1
|
Farmahin R, Jones SP, Crump D, Hahn ME, Giesy JP, Zwiernik MJ, Bursian SJ, Kennedy SW. Species-specific relative AHR1 binding affinities of 2,3,4,7,8-pentachlorodibenzofuran explain avian species differences in its relative potency. Comp Biochem Physiol C Toxicol Pharmacol 2014; 161:21-5. [PMID: 24434118 DOI: 10.1016/j.cbpc.2013.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 12/24/2013] [Accepted: 12/30/2013] [Indexed: 10/25/2022]
Abstract
Results of recent studies showed that 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are equipotent in domestic chicken (Gallus gallus domesticus) while PeCDF is more potent than TCDD in ring-necked pheasant (Phasianus colchicus) and Japanese quail (Coturnix japonica). To elucidate the mechanism(s) underlying these differences in relative potency of PeCDF among avian species, we tested the hypothesis that this is due to species-specific differential binding affinity of PeCDF to the aryl hydrocarbon receptor 1 (AHR1). Here, we modified a cell-based binding assay that allowed us to measure the binding affinity of dioxin-like compounds (DLCs) to avian AHR1 expressed in COS-7 (fibroblast-like cells). The results of the binding assay show that PeCDF and TCDD bind with equal affinity to chicken AHR1, but PeCDF binds with greater affinity than TCDD to pheasant (3-fold) and Japanese quail (5-fold) AHR1. The current report introduces a COS-7 whole-cell binding assay and provides a mechanistic explanation for differential relative potencies of PeCDF among species of birds.
Collapse
Affiliation(s)
- Reza Farmahin
- Centre for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada; Environment Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
| | - Stephanie P Jones
- Environment Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
| | - Doug Crump
- Environment Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
| | - Mark E Hahn
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - John P Giesy
- Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada; Department of Zoology and Center for Integrative Toxicology, Michigan State University, East Lansing, MI 48824, USA; Department of Biology & Chemistry, City University of Hong Kong, Kowloon, Hong Kong, SAR, China
| | - Matthew J Zwiernik
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| | - Steven J Bursian
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| | - Sean W Kennedy
- Centre for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada; Environment Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada.
| |
Collapse
|
2
|
Expression and pharmacology of endogenous Cav channels in SH-SY5Y human neuroblastoma cells. PLoS One 2013; 8:e59293. [PMID: 23536870 PMCID: PMC3607609 DOI: 10.1371/journal.pone.0059293] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Accepted: 02/13/2013] [Indexed: 12/24/2022] Open
Abstract
SH-SY5Y human neuroblastoma cells provide a useful in vitro model to study the mechanisms underlying neurotransmission and nociception. These cells are derived from human sympathetic neuronal tissue and thus, express a number of the Cav channel subtypes essential for regulation of important physiological functions, such as heart contraction and nociception, including the clinically validated pain target Cav2.2. We have detected mRNA transcripts for a range of endogenous expressed subtypes Cav1.3, Cav2.2 (including two Cav1.3, and three Cav2.2 splice variant isoforms) and Cav3.1 in SH-SY5Y cells; as well as Cav auxiliary subunits α2δ1–3, β1, β3, β4, γ1, γ4–5, and γ7. Both high- and low-voltage activated Cav channels generated calcium signals in SH-SY5Y cells. Pharmacological characterisation using ω-conotoxins CVID and MVIIA revealed significantly (∼ 10-fold) higher affinity at human versus rat Cav2.2, while GVIA, which interacts with Cav2.2 through a distinct pharmacophore had similar affinity for both species. CVID, GVIA and MVIIA affinity was higher for SH-SY5Y membranes vs whole cells in the binding assays and functional assays, suggesting auxiliary subunits expressed endogenously in native systems can strongly influence Cav2.2 channels pharmacology. These results may have implications for strategies used to identify therapeutic leads at Cav2.2 channels.
