Source: UNIVERSITY OF CALIFORNIA, DAVIS submitted to NRP
MOLECULAR MECHANISMS OF ACTION OF ENVIRONMENTAL ENDOCRINE DISRUPTING CHEMICALS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0160585
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Oct 1, 1999
Project End Date
Sep 30, 2005
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
ENVIRONMENTAL TOXICOLOGY
Non Technical Summary
(N/A)
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3143840104035%
3143840115035%
3143899114010%
3143899115010%
3147299115010%
Knowledge Area
314 - Toxic Chemicals, Poisonous Plants, Naturally Occurring Toxins, and Other Hazards Affecting Animals;

Subject Of Investigation
3840 - Laboratory animals; 3899 - Other animals, general; 7299 - Research equipment and methods, general/other;

Field Of Science
1040 - Molecular biology; 1140 - Weed science; 1150 - Toxicology;
Goals / Objectives
The overall goals of this research program are to investigate the molecular mechanism by which environmental and agricultural chemicals regulate nuclear hormone receptors and gene expression, with an emphasis on those chemicals which are endocrine disruptors. A major focus will be examine the Ah receptor-dependent molecular mechanism by which potent endocrine disruptor, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related halogenated aromatic hydrocarbons, exerts their biochemical and toxicological actions. An additional major focus will be the development of rapid cell- and receptor-based bioassays for the detection and characterization of novel endocrine disruptors and TCDD-like chemicals. The results of these studies will provide insights into the mechanisms by which widespread environmental and agricultural chemicals can alter gene expression and disrupt normal hormone actions.
Project Methods
We propose to: 1. Examine the molecular mechanism by which the interacts with nuclear factors to regulate gene expression; 2. Express, crystallize and examine the protein structure of the AhR ligand binding domain; 3. Examine the role of the AhR in the reproductive toxicity and endocrine disrupting activity of TCDD in human placental cells; and, 4. Develop rapid and sensitive cell-based bioassay systems for detection of endocrine disrupting and dioxin-like chemicals present in complex mixtures of chemicals.

Progress 10/01/99 to 09/30/05

Outputs
The application has continued of our validated recombinant and in vitro bioassays for both environmental contaminants (i.e. dioxins and related chemicals) and endocrine disruptors (xenoestrogens) by screening of extracts from environmental samples (soil and sediment from California coastal areas) and diverse commercial and consumer products for the presence of these xenobiotics. The presence of relatively high concentrations of Ah receptor agonists (dioxin-like chemicals) was detected in extracts from soil/sediment samples and commercial products (paper, plastics, and rubber products). The ability of water and ethanol extracts of these products to bind to and activate the Ah (dioxin) receptor not only demonstrates that humans and animals can be exposed to these chemicals from a much wider variety of sources than has been realized, but reveals the existence of novel water-soluble receptor ligands in these extracts; studies to date indicate that all Ah receptor agonists are poorly water-soluble. The identity and toxicological/biological significance of these novel water-soluble Ah (dioxin) receptor ligands remains to be established. Dioxin-like chemicals and xenoestrogenic endocrine disruptors have been found in environmental extracts of soil and sediment samples from coastal esturaries of California. While the identity of the responsible chemicals is currently being determined, their presence in these environmental samples suggest that they may contribute to some of the endocrine disrupting effects observed in coastal marine species. Overall, these bioassays have revealed the presence of potentially toxic/adverse chemical compounds in extracts of environmental samples and commercial products and demonstrate the widespread nature of these toxicologically relevant environmental contaminants.

Impacts
Mechanism-based recombinant cell bioassays have been used to screen a variety of environmental, biological and food samples for the presence of environmental contaminants and endocrine disruptors. These studies have not only revealed the presence of such chemicals in environmental extracts, particularly sediment and soils from California coastal areas, but also revealed their presence in extracts from a wide variety of commercial and consumer products.

Publications

  • Hall, L.C., Rogers, J.M., Denison, M.S. and Johnson, M.L. (2005) Identification of the herbicide Surflan and its active ingredient Oryzalin, a dinitrosulfonamide, as xenoestrogens, Arch. Environ. Contam. Toxicol., 48, 201-208.
  • Jeong, S.H., Cho, J.H., Park, J.M. and Denison, M.S. (2005) Rapid bioassay for the determination of dioxins and dioxin-like PCDFs and PCBs in meat and animal feeds, J. Anal. Toxicol. 29, 156-162.
  • Windal, I., Denison, M.S., Birnbaum, L.S., Van Wouwe, N., Baeyens, W. And Goeyens, L. (2005) CALUX cell bioassay analysis for the estimation of dioxin-like activity: critical parameters of the CALUX procedure that impact assay results, Environ. Sci. Technol. 39, 7357-7364.
  • Denison, M.S., Soshilov, A., Song, Y., Pandini, A. and Bonati, L. (2005) The Ah receptor ligand binding domain: homology modeling and functional analysis, Organohalogen Compounds 67, 114-117.


Progress 01/01/04 to 12/31/04

Outputs
Using our recently validated recombinant and in vitro bioassays for environmental contaminants (i.e. dioxins and related chemicals) and endocrine disruptors (xenoestrogens) we have carried out extensive screening for the presence of these xenobiotics in extracts of diverse products. We have demonstrated the presence of Ah receptor agonists (dioxin-like chemicals) present in extracts from common commercial products that are in public use. In addition, the ability of water and ethanol extracts of these products to bind to and activate the AhR is a novel finding since all known Ah receptor agonists are hydrophobic chemicals. These results demonstrate that novel classes of water-soluble agonists exist in these products. Although the identity and toxicological/biological significance of these novel ligands remains to be established, these studies demonstrate that we are chronically exposed to ligands for the Ah (dioxin) receptor from a diverse range of sources in addition to environmental samples and food products as commonly assumed. In addition to these studies we have continued our analysis of a library of novel flavonoid chemicals in both the dioxin and endocrine disruptor cell bioassay systems. We have identified highly potent novel flavonoid ligands/agonists for the Ah receptor and have also found that many of these chemicals are either inducers and/or inhibitors of aromatase, a major enzyme involved in estrogen synthesis. Given its clinical importance, these chemicals may provide very useful in the design of novel aromatase inhibitors and inducers. Together, our bioassay systems have not only allowed us to identify and characterize potentially toxic/adverse chemical compounds, but they have great utility for high throughput screening for novel clinically relevant lead compounds.

