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Molecular dynamics of estrogen-related receptors and their regulatory proteins: roles in transcriptional control for endocrine and metabolic signaling. Anat Sci Int 2021; 97:15-29. [PMID: 34609710 DOI: 10.1007/s12565-021-00634-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 09/23/2021] [Indexed: 10/20/2022]
Abstract
Estrogen-related receptor (ERR) is a member of the nuclear receptor (NR) superfamily and has three subtypes α, β, and γ. Despite their strong homology with estrogen receptor (ER) α, ERRs cannot accommodate endogenous hormones. However, they are able to regulate gene expression without ligand binding. ERRα and ERRγ orchestrate the expression of genes involved in bioenergetic pathways, while ERRβ controls placental development and stem cell maintenance. Evidence from recent studies, including clinical research, has also demonstrated close associations of ERRs with the pathophysiology of hormone-related cancers and metabolic disorders including type 2 diabetes mellitus. This review summarizes the basic knowledge and recent advances in ERRs and their associated proteins, focusing on the subcellular dynamics involved in transcriptional regulation. Fluorescent protein labeling enabled monitoring of ERRs in living cells and revealed previously unrecognized characteristics. Using this technique, we demonstrated a role of ERRβ in controlling estrogen signaling by regulating the subnuclear dynamics of ligand-activated ERα. Visualization of ERRs and related proteins and subsequent analyses also revealed a function of ERRγ in promoting liver lactate metabolism in association with LRPGC1, a recently identified lactic acid-responsive protein. These findings suggest that ERRs activate unique transregulation mechanisms in response to extracellular stimuli such as hormones and metabolic signals, implying an adaptive system behind the cellular homeostatic regulation by orphan NRs. Control of subcellular ERR dynamics will contribute toward the development of therapeutic approaches to treat various diseases including hormone-related cancers and metabolic disorders associated with abnormal ERR signaling pathways.
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Pace F, Watnick PI. The Interplay of Sex Steroids, the Immune Response, and the Intestinal Microbiota. Trends Microbiol 2020; 29:849-859. [PMID: 33257138 DOI: 10.1016/j.tim.2020.11.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 11/01/2020] [Accepted: 11/03/2020] [Indexed: 12/11/2022]
Abstract
The role of sex steroids in mammalian maturation is well established. Recently, it has been increasingly appreciated that sex steroids also play an important role in the propensity of adults to develop a myriad of diseases. The exposure and responsiveness of tissues to sex steroids varies among individuals and between the sexes, and this has been correlated with gender-specific differences in the composition of the intestinal microbiota and in susceptibility to metabolic, autoimmune, and neoplastic diseases. Here we focus on recent studies that demonstrate an interplay between sex steroids, the intestinal immune response, and the intestinal microbiota. While correlations between biological sex, the intestinal innate immune response, intestinal inflammation, and intestinal microbiota have been established, many gaps in our knowledge prevent the emergence of an overarching model for this complex interaction. Such a model could aid in the development of prebiotic, probiotic, or synthetic therapeutics that decrease the risk of autoimmune, metabolic, neoplastic, and infectious diseases of the intestine and mitigate the particular health risks faced by individuals receiving sex steroid treatment.
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Affiliation(s)
- Fernanda Pace
- Division of Infectious Diseases, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Paula I Watnick
- Division of Infectious Diseases, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; Department of Microbiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
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Tecalco-Cruz AC. Molecular pathways involved in the transport of nuclear receptors from the nucleus to cytoplasm. J Steroid Biochem Mol Biol 2018; 178:36-44. [PMID: 29107180 DOI: 10.1016/j.jsbmb.2017.10.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/18/2017] [Accepted: 10/25/2017] [Indexed: 12/30/2022]
Abstract
Nuclear receptors (NRs) are transcription regulators that direct the expression of many genes linked to cellular processes, such as proliferation, differentiation, and apoptosis. Additionally, some cellular events are also modulated by signaling pathways induced by NRs outside of the nucleus. Hence, the subcellular transport of NRs is dynamic and is modulated by several signals, protein-protein interactions, and posttranslational modifications. Particularly, the exit of NRs from the nucleus to cytoplasm and/or other compartments is transcendental, as it is this export event, which determines their abundance in the cells' compartments, the activation or attenuation of nuclear or extranuclear pathways, and the magnitude and duration of their effects inside or outside of the nucleus. Consequently, an adequate control of the distribution of NRs is critical for homeostasis, because a deregulation in the nucleo-cytoplasmic transport of NRs could be involved in diseases including cancer as well as metabolic and vascular alterations. In this review, we investigated the pathways and molecular and biological aspects that have been described for the nuclear export of NRs so far and their functional relevance in some diseases. This information suggests that the transport of NRs out of the nucleus is a key mechanism for the identification of new therapeutic targets for alterations associated with the deregulation of the function of NRs.