Collapse
|
3
|
Cheng W, Chen L, Yang S, Han J, Zhai D, Ni J, Yu C, Cai Z. Puerarin suppresses proliferation of endometriotic stromal cells partly via the MAPK signaling pathway induced by 17ß-estradiol-BSA. PLoS One 2012; 7:e45529. [PMID: 23029074 PMCID: PMC3446905 DOI: 10.1371/journal.pone.0045529] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 08/20/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Puerarin is a major isoflavonoid compound extracted from Radix puerariae. It has a weak estrogenic action by binding to estrogen receptors (ERs). In our early clinical practice to treat endometriosis, a better therapeutic effect was achieved if the formula of traditional Chinese medicine included Radix puerariae. The genomic and non-genomic effects of puerarin were studied in our Lab. This study aims to investigate the ability of puerarin to bind competitively to ERs in human endometriotic stromal cells (ESCs), determine whether and how puerarin may influence phosphorylation of the non-genomic signaling pathway induced by 17ß-estradiol conjugated to BSA (E(2)-BSA). METHODOLOGY ESCs were successfully established. Binding of puerarin to ERs was assessed by a radioactive competitive binding assay in ESCs. Activation of the signaling pathway was screened by human phospho-kinase array, and was further confirmed by western blot. Cell proliferation was analyzed according to the protocol of CCK-8. The mRNA and protein levels of cyclin D1, Cox-2 and Cyp19 were determined by real-time PCR and western blotting. Inhibitor of MEK1/2 or ER antagonist was used to confirm the involved signal pathway. PRINCIPAL FINDINGS Our data demonstrated that the total binding ability of puerarin to ERs on viable cells is around 1/3 that of 17ß-estradiol (E(2)). E(2)-BSA was able to trigger a rapid, non-genomic, membrane-mediated activation of ERK1/2 in ESCs and this phenomenon was associated with an increased proliferation of ESCs. Treating ESCs with puerarin abrogated the phosphorylation of ERK and significantly decreased cell proliferation, as well as related gene expression levels enhanced by E(2)-BSA. CONCLUSIONS/SIGNIFICANCE Puerarin suppresses proliferation of ESCs induced by E(2)-BSA partly via impeding a rapid, non-genomic, membrane-initiated ERK pathway, and down-regulation of Cyclin D1, Cox-2 and Cyp19 are involved in the process. Our data further show that puerarin may be a new candidate to treat endometriosis.
Collapse
Affiliation(s)
- Wen Cheng
- Department of Traditional Chinese Medicine, Changhai Hospital and Department of Biochemistry and Molecular Biology, Second Military Medical University, Shanghai, China
| | - Lizao Chen
- Department of Traditional Chinese Medicine, Changhai Hospital and Department of Biochemistry and Molecular Biology, Second Military Medical University, Shanghai, China
| | - Shengsheng Yang
- Department of Traditional Chinese Medicine, Changhai Hospital and Department of Biochemistry and Molecular Biology, Second Military Medical University, Shanghai, China
| | - Jie Han
- Department of Traditional Chinese Medicine, Changhai Hospital and Department of Biochemistry and Molecular Biology, Second Military Medical University, Shanghai, China
| | - Dongxia Zhai
- Department of Traditional Chinese Medicine, Changhai Hospital and Department of Biochemistry and Molecular Biology, Second Military Medical University, Shanghai, China
| | - Jian Ni
- Institute of Micro/Nano Science and Technology, Shanghai Jiaotong University, Shanghai, China
| | - Chaoqin Yu
- Department of Traditional Chinese Medicine, Changhai Hospital and Department of Biochemistry and Molecular Biology, Second Military Medical University, Shanghai, China
| | - Zailong Cai
- Department of Traditional Chinese Medicine, Changhai Hospital and Department of Biochemistry and Molecular Biology, Second Military Medical University, Shanghai, China
| |
Collapse
|
4
|
Billiard SM, Hahn ME, Franks DG, Peterson RE, Bols NC, Hodson PV. Binding of polycyclic aromatic hydrocarbons (PAHs) to teleost aryl hydrocarbon receptors (AHRs). Comp Biochem Physiol B Biochem Mol Biol 2002; 133:55-68. [PMID: 12223212 DOI: 10.1016/s1096-4959(02)00105-7] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous, environmental contaminants that pose a potential risk to fish populations. Both field and laboratory studies suggest that exposure of the early life stages of fish to PAH can mimic the embryotoxic effects of the planar halogenated hydrocarbons (PHHs), the most potent of which is 2,3,7,8-tetrachlorodibenzo-p-dioxin. PHH toxicity is mediated by the aryl hydrocarbon receptor (AHR) and PHH potency is predicted by its AHR-binding affinity and CYP1A induction potency. However, the role of the AHR, if any, in mediating the developmental effects of PAH to fish remains unknown. In this study we looked at the AHR binding affinity of a test set of PAH that had been previously ranked for their potency for inducing teleost CYP1A. PAH that induced CYP1A inhibited [3H]TCDD binding to in vitro-expressed AHRs from rainbow trout and the AHR expressed in PLHC-1 fish hepatoma cells. Generally, the relative rank order for AHR binding affinity predicted the rank order of these same PAH for inducing CYP1A reported in other studies. There was a strong, positive relationship between binding to the PLHC-1 AHR (stimulus) and the EC50s for CYP1A induction (response) in whole juvenile trout and in RTL-W1 cells, but EC50s were much higher than expected for a 1:1 stimulus/response relationship. These data show that the ability of PAH to bind to teleost AHR predicts PAH potency for CYP1A induction. If PAH toxicity is receptor-mediated and predicted by induction potencies, we will have a powerful mechanistic-based tool for rapidly assessing the risk of toxicity to fish of PAH from any source.
