The long-term goals of this research are to determine the mechanisms by which polychlorinated biphenyls (PCBs) disrupt thyroid hormone (TH) action during brain development, to define the neurological consequences of this disruption in rodent model systems, and to translate this information to study human populations. PCBs are widespread and persistent environmental contaminants, and incidental exposure to PCBs has been associated with reduced TH levels in pregnant women, lower birth weight and early growth rate, and neurological deficits. We propose that a combination of coplanar (dioxin-like) and non-coplanar PCBs are required to produce metabolites that bind to the TH receptor (TR), producing effects that are dependent on the TH response element (TRE), cellular context and TR isoform. The resulting effects on brain development are not predictable based on our current knowledge. To test this hypothesis and its implications, we will identify specific PCB metabolites in cell culture and in animals following treatments with defined mixtures. AhR-null and CYP1A1-null mice will be employed to confirm the role of AhR and CYP in the generation of PCB metabolites and effects on TH signaling. Specific metabolites will be tested for their ability to bind to rat and human TR11 and TR21 isoforms. Metabolites that exhibit binding will be characterized for their ability to interfere with TH signaling in selected cells in culture. In vitro studies will specifically address the ability of PCB metabolites to act as thyroid hormone agonists or antagonists. A combination of approaches including luciferase reporter assays, electrophoretic mobility shift (EMSA) and chromatin immunoprecipitation (ChIP) will be use in these in vitro studies. Human cells lines derived from liver, fibroblast, monocytes and neurons will be used to test whether these molecular events occur in humans. Endpoints of TH actions disrupted by PCBs in human fibroblasts or monocytes may be useful in studying these events in human populations.

Public Health Relevance

Polychlorinated biphenyls (PCBs) are known to affect brain development in humans, but no child born in the United States is free of contamination with these chemicals. We are testing the novel hypothesis that a combination of PCB types must be present to induce the ability of the human body to modify the PCB structure;these modified structures appear to interfere directly with the ability of thyroid hormone to perform its normal role in development. These studies will provide important new information about the toxicity of PCBs, and perhaps other common contaminants in the human population.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES010026-10
Application #
8391746
Study Section
Special Emphasis Panel (ZRG1-EMNR-A (02))
Program Officer
Heindel, Jerrold
Project Start
2000-05-01
Project End
2014-11-30
Budget Start
2012-12-01
Budget End
2014-11-30
Support Year
10
Fiscal Year
2013
Total Cost
$334,769
Indirect Cost
$118,656
Name
University of Massachusetts Amherst
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
153926712
City
Amherst
State
MA
Country
United States
Zip Code
01003
Zota, Ami R; Linderholm, Linda; Park, June-Soo et al. (2013) Temporal comparison of PBDEs, OH-PBDEs, PCBs, and OH-PCBs in the serum of second trimester pregnant women recruited from San Francisco General Hospital, California. Environ Sci Technol 47:11776-84
Vandenberg, Laura N; Colborn, Theo; Hayes, Tyrone B et al. (2013) Regulatory decisions on endocrine disrupting chemicals should be based on the principles of endocrinology. Reprod Toxicol 38:1-15
Giera, Stefanie; Bansal, Ruby; Ortiz-Toro, Theresa M et al. (2011) Individual polychlorinated biphenyl (PCB) congeners produce tissue- and gene-specific effects on thyroid hormone signaling during development. Endocrinology 152:2909-19
Zota, Ami R; Park, June-Soo; Wang, Yunzhu et al. (2011) Polybrominated diphenyl ethers, hydroxylated polybrominated diphenyl ethers, and measures of thyroid function in second trimester pregnant women in California. Environ Sci Technol 45:7896-905
Degon, Mike; Chipkin, Stuart R; Hollot, C V et al. (2008) A computational model of the human thyroid. Math Biosci 212:22-53
Sharlin, David S; Bansal, Ruby; Zoeller, R Thomas (2006) Polychlorinated biphenyls exert selective effects on cellular composition of white matter in a manner inconsistent with thyroid hormone insufficiency. Endocrinology 147:846-58
You, Seo-Hee; Gauger, Kelly J; Bansal, Ruby et al. (2006) 4-Hydroxy-PCB106 acts as a direct thyroid hormone receptor agonist in rat GH3 cells. Mol Cell Endocrinol 257-258:26-34
Bansal, Ruby; You, Seo-Hee; Herzig, Carolyn T A et al. (2005) Maternal thyroid hormone increases HES expression in the fetal rat brain: an effect mimicked by exposure to a mixture of polychlorinated biphenyls (PCBs). Brain Res Dev Brain Res 156:13-22
Zoeller, R Thomas; Bansal, Ruby; Parris, Colleen (2005) Bisphenol-A, an environmental contaminant that acts as a thyroid hormone receptor antagonist in vitro, increases serum thyroxine, and alters RC3/neurogranin expression in the developing rat brain. Endocrinology 146:607-12
Zoeller, R T; Rovet, J (2004) Timing of thyroid hormone action in the developing brain: clinical observations and experimental findings. J Neuroendocrinol 16:809-18

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