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Affiliation(s)
- Angeles C Tecalco-Cruz
- Programa de Investigación de Cáncer de Mama, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Apdo Postal, D.F. 04510, Mexico.
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Nucleo-cytoplasmic transport of estrogen receptor alpha in breast cancer cells. Cell Signal 2017; 34:121-132. [PMID: 28341599 DOI: 10.1016/j.cellsig.2017.03.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 03/19/2017] [Accepted: 03/21/2017] [Indexed: 02/07/2023]
Abstract
Approximately 70% cases of breast cancers exhibit high expression and activity levels of estrogen receptor alpha (ERα), a transcription regulator that induces the expression of genes associated with cellular proliferation and survival. These nuclear functions of the receptor are associated with the development of breast cancer. However, ERα localization is not static, but rather, dynamic with continuous shuttling between the nucleus and the cytoplasm. Interestingly, both the nuclear import and export of ERα are modulated by several stimuli that include estradiol, antiestrogens, and growth factors. As ERα nuclear accumulation is critical to the regulation of gene expression, nuclear export of this receptor modulates the intensity and duration of its transcriptional activity. Thus, the subcellular spatial distribution of ERα ensures tight modulation of its concentration in cellular compartments, as well as of its nuclear and extranuclear functions. In this review, we will discuss current findings regarding the biological importance of molecular mechanisms of, and proteins responsible for, the nuclear import and export of ERα in breast cancer cells.
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Garland T, Zhao M, Saltzman W. Hormones and the Evolution of Complex Traits: Insights from Artificial Selection on Behavior. Integr Comp Biol 2016; 56:207-24. [PMID: 27252193 PMCID: PMC5964798 DOI: 10.1093/icb/icw040] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Although behavior may often be a fairly direct target of natural or sexual selection, it cannot evolve without changes in subordinate traits that cause or permit its expression. In principle, changes in endocrine function could be a common mechanism underlying behavioral evolution because they are well positioned to mediate integrated responses to behavioral selection. More specifically, hormones can influence both motivational (e.g., brain) and performance (e.g., muscles) components of behavior simultaneously and in a coordinated fashion. If the endocrine system is often "used" as a general mechanism to effect responses to selection, then correlated responses in other aspects of behavior, life history, and organismal performance (e.g., locomotor abilities) should commonly occur because any cell with appropriate receptors could be affected. Ways in which behavior coadapts with other aspects of the phenotype can be studied directly through artificial selection and experimental evolution. Several studies have targeted rodent behavior for selective breeding and reported changes in other aspects of behavior, life history, and lower-level effectors of these organismal traits, including endocrine function. One example involves selection for high levels of voluntary wheel running, one aspect of physical activity, in four replicate High Runner (HR) lines of mice. Circulating levels of several hormones (including insulin, testosterone, thyroxine, triiodothyronine) have been characterized, three of which-corticosterone, leptin, and adiponectin-differ between HR and control lines, depending on sex, age, and generation. Potential changes in circulating levels of other behaviorally and metabolically relevant hormones, as well as in other components of the endocrine system (e.g., receptors), have yet to be examined. Overall, results to date identify promising avenues for further studies on the endocrine basis of activity levels.
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Affiliation(s)
- Theodore Garland
- *Department of Biology, University of California, Riverside, Riverside, CA 92506, USA
| | - Meng Zhao
- *Department of Biology, University of California, Riverside, Riverside, CA 92506, USA
| | - Wendy Saltzman
- *Department of Biology, University of California, Riverside, Riverside, CA 92506, USA
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Hoffmann JM, Partridge L. Nuclear hormone receptors: Roles of xenobiotic detoxification and sterol homeostasis in healthy aging. Crit Rev Biochem Mol Biol 2015; 50:380-92. [PMID: 26383043 DOI: 10.3109/10409238.2015.1067186] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Health during aging can be improved by genetic, dietary and pharmacological interventions. Many of these increase resistance to various stressors, including xenobiotics. Up-regulation of xenobiotic detoxification genes is a transcriptomic signature shared by long-lived nematodes, flies and mice, suggesting that protection of cells from toxicity of xenobiotics may contribute to longevity. Expression of genes involved in xenobiotic detoxification is controlled by evolutionarily conserved transcriptional regulators. Three closely related subgroups of nuclear hormone receptors (NHRs) have a major role, and these include DAF-12 and NHR-8 in C. elegans, DHR96 in Drosophila and FXR, LXRs, PXR, CAR and VDR in mammals. In the invertebrates, these NHRs have been experimentally demonstrated to play a role in extension of lifespan by genetic and environmental interventions. NHRs represent critical hubs in that they regulate detoxification enzymes with broad substrate specificities, metabolizing both endo- and xeno-biotics. They also modulate homeostasis of steroid hormones and other endogenous cholesterol derivatives and lipid metabolism, and these roles, as well as xenobiotic detoxification, may contribute to the effects of NHRs on lifespan and health during aging, an issue that is being increasingly addressed in C. elegans and Drosophila. Disentangling the contribution of these processes to longevity will require more precise understanding of the molecular mechanisms by which each is effected, including identification of ligands and co-regulators of NHRs, patterns of tissue-specificity and mechanisms of interaction between tissues. The roles of vertebrate NHRs in determination of health during aging and lifespan have yet to be investigated.