Collapse
Affiliation(s)
- Sonya M Billiard
- Department of Biology, Queen's University, ON, Kingston, Canada.
| | | | | | | | | | | |
Collapse
|
5
|
Hestermann EV, Stegeman JJ, Hahn ME. Relationships among the cell cycle, cell proliferation, and aryl hydrocarbon receptor expression in PLHC-1 cells. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2002; 58:201-213. [PMID: 12007875 DOI: 10.1016/s0166-445x(01)00229-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Aryl hydrocarbon receptor (AHR) ligands such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) cause altered cell proliferation in many tissues in vivo and cell types in vitro, and the AHR has been suggested to play a role in cell cycle regulation in mammalian systems. However, the mechanisms underlying these effects are poorly understood. The overall objective of the present work was to investigate possible interactions between cell proliferation, the cell cycle, and AHR signal transduction in a piscine system, the PLHC-1 cell line, which is being used increasingly in aquatic toxicological research. The specific objectives were to characterize proliferation rates and the cell cycle in these cells, to measure effects of TCDD on cell proliferation, and to determine if expression of the AHR varies during the cell cycle. The doubling time of PLHC-1 cells was determined to be 22 h, and the durations of the G1, S and G2/M stages of the cell cycle were 13, 3, and 6 h, respectively. A minimum seeding density of 1.2 x 10(5) cells/cm(2) in medium with 10% calf serum and 0.3 x 10(5) cells/cm(2) in 10% fetal bovine serum was found to be required for subsequent proliferation. Of several cell cycle inhibitors tested, only aphidicolin and nocodazole were effective for obtaining synchronous cell populations. TCDD was found to inhibit PLHC-1 cell proliferation in a time- and dose-dependent manner in multiple passages of one sub-clone, but not in several other sub-clones. Neither AHR mRNA nor protein expression varied during the cell cycle, as measured by RT-PCR and specific binding of [(3)H]TCDD in synchronous PLHC-1 cells. This work establishes techniques for identifying and characterizing possible interactions between the cell cycle and AHR signal transduction in PLHC-1 cells. Taken together, the results indicate that PLHC-1 cells are amenable to analysis of AHR-cell cycle interactions, but that heterogeneity of sub-clones may complicate their use for investigating AHR-mediated changes in proliferation.
Collapse
Affiliation(s)
- Eli V Hestermann
- Biology Department, Redfield 340, MS 32, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | | | | |
Collapse
|
6
|
Hestermann EV, Stegeman JJ, Hahn ME. Serum withdrawal leads to reduced aryl hydrocarbon receptor expression and loss of cytochrome P4501A inducibility in PLHC-1 cells. Biochem Pharmacol 2002; 63:1405-14. [PMID: 11996881 DOI: 10.1016/s0006-2952(02)00892-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Changes in the expression of the aryl hydrocarbon receptor (AHR) have been documented in several systems and in response to a variety of treatments. The significance of these findings is unclear, because the effects of such changes on subsequent responses to AHR ligands seldom have been measured. We tested the ability of changes in serum used in cell culture medium to alter expression of the AHR and induction of cytochrome P4501A (CYP1A) in PLHC-1 teleost hepatoma cells. Culture of early-passage cells in serum-free medium for 2 days led to a loss of CYP1A inducibility by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In contrast, culture in 10% delipidated calf serum increased the TCDD-induced levels of both CYP1A protein and enzymatic activity relative to levels in cells cultured in 10% complete calf serum. These effects were consistent between 8 and 24hr post-treatment, indicating that the kinetics of induction were unaffected. In cells cultured in serum-free medium for 1 and 2 days there was a progressive loss of CYP1A inducibility. This loss of response paralleled a time-dependent decline in AHR protein, as measured by specific binding of [3H]TCDD. Using an operational model for AHR action in PLHC-1 cells, the measured reduction in AHR could be shown to predict the loss of CYP1A induction. Expression of AHR protein was unaffected by culture in 10% delipidated serum. The effects of serum-free medium and delipidated serum were found only in early-passage cells; inducibility of CYP1A and expression of AHR protein in late-passage cells were unaffected by serum withdrawal. Comparison of early- and late-passage cells revealed a 2-fold greater rate of proliferation in the latter, suggesting that a growth advantage is coincident with loss of the serum-dependency of AHR expression. These results provide a quantitative link between changes in receptor expression and a downstream response, establishing a foundation for future studies of receptor expression and sensitivity to toxic responses in vitro and in vivo.