Impacts
We have developed and validated several mechanistically-based recombinant in vitro and cell bioassays that can be used for screening of a variety of environmental, biological and food samples for the presence of environmental contaminants and endocrine disruptors. Using these methods we identified dioxin-like chemicals in extracts from commercial and consumer products and the ability of naturally occurring flavones to act as endocrine disrupting chemicals.

Publications

  • Brown, D.J., Van Overmeire, I., Goeyens, L., Denison, M.S., De Vito, M.J. and Clark, G.C. (2004) Analysis of Ah receptor pathway activation by brominated flame retardants, Chemosphere 55, 1508-1518.
  • Zhao, B. and Denison, M.S. (2004) Development and characterization of a green fluorescent protein-based rat cell bioassay system for detection of Ah receptor ligands, Organohalogen Compounds 66, 3332-3337.
  • Knockaert, M., Blondel, M., Bach, S., Leost, M., Elbi, C., Hager, G.L., Nagy, S.R., Han, D., Denison, M., French, M., Ryan, X.P., Magiatis, P., Polychronopoulos, P., Greengard, P., Skaltsounis, L. and Meijer, L. (2004) Independent actions on cyclin-dependent kinases and aryl hydrocarbon receptor mediate the antiproliferative effects of indirubins, Oncogene 23, 4400-4412.
  • Han, D.-H., Nagy, S.R. and Denison, M.S. (2004) Comparison of recombinant cell bioassays for the detection of Ah receptor agonists, Biofactors 20, 11-22.
  • Denison, M.S., Zhao, B., Baston, D.S., Clark, G.C., Murata, H. and Han, D.-H. (2004) Recombinant Cell Bioassay Systems for the Detection and Relative Quantitation of Halogenated Dioxins and Related Chemicals, Talanta 63, 1123-1133.
  • Zhao, B., Nagy, S.R., Rogers, J., Nantz, M. Kurth, M., Springsteel, M. and Denison, M.S. (2004) Identification and analysis of novel flavonoid agonists and antagonists for the Ah and estrogen receptor, Organohalogen Compounds 66, 2960-2965.
  • Bohonowych, J.E. and Denison, M.S. (2004) Binding of 2,3,7,8-Tetrachlorodibenzo-p-dioxin to the AhR from various species is essentially irreversible, Organohalogen Compounds 66, 3338-3342.
  • Sanderson, J.T., Hordijk, J., Denison, M.S., Springsteel, M., Nantz, M.H. and van den Berg, M. (2004) Induction and inhibition of aromatase (CYP19) activity by natural and synthetic flavonoid compounds in H295R human adrenocortial carcinoma cells, Toxicol. Sci. 82, 70-79.
  • Peters AK, Van Londen K, Bergman A, Bohonowych J, Denison MS, Van Den Berg M, Sanderson JT. (2004) Effects of Polybrominated Diphenyl Ethers (PBDEs) on Basal and TCDD-Induced Ethoxyresorufin (EROD) Activity and Cytochrome P450-1A1 Expression in MCF-7, HepG2 and H4IIE Cells, Toxicol Sci. 82, 488-4896.
  • M.S. Denison, W.J. Rogers, J.E. Bohonowych, M.E. Ziccardi and B. Zhao (2004) Promiscuous ligand-dependent activation of the Ah receptor: chemicals in crude extracts from commercial and consumer products bind to and activate the Ah receptor and Ah receptor-dependent gene expression, Organohalogen Compounds 66, 2966-2971.
  • Gordon, J.D., Chu, A.C., Chu, M.D., Denison, M.S. and Clark, G.C. (2004) Detection of estrogen receptor endocrine disruptor potency of commonly used organochlorine pesticides using The LUMI-CELLīƒ¤ bioassay, Organohalogen Compounds 656, 3009-3015.


Progress 01/01/03 to 12/31/03

Outputs
Development has been completed on the novel recombinant cell bioassay systems for environmental contaminants (i.e. dioxins and related chemicals) and endocrine disruptors (xenoestrogens). Using these novel cell bioassays we have demonstrated the utility of these systems for detection of these chemicals in environmental (soil, ash, exhaust gas), biological (blood and tissue) and food samples (vegetables and dietary herbal products). We have screened chemical libraries containing a diverse array of flavonoids (based on the structure of naturally-occurring flavonoids found in food and feed). These studies revealed the presence of relatively high levels of biologically active chemicals in foods and numerous potent flavonoid-like chemicals that can activate endogenous cellular receptor systems. Our recent demonstration that activation of one of these receptor systems (the Ah receptor) can inhibit growth and proliferation of a variety of human cancer cells suggests that this approach may allow identification of novel chemotherapeutic agents. Our studies also suggest the possibility of using whole foods (vegetables and dietary herbal products), food extracts and synthetic chemicals based on the structure of natural chemicals to stop or slow cancer growth. Studies will continue to identify the novel chemotherapeutic chemicals present in these foods and to determine the molecular mechanism of action of these chemicals. We hope these studies will provide support for the use of various dietary components in the fight against cancer.

Impacts
A variety of mechanistically-based recombinant bioassay methodologies have been utilized to develop and optimize screening a variety of environmental, biological and food samples for the presence of environmental contaminants and endocrine disruptors. These bioanalytical methods have also revealed a variety of naturally-occurring and synthetic chemicals that may be useful novel chemotherapeutic agents that can block cancer cell growth.

