The overall goal of this five year research plan is to test the Hypothesis: TCDD acts directly on B-cells to suppress immunoglobulin secretion. This suppression is mediated by the AhR which adversely regulates immunologically relevant genes possessing DREs in their 5' regulatory regions. Toward characterizing the putative role by the AhR in TCDD-mediated B-cell dysfunction, our results have shown that mouse leukocytes and purified B-cells express functional Ah receptor and ARNT as evidenced by (a) Western blot; (b) increased DRE binding in the presence of TCDD, and (c) induction of cytochrome-P450 1A1 (Cyp1A1) gene expression. Moreover, we demonstrated that activation of mouse splenocytis, or primary B-cells, produced a marked increase in AhR mRNA and protein following activation. The significance of AhR up-regulation is unclear but may explain the sensitivity of immunocompetent cells to TCDD. Identical results were observed in the CH12.LX B-cell line following LPS activation. In the presence of TCDD CH12.LX cells exhibited inhibition in LPS-induced immunoglobulin secretion and induction of Cyp1A1. A second B-cell line, BCL-1, possesses ARNT but is AhR-deficient. BCL-1 cells in the presence of TCDD exhibited no inhibition of LPS-induced immunoglobulin secretion and no induction of Cyp1A1. Most recently, we have also demonstrated that TCDD induced a marked increase in the tumor suppressor gene and transcription factor, p53 which we believe plays a critical role in B-cell dysfunction by TCDD. In light of the above findings. We will test our hypothesis using the following specific aims (SA): In SA number1, we will characterize the structure activity relationship between TCDD-mediated inhibition of immunoglobulin secretion and heavy chain mRNA expression versus the regulation of gene transcription through the DRE. In SA number2, we will determine whether transfection of the AhR into an AhR-deficient cell-line (BCL-1) can confer sensitivity to TCDD. In SA number3, we will determine whether TCDD treatment of B-cells interferes with the ability of the transcription factor, B-cell specific activator protein (BSAP), in binding to its consensus recognition sequence. In, SA number4, we will characterize the role of premature p53 upregulation by TCDD in B-cells on cell cycle progression and immunoglobulin secretion. Lastly, in SA number5 we will determine whether up-regulation of p53 by TCDD in B-cells is mediated through the binding of the AhR/ARNT complex to a DRE-like site in the p53 promotor.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
2R01ES002520-15A2
Application #
2757877
Study Section
Special Emphasis Panel (ZRG4-ALTX-4 (01))
Project Start
1981-09-01
Project End
2003-12-31
Budget Start
1999-01-01
Budget End
1999-12-31
Support Year
15
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Michigan State University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
193247145
City
East Lansing
State
MI
Country
United States
Zip Code
48824
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Li, Jinpeng; Bhattacharya, Sudin; Zhou, Jiajun et al. (2017) Aryl Hydrocarbon Receptor Activation Suppresses EBF1 and PAX5 and Impairs Human B Lymphopoiesis. J Immunol 199:3504-3515
Kovalova, Natalia; Nault, Rance; Crawford, Robert et al. (2017) Comparative analysis of TCDD-induced AhR-mediated gene expression in human, mouse and rat primary B cells. Toxicol Appl Pharmacol 316:95-106
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Phadnis-Moghe, Ashwini S; Li, Jinpeng; Crawford, Robert B et al. (2016) SHP-1 is directly activated by the aryl hydrocarbon receptor and regulates BCL-6 in the presence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Toxicol Appl Pharmacol 310:41-50
Kovalova, Natalia; Manzan, Maria; Crawford, Robert et al. (2016) Role of aryl hydrocarbon receptor polymorphisms on TCDD-mediated CYP1B1 induction and IgM suppression by human B cells. Toxicol Appl Pharmacol 309:15-23
Phadnis-Moghe, Ashwini S; Crawford, Robert B; Kaminski, Norbert E (2015) Suppression of human B cell activation by 2,3,7,8-tetrachlorodibenzo-p-dioxin involves altered regulation of B cell lymphoma-6. Toxicol Sci 144:39-50
De Abrew, K Nadira; Phadnis, Ashwini S; Crawford, Robert B et al. (2011) Regulation of Bach2 by the aryl hydrocarbon receptor as a mechanism for suppression of B-cell differentiation by 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol Appl Pharmacol 252:150-8
Sulentic, Courtney E W; Kaminski, Norbert E (2011) The long winding road toward understanding the molecular mechanisms for B-cell suppression by 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol Sci 120 Suppl 1:S171-91
Lu, Haitian; Crawford, Robert B; Kaplan, Barbara L F et al. (2011) 2,3,7,8-Tetrachlorodibenzo-p-dioxin-mediated disruption of the CD40 ligand-induced activation of primary human B cells. Toxicol Appl Pharmacol 255:251-60

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