Collapse
Affiliation(s)
- Eli V Hestermann
- Biology Department, Redfield 340, MS 32, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | | | | |
Collapse
|
7
|
Hestermann EV, Stegeman JJ, Hahn ME. Relative contributions of affinity and intrinsic efficacy to aryl hydrocarbon receptor ligand potency. Toxicol Appl Pharmacol 2000; 168:160-72. [PMID: 11032772 DOI: 10.1006/taap.2000.9026] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Models of receptor action are valuable for describing properties of ligand-receptor interactions and thereby contribute to mechanism-based risk assessment of receptor-mediated toxic effects. In order to build such a model for the aryl hydrocarbon receptor (AHR), binding affinities and CYP1A induction potencies were measured in PLHC-1 cells and were used to determine intrinsic efficacies for 10 halogenated aromatic hydrocarbons (HAH): 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7, 8-tetrachlorodibenzofuran (TCDF), and eight polychlorinated biphenyls (PCB). TCDD, TCDF, and non-ortho-substituted PCBs 77, 81, 126, and 169 behaved as full agonists and displayed high-intrinsic efficacy. In contrast, the mono- and di-ortho-substituted PCBs bound to the AHR but displayed lower or no intrinsic efficacy. PCB 156 was a full agonist, but with an intrinsic efficacy 10- to 50-fold lower than non-ortho-substituted PCBs. PCB 118 was a very weak partial agonist. PCBs 105 and 128 were shown to be competitive antagonists in this system. The model was then used to predict CYP1A induction by binary mixtures. These predictions were tested with binary mixtures of PCB 126, 128, or 156 with TCDD. Both PCB 156 (a low-intrinsic efficacy agonist) and PCB 128 (a competitive antagonist) inhibited the response to TCDD, while the response to TCDD and PCB126 was additive. These data support the following conclusions: 1) only 1-2% of the receptors in the cell need be occupied to achieve 50% of maximal CYP1A induction by one of the high-intrinsic efficacy agonists, demonstrating the existence of "spare" receptors in this system; 2) the insensitivity of fish to ortho-substituted PCBs is due to both reduced affinity and reduced intrinsic efficacy compared to non-ortho-substituted PCBs; 3) PCB congeners exhibit distinct structure-affinity and structure-efficacy relationships. Separation of AHR ligand action into the properties of affinity and intrinsic efficacy allows for improved prediction of the behavior of complex mixtures of ligands, as well as mechanistic comparisons across species and toxic endpoints.
Collapse
Affiliation(s)
- E V Hestermann
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, 02543, USA
| | | | | |
Collapse
|
8
|
Hahn ME. The aryl hydrocarbon receptor: a comparative perspective. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART C, PHARMACOLOGY, TOXICOLOGY & ENDOCRINOLOGY 1998; 121:23-53. [PMID: 9972449 DOI: 10.1016/s0742-8413(98)10028-2] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The aryl hydrocarbon receptor (Ah receptor or AHR) is a ligand-activated transcription factor involved in the regulation of several genes, including those for xenobiotic-metabolizing enzymes such as cytochrome P450 1A and 1B forms. Ligands for the AHR include a variety of aromatic hydrocarbons, including the chlorinated dioxins and related halogenated aromatic hydrocarbons whose toxicity occurs through activation of the AHR. The AHR and its dimerization partner ARNT are members of the emerging bHLH-PAS family of transcriptional regulatory proteins. In this review, our current understanding of the AHR signal transduction pathway in non-mammalian and other non-traditional species is summarized, with an emphasis on similarities and differences in comparison to the AHR pathway in rodents and humans. Evidence and prospects for the presence of a functional AHR in early vertebrates and invertebrates are also examined. An overview of the bHLH-PAS family is presented in relation to the diversity of bHLH-PAS proteins and the functional and evolutionary relationships of the AHR and ARNT to the other members of this family. Finally, some of the most promising directions for future research on the comparative biochemistry and molecular biology of the AHR and ARNT are discussed.
Collapse
Affiliation(s)
- M E Hahn
- Biology Department, Woods Hole Oceanographic Institution, MA 02543-1049, USA.
| |
Collapse
|
9
|
Sutter TR, Guzman K, Dold KM, Greenlee WF. Targets for dioxin: genes for plasminogen activator inhibitor-2 and interleukin-1 beta. Science 1991; 254:415-8. [PMID: 1925598 DOI: 10.1126/science.1925598] [Citation(s) in RCA: 233] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD), a widespread environmental contaminant, may elicit its effects by altering gene expression in susceptible cells. Five TCDD-responsive complementary DNA clones were isolated from a human keratinocyte cell line. One of these clones encodes plasminogen activator inhibitor-2, a factor that influences growth and differentiation by regulating proteolysis of the extracellular matrix. Another encodes the cytokine interleukin-1 beta. Thus, TCDD alters the expression of growth regulatory genes and has effects similar to those of other tumor-promoting agents that affect both inflammation and differentiation.
Collapse
Affiliation(s)
- T R Sutter
- Chemical Industry Institute of Toxicology, Research Triangle Park, NC 27709
| | | | | | | |
Collapse
|