Publications

  • Shaw, S.D., Brenner, D., Mahaffey, C.A., De Guise, S., Perkins, C.R., Clark, G.C., Denison, M.S. and Waring, G.T. (2003) Persistent organic pollutants (POPs) and immune function in US Atlantic coast Harbor Seals, Organohalogen compounds 62, 220-223.
  • Zhao, B., Nagy, S.R., Baston, D.S., Han, D.-H., Nantz, M., Kurrth, M., Springsteel, M.H. and Denison, M.S. (2003) Screening and analysis of novel naphthoflavone ligands for the Ah receptor, Organohalogen compounds 65, 102-105.
  • Arrieta, D.E., Ontiveros, C.C., Li, W.-W., Garcia, J.H., Denison, M.S., McDonald, J.D., Burchiel, S.W. and Washburn, B.S. (2003) Aryl hydrocarbon receptor-mediated activity of particulate organic matter from the Paso del Norte airshed along the U.S.-Mexico Border, Environ. Health Perspect. 111, 1299-305.
  • Baston, D.S., Nagy, S.R., Nantz, M., Kurth, M., Springsteel, M. and Denison, M.S. (2003) Identification of novel agonists and antagonists of the Ah receptor signal transduction pathway, Organohalogen compounds 65, 142-145.
  • Denison, M.S. and Nagy, S.R. (2003) Activation of the aryl hydrocarbon receptor by structurally diverse exogenous and endogenous chemicals, Ann. Rev. Pharmacol. Toxicol. 43, 309-334.
  • Denison, M.S., Han, D.-H., Heath-Pagliuso, S., Scovill, J., Meijer, L., Skaltounis, L., Gillam, E.M.J. and Nagy, S.R. (2003) Activation of the Ah receptor and Ah receptor signal transduction pathway by tryptophan-derived agonists, Organohalogen compounds 65, 90-93.
  • Gordon, J.D., Chu, A.C., Chu, M.D., Taylor, C.L., Denison, M.S. and Clark, G.C. (2003) Validation of the Lumi-Cell ER recombinant bioassay for rapid evaluation of chemicals for potential estrogenic activity, Organohalogen Compounds 65, 78-81.
  • Han, D.-H., Zhao, B., Baston, D.S., Springsteel, M., Kurth, M., Nantz, M.H. and Denison, M.S. (2003) Identification and characterization of novel flavone agonists of the Ah receptor, Organohalogen compounds 65, 126-129.
  • Han, D., Denison, M.S., Tachibana, H. and Yamada, K. (2002) Effects of estrogenic compounds on immunoglobin production by mouse splenocytes, Biol. Pharm. Bull. 1263-1267.
  • Jeuken, A., Keser, B.J.G., Khan, E., Brouwer, A., Koeman, Jan and Denison, M.S. (2003) Activation of the Ah Receptor by Extracts of Dietary Herbal Supplements, Vegetables and Fruits, J. Agr. Food Chem. 51, 5478-5487.
  • Monk, S.A., Denison, M.S. and Rice, R.H. (2003) Reversible stepwise negative regulation of CYP1A1 in cultured rat epidermal cells, Arch. Biochem. Biophys. 419, 158-169.


Progress 01/01/02 to 12/31/02

Outputs
Taking advantage of specific chemical-dependent receptor proteins present in cells in culture, work continued to develop, optimize and validate several novel recombinant cell bioassays for the detection of toxic chemicals. The previously generated cell bioassay system for the detection of halogenated aromatic hydrocarbons, such as the chlorinated dioxins, dibenzofurans and PCBs, was further validated. Soil, ash, exhaust gas and blood extracts were used to validate this bioassay system for the detection of these chemicals by demonstrating a high degree of correlation between the relative amounts of toxic dioxins and dibenzofurans detected using our cell bioassay and instrumental analysis (GC/MS). The utility of this bioassay has been demonstrated to detect polycyclic aromatic hydrocarbons and have shown its application for use in the screening of wildlife tissue samples for assessment of their exposure to crude oil. The high throughput nature of the dioxin cell bioassay was shown by the ability of one person to screen over 12,500 chemicals for dioxin-like activity in less than one week. Work continued on development of endocrine disruptor rcell bioassays and using a recombinant estrogen-responsive human ovarian cell line, we have demonstrated that the mechanism by which dioxins can block estrogen action in these cells requires it to induce expression of a novel antiestrogenic gene product. Overall results clearly demonstrate the application of our novel cell bioassay systems for both basic and applied research.

Impacts
Development and validation of bioassay systems for detection and relative quantitation of dioxins and endocrine disruptors provides an avenue for widespread monitoring of environmental, biological and food samples for these hazardous chemicals. Our bioassays are simple, rapid and inexpensive alternatives to the more expensive analysis techniques and they are gaining national and international acceptance and use for monitoring purposes.

