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Salas-Lucia F, Escamilla S, Bianco AC, Dumitrescu A, Refetoff S. Impaired T3 uptake and action in MCT8-deficient cerebral organoids underlie Allan-Herndon-Dudley syndrome. JCI Insight 2024; 9:e174645. [PMID: 38376950 PMCID: PMC11128209 DOI: 10.1172/jci.insight.174645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 02/15/2024] [Indexed: 02/22/2024] Open
Abstract
Patients with mutations in the thyroid hormone (TH) cell transporter monocarboxylate transporter 8 (MCT8) gene develop severe neuropsychomotor retardation known as Allan-Herndon-Dudley syndrome (AHDS). It is assumed that this is caused by a reduction in TH signaling in the developing brain during both intrauterine and postnatal developmental stages, and treatment remains understandably challenging. Given species differences in brain TH transporters and the limitations of studies in mice, we generated cerebral organoids (COs) using human induced pluripotent stem cells (iPSCs) from MCT8-deficient patients. MCT8-deficient COs exhibited (i) altered early neurodevelopment, resulting in smaller neural rosettes with thinner cortical units, (ii) impaired triiodothyronine (T3) transport in developing neural cells, as assessed through deiodinase-3-mediated T3 catabolism, (iii) reduced expression of genes involved in cerebral cortex development, and (iv) reduced T3 inducibility of TH-regulated genes. In contrast, the TH analogs 3,5-diiodothyropropionic acid and 3,3',5-triiodothyroacetic acid triggered normal responses (induction/repression of T3-responsive genes) in MCT8-deficient COs, constituting proof of concept that lack of T3 transport underlies the pathophysiology of AHDS and demonstrating the clinical potential for TH analogs to be used in treating patients with AHDS. MCT8-deficient COs represent a species-specific relevant preclinical model that can be utilized to screen drugs with potential benefits as personalized therapeutics for patients with AHDS.
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Affiliation(s)
- Federico Salas-Lucia
- Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Department of Medicine, The University of Chicago, Chicago, Illinois, USA
| | - Sergio Escamilla
- Instituto de Neurociencias de Alicante, Miguel Hernández-CSIC University, Sant Joan d’Alacant, Alicante, Spain
| | - Antonio C. Bianco
- Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Department of Medicine, The University of Chicago, Chicago, Illinois, USA
| | - Alexandra Dumitrescu
- Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Department of Medicine, The University of Chicago, Chicago, Illinois, USA
- Committee on Molecular Metabolism and Nutrition
| | - Samuel Refetoff
- Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Department of Medicine, The University of Chicago, Chicago, Illinois, USA
- Department of Pediatrics, and Committee on Genetics, The University of Chicago, Chicago, Illinois, USA
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2
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Khumpirapang N, Suknuntha K, Wongrattanakamon P, Jiranusornkul S, Anuchapreeda S, Wellendorph P, Müllertz A, Rades T, Okonogi S. The Binding of Alpinia galanga Oil and Its Nanoemulsion to Mammal GABAA Receptors Using Rat Cortical Membranes and an In Silico Modeling Platform. Pharmaceutics 2022; 14:pharmaceutics14030650. [PMID: 35336025 PMCID: PMC8948626 DOI: 10.3390/pharmaceutics14030650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/04/2022] [Accepted: 03/14/2022] [Indexed: 12/10/2022] Open
Abstract
The anesthetic effect of Alpinia galanga oil (AGO) has been reported. However, knowledge of its pathway in mammals is limited. In the present study, the binding of AGO and its key compounds, methyl eugenol, 1,8-cineole, and 4-allylphenyl acetate, to gamma-aminobutyric acid type A (GABAA) receptors in rat cortical membranes, was investigated using a [3H]muscimol binding assay and an in silico modeling platform. The results showed that only AGO and methyl eugenol displayed a positive modulation at the highest concentrations, whereas 1,8-cineole and 4-allylphenyl acetate were inactive. The result of AGO correlated well to the amount of methyl eugenol in AGO. Computational docking and dynamics simulations into the GABAA receptor complex model (PDB: 6X3T) showed the stable structure of the GABAA receptor–methyl eugenol complex with the lowest binding energy of −22.16 kcal/mol. This result shows that the anesthetic activity of AGO and methyl eugenol in mammals is associated with GABAA receptor modulation. An oil-in-water nanoemulsion containing 20% w/w AGO (NE-AGO) was formulated. NE-AGO showed a significant increase in specific [3H]muscimol binding, to 179% of the control, with an EC50 of 391 µg/mL. Intracellular studies show that normal human cells are highly tolerant to AGO and the nanoemulsion, indicating that NE-AGO may be useful for human anesthesia.
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Affiliation(s)
- Nattakanwadee Khumpirapang
- Department of Pharmaceutical Chemistry and Pharmacognosy, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok 65000, Thailand;
| | - Krit Suknuntha
- Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Songkhla 90112, Thailand;
| | - Pathomwat Wongrattanakamon
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand; (P.W.); (S.J.)
| | - Supat Jiranusornkul
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand; (P.W.); (S.J.)
| | - Songyot Anuchapreeda
- Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand;
- Research Center of Pharmaceutical Nanotechnology, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Petrine Wellendorph
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark;
| | - Anette Müllertz
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark; (A.M.); (T.R.)
| | - Thomas Rades
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark; (A.M.); (T.R.)
| | - Siriporn Okonogi
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand; (P.W.); (S.J.)