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Affiliation(s)
| | - Linda Partridge
- a Max Planck Institute for Biology of Ageing , Cologne , Germany and.,b Institute of Healthy Ageing, and GEE (Genetics, Evolution and Environment), University College , London , UK
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Piotrowska K, Sluczanowska-Glabowska S, Kucia M, Bartke A, Laszczynska M, Ratajczak MZ. Histological changes of testes in growth hormone transgenic mice with high plasma level of GH and insulin-like growth factor-1. Folia Histochem Cytobiol 2015; 53:249-58. [PMID: 26348370 DOI: 10.5603/fhc.a2015.0024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 09/08/2015] [Accepted: 09/07/2015] [Indexed: 11/25/2022] Open
Abstract
INTRODUCTION Overexpression of growth hormone (GH) leads to increase in insulin-like growth factor-1 (IGF-1) plasma level, stimulation of growth and increase in body size, organomegaly and reduced body fat. The action of GH affects all the organs and transgenic mice that overexpress bovine GH (bGH mice) serve as convenient model to study somatotropic axis. Male mice overexpressing GH are fertile, however, they show reduced overall lifespan as well as reproductive life span. The aim of the study was to evaluate the morphology and expression of androgen receptor (AR) and luteinizing hormone receptor (LHR) of bGH mice testes. MATERIAL AND METHODS The experiment was performed on 6 and 12 month-old bGH male mice and 6 and 12 month-old wild type (WT) littermates (8 animals in each group). The morphology of testes was evaluated on deparaffinized sections stained by the periodic acid-Schiff (PAS) method. Expression of AR and LHR was investigated by immunohistochemistry and diameters of seminiferous tubules (ST) were measured on round cross sections of ST. RESULTS We noted larger testes in 6-month bGH mice as compared to normal WT littermates. The morpho-logical observations revealed essentially normal structure of Leydig cells, seminiferous epithelium and other morphological structures. However, some changes like tubules containing only Sertoli cells, tubules with arrested spermatogenesis or vacuoles in seminiferous epithelium could be attributed to the overexpression of GH. In contrast to WT mice, 12 month-old bGH mice displayed first symptoms of testicular aging. The immunoexpres-sion of AR and LHR was decreased in 12 month-old bGH males as compared to 12 month-old WT mice and younger animals. CONCLUSION Chronic exposure to elevated GH level accelerates testicular aging and thus potentially may change response of Leydig cells to LH and Sertoli and germ cells to testosterone.
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Mukudai S, Matsuda KI, Nishio T, Sugiyama Y, Bando H, Hirota R, Sakaguchi H, Hisa Y, Kawata M. Differential responses to steroid hormones in fibroblasts from the vocal fold, trachea, and esophagus. Endocrinology 2015; 156:1000-9. [PMID: 25514085 PMCID: PMC4330318 DOI: 10.1210/en.2014-1605] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There is accumulating evidence that fibroblasts are target cells for steroids such as sex hormones and corticoids. The characteristics of fibroblasts vary among tissues and organs. Our aim in this study is to examine differences in responses to steroid hormones among fibroblasts from different cervicothoracic regions. We compared the actions of steroid hormones on cultured fibroblasts from the vocal folds, which are considered to be the primary target of steroid hormones, and the trachea and esophagus in adult male rats. Expression of steroid hormone receptors (androgen receptor, estrogen receptor α, and glucocorticoid receptor) was identified by immunofluorescence histochemistry. Androgen receptor was much more frequently expressed in fibroblasts from the vocal fold than in those from the trachea and esophagus. Cell proliferation analysis showed that administration of testosterone, estradiol, or corticosterone suppressed growth of all 3 types of fibroblasts. However, mRNA expression for extracellular matrix-associated genes, including procollagen I and III and elastin, and hyaluronic acid synthase I was elevated only by addition of testosterone to fibroblasts from the vocal fold. These results indicate that each steroid hormone exerts region-specific effects on cervicothoracic fibroblasts with different properties through binding to specific receptors.