Publications

  • Nagy, S.R., Sanborn, J.R., Hammock, B.D. and Denison, M.S. (2002) Development of a green fluorescent protein based cell bioassay for the rapid and inexpensive detection and characterization of AhR agonists, Toxicol. Sci. 65, 200-210.
  • Nagy, S.R., Liu, G., Lam, K. and Denison, M.S. (2002) identification of novel Ah receptor agonists using a high-throughput green fluorescent protein-based recombinant cell bioassay, Biochem. 41, 861-868.
  • Natarajan, K., Overstreet, J.W., Rogers, J.M., Denison, M.S., Chen, J., Lohstroh, P.N., McConnell, D.S., and Lasley, B.L. (2002) Detection of xenoestrogens in serum after immunoprecipitation of endogenous steroidal estrogens, Environ. Health Perspect. 110, 791-795.
  • Ziccardi, M.H., Gardner, I.A., Manzet, J.A.K. and Denison, M.S. (2002) Application of the luciferase cell culture bioassay for the detection of refined petroleum products, Marine Poll. Bull. 44, 1-9.
  • Rogers, J.M. and Denison, M.S. (2002) Analysis of the anitestrogenic activity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in human ovarian carcinoma (BG-1) cells, Molec. Pharamcol. 61, 1393-1403.
  • Ziccardi, M.H., Manzet, J.A.K., Gardner, I.A., Boyce, W.M. and Denison, M.S. (2002) Validation of a cell culture bioassay for detection of petroleum exposure in mink (Mustela vison) as a model for detection in sea otters (Enhydra lutris), Amer. J. Vet. Res. 63, 963-968.
  • Han, D.-H., Denison, M.S., Tachibana, H. and Yamada, K. (2002) Relationship between estrogen receptor binding and estrogenic activities of environmental estrogens and suppression by flavonoids, Biosci., Biotechnol. Biochem. 66, 1479-1487.
  • Liu, P.C.C., Morena-Aliaga, M.J., Dunlap, D.Y., Hu, X.-M., Denison, M.S. and Matsumura, F. (2002) Correlation between the high expression of C/EBPa protein in F442A cells and their relative resistance to antiadipogenic action of TCDD in comparison to 3T3-L1 cells, J. Biochem. Molec. Toxicol. 16, 70-83.
  • Brown, D.J., Nakamura, M., Chu, M.D., Denison, M.S., Murata, H. and Clark, G.C. (2002) Recovery determinations for bioassay analysis: considerations and results, Organohal. Cmpds. 58, 357-360.
  • Han, D.-H., Nagy, S.R. and Denison, M.S. (2002) Recombinant cell lines for the detection of dioxins and Ah receptor ligands ? not all assays are created equal, Organohal. Cmpds. 58, 421-424.
  • Rushing, S.R. and Denison, M.S. (2002) The silencing mediator of retinoic acid and thyroid hormone receptors (SMRT) can interact with the Ah receptor but fails to repress ah receptor-dependent gene expression, Arch. Biochem. Biophys. 403, 189-201.
  • Nagy, S.R. and Denison, M.S. (2002) Specificity of nuclear protein binding to a CYP1A1 negative regulatory element, Biochem. Biophys. Res. Comm. 296, 799-805.
  • Ziccardi, M.H., Gardner, I.A. and Denison, M.S. (2002) Application of the luciferase recombinant cell culture bioassay system for the analysis of polycyclic aromatic hydrocarbons, Environ. Contam. & Toxicol. 21, 2027-2033.
  • Brown, D.J., Van Overmeire, I. Chu, M.D., Denison, M.S., Murata, H. and Clark, G.C. (2002) Elimination of interfering compounds in preparation for analysis by an Ah receptor based bioassay, Organohal. Cmpds. 58, 401-404.
  • Bonati, L., Padini, A., Pitea, D., Song, Y. and Denison, M.S. (2002) New insights into the structure of the mAhR ligand binding domain, Organohal. Cmpds. 59, 429-432.
  • Denison, M.S. Nagy, S.R., Ziccardi, M., Clark, G.C., Chu, M., Brown, D.J., Shan, G., Sugawara, Y., Shirley J. Gee, S.J., James Sanborn, J. and Hammock, B.D. (2002) Bioanalytical approaches for the detection of dioxin and related halogenated aromatic hydrocarbons, in: Technology-Driven Biomarkers Development and Application in Environmentally-Associated Diseases, Wilson, D. and W. Suk, W., eds., pp. 483-494, Lewis Press, Boca Raton, FL.
  • Lashley, M.R., Niedzinski, E.J., Rogers, J.M., Denison, M.S. and Nantz, M.H. (2002) Synthesis and estrogen receptor affinity of a 4-hydroxytamoxifen?labeled ligand for magnetic resonance imaging, Bioorg. & Med. Chem. 10, 4075-4082.
  • Han, D., Denison, M.S., Tachibana, H. and Yamada, K. (2002) Effects of estrogenic compounds on immunoglobulin production by mouse splenocytes, Biol. Pharm. Bull. 25, 1263-1267.
  • Denison, M.S., Pandini, A., Nagy, S.R., Baldwin, E.P. and Bonati, L. (2002) Ligand binding and activation of the Ah receptor, Chem. Biol. Int. 141, 3-24.
  • Denison, M.S., Rogers, J.M., Rushing, S.R., Jones, C.L., Tetangco, S.C. and Heath-Pagliuso, S. (2002) Analysis of the Ah receptor signal transduction pathway, in: Current Protocols in Toxicology (Maines, M., Costa, L.G., Reed, D.J. Sassa, S. and Sipes, I.G., eds.), pp. 4.8.1- 4.8.45, John Wiley and Sons, NY.
  • Khan, E.M. and Denison, M.S. (2002) NF-kB is involved in cross-talk between Ah receptor and signal transduction pathways, Organohal. Cmpds. 59, 411-414.
  • Feidler H. and Denison, M.S. (2002) 22nd International symposium on Environmental Halogenated Organic Pollutants and POPs, Introduction, Environ. Sci. Poll. Res. 9, 296.


Progress 01/01/01 to 12/31/01

Outputs
Halogenated aromatic hydrocarbons (HAHs), such as the chlorinated dioxins, are persistent and widespread environmental contaminants whose adverse effects are mediated by the Ah receptor (AhR), a chemically-activated DNA-binding protein that alters gene expression. Given the pivotal role of the AhR in the adverse effects of HAHs and in normal development, a better understanding of the chemicals that can activate the AhR is of important. Using molecular biological approaches we demonstrated the ability of some naturally occurring chemicals to activate the AhR and AhR-dependent gene expression. The identification of prostaglandins as a AhR ligands provides new insights into the mechanisms by which the AhR may be regulated in normal tissues. The ability of the AhR to also be activated by suspension of cells in methylcellulose also strongly supports the existence of other endogenous activators of the AhR. The isolation and identification of the responsible endogenous substances and their role in normal physiological processes will aid in our understanding of the normal function of the AhR as will reveal potential new targets by which environmental chemicals can disrupt normal cellular processes. Our cell bioassay system has also identified other novel classes of environmental chemicals that can exert their action via the AhR, like dioxin. Finally, the cell bioassay system has been successfully used as a rapid and quantitative screening system for the detection of dioxin and related chemicals in food and feed a wide variety of environmental and biological samples.

Impacts
(N/A)

Publications

  • Seidel, S.D., Winters, G.M., Rogers, W.J., Ziccardi, M.H., Li, V., Keser, B. and Denison, M.S. (2001) Activation of the Ah receptor signaling pathway by prostaglandins, J. Biochem. Molec. Toxicol. 15, 187-196.
  • Monk, S.A., Denison, M.S. and Rice, R.H. (2001) Transient expression of CYP1A1 in rat epithelial cells cultured in suspension, Arch. Biochem. Biophys. 393, 154-162.
  • Van Overmeire, I., Clark, G.C., Brown, D., Chu, M.D., Cooke, W.M., Denison, M.S., Baeyens, W., Srebrnik, S. and Goeyens, L. (2001) Trace contamination with dioxin-like chemicals in feed and food substances: evaluation of the TEQ determination for risk assessment and regulatory responses, Env. Sci. & Policy 4, 345-357.
  • Ziccardi, M.H., Gardner, I.A. and Denison, M.S. (2001) Application of the luciferase recombinant cell culture bioassay for the detection of dioxin-like activity of PAHs in the serum of wildlife, Organohalogen Compounds 54, 73-76.
  • Rogers, J.M. and Denison, M.S. (2001) Analysis of the anti-estrogenic effect of TCDD in human ovarian carcinoma (BG-1) cells, Organohalogen Compounds 53, 5-9.
  • Jeong, S.-H., Cho, J.-H., Denison, M.S. and Kim, O.-K. (2001) High-throughput molecular bioassay for the determination of dioxins and PCBs in meat and animal feeds, Organohalogen Compounds 54, 16-22.
  • Brown, D.J., Van Overmeire, I., Goeyens, L., Denison, M.S. and Clark, G.C. (2001) Analysis of brominated flame retardants and brominated dibenzodioxins and biphenyls for Ah receptor activation using the CALUX bioassay, Organohalogen Compounds 54, 12-15.
  • Denison, M.S., Nagy, S.R., Clark, G.C., Chu, M., Brown, D.J., Murata, H., Shan, G., Snaborn, J.R. and Hammock, B.D. (2001) Bioanalytical approaches for the detection of dioxin and related halogenated aromatic hydrocarbons, Organohalogen Compounds 54, 8-11.