- Research Center of Pharmaceutical Nanotechnology, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand
- Correspondence: ; Tel.: +66-5394-4311
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3
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Jehanno C, Percevault F, Boujrad N, Le Goff P, Fontaine C, Arnal JF, Primig M, Pakdel F, Michel D, Métivier R, Flouriot G. Nuclear translocation of MRTFA in MCF7 breast cancer cells shifts ERα nuclear/genomic to extra-nuclear/non genomic actions. Mol Cell Endocrinol 2021; 530:111282. [PMID: 33894309 DOI: 10.1016/j.mce.2021.111282] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 01/15/2021] [Accepted: 04/11/2021] [Indexed: 01/22/2023]
Abstract
The Myocardin-related transcription factor A [MRTFA, also known as Megakaryoblastic Leukemia 1 (MKL1))] is a major actor in the epithelial to mesenchymal transition (EMT). We have previously shown that activation and nuclear accumulation of MRTFA mediate endocrine resistance of estrogen receptor alpha (ERα) positive breast cancers by initiating a partial transition from luminal to basal-like phenotype and impairing ERα cistrome and transcriptome. In the present study, we deepen our understanding of the mechanism by monitoring functional changes in the receptor's activity. We demonstrate that MRTFA nuclear accumulation down-regulates the expression of the unliganded (Apo-)ERα and causes a redistribution of the protein localization from its normal nuclear place to the entire cell volume. This phenomenon is accompanied by a shift in Apo-ERα monomer/dimer ratio towards the monomeric state, leading to significant functional consequences on ERα activities. In particular, the association of Apo-ERα with chromatin is drastically decreased, and the remaining ERα binding sites are substantially less enriched in ERE motifs than in control conditions. Monitored by proximity Ligation Assay, ERα interactions with P160 family coactivators are partly impacted when MRTFA accumulates in the nucleus, and those with SMRT and NCOR1 corepressors are abolished. Finally, ERα interactions with kinases such as c-src and PI3K are increased, thereby enhancing MAP Kinase and AKT activities. In conclusion, the activation and nuclear accumulation of MRTFA in ERα positive breast cancer cells remodels both ERα location and functions by shifting its activity from nuclear genome regulation to extra-nuclear non-genomic signaling.
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Affiliation(s)
- Charly Jehanno
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France; University Hospital Basel, University of Basel, Basel, Switzerland
| | - Frédéric Percevault
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France
| | - Noureddine Boujrad
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France
| | - Pascale Le Goff
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France
| | - Coralie Fontaine
- INSERM U1048, Institut des Maladies Métaboliques et Cardiovasculaires, Université de Toulouse - UPS, Toulouse, France
| | - Jean-François Arnal
- INSERM U1048, Institut des Maladies Métaboliques et Cardiovasculaires, Université de Toulouse - UPS, Toulouse, France
| | - Michael Primig
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France
| | - Farzad Pakdel
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France
| | - Denis Michel
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France
| | - Raphaël Métivier
- Univ Rennes, Institut de Génétique et Développement de Rennes, UMR 6290 CNRS, Rennes, France
| | - Gilles Flouriot
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France.
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Abstract
Numerical data in biology and medicine are commonly presented as mean or median with error or confidence limits, to the exclusion of individual values. Analysis of our own and others' data indicates that this practice risks excluding 'Goldilocks' effects in which a biological variable falls within a range between 'too much' and 'too little' with a region between where its function is 'just right'; a concept captured by the Swedish term 'Lagom'. This was confirmed by a narrative search of the literature using the PubMed database, which revealed numerous relationships of biological and clinical phenomena of the Goldilocks/Lagom form including quantitative and qualitative examples from the health and social sciences. Some possible mechanisms underlying these phenomena are considered. We conclude that retrospective analysis of existing data will most likely reveal a vast number of such distributions to the benefit of medical understanding and clinical care and that a transparent approach of presenting each value within a dataset individually should be adopted to ensure a more complete evaluation of research studies in future.
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Affiliation(s)
- Henry J Leese
- Centre for Atherothrombosis and Metabolic Disease, Hull York Medical School, University of Hull, Hull, UK
| | - Thozhukat Sathyapalan
- Academic Diabetes, Endocrinology and Metabolism, Hull York Medical School, University of Hull, Hull, UK
| | - Victoria Allgar
- Hull York Medical School, Department of Health Sciences, University of York, York, UK
| | - Daniel R Brison
- Department of Reproductive Medicine, Manchester University NHS Foundation Trust, Manchester, UK
| | - Roger Sturmey
- Centre for Atherothrombosis and Metabolic Disease, Hull York Medical School, University of Hull, Hull, UK
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5
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Santangeli S, Maradonna F, Zanardini M, Notarstefano V, Gioacchini G, Forner-Piquer I, Habibi H, Carnevali O. Effects of diisononyl phthalate on Danio rerio reproduction. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 231:1051-1062. [PMID: 28915543 DOI: 10.1016/j.envpol.2017.08.060] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 07/07/2017] [Accepted: 08/14/2017] [Indexed: 05/22/2023]
Abstract
Di-isononyl phthalate (DiNP) is a high molecular weight phthalate commonly used as a plasticizer. It was introduced as a replacement for bis (2-ethylhexyl) phthalate (DEHP) which is used in the production of plasticized polyvinyl chloride (PVC). The purpose of this study was to investigate for the first time the effect of DiNP on female reproductive physiology in Danio rerio. Fish were exposed to five different doses of DiNP plus control (0 μg/L; 0.42 μg/L; 4.2 μg/L; 42 μg/L; 420 μg/L; 4200 μg/L) for a period of 21 days. We evaluated fish fecundity, oocyte growth, autophagic and apoptotic processes, as well as changes in morphological and biochemical composition of oocytes, using, qPCR analysis, histology and Fourier transform infrared imaging. The results demonstrate a non-monotonic dose response to DiNP. Greater differences were observed at the lowest (0.42 μg/L) and higher concentrations (420 μg/L; 4200 μg/L) of DiNP. The findings provide evidence that exposure to DiNP adversely affect oocytes growth and maturation, leading to abnormal gonadal development and reproduction in zebrafish.
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Affiliation(s)
- Stefania Santangeli
- Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Francesca Maradonna
- Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy; INBB Consorzio Interuniversitario di Biosistemi e Biostrutture, 00136 Roma, Italy
| | - Maya Zanardini
- Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Valentina Notarstefano
- Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Giorgia Gioacchini
- Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Isabel Forner-Piquer
- Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Hamid Habibi
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Oliana Carnevali
- Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy; INBB Consorzio Interuniversitario di Biosistemi e Biostrutture, 00136 Roma, Italy.
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6
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Using TR-FRET to Investigate Protein-Protein Interactions: A Case Study of PXR-Coregulator Interaction. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2017; 110:31-63. [PMID: 29412999 DOI: 10.1016/bs.apcsb.2017.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Time-resolved fluorescence resonance energy transfer (TR-FRET) protein-protein interaction assays, especially in the format of receptor coregulator (coactivator and corepressor) recruitment/repression assays, have been widely used in nuclear receptor research to characterize the modes of action, efficacies, and binding affinities of ligands (including their properties as agonists, antagonists, and inverse agonists). However, there has been only limited progress in using this assay format for pregnane X receptor (PXR). In this chapter, we discuss TR-FRET protein-protein interaction assays and focus on a novel PXR TR-FRET coactivator interaction assay that we have developed based on a PXR coactivator cocrystal study. This new PXR TR-FRET coactivator interaction assay can characterize the binding affinities of PXR ligands and also differentiate antagonists from agonists. This assay is very robust, with the signal remaining stable over a long incubation time (up to 300min has been tested). It can tolerate high concentrations of DMSO (up to 5%) and has a high signal-to-noise ratio (six under typical assay conditions). This newly developed PXR TR-FRET coactivator interaction assay has potential application in high-throughput screening to identify and characterize novel PXR agonists and antagonists.
