for the aryl hydrocarbon receptor (AhR) ligands 3,3Ј,4,4Ј,5-pentachlorobiphenyl (PCB-126), indolo[3,2-b]-carbazole, and ␤-naphthoflavone. Experiments with cycloheximide and AhR-deficient B cells indicated that Socs2 mRNA induction is a primary effect that is AhR-dependent. Western blot analysis confirmed that Socs2 and Cyp1a1 protein levels were also induced in CH12.LX cells. Promoter analysis revealed the presence of four dioxin-response elements within 1000 base pairs upstream of the Socs2 transcriptional start site, and a reporter gene regulated by the Socs2 promoter was inducible by TCDD. Promoter activity was also dependent on a functional AhR signaling pathway. These results indicate that Socs2 is a primary TCDD-inducible gene that may represent a novel mechanism by which TCDD elicits its immunosuppressive effects.TCDD and related compounds are ubiquitous environmental contaminants that elicit a wide array of toxic and biochemical responses in a tissue-, sex-, age-and species-specific manner (Poland and Knutson, 1982). These responses are mediated by the AhR, a member of the basic helix-loop-helix/ periodicity/aryl hydrocarbon receptor nuclear translocator/ simple-minded family (Poland and Knutson, 1982;Denison and Heath-Pagliuso, 1998), and include a wasting syndrome, tumor promotion, teratogenesis, hepatotoxicity, modulation of endocrine systems, immunotoxicity, and enzyme induction. The proposed mechanism for mediating these responses involves ligand binding to the cytoplasmic AhR complex and the dissociation of interacting inhibitory proteins. The ligand-bound AhR then translocates to the nucleus, in which it forms a heterodimer with the aryl hydrocarbon receptor nuclear translocator ARNT, another member of the basic helixloop-helix/periodicity/aryl hydrocarbon receptor nuclear translocator/simple-minded family. This heterodimer then binds specific DNA elements, termed dioxin-response elements (DREs), in the regulatory regions of target genes, leading to changes in gene expression and ultimately resulting in the observed toxic and biochem...

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“…The relative intensity for the 0 time treatment group was arbitrarily assigned a value of 1.00 to which all other treatment groups are compared. [5][6][7], same as 2-4 except the mouse splenocytes were stimulated with PMA/Io for 12 hr. B, DRE-EMSA Western analysis was used to confirm that the AhR is part of the protein complex bound to the DRE.…”

Section: Downloaded Frommentioning

confidence: 99%

“…Based on this well established mechanism of gene regulation by TCDD, it has been widely presumed that the mechanism for immune suppression by TCDD is likewise mediated through the AhR. However, even though the immune system is one of the most sensitive target organs to TCDD-mediated toxicity, leukocytes possess relatively low amounts of AhR compared with other TCDD-sensitive tissues, such as the liver (6). One notable difference between leukocytes and other previously examined TCDD-sensitive tissues is that leukocytes are quiescent cells that are critically dependent on activation, proliferation, and differentiation before mediating their respective immune effector functions.…”

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confidence: 99%

Leukocyte Activation Induces Aryl Hydrocarbon Receptor Up-Regulation, DNA Binding, and IncreasedCyp1a1Expression in the Absence of Exogenous Ligand

1997

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Identification of functional aryl hydrocarbon receptor and aryl hydrocarbon receptor nuclear translocator in murine splenocytes

Cited by 24 publications

References 33 publications

2,3,7,8-Tetrachlorodibenzo-p-dioxin, an Exogenous Modulator of the 3′α Immunoglobulin Heavy Chain Enhancer in the CH12.LX Mouse Cell Line

2,3,7,8-Tetrachlorodibenzo-p-dioxin, an Exogenous Modulator of the 3′α Immunoglobulin Heavy Chain Enhancer in the CH12.LX Mouse Cell Line

2,3,7,8-Tetrachlorodibenzo-p-dioxin Induces Suppressor of Cytokine Signaling 2 in Murine B Cells

Leukocyte Activation Induces Aryl Hydrocarbon Receptor Up-Regulation, DNA Binding, and IncreasedCyp1a1Expression in the Absence of Exogenous Ligand

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