Progress 01/01/00 to 12/31/00

Outputs
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related chemicals are persistent and widespread environmental contaminants whose adverse effects are mediated by the Ah receptor (AhR), a ligand-dependent DNA-regulatory protein that alters gene expression. Using molecular biological approaches we have examined the molecular mechanism of TCDD/AhR action and have demonstrated that the binding of several nuclear protein factors to the AhR can either facilitate or inhibit the ability of the liganded receptor complex to turn on gene expression. These results provide insights into the mechanisms by which the adverse effects of environmental toxicants can be modulated by endogenous signaling factors and pathways. We have also used our AhR-based recombinant cell bioassay to demonstrate the presence of TCDD and TCDD-like chemicals in commercial and consumer products as well as the presence of these chemicals in a natural dietary supplements. New recombinant luciferase reporter plasmids have also been developed which respond to retinoids or androgens with the induction of luciferase gene expression when inserted into appropriate cell lines. We also generated a recombinant human ovarian carcinoma cell line which responds to estrogens and estrogenic chemicals with the induction of luciferase gene expression. This novel cell bioassay system responds in a dose-dependent manner to estradiol and can detect as little as 0.1 pM of estradiol. Using the optimized cell bioassay, we demonstrated the ability of numerous xenoestrogens (including o'p'-DDT, methoxychlor, kepone, bisphenol A and nonylphenol) to activate this bioassay demonstrates the utility for screening. Similar cell-based bioassay systems for the detection of xenobiotics which disrupt androgen, thyroid hormone and retinoid signaling pathways are being developed.

Impacts
(N/A)

Publications

  • Lee, C.Z., Royce, F.H., Denison, M.S. and Pinkerton, K.E. (2000) Effect of in utero and postnatal exposure to environmental tobacco smoke (RTC) on the developmental expression of pulmonary cytochrome P450 monooxygenases, J. Biochem. Molec. Toxicol. 14, 121-130.
  • Seidel, S.D., Li, V., Winter, G.M., Rogers, W.J., Martinez, E.I. and Denison, M.S. (2000) Ah receptor-based chemical screening bioassays: application and limitations for the detection of Ah receptor agonists, Toxicol. Sci, 55,107-115.
  • Rogers, J.M. and Denison, M.S. (2000) Recombinant cell bioassays for endocrine disruptors: development of a stably transfected human ovarian cell line for the detection of estrogenic and anti-estrogenic chemicals, In Vitro & Molec. Toxicol. 13, 67-82.
  • Williams, S.N., Shih, S., Guenette, D.K., Brackney, W., Denison, M.S., Pickwell, G.V. and Quattrochi, L.C. (2000) Green tea flavonoids inhibit TCDD-induced CYP1A1 and CYP1A2 gene expression in human livers cells, Chem. Biol. Interact. 28, 211-219.
  • Rogers, J.M. and Denison, M.S. (2000) Application of a human ovarian cell bioassay for the detection and analysis of estrogen-toxicant interaction, Organohalogen Compounds 49, 334-337.
  • Heath-Pagliuso, S., Mui, R., Milici, A., Giese, S., Chin, R. and Denison, M.S. (2000) Tryptophan metabolites, indole-3-pyruvic acid, DL-3-indolelactic acid, L-kynurenine, and kynurenic acid activate Ah receptor signal transduction, Organohalogen Compounds 49, 289-292.
  • Jones, C.L., Bank, A., Seidel, S.D., Schafer, M.W., Verhagen, M. and Denison, M.S. (2000) Role of chelatable metal ions in aryl hydrocarbon receptor (AhR) function, Organohalogen Compounds 49, 293-296.
  • Jones, C.L. and Denison, M.S. (2000) A model for functional analyses of coadaptor involvement in dioxin-inducible gene expression, Organohalogen Compounds 49, 29-32
  • Rushing, S.R., Wong, C., Privalsky, M.L. and Denison, M.S. (2000) SMRT mediated transcriptional silencing of the ah receptor signaling pathway is not observed in human MCF-7 or BG-1 cell lines, Organohalogen Compounds 49, 45-48.
  • Khan, E.M. and Denison, M.S. (2000) Synergistic Activation of Ah receptor-dependent gene expression by activators of protein kinase C, Organohalogen Compounds 49, 143-146.
  • Shan, G., Sanborn, J.R., Gilman, S.D., Nagy, S.R., Gee, S.J., Stoutamire, D.W., Mercer, R., Jones, A.D., Stanker, L.H., Denison, M.S. and Hammock, B.D. (2000) Surrogates for dioxin analyses: analytical, ELISA and toxicological aspects, Organohalogen Compounds 45, 228-231.
  • Arrieta, D.E., Ontiveros, C., Denison, M.S., and Washburn, B.S. (2000) Ah receptor mediated effects of particulate organic extracts from the Paso Del Norte airshed along the U.S.-Mexico border, Organohalogen Compounds 45, 212-215.
  • Nagy, S.R., Lui, G., Lam, K. and Denison, M.S. (2000) A green fluorescent protein based recombinant cell bioassay for the detection of activators of the aryl hydrocarbon receptor: application for screening of a 1,5-dialkylamino-2,4-dinitrobenzene combinatorial chemical library, Organohalogen Compounds 45, 232-235.
  • Bohonowych, J.E., Rogers, J.M., Jeuken, A. and Denison, M.S. (2000) Activation of Ah and estrogen receptor-based cell bioassay systems by extracts of natural dietary herbal supplements, Organohalogen Compounds 45, 240-243.
  • Monk, S.A., Denison, M.S. and Rice, R.H. (2000) Progressive silencing of CYP1A1 induction in rat keratinocytes, Organohalogen Compounds 49, 285-288.
  • Garrison, P. M. and Denison, M. S. (2000) Analysis of the murine AhR gene promoter, J. Biochem. Molec. Toxicol. 14, 1-10.
  • Garrison, P. M., Rogers, J. M., Brackney, W. R. and Denison, M. S. (2000) Effect of histone deacetylase inhibitors on the Ah receptor gene promoter, Arch. Biochem. Biophys. 374(2):161-171.
  • Ziccardi, M.H., Gardner I.A. and Denison, M.S. (2000) Development and modification of a recombinant cell bioassay to directly detect halogenated and polycyclic aromatic hydrocarbons in serum, Toxicol. Sci. 54, 183-193.
  • Fry, D.M., Hayes, L., Robbins, P.K., Herrenstein, L.A., Denison, M.S., Ziccardi, M. and Orazio, C.E. (2000) Dioxin exposure and effects assessment of red-tailed tropic birds nesting on Johnston Island, central Pacific Ocean, Organohalogen Compounds 49, 430-433.