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7
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Hernández-Puga G, Mendoza A, León-Del-Río A, Orozco A. Jab1 is a T2-dependent coactivator or a T3-dependent corepressor of TRB1-mediated gene regulation. J Endocrinol 2017; 232:451-459. [PMID: 28053002 DOI: 10.1530/joe-16-0485] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 01/04/2017] [Indexed: 12/14/2022]
Abstract
Thyroid hormones (THs) induce pleiotropic effects in vertebrates, mainly through the activation or repression of gene expression. These mechanisms involve thyroid hormone binding to thyroid hormone receptors, an event that is followed by the sequential recruitment of coactivator or corepressor proteins, which in turn modify the rate of transcription. In the present study, we looked for specific coregulators recruited by the long isoform of the teleostean thyroid hormone receptor beta 1 (L-Trb1) when bound to the bioactive TH, 3,5-T2 (T2). We found that jun activation domain-binding protein1 (Jab1) interacts with L-Trb1 + T2 complex. Using both the teleostean and human TRB1 isoforms, we characterized the Jab1-TRB1 by yeast two-hybrid, pull-down and transactivation assays. Our results showed that the TRB1-Jab1 interaction was ligand dependent and involved the single Jab1 nuclear receptor box, as well as the ligand-binding and N-terminal domains of TRB1. We also provide evidence of ligand-dependent, dual coregulatory properties of Jab1. Indeed, when T2 is bound to L-Trb1 or hTRB1, Jab1 acts as a coactivator of transcription, whereas it has corepressor activity when interacting with the T3-bound S-Trb1 or hTRB1. These mechanisms could explain some of the pleiotropic actions exerted by THs to regulate diverse biological processes.
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Affiliation(s)
- Gabriela Hernández-Puga
- Departamento de Neurobiología Celular y MolecularInstituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Arturo Mendoza
- Departamento de Neurobiología Celular y MolecularInstituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Alfonso León-Del-Río
- Programa de Investigación de Cáncer de Mama y Departamento de Biología Molecular y BiotecnologíaInstituto de Investigaciones Biomédicas, UNAM, México, Mexico
| | - Aurea Orozco
- Departamento de Neurobiología Celular y MolecularInstituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
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8
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Lipchik AM, Perez M, Cui W, Parker LL. Multicolored, Tb³⁺-Based Antibody-Free Detection of Multiple Tyrosine Kinase Activities. Anal Chem 2015. [PMID: 26207839 DOI: 10.1021/acs.analchem.5b02233] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Kinase signaling is a major mechanism driving many cancers. While many inhibitors have been developed and are employed in the clinic, resistance due to crosstalk and pathway reprogramming is an emerging problem. High-throughput assays to detect multiple pathway kinases simultaneously could better model these complex relationships and enable drug development to combat this type of resistance. We developed a strategy to take advantage of time-resolved luminescence of Tb(3+)-chelated phosphotyrosine-containing peptides, which facilitated efficient energy transfer to small molecule fluorophores conjugated to the peptides to produce orthogonally colored biosensors for two different kinases. This enabled multiplexed detection with high signal-to-noise in a high-throughput-compatible format. This proof-of-concept study provides a platform that could be applied to other lanthanide metal and fluorophore combinations to achieve even greater multiplexing without the need for phosphospecific antibodies.
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Affiliation(s)
- Andrew M Lipchik
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy and Purdue Center for Cancer Research, Purdue University, 201 S. University Street, West Lafayette, Indiana 47907, United States
| | - Minervo Perez
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy and Purdue Center for Cancer Research, Purdue University, 201 S. University Street, West Lafayette, Indiana 47907, United States
| | - Wei Cui
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy and Purdue Center for Cancer Research, Purdue University, 201 S. University Street, West Lafayette, Indiana 47907, United States
| | - Laurie L Parker
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy and Purdue Center for Cancer Research, Purdue University, 201 S. University Street, West Lafayette, Indiana 47907, United States
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Zoeller RT, Vandenberg LN. Assessing dose-response relationships for endocrine disrupting chemicals (EDCs): a focus on non-monotonicity. Environ Health 2015; 14:42. [PMID: 25533907 PMCID: PMC4440251 DOI: 10.1186/s12940-015-0029-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/29/2015] [Indexed: 05/02/2023]
Abstract
The fundamental principle in regulatory toxicology is that all chemicals are toxic and that the severity of effect is proportional to the exposure level. An ancillary assumption is that there are no effects at exposures below the lowest observed adverse effect level (LOAEL), either because no effects exist or because they are not statistically resolvable, implying that they would not be adverse. Chemicals that interfere with hormones violate these principles in two important ways: dose-response relationships can be non-monotonic, which have been reported in hundreds of studies of endocrine disrupting chemicals (EDCs); and effects are often observed below the LOAEL, including all environmental epidemiological studies examining EDCs. In recognition of the importance of this issue, Lagarde et al. have published the first proposal to qualitatively assess non-monotonic dose response (NMDR) relationships for use in risk assessments. Their proposal represents a significant step forward in the evaluation of complex datasets for use in risk assessments. Here, we comment on three elements of the Lagarde proposal that we feel need to be assessed more critically and present our arguments: 1) the use of Klimisch scores to evaluate study quality, 2) the concept of evaluating study quality without topical experts' knowledge and opinions, and 3) the requirement of establishing the biological plausibility of an NMDR before consideration for use in risk assessment. We present evidence-based logical arguments that 1) the use of the Klimisch score should be abandoned for assessing study quality; 2) evaluating study quality requires experts in the specific field; and 3) an understanding of mechanisms should not be required to accept observable, statistically valid phenomena. It is our hope to contribute to the important and ongoing debate about the impact of NMDRs on risk assessment with positive suggestions.
