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TCDD represses 3'IghRR activation through an AhR-dependent shift in the NF-κB/Rel protein complexes binding to κB motifs within the hs1,2 and hs4 enhancers

Salisbury, Richard L., Jr.
http://rave.ohiolink.edu/etdc/view?acc_num=wright1401136335

Abstract Details

2014, Doctor of Philosophy (PhD), Wright State University, Environmental Sciences PhD.
Transcriptional regulation of the murine immunoglobulin heavy chain gene involves several regulatory elements including the 3'Igh regulatory region (3'IghRR) composed of at least four enhancers (hs3A; hs1,2; hs3B; hs4). Enhancers hs1,2 and hs4 contain binding sites for several transcription factors including NF-κB/Rel proteins and the AhR. Interestingly, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) profoundly inhibits 3'IghRR and hs1,2 activation induced by the B-cell activator lipopolysaccharide (LPS), but enhances the activation of the hs4. Within the hs4, the AhR binding site overlaps an NF-κB/Rel binding site suggesting that both the AhR and the NF-κB together may modulate of the 3'IghRR. The objective of the current study was to evaluate the role of NF-κB/Rel and the AhR following LPS stimulation and TCDD treatment on 3'IghRR, hs1,2, and hs4. In our studies we utilized the CH12.LX B cell line; the CH12.IκBαAA cell line, which expresses an inducible IκBα super repressor (IκBαAA); the CH12.γ2b-3'IghRR cell line that stably expresses a γ2b-3'IghRR-regulated γ2b transgene reporter; and splenocytes derived from B6C3F1 mice. The stimulation of the CH12.γ2b-3'IghRR cell line with Toll-like receptor (TLR) agonists LPS, Resiquimod (R848), or Cytosine-phosphate-Guanine (CpG)-oligodeoxynucleotides combined with a co-treatment of TCDD significantly inhibited the TLR-induced activation of the 3'IghRR. Utilizing transiently expressed luciferase reporters, we found induction of IκBαAA expression partially attenuated LPS-induced activation of the 3'IghRR and hs4, partially reversed the effects of a TCDD and LPS co-treatment on the activity of the 3'IghRR and hs4, and the addition of an AhR antagonist, CH223191, markedly reversed the LPS and TCDD induced inhibition of the 3'IghRR and inhibited the synergistic activation of the hs4. Chromatin immunoprecipitation analysis of CH12.LX and murine splenocytes demonstrated a LPS and a LPS co-treatment with TCDD-dependent increase in RelA and AhR binding, and a significant decrease in RelB binding to the hs4 and hs1,2. These results suggest that a shift in binding of the NF-κB/Rel proteins, perhaps through an interaction with the AhR are partially responsible for 3'IghRR modulation by LPS and TCDD. These results suggest that interactions between the AhR and NF-κB within the 3'IghRR mediate the inhibitory effects of TCDD on immunoglobulin (Ig) expression and therefore antibody levels.
Courtney Sulentic, Ph.D. (Advisor)
Michael Leffak, Ph.D. (Committee Member)
Mill Miller, Ph.D. (Committee Member)
David Cool, Ph.D. (Committee Member)
Rodney DeKoter, Ph.D. (Committee Member)
Don Cipollini, Ph.D. (Other)
114 p.
Environmental Science; Immunology; Molecular Biology; Toxicology
NF-kappaB; NF-kB; TCDD; Immonotoxicology; AhR; aryl hydrocarbon receptor; Toll-like receptor; Dioxin; B-cell, immunosuppression; RelA; RelB; TLR

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Citations

  • Salisbury, Jr., R. L. (2014). TCDD represses 3'IghRR activation through an AhR-dependent shift in the NF-κB/Rel protein complexes binding to κB motifs within the hs1,2 and hs4 enhancers [Doctoral dissertation, Wright State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401136335

    APA Style (7th edition)

  • Salisbury, Jr., Richard. TCDD represses 3'IghRR activation through an AhR-dependent shift in the NF-κB/Rel protein complexes binding to κB motifs within the hs1,2 and hs4 enhancers. 2014. Wright State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=wright1401136335.

    MLA Style (8th edition)

  • Salisbury, Jr., Richard. "TCDD represses 3'IghRR activation through an AhR-dependent shift in the NF-κB/Rel protein complexes binding to κB motifs within the hs1,2 and hs4 enhancers." Doctoral dissertation, Wright State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401136335

    Chicago Manual of Style (17th edition)

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This open access ETD is published by Wright State University and OhioLINK.