Progress 01/01/99 to 12/31/99

Outputs
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related chemicals, represent a diverse group of persistent and widespread environmental contaminants. The toxic and biological effects of these chemicals are mediated via their interaction with the Ah receptor (AhR), a ligand-dependent DNA-regulatory protein which can affect gene expression. Using various molecular biological approaches we have demonstrated that the AhR can directly interact with NF-kB, a critical DNA regulatory factor which plays a crucial role in modulating immunological responsiveness. These results demonstrate one avenue by which dioxin-like chemicals can adversely affect signaling events in immune cells, an area in which little is known. Application of our AhR-based recombinant bioassay systems for the detection and relative quantitation of TCDD-like chemicals has demonstrated dioxin-like activity in technical grade propriconazole, a commercially available lampricide used extensively in the Great Lakes area. We have also compared our AhR-based dioxin screening bioassay systems to other similar systems and find that our cell-based bioassay is significantly more sensitive (with a minimal detection limit of TCDD as low as 100 parts-per-quadrillion). In addition, our bioassay system is significantly less affected by those chemicals which result in large numbers of false positives in the currently available in vitro bioassay systems. We are currently developing similar cell-based bioassay systems for the detection of xenoestrogens and other environmental endocrine disruptors.

Impacts
(N/A)

Publications

  • Tian Y., Ke S., Denison, M. S., Rabson, A. B. and Gallo M. A. 1999. Ah receptor and NF-kappaB interactions, a potential mechanism for dioxin toxicity, J. Biol. Chem. 274, 510-515.
  • Levine, S.L., Oris, J.T. and Denison, M.S. 1999. Modulation of CYP1A expression in rainbow trout by a technical grade formulation of propriconazole, Environ. Toxicol. Chem. 18, 2565-2573.
  • Seidel, S. D. and Denison, M. S. 1999. Differential gene expression in wild-type and Arnt-defective mouse hepatoma (Hepa1c1c7) cells, Toxicol. Sci. 52, 217-225.
  • Denison, M.S., Seidel, S.D., Ziccardi, M., Rogers, W.I., Brown, D.J. and Clark, G.C. 1999. Ah receptor-based bioassays for dioxins and related chemicals: applications and limitations, Organohalogen Compounds 40, 27-30.
  • Clark, G.C., Brown, D.J., Seidel, S.D., Phelan, D. and Denison, M.S. 1999. Characterization of the CALUX and GRAB bioassays for sensitivity and specificity in detection of pharmacological agents that activate the Ah receptor signaling system, Organohalogen Compounds 42, 309-312.
  • Schecter, A.J., Sheu, S.U., Birnbaum, L.S., Devito, M.J., Denison, M.S. and Papke, O. 1999. A comparison and discussion of two differing methods of measuring dioxin-like compounds: gas chromatography-mass spectrometry and the CALUX bioassay - implications for health studies, Organohalogen Compounds 40, 247-250.


Progress 01/01/98 to 12/01/98

Outputs
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related halogenated aromatic hydrocarbons (such as polychlorinated biphenyls (PCBs)), represent a widespread group of persistent and highly toxic environmental chemicals. These chemicals exert their toxic effects through an interaction with the Ah receptor (AhR), a ligand-dependent DNA-regulatory protein, and their adverse effects appear to occur by differentially enhancing gene expression. We have developed two mechanism-based recombinant bioassay systems for sensitive and rapid detection and relative quantitation of TCDD and related chemicals in sample extracts. These assays have revealed that numerous natural and synthetic chemicals, as well as extracts from a wide variety of commercial, consumer, industrial and food products contain chemicals/AhR ligands that can activate these bioassays. A major unresolved issue has been the question of the identity of the natural physiological ligand(s) for this receptor. We have identified several naturally occurring classes of physiological chemicals which can activate our bioassay systems including two tryptophan-derived chemicals, namely tryptamine and indole acetic acid, and bilirubin and biliverdin as full AhR agonists. Examination of synthetic chemicals has also revealed that Carbaryl, an insecticide used commonly throughout the world, is an AhR ligand. Studies are underway to further identify and characterize these and other natural and synthetic AhR ligands and determine their physiological and toxicological significance. (1557 letters, including spaces).