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10
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An exposure:activity profiling method for interpreting high-throughput screening data for estrogenic activity—Proof of concept. Regul Toxicol Pharmacol 2015; 71:398-408. [DOI: 10.1016/j.yrtph.2015.01.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 01/13/2015] [Accepted: 01/17/2015] [Indexed: 11/17/2022]
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11
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Hildebrandt N, Wegner KD, Algar WR. Luminescent terbium complexes: Superior Förster resonance energy transfer donors for flexible and sensitive multiplexed biosensing. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.01.020] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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12
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Romagnolo DF, Zempleni J, Selmin OI. Nuclear receptors and epigenetic regulation: opportunities for nutritional targeting and disease prevention. Adv Nutr 2014; 5:373-85. [PMID: 25022987 PMCID: PMC4085186 DOI: 10.3945/an.114.005868] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Posttranslational modifications of histones, alterations in the recruitment and functions of non-histone proteins, DNA methylation, and changes in expression of noncoding RNAs contribute to current models of epigenetic regulation. Nuclear receptors (NRs) are a group of transcription factors that, through ligand-binding, act as sensors to changes in nutritional, environmental, developmental, pathophysiologic, and endocrine conditions and drive adaptive responses via gene regulation. One mechanism through which NRs direct gene expression is the assembly of transcription complexes with cofactors and coregulators that possess chromatin-modifying properties. Chromatin modifications can be transient or become part of the cellular "memory" and contribute to genomic imprinting. Because many food components bind to NRs, they can ultimately influence transcription of genes associated with biologic processes, such as inflammation, proliferation, apoptosis, and hormonal response, and alter the susceptibility to chronic diseases (e.g., cancer, diabetes, obesity). The objective of this review is to highlight how NRs influence epigenetic regulation and the relevance of dietary compound-NR interactions in human nutrition and for disease prevention and treatment. Identifying gene targets of unliganded and bound NRs may assist in the development of epigenetic maps for food components and dietary patterns. Progress in these areas may lead to the formulation of disease-prevention models based on epigenetic control by individual or associations of food ligands of NRs.
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Affiliation(s)
- Donato F Romagnolo
- Department of Nutritional Sciences and University of Arizona Cancer Center, University of Arizona, Tucson, AZ; and
| | - Janos Zempleni
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE
| | - Ornella I Selmin
- Department of Nutritional Sciences and University of Arizona Cancer Center, University of Arizona, Tucson, AZ; and
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13
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Vandenberg LN. Non-monotonic dose responses in studies of endocrine disrupting chemicals: bisphenol a as a case study. Dose Response 2013; 12:259-76. [PMID: 24910584 DOI: 10.2203/dose-response.13-020.vandenberg] [Citation(s) in RCA: 237] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Non-monotonic dose response curves (NMDRCs) have been demonstrated for natural hormones and endocrine disrupting chemicals (EDCs) in a variety of biological systems including cultured cells, whole organ cultures, laboratory animals and human populations. The mechanisms responsible for these NMDRCs are well known, typically related to the interactions between the ligand (hormone or EDC) and a hormone receptor. Although there are hundreds of examples of NMDRCs in the EDC literature, there are claims that they are not 'common enough' to influence the use of high-to-low dose extrapolations in risk assessments. Here, we chose bisphenol A (BPA), a well-studied EDC, to assess the frequency of non-monotonic responses. Our results indicate that NMDRCs are common in the BPA literature, occurring in greater than 20% of all experiments and in at least one endpoint in more than 30% of all studies we examined. We also analyzed the types of endpoints that produce NMDRCs in vitro and factors related to study design that influence the ability to detect these kinds of responses. Taken together, these results provide strong evidence for NMDRCs in the EDC literature, specifically for BPA, and question the current risk assessment practice where 'safe' low doses are predicted from high dose exposures.
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Jiang Y, Gong P, Madak-Erdogan Z, Martin T, Jeyakumar M, Carlson K, Khan I, Smillie TJ, Chittiboyina AG, Rotte SCK, Helferich WG, Katzenellenbogen JA, Katzenellenbogen BS. Mechanisms enforcing the estrogen receptor β selectivity of botanical estrogens. FASEB J 2013; 27:4406-18. [PMID: 23882126 DOI: 10.1096/fj.13-234617] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Because little is known about the actions of botanical estrogens (BEs), widely consumed by menopausal women, we investigated the mechanistic and cellular activities of some major BEs. We examined the interactions of genistein, daidzein, equol, and liquiritigenin with estrogen receptors ERα and ERβ, with key coregulators (SRC3 and RIP140) and chromatin binding sites, and the regulation of gene expression and proliferation in MCF-7 breast cancer cells containing ERα and/or ERβ. Unlike the endogenous estrogen, estradiol (E2), BEs preferentially bind to ERβ, but their ERβ-potency selectivity in gene stimulation (340- to 830-fold vs. E2) is enhanced at several levels (coregulator recruitment, chromatin binding); nevertheless, at high (0.1 or 1 μM) concentrations, BEs also fully activate ERα. Because ERα drives breast cancer cell proliferation and ERβ dampens this, the relative levels of these two ERs in target cells and the BE dose greatly affect gene expression and proliferative response and will be crucial determinants of the potential benefits vs. risks of BEs. Our findings reveal key and novel mechanistic differences in the estrogenic activities of BEs vs. E2, with BEs displaying patterns of activity distinctly different from those seen with E2 and provide valuable information to inform future studies.
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Affiliation(s)
- Yan Jiang
- 1Department of Molecular and Integrative Physiology, University of Illinois and College of Medicine at Urbana-Champaign, Urbana, IL 61801, USA.
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15
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Yu DD, Lin W, Chen T, Forman BM. Development of time resolved fluorescence resonance energy transfer-based assay for FXR antagonist discovery. Bioorg Med Chem 2013; 21:4266-78. [PMID: 23688559 DOI: 10.1016/j.bmc.2013.04.069] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 04/17/2013] [Accepted: 04/26/2013] [Indexed: 01/14/2023]
Abstract
FXR (farnesoid X receptor, NRIH4), a nuclear receptor, plays a major role in the control of cholesterol metabolism. FXR ligands have been investigated in preclinical studies for targeted therapy against metabolic diseases, but have shown limitations. Therefore, there is a need for new agonist or antagonist ligands of FXR, both for potential clinical applications, as well as to further elucidate its biological functions. Here we describe the use of the X-ray crystal structure of FXR complexed with the potent small molecule agonist GW4064 to design and synthesize a novel fluorescent, high-affinity probe (DY246) for time resolved fluorescence resonance energy transfer (TR-FRET) assays. We then used the TR-FRET assay for high throughput screening of a library of over 5000 bioactive compounds. From this library, we identified 13 compounds that act as putative FXR transcriptional antagonists.
