TY - JOUR
T1 - Chronic exposure of killifish to a highly polluted environment desensitizes estrogen-responsive reproductive and biomarker genes
AU - Bugel, Sean M.
AU - Bonventre, Josephine A.
AU - White, Lori A.
AU - Tanguay, Robert L.
AU - Cooper, Keith R.
N1 - Funding Information:
We wish to thank Craig Harvey for assistance with the E2 radioimmunoassay, Caprice Rosato at the Oregon State University Center for Genome Research & Biocomputing for assistance with bisulphite sequencing, and Michael Simonich for critical comments on the manuscript. Gene methylation studies were aided by early access to a preliminary draft of the F. heteroclitus genome sequence, which was supported by funding from the National Science Foundation [ DEB-1120512 ].
Funding Information:
This work was partially carried out at Rutgers, The State University of New Jersey, with funding support to K.R.C. from the NJ Agricultural Experiment Station through Cooperative State Research, Education, and Extension Services [ 01201 ], The Environmental and Occupational Health Sciences Institute [ ES05022 ], the NJ Water Resources Research Institute [ 2009NJ198B ], NJ Department of Environmental Protection Agency, Division of Science, Research and Technology [ SR09-019 ], and the National Oceanic and Atmospheric Administration [ 432742 ]. This work was also partially conducted at Oregon State University, with funding support to R.L.T. by U.S. National Institute of Environmental Health Sciences (NIEHS) Environmental Health Sciences Core Center grant [ P30 ES000210 ], NIEHS Training grant T32 [ ES007060 ], and an NIEHS Superfund Basic Research Program grant [ P42 ES016465 ].
PY - 2014/7
Y1 - 2014/7
N2 - Reproductive and endocrine disruption is commonly reported in aquatic species exposed to complex contaminant mixtures. We previously reported that Atlantic killifish (. Fundulus heteroclitus) from the chronically contaminated Newark Bay, NJ, exhibit multiple endocrine disrupting effects, including inhibition of vitellogenesis (yolk protein synthesis) in females and false negative vitellogenin biomarker responses in males. Here, we characterized the effects on estrogen signaling and the transcriptional regulation of estrogen-responsive genes in this model population. First, a dose-response study tested the hypothesis that reproductive biomarkers (. vtg1, vtg2, chg H, chg Hm, chg L) in Newark Bay killifish are relatively less sensitive to 17β-estradiol at the transcriptional level, relative to a reference (Tuckerton, NJ) population. The second study assessed expression for various metabolism (. cyp1a, cyp3a30, mdr) and estrogen receptor (. ER α, ER βa, ER βb) genes under basal and estrogen treatment conditions in both populations. Hepatic metabolism of 17β-estradiol was also evaluated in vitro as an integrated endpoint for adverse effects on metabolism. In the third study, gene methylation was evaluated for promoters of vtg1 (8 CpGs) and vtg2 (10 CpGs) in both populations, and vtg1 promoter sequences were examined for single nucleotide polymorphism (SNPs). Overall, these studies show that multi-chemical exposures at Newark Bay have desensitized all reproductive biomarkers tested to estrogen. For example, at 10. ng/g 17β-estradiol, inhibition of gene induction ranged from 62% to 97% for all genes tested in the Newark Bay population, relative to induction levels in the reference population. The basis for this recalcitrant phenotype could not be explained by a change in 17β-estradiol metabolism, nuclear estrogen receptor expression, promoter methylation (gene silencing) or SNPs, all of which were unaltered and normal in the Newark Bay population. The decreased transcriptional sensitivity of estrogen-responsive genes is suggestive of a broad effect on estrogen receptor pathway signaling, and provides insight into the mechanisms of the endocrine disrupting effects in the Newark Bay population.
AB - Reproductive and endocrine disruption is commonly reported in aquatic species exposed to complex contaminant mixtures. We previously reported that Atlantic killifish (. Fundulus heteroclitus) from the chronically contaminated Newark Bay, NJ, exhibit multiple endocrine disrupting effects, including inhibition of vitellogenesis (yolk protein synthesis) in females and false negative vitellogenin biomarker responses in males. Here, we characterized the effects on estrogen signaling and the transcriptional regulation of estrogen-responsive genes in this model population. First, a dose-response study tested the hypothesis that reproductive biomarkers (. vtg1, vtg2, chg H, chg Hm, chg L) in Newark Bay killifish are relatively less sensitive to 17β-estradiol at the transcriptional level, relative to a reference (Tuckerton, NJ) population. The second study assessed expression for various metabolism (. cyp1a, cyp3a30, mdr) and estrogen receptor (. ER α, ER βa, ER βb) genes under basal and estrogen treatment conditions in both populations. Hepatic metabolism of 17β-estradiol was also evaluated in vitro as an integrated endpoint for adverse effects on metabolism. In the third study, gene methylation was evaluated for promoters of vtg1 (8 CpGs) and vtg2 (10 CpGs) in both populations, and vtg1 promoter sequences were examined for single nucleotide polymorphism (SNPs). Overall, these studies show that multi-chemical exposures at Newark Bay have desensitized all reproductive biomarkers tested to estrogen. For example, at 10. ng/g 17β-estradiol, inhibition of gene induction ranged from 62% to 97% for all genes tested in the Newark Bay population, relative to induction levels in the reference population. The basis for this recalcitrant phenotype could not be explained by a change in 17β-estradiol metabolism, nuclear estrogen receptor expression, promoter methylation (gene silencing) or SNPs, all of which were unaltered and normal in the Newark Bay population. The decreased transcriptional sensitivity of estrogen-responsive genes is suggestive of a broad effect on estrogen receptor pathway signaling, and provides insight into the mechanisms of the endocrine disrupting effects in the Newark Bay population.
KW - Biomarkers
KW - Choriogenin
KW - Endocrine disruption
KW - Estrogen
KW - Killifish
KW - Vitellogenin
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U2 - 10.1016/j.aquatox.2014.04.014
DO - 10.1016/j.aquatox.2014.04.014
M3 - Article
C2 - 24794048
AN - SCOPUS:84899755221
SN - 0166-445X
VL - 152
SP - 222
EP - 231
JO - Aquatic Toxicology
JF - Aquatic Toxicology
ER -