Impacts
(N/A)

Publications

  • JOHNSON, M. L., SALVESON, A., HOLMES, L., DENISON, M. S. and FRY, D. M. (1998) The Presence of Environmental Estrogens in Agricultural Drain Water from the Central Valley of California, Bull. Environ.
  • DENISON, M. S., PHELEN, D. and ELFERINK, C. J. (1998) The Ah receptor signal transduction pathway, "Xenobiotics, receptors and Gene Expression", Denison, M.S. and Helferich, eds., pp. 3-33, Taylor and
  • DENISON, M. S., SEIDEL, S. D., ROGERS, W. J., ZICCARDI, M., WINTERS, G. M. and HEATH-PAGLIUSO, S. (1998) Natural and synthetic ligands for the Ah receptor, in: Molecular Biology of the Toxic Response (Puga, A. and Wallace, K. B., eds.), pp.
  • PHELEN, D. M., BRACKNEY, W. R. and DENISON, M. S. (1998) The Ah Receptor can bind ligand in the absence of receptor-associated heat-shock (hsp) 90, Arch. Biochem. Biophys. 353, 47-54.
  • BESSELINK, H. T., DENISON, M. S., HAHN, M. E., VETHAAK, A. D., KOEMAN, J. H. and BROUWER, A. (1998) Molecular studies towards understanding the low responsiveness of hepatic cytochrome P4501A
  • HEATH-PAGLIUSO, S. ROGERS, W. J., TULLIS, K., SEIDEL, S. D., CENIJN, P. H., BROUWER, A. and DENISON, M. S. (1998) Activation of the Ah receptor by tryptophan and tryptophan metabolites, Biochem. 37,
  • PHELAN, D., WINTER, G. M., ROGERS, W. J., LAM, J. C. and DENISON, M. S. (1998) Activation of the Ah receptor signal transduction pathway by bilirubin and biliverdin. Arch. Biochem. Biophys. 357, 155-163.


Progress 01/01/97 to 12/01/97

Outputs
The Ah receptor (AhR) is a ligand-dependent DNA-regulatory protein that mediates he toxic/biological effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related chemicals by differentially enhancing gene expression. We have developed mechanism-based recombinant bioassay systems for use in the detection and relative quantitation of TCDD-like chemicals in sample extracts. Using these methods, we identified a wide variety of natural and synthetic chemicals, commercial, consumer and industrial products and vegetable and herbal extracts that contain a TCDD-like chemicals. Although the identity and toxic potency of the chemical(s) in these extracts remain to be determined, the widespread nature of these chemicals may be of concern. To demonstrate the presence or absence of dioxin in these crude sample extracts, a rapid micro-scale extraction procedure for isolation of dioxin-like HAHs from biological and environmental matrices was developed which effectively separates the dioxins from other interfering chemicals (such as the polycyclic aromatic hydrocarbons) in the extract. This procedure is a major step forward in our attempts to develop a bioassay applicable for field use. The cell bioassay systems we have developed for detection of TCDD-like chemicals will allow high through-put analysis of samples and sample extracts as well as providing researchers with a sensitive bioassays for direct screening of serum for TCDD-like chemicals, a procedure we are using for rapid large scale screening of human and animal blood and serum samples in epidemiological studies.

Impacts
(N/A)

Publications

  • RICHTER, C.A., TIEBER, V.L., DENISON, M.S. and GIESY, J.P. (1996), An in vitro rainbow trout cell bioassay for AhR-mediated toxins, Environ. Toxicol. Chem. 16, 543-550.
  • WASHBURN, B.S., HINTON, D.E., REIN, K.X., BADEN, D.G., WALSH, P.J., TULLIS, K. and DENISON, M.S. (1997) Brevetoxin-6 (PbTx-6), a non-aromatic marine neurotoxin, is a ligand for the aromatic hydrocarbon receptor, Arch. Biochem. Biophys.
  • MURK, A.J., LEONARDS, P.E.G., BULDER, A.S., JONAS, A.S., ROZEMEIJER, M.J.C., DENISON, M.S., KOEMAN, J.H. and BROUWER, A. (1997) The CALUX (chemical-activated luciferase expression) assay adapted and validated for measuring TCDD equivalents.
  • JOHNSON, M. L., SALVESON, A., HOLMES, L., DENISON, M. S. and FRY, D. M. (1998) The presence of environmental estrogens in agricultural drain water from the central valley of California, Bull. Environ.
  • DENISON, M.S. (1998) The Ah receptor: a regulator of the biochemical and toxicological Actions of structurally diverse chemicals, Toxicol. and Ecotoxicol. News. IN PRESS.
  • DENISON, M.S., SEIDEL, S.D., ROGERS, W.J., ZICCARDI, M., WINTER, G.M. and HEATH-PAGLIUSO, S. (1998) Natural and synthetic ligands for the Ah receptor, in: Molecular Biology Approaches to Toxicology (Puga, A and Wallace, K.B., eds).
  • DENISON, M.S., PHELAN, D. and ELFERINK, C.J. (1998) The Ah Receptor Signal Transduction Pathway. In:Toxicant-Receptor Interactions: Modulation of Signal Transduction and Gene Expression (Denison M.S.


Progress 01/01/96 to 12/30/96

Outputs
The Ah receptor (AhR) is a ligand-dependent, DNA-regulatory protein that mediates many of the biological/toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related halogenated aromatic hydrocarbons (HAHs). Mechanistically, the AhR exerts many of its biological actions by differentially enhancing the expression of selected genes. In studies carried out during this period, we have taken advantage of this aspect of TCDD action to develop a series of recombinant bioassay systems for the detection of TCDD-like chemicals. These bioassay systems are very sensitive to these chemicals, with a minimal detection level of 0.01 ppb TCDD, and they respond in a time-, dose- and AhR-dependent manner. Not only have we used the bioassays as a screening system for the detection of TCDD-like chemicals in a variety of environmental and biological materials, but we have examined the ability of a wide variety of natural and synthetic chemicals to regulate gene expression via the AhR. More recently, we have modified the bioassay system for use in direct screening of small amounts of blood for dioxin-like chemicals. This modification allows large scale blood screening for epidemiological surveys prior to more costly chemical analysis.