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Affiliation(s)
- Donna D Yu
- Department of Diabetes, Endocrinology and Metabolism, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA 91010, USA.
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16
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Ren XM, Guo LH. Molecular toxicology of polybrominated diphenyl ethers: nuclear hormone receptor mediated pathways. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2013; 15:702-8. [PMID: 23467608 DOI: 10.1039/c3em00023k] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are used in large quantities as flame retardant additives in commercial products. Bio-monitoring data show that PBDE concentrations have increased rapidly in the bodies of wildlife and human over the last few decades. Based on the studies on experimental animals, the toxicological endpoints of exposure to PBDEs are likely to be thyroid homeostasis disruption, neuro-developmental deficits, reproductive ineffectiveness and even cancer. Unfortunately, the available molecular toxicological evidence for these endpoints is still very limited. This review focuses on the recent studies on the molecular mechanisms of PBDE toxicities carried out through the hormone receptor pathways, including thyroid hormone receptor, estrogen receptor, androgen receptor, progesterone receptor and aryl hydrocarbon receptor pathways. The general approach in the mechanistic investigation is to examine the in vitro direct binding of a PBDE with a receptor, the in vitro recruitment of a co-activator or co-repressor by the ligand-bound receptor, and the participation of the ligand in the receptor-mediated transcription pathways in cells. It is hoped that further studies in this area would provide more insights into the potential risks of PBDEs to human health.
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Affiliation(s)
- Xiao-Min Ren
- State Key Laboratory of Environmental Chemistry and Eco-toxicology, Research Centre for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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17
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Santillo A, Burrone L, Ferrara D, Minucci S, Pinelli C, Chieffi Baccari G. Thyroid hormone receptor-β gene expression in the brain of the frog Pelophylax esculentus: seasonal, hormonal and temperature regulation. Gen Comp Endocrinol 2012; 178:511-8. [PMID: 22841764 DOI: 10.1016/j.ygcen.2012.07.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 07/02/2012] [Accepted: 07/15/2012] [Indexed: 11/25/2022]
Abstract
Thyroid hormone receptor-β (trβ) cDNA was identified in the adult of Pelophylax esculentus (previously: Rana esculenta), a seasonally breeding species, in order to detect spatial brain trβ expression, its levels through the seasons and in response to 6-n-propyl-2-thiouracil, T(4) and T(3) administrations as well as to thermal manipulations. The deduced amino acid sequence of P. esculentus trβ showed a high similarity to the homologous of other vertebrates. By in situ hybridization we found trβ mRNA signal in the anterior preoptic nucleus, the habenulae, the hypothalamic-pituitary region and the ependyma. Brain trβ transcript levels varied through the seasons, and they were well correlated with brain T(4) levels but only partially with T(3) levels. Experimentally-induced hypothyroidism decreased brain trβ expression. The administration of exogenous thyroid hormones increased brain trβ expression, with T(4) appearing more potent than T(3). The experiments of thermal manipulations further strengthen the hypothesis that T(4) is more effective than T(3) in brain trβ regulation. This study also shows that, as in other vertebrates, deiodinase enzymes could modulate trβ expression via thyroid hormone regulation.
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Affiliation(s)
- Alessandra Santillo
- Dipartimento di Scienze della Vita, Seconda Università di Napoli, via Vivaldi 43, 81100 Caserta, Italy
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18
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Vandenberg LN, Colborn T, Hayes TB, Heindel JJ, Jacobs DR, Lee DH, Shioda T, Soto AM, vom Saal FS, Welshons WV, Zoeller RT, Myers JP. Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses. Endocr Rev 2012; 33:378-455. [PMID: 22419778 PMCID: PMC3365860 DOI: 10.1210/er.2011-1050] [Citation(s) in RCA: 1980] [Impact Index Per Article: 165.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 02/07/2012] [Indexed: 02/08/2023]
Abstract
For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.
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Affiliation(s)
- Laura N Vandenberg
- Tufts University, Center for Regenerative and Developmental Biology, Department of Biology, 200 Boston Avenue, Suite 4600, Medford, Massachusetts 02155, USA.
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19
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Lévy-Bimbot M, Major G, Courilleau D, Blondeau JP, Lévi Y. Tetrabromobisphenol-A disrupts thyroid hormone receptor alpha function in vitro: use of fluorescence polarization to assay corepressor and coactivator peptide binding. CHEMOSPHERE 2012; 87:782-788. [PMID: 22277881 DOI: 10.1016/j.chemosphere.2011.12.080] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 12/16/2011] [Accepted: 12/30/2011] [Indexed: 05/27/2023]
Abstract
Thyroid hormone receptors (TRs) recruit corepressor or coactivator factors to the promoters of target genes to regulate their transcription. Corepressors such as nuclear hormone receptor corepressor (NCoR) are recruited by unliganded TRs, whereas coactivators such as steroid receptor coactivator-2 (SRC2) are recruited when triiodothyronine (T3) is bound to TRs. These coregulator proteins interact with the ligand binding domain (LBD) of TRs via short, conserved peptide sequences that can be used to probe the conformational changes induced in TR LBD by TR ligands. Recombinant LBD of the human TRα1 isoform (hTRα1 LBD) was produced as a fusion with glutathione S-transferase, and used to develop assays based on fluorescence polarization to quantify the binding of either NCoR- or SRC2-derived fluorescent peptides to the hTRα1 LBD. The optimum concentrations of recombinant hTRα1 LBD, and of peptide probes were adjusted in order to produce the greatest possible T3-dependent signal variations in fluorescence polarization. Under these conditions, T3 induced a dose-dependent decrease in NCoR peptide binding, and a reciprocal dose-dependent increase in SRC2 peptide binding, in both cases at similar 50%-effective doses. The TR agonists triiodothyroacetic acid and thyroxine were also effective in preventing NCoR peptide binding and increasing SRC2 peptide binding, whereas reverse-triiodothyronine was less efficient and the biologically inactive thyronine had no effect on either process. These experiments validate cell-free assays based on the use of binding of corepressor or coactivator peptide probes, as measured by fluorescence polarization, for investigating the conformational changes of TRα1 LBD induced by potentially TR-interfering compounds. Both these methods were used to elucidate the mechanism of the disrupting effects of tetrabromobisphenol-A (TBBPA) on the hTRα1 LBD conformation related to the transcriptional activity of the receptor. TBBPA is a flame retardant that is released into the environment, and is a suspected disrupter of thyroid homeostasis. The present results indicate that TBBPA did indeed interfere with the ability of the hTRα1 LBD to bind both NCoR and SRC2. TBBPA behaved similarly to T3 in promoting the release of NCoR from LBD, whereas it failed to promote LBD interactions with SRC2. However, it did reduce the T3-induced interactions between LBD and the coactivator peptide. This study therefore suggests that TBBPA in the micromolar range can affect the regulation of transcription by both the apo- and the holo-TRα1, with potential disruption of the expression of genes that are either up- or down-regulated by T3.
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20
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Structural basis for negative cooperativity within agonist-bound TR:RXR heterodimers. Proc Natl Acad Sci U S A 2012; 109:6084-7. [PMID: 22474364 DOI: 10.1073/pnas.1119852109] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Thyroid hormones such as 3,3',5 triiodo-L-thyronine (T3) control numerous aspects of mammalian development and metabolism. The actions of such hormones are mediated by specific thyroid hormone receptors (TRs). TR belongs to the nuclear receptor family of modular transcription factors that binds to specific DNA-response elements within target promoters. These receptors can function as homo- or heterodimers such as TR:9-cis retinoic acid receptor (RXR). Here, we present the atomic resolution structure of the TRα•T3:RXRα•9-cis retinoic acid (9c) ligand binding domain heterodimer complex at 2.95 Å along with T3 hormone binding and dissociation and coactivator binding studies. Our data provide a structural basis for allosteric communication between T3 and 9c and negative cooperativity between their binding pockets. In this structure, both TR and RXR are in the active state conformation for optimal binding to coactivator proteins. However, the structure of TR•T3 within TR•T3:RXR•9c is in a relative state of disorder, and the observed kinetics of binding show that T3 dissociates more rapidly from TR•T3:RXR•9c than from TR•T3:RXR. Also, coactivator binding studies with a steroid receptor coactivator-1 (receptor interaction domains 1-3) fragment show lower affinities (K(a)) for TR•T3:RXR•9c than TR•T3:RXR. Our study corroborates previously reported observations from cell-based and binding studies and offers a structural mechanism for the repression of TR•T3:RXR transactivation by RXR agonists. Furthermore, the recent discoveries of multiple endogenous RXR agonists that mediate physiological tasks such as lipid biosynthesis underscore the pharmacological importance of negative cooperativity in ligand binding within TR:RXR heterodimers.
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21
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Carroll VM, Jeyakumar M, Carlson KE, Katzenellenbogen JA. Diarylpropionitrile (DPN) enantiomers: synthesis and evaluation of estrogen receptor β-selective ligands. J Med Chem 2011; 55:528-37. [PMID: 22122563 DOI: 10.1021/jm201436k] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Two estrogen receptor (ER) subtypes, ERα and ERβ, mediate the actions of estrogens in diverse reproductive and nonreproductive target tissues. ER subtype-selective ligands, which bind to and activate these subtypes differentially, have proved to be useful in elucidating which actions of estrogens proceed through ERα vs ERβ. Some of these ligands show potential as novel therapeutic agents. Diarylpropionitrile (DPN), an ERβ selective ligand that we developed, is a chiral molecule, but it has been studied almost exclusively as the racemic mixture (rac-DPN, 1). Herein we report the development of an efficient enantioselective synthesis of the two isomers, R-DPN (3) and S-DPN (2), and we have compared the in vitro ligand binding affinities, coactivator binding affinities, recruitment potencies, and cellular transcriptional potencies of these isomers. Both enantiomers show a very high affinity and potency preference for ERβ over ERα, typically in the range of 80-300-fold. Although the enantioselectivity is only modest (3-4-fold), the R-enantiomer is the higher affinity and more potent isomer. While ERβ can be effectively and selectively stimulated by rac-DPN or by either R-DPN or S-DPN, R-DPN might be the preferred member of this isomeric series for biological studies of ERβ function.
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Affiliation(s)
- Vincent M Carroll
- Department of Chemistry, University of Illinois, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
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22
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Kachaylo EM, Pustylnyak VO, Lyakhovich VV, Gulyaeva LF. Constitutive androstane receptor (CAR) is a xenosensor and target for therapy. BIOCHEMISTRY (MOSCOW) 2011; 76:1087-97. [DOI: 10.1134/s0006297911100026] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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23
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Klootwijk W, Friesema ECH, Visser TJ. A nonselenoprotein from amphioxus deiodinates triac but not T3: is triac the primordial bioactive thyroid hormone? Endocrinology 2011; 152:3259-67. [PMID: 21652724 DOI: 10.1210/en.2010-1408] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thyroid hormone (TH) is important for metamorphosis in many species, including the cephalochordate Branchiostoma floridae, a marine invertebrate (amphioxus) living in warmer coastal areas. Branchiostoma expresses a TH receptor, which is activated by 3,3',5-triiodothyroacetic acid (TA(3)) but not by T(3). The Branchiostoma genome also contains multiple genes coding for proteins homologous to iodothyronine deiodinases in vertebrates, selenoproteins catalyzing the activation or inactivation of TH. Three Branchiostoma deiodinases have been cloned: two have a catalytic Sec, and one, bfDy, has a Cys residue. We have studied the catalytic properties of bfDy in transfected COS1 cells by HPLC analysis of reactions with (125)I-labeled substrates and dithiothreitol as cofactor. We could not detect deiodination of T(4), T(3), or rT(3) by bfDy but observed rapid and selective inner ring deiodination (inactivation) of TA(3) and 3,3',5,5'-tetraiodothyroacetic acid (TA(4)). Deiodination of TA(3) by bfDy was optimal at 25 C and 10 mm dithiothreitol. bfDy was extremely labile at 37 C, showing a half-life of less than 2 min, in contrast with a half-life of more than 60 min at 25 C. Deiodination of labeled TA(3) was inhibited dose dependently by unlabeled TA(3)≈TA(4)>T(4)≈T(3). Michaelis-Menten analysis yielded Michaelis-Menten constant values of 6.8 and 68 nm and maximum velocity values of 1.4 and 5.4 pmol/min·mg protein for TA(3) and TA(4), respectively. bfDy was not inhibited by propylthiouracil and iodoacetate and only weakly by goldthioglucose and iopanoic acid. In conclusion, we demonstrate rapid inactivation of TA(3) and TA(4) but not of T(3) and T(4) by the first reported natural nonselenodeiodinase. Our findings support the hypothesis that TA(3) is a primordial bioactive TH.