Impacts
(N/A)

Publications

  • GARRISON, P.M., AARTS, J.M.M.J. G., BROUWER, A. and GIESY, J.P. and DENISON, M.S.(1996) Ah receptor-mediated gene expression: production of a recombinant mouse hepatoma cell bioassay system for detection of 2,3,7,8-tetrachlorodibenzo-p.
  • SANDERSON, J., AARTS, J.M.M.J.G., BROUWER, A., FROESE, K. L., DENISON, M.S. and GIESY, J.P. (1996) Comparisons of Ah receptor-mediated luciferase and ethoxyresorufin O-dethylase induction in H4IIE cells: implications for their useas bio.
  • BALAGUER, P., JOYEAUX, A. M., DENISON, M. S., VINCENT, R., GILLESBY, B. and ZACHAREWSKI, T. (1996) Assessing the estrogenic and dioxin-like activities of chemicals and complex mixtures using in vitro recombinant receptor/reporter geneassay.
  • VILLALOBOS, A., ANDERSON, M.J., DENISON, M.S., HINTON, D., KENNEDY, I.M., JONES,A.D., CHANG, D.P. Y., YANG, G. and KELLY, P. (1996) Toxicity and biological activity of a trichloroethylene combustion generated aerosol, Environmental Health.
  • MURK, A.J., LEGLER, J., DENISON, M. S., VAN DER GUCHTE, C.J. and BROUWER, A. (1996) Chemical-activated luciferase expression (CALUX): a novel in vitro bioassay for Ah receptor active compounds in sediments and pore water, Fun. Appl. Toxicol.
  • GABRIELMICHAEL, A., TULLIS, K., DENISON, M. S., CHEEK, J.M. and PINKERTON, K.E.


Progress 01/01/95 to 12/30/95

Outputs
The Ah receptor (AhR) is an intracellular ligand-dependent, DNA-regulatory protein that mediates many of the biological/toxic effects of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related halogenated aromatic hydrocarbons (HAHs) by differentially enhancing the expression of several genes. During this period, we have examined the ability of a wide variety of chemicals to regulate gene expression via the AhR. Our work has focused primarily on the widespread environmental contaminant 2,2',5,5'-tetrachlorobiphenyl (TCB) and the naturally-occurring dietary plant derivative indolo 3,2-b carbazole (ICZ). Our results demonstrate that TCB is a species-specific antagonist of the Ah receptor blocking the action of TCDD and related chemicals in mouse but not in rat, guinea pig and human cells. This inhibition is due to selective inhibition of TCDD binding to the murine AhR but not the AhR of other species. These results provide the first evidence for distinct species differences in AhR ligand binding specificity and provides some insight into understanding the observed species specific differences in responsiveness to these chemicals. In contrast to TCB, the dietary plant product IC appears to act as a TCDD-like chemical in that it exhibits full agonist activity (e.g., it binds to the AhR, stimulates AhR transformation, nuclear accumulation and DNA binding and it activates gene expression).

Impacts
(N/A)

Publications

  • CHEN, Y.H., RIBY, J., SRIVASTAVE, R., BARTHOLOMEW, J., DENISON, M. and BJELDANES, L. 1995. Regulation of CYP1A1 by indolo 3,2-b
  • ARTS, J.M.M.J.G., DENISON, M.S., COX, M.A., SCHALK, M.A.C., GARRISON, P.M., TULLIS, K. DEHAAN, L.H.J. and BROUWER, A. 1995. Species-specific antagonism of Ah receptor action by 2,2',5,5'-tetrachloro- and 2,2',3',4,4'-hexachlorobiphenyl,.
  • DENISON, M.S. and WHITLOCK, J.P., JR. 1995. Xenobiotic-inducible transcription of cytochrome P450 genes, J. Biol. Chem. 270, 18175-18178.


Progress 01/01/94 to 12/30/94

Outputs
The Ah receptor (AhR) is an intracellular protein that mediates many of the biological/toxic effects of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related halogenated aromatic hydrocarbons (HAHs). The AhR is a ligand-dependent, DNA-regulatory protein that exerts its biological action by differentially enhancing the expression of several genes. In studies carried out during this period, we have identified two distinct high affinity DNA binding forms of the AhR complex which exhibit similar DNA binding affinity and nucleotide specificity. The role of these multiple AhR complexes in the biochemical/toxicological action of these chemicals is being examined. The presence of HAHs in environmental samples as complex mixtures has made it difficult to predict the biological and toxic potency of these chemicals. We have utilized aspects of the AhR-dependent mechanism of action of these chemicals to develop a highly specific bioassay system for the detection of bioactive/toxic HAHs in complex mixtures. We have constructed and utilized a recombinant plasmid vector which contains an alkaline phosphatase reporter gene whose expression is inducible by dioxin-like chemicals and whose enzymatic activity can be rapidly and inexpensively measured. Stable transfection of this vector into mouse hepatoma cells has produced a novel cell line in which chemical-induced gene expression can easily be measured.

Impacts
(N/A)

Publications


    Progress 01/01/93 to 12/30/93

    Outputs
    The Ah receptor (AhR) mediates many, if not all, of the toxic and biological effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related chemicals. Studies carried out in the current year have focused on a detailed examination of the functionality of the TCDD:AhR complex and its interaction with its DNA recognition site. We have carried out studies to examine the role of protein kinase c (PKC) on AhR functionality and our experiments have revealed that inhibition of PKC activity, by the use of selective inhibitors, had no significant effect on AhR ligand or DNA binding and demonstrate that PKC is not involved in AhR functionality. Additionally, we have examined the high affinity binding of transformed TCDD:AHR complex with the DNA utilizing UV-crosslinking and gel retardation analysis. Our results have revealed that the DNA binding forms of the transformed AhR complex consist of proteins with molecular weights of about 97, 105, 115 kDa and we have identified the spatial arrangement of these proteins on the DNA. Photoaffinity labeling with a radioiodinated TCDD agonist indicated the 105 kDa protein as the ligand binding subunit; the identity of the remaining proteins components remains to be determined. Overall, our results not only demonstrate that the critical protein-DNA contacts which occur between the AhR complex and the DNA are made by the ligand-binding subunit but they indicate that the DNA-binding form of the AhR complex exists as two distinct heteromeric protein complexes.

    Impacts
    (N/A)

    Publications

    • SWANSON, H.I., TULLIS, K. AND DENISON, M.S. (1993) Binding of transformed Ah receptor complex to a dioxin responsive transcriptional enhancer: identification of two distinct heterodimeric DNA-binding forms, Biochemistry, 32, 12841-12849.
    • SCHAFER, M., MADHUKAR, B.V., SWANSON, H.I., TULLIS, K. AND DENISON, M.S. (1993) Protein kinase c is not involved in Ah receptor transformation and DNA binding, Arch. Biochem. Biophys. 307, 267-271.
    • GANEY, P.E., SIROIS, J.E., DENISON, M.S., ROBINSON, J.P. AND ROTH, R.A. (1993) Neutrophil function after polychlorinated biphenyls in vivo, Environ. Health Perspect. 101, 430-434.