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Affiliation(s)
- Wim Klootwijk
- Department of Internal Medicine, Erasmus University Medical Center, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
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24
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Jeyakumar M, Carlson KE, Gunther JR, Katzenellenbogen JA. Exploration of dimensions of estrogen potency: parsing ligand binding and coactivator binding affinities. J Biol Chem 2011; 286:12971-82. [PMID: 21321128 PMCID: PMC3075970 DOI: 10.1074/jbc.m110.205112] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 02/04/2011] [Indexed: 12/19/2022] Open
Abstract
The estrogen receptors, ERα and ERβ, are ligand-regulated transcription factors that control gene expression programs in target tissues. The molecular events underlying estrogen action involve minimally two steps, hormone binding to the ER ligand-binding domain followed by coactivator recruitment to the ER·ligand complex; this ligand·receptor·coactivator triple complex then alters gene expression. Conceptually, the potency of an estrogen in activating a cellular response should reflect the affinities that characterize both steps involved in the assembly of the active ligand·receptor·coactivator complex. Thus, to better understand the molecular basis of estrogen potency, we developed a completely in vitro system (using radiometric and time-resolved FRET assays) to quantify independently three parameters: (a) the affinity of ligand binding to ER, (b) the affinity of coactivator binding to the ER·ligand complex, and (c) the potency of ligand recruitment of coactivator. We used this system to characterize the binding and potency of 12 estrogens with both ERα and ERβ. Some ligands showed good correlations between ligand binding affinity, coactivator binding affinity, and coactivator recruitment potency with both ERs, whereas others showed correlations with only one ER subtype or displayed discordant coactivator recruitment potencies. When ligands with low receptor binding affinity but high coactivator recruitment potencies to ERβ were evaluated in cell-based assays, elevation of cellular coactivator levels significantly and selectively improved their potency. Collectively, our results indicate that some low affinity estrogens may elicit greater cellular responses in those target cells that express higher levels of specific coactivators capable of binding to their ER complexes with high affinity.
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Affiliation(s)
- M. Jeyakumar
- From the Department of Chemistry, University of Illinois, Urbana, Illinois 61801
| | - Kathryn E. Carlson
- From the Department of Chemistry, University of Illinois, Urbana, Illinois 61801
| | - Jillian R. Gunther
- From the Department of Chemistry, University of Illinois, Urbana, Illinois 61801
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25
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Chen Y, Young MA. Structure of a thyroid hormone receptor DNA-binding domain homodimer bound to an inverted palindrome DNA response element. Mol Endocrinol 2010; 24:1650-64. [PMID: 20610536 PMCID: PMC5417456 DOI: 10.1210/me.2010-0129] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Thyroid hormone receptor (TR), as a member of the nuclear hormone receptor family, can recognize and bind different classes of DNA response element targets as either a monomer, a homooligomer, or a heterooligomer. We report here the first crystal structure of a homodimer TR DNA-binding domain (DBD) in complex with an inverted repeat class of thyroid response element (TRE). The structure shows a nearly symmetric structure of the TR DBD assembled on the F2 TRE where the base recognition contacts in the homodimer DNA complex are conserved relative to the previously published structure of a TR-9-cis-retinoic acid receptor heterodimer DNA complex. The new structure also reveals that the T-box region of the DBD can function as a structural hinge that enables a large degree of flexibility in the position of the C-terminal extension helix that connects the DBD to the ligand-binding domain. Although the isolated TR DBDs exist as monomers in solution, we have measured highly cooperative binding of the two TR DBD subunits onto the inverted repeat DNA sequence. This suggests that elements of the DBD can influence the specific TR oligomerization at target genes, and it is not just interactions between the ligand-binding domains that are responsible for TR oligomerization at target genes. Mutational analysis shows that intersubunit contacts at the DBD C terminus account for some, but not all, of the cooperative homodimer TR binding to the inverted repeat class TRE.
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26
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Abstract
Most transcription factors including nuclear receptors (NRs) act as sensors of the extracellular and intracellular compartments. As such, NRs serve as integrating platforms for a variety of stimuli and are targets for Post-translational modifications such as phosphorylations. During the last decade, knowledge of NRs phosphorylation advanced considerably because of the emergence of new technologies. Indeed, the development of a wide range of phosphorylation site databases, high accuracy mass spectrometry, and phospho-specific antibodies allowed the identification of multiple novel phosphorylation sites in NRs. New and improved methods also emerge to connect these data with the downstream consequences of phosphorylation on NRs structure (computational prediction, NMR), intracellular localization (FRAP), interaction with coregulators (proteomics, FRET, FLIM), and affinity for DNA (ChIP, ChIP-seq, FRAP). In the future, such integrated strategies should provide data with a treasure-trove of information about the integration of numerous signaling events by NRs.
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27
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Moore TW, Mayne CG, Katzenellenbogen JA. Minireview: Not picking pockets: nuclear receptor alternate-site modulators (NRAMs). Mol Endocrinol 2009; 24:683-95. [PMID: 19933380 DOI: 10.1210/me.2009-0362] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Because of their central importance in gene regulation and mediating the actions of many hormones, the nuclear receptors (NRs) have long been recognized as very important biological and pharmaceutical targets. Of all the surfaces available on a given NR, the singular site for regulation of receptor activity has almost invariably been the ligand-binding pocket of the receptor, the site where agonists, antagonists, and selective NR modulators interact. With our increasing understanding of the multiple molecular components involved in NR action, researchers have recently begun to look to additional interaction sites on NRs for regulating their activities by novel mechanisms. The alternate NR-associated interaction sites that have been targeted include the coactivator-binding groove and allosteric sites in the ligand-binding domain, the zinc fingers of the DNA-binding domain, and the NR response element in DNA. The studies thus far have been performed with the estrogen receptors, the androgen receptor (AR), the thyroid hormone receptors, and the pregnane X receptor. Phenotypic and conformation-based screens have also identified small molecule modulators that are believed to function through the NRs but have, as yet, unknown sites and mechanisms of action. The rewards from investigation of these NR alternate-site modulators should be the discovery of new therapeutic approaches and novel agents for regulating the activities of these important NR proteins.
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Affiliation(s)
- Terry W Moore
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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28
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Lima STC, Nguyen NH, Togashi M, Apriletti JW, Nguyen P, Polikarpov I, Scanlan TS, Baxter JD, Webb P. Differential effects of TR ligands on hormone dissociation rates: evidence for multiple ligand entry/exit pathways. J Steroid Biochem Mol Biol 2009; 117:125-31. [PMID: 19729063 PMCID: PMC2784034 DOI: 10.1016/j.jsbmb.2009.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 08/16/2009] [Accepted: 08/21/2009] [Indexed: 11/26/2022]
Abstract
Some nuclear receptor (NR) ligands promote dissociation of radiolabeled bound hormone from the buried ligand binding cavity (LBC) more rapidly than excess unlabeled hormone itself. This result was interpreted to mean that challenger ligands bind allosteric sites on the LBD to induce hormone dissociation, and recent findings indicate that ligands bind weakly to multiple sites on the LBD surface. Here, we show that a large fraction of thyroid hormone receptor (TR) ligands promote rapid dissociation (T(1/2)<2h) of radiolabeled T(3) vs. T(3) (T(1/2) approximately 5-7h). We cannot discern relationships between this effect and ligand size, activity or affinity for TRbeta. One ligand, GC-24, binds the TR LBC and (weakly) to the TRbeta-LBD surface that mediates dimer/heterodimer interaction, but we cannot link this interaction to rapid T(3) dissociation. Instead, several lines of evidence suggest that the challenger ligand must interact with the buried LBC to promote rapid T(3) release. Since previous molecular dynamics simulations suggest that TR ligands leave the LBC by several routes, we propose that a subset of challenger ligands binds and stabilizes a partially unfolded intermediate state of TR that arises during T(3) release and that this effect enhances hormone dissociation.
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Affiliation(s)
- Suzana T. Cunha Lima
- Department of General Biology, Biology Institute. Federal University of Bahia. 147, Barão de Geremoabo Street, - Campus of Ondina, Salvador, BA, 40170–290 Brazil
| | - Ngoc-Ha Nguyen
- Department of Biochemistry and Biophysics, University of California School of Medicine, San Francisco, CA 94143, USA
| | - Marie Togashi
- Health Science Institute. Brasilia University, Asa Norte, Brasilia, DF 70919–970, Brazil
| | - James W. Apriletti
- Diabetes Center, University of California School of Medicine, San Francisco, CA 94143, USA
| | - Phuong Nguyen
- Diabetes Center, University of California School of Medicine, San Francisco, CA 94143, USA
| | - Igor Polikarpov
- Physics Institute of São Carlos, University of São Paulo. 400, Trabalhador São Carlense Av., São Carlos, SP 13560–970, Brazil
| | - Thomas S. Scanlan
- Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR97239
| | - John D. Baxter
- The Methodist Hospital Research Institute. 6565 Fannin St. Houston, TX 77030, USA
| | - Paul Webb
- The Methodist Hospital Research Institute. 6565 Fannin St. Houston, TX 77030, USA
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Koury EJ, Pawlyk AC, Berrodin TJ, Smolenski CL, Nagpal S, Deecher DC. Characterization of ligands for thyroid receptor subtypes and their interactions with co-regulators. Steroids 2009; 74:270-6. [PMID: 19073200 DOI: 10.1016/j.steroids.2008.11.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 11/10/2008] [Accepted: 11/17/2008] [Indexed: 11/30/2022]
Abstract
Thyroid hormone receptors (TRs) are nuclear receptors that are activated by thyroid hormone ligands and co-regulator proteins. Two receptor subtypes, TRalpha and TRbeta, have been suggested to play a role in numerous physiological functions. However, specificity of receptor subtype function and co-regulator interaction is unclear due to the lack of TR subtype-specific ligands. Five TR ligands were evaluated for their selectivity and interaction with the TR subtypes. A multiplex assay was used to identify co-regulator peptide interaction, and biochemical assays were used to characterize ligand-receptor specificity. In the biochemical assay, rank order ligand potencies were similar in the presence of co-activator peptides, SRC1-2 and SRC3-2, and the co-repressor peptide, NCoR1-2, with T3 and Triac potencies greater in the presence of the co-repressor. The potency of Tetrac was similar regardless of the co-regulator used while T4 and rT3 demonstrated selectivity for TRalpha subtype. The rank order among TR ligands at either receptor subtype in the biochemical assay correlated with the multiplex assay. These assays can be used to identify new ligands that can provide further insight into TR biology.
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Affiliation(s)
- Elizabeth J Koury
- Women's Health and Musculoskeletal Biology, Wyeth Research, RN3164, 500 Arcola Road, Collegeville, PA 19426, United States
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Jeyakumar M, Katzenellenbogen JA. A dual-acceptor time-resolved Föster resonance energy transfer assay for simultaneous determination of thyroid hormone regulation of corepressor and coactivator binding to the thyroid hormone receptor: Mimicking the cellular context of thyroid hormone action. Anal Biochem 2008; 386:73-8. [PMID: 19111515 DOI: 10.1016/j.ab.2008.11.039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Revised: 11/20/2008] [Accepted: 11/21/2008] [Indexed: 11/18/2022]
Abstract
Previously, we reported the development of two in vitro time-resolved Föster resonance energy transfer (tr-FRET)-based assays for evaluating the potency and efficacy of different ligands of thyroid hormone receptor (TR) for regulating the recruitment of coregulators. We could measure independently, in separate assays, both the recruitment of SRC3 (steroid receptor coactivator 3, a transcriptional coactivator) and the dissociation of NCoR (nuclear receptor corepressor, a transcriptional corepressor) from a TR*retinoid X receptor (RXR) heterodimer bound to a DR+4 thyroid hormone response element (TRE). Here, by using the distinct emission peaks of Tb(3+), the donor fluorophore used to label the TRE-bound TR*RXR heterodimers, and selecting two distinct acceptor fluorophores, fluorescein and cyanine 5, to label of NCoR and SRC3, respectively, we have integrated our previous two assay formats into a single assay. Thus, we can measure the potency of TR ligands simultaneously for NCoR dissociation and SRC3 recruitment activities in a system that mimics many features of the cellular context of TR action. The performance of this dual assay was tested with a known, highly potent physiological TR ligand, triiodothyronine (T(3)), and with a synthetic TR antagonist, NH-3. Measured potencies and efficacies of these two TR ligands from this dual assay are highly comparable to those obtained from the two independent assays. Thus, this dual-acceptor tr-FRET assay further simplifies the measurement of ligand-modulated TR-coregulator interactions and should improve the overall efficiency of the screening process of TR drug discovery programs.
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Affiliation(s)
- M Jeyakumar
- Department of Chemistry, University of Illinois, Urbana, IL 61801, USA
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