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Affiliation(s)
- Shigeyuki Mukudai
- Departments of Anatomy and Neurobiology (S.M., K.I.M., M.K.) and Otolaryngology-Head and Neck Surgery (S.M., T.N., Y.S., H.B., R.H., H.S., Y.H.), Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
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Broide E, Bloch O, Ben-Yehudah G, Cantrell D, Shirin H, Rapoport MJ. GLP-1 receptor is expressed in human stomach mucosa: analysis of its cellular association and distribution within gastric glands. J Histochem Cytochem 2013; 61:649-58. [PMID: 23803499 DOI: 10.1369/0022155413497586] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The stomach is a target organ of the incretin hormone glucagon-like peptide-1 (GLP-1). However, the cellular expression and glandular distribution of its receptor (GLP-1R) in human gastric mucosa are not known. We determined the expression of GLP-1R in different regions of human stomach mucosa and its specific cellular association and distribution within gastric glands. Tissue samples from stomach body and antrum were obtained from 20 patients during routine esophagogastroduodenoscopy. mRNA encoding GLP-1R protein expression was evaluated by RT-PCR. Determination of cell types bearing GLP-1R, their localization, and their frequency in gastric glands in different gastric regions were estimated by immunohistochemical morphological analysis. Levels of GLP-1R mRNA were similar in body and antrum. GLP-1R immunoreactivity was found throughout the gastric mucosa in various types of glandular cells. The highest frequency of GLP-1R immunoreactive cells was found in the neck area of the principal glands in cells morphologically identified as parietal cells. GLP-1R immunostaining was also found on enteroendocrine-like cells in the pyloric glands. This study provides the first description of GLP-1R expression in human gastric glands and its specific cellular association. Our data suggest that GLP-1 may act directly on the gastric mucosa to modulate its complex functions.
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Affiliation(s)
- Efrat Broide
- Institute of Gastroenterology, Assaf Harofeh Medical Center, Zerifin, Israel
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10
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Distribution of glucocorticoid receptors and 11 beta-hydroxysteroid dehydrogenase isoforms in the rat inner ear. Hear Res 2011; 280:148-56. [DOI: 10.1016/j.heares.2011.05.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 05/05/2011] [Accepted: 05/12/2011] [Indexed: 02/07/2023]
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11
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Cadwallader AB, Rollins DE, Lim CS. Effect of anabolic-androgenic steroids and glucocorticoids on the kinetics of hAR and hGR nucleocytoplasmic translocation. Mol Pharm 2010; 7:689-98. [PMID: 20230007 PMCID: PMC2882525 DOI: 10.1021/mp900259w] [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] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Although the qualitative nucleocytoplasmic transport of nuclear hormone receptors (NHRs) has been studied, there is little documentation of the cellular kinetics of this transport. Here, translocation studies using the human androgen receptor (hAR) and the human glucocorticoid receptor (hGR) were performed to aid in identifying the mechanism by which anabolic-androgenic steroids (AAS) were activating hAR and potentially interacting with hGR and how glucocorticoid ligands were interacting with the hGR and hAR. The real-time analysis of EGFP-labeled hAR and hGR ligand-induced cytoplasm-to-nucleus translocation was performed using fluorescence microscopy to better understand the action of these NHRs in a physiologically relevant cell-based model. After transient transfection, the hAR and hGR individually translocate as expected (i.e., transport is ligand-induced and dose-dependent) in this model biological system. Testosterone (TEST) had the fastest translocation rate for the hAR of 0.0525 min(-1). The other endogenous steroids, androstenedione (ANE) and dihydrotestosterone (DHT), had considerably lower hAR transport rates. The rates of hAR transport for the exogenous steroids methyltrienelone (MET), nandrolone (NAN), and oxandrolone (OXA) are lower than that of testosterone and similar to those of the endogenous steroids ANE and DHT. The hGR transport rates for cortisol (COR) and dexamethasone (DEX) are also presented. The synthetic GC, DEX, had a more rapid translocation rate (0.1599 min(-1)) at the highest dose of 100 nM compared to the endogenous GC COR (0.0431 min(-1)). The data obtained agrees with the existing qualitative data and adds an important ligand-dependent kinetic component to hAR and hGR transport. These kinetic data can aid our understanding of NHR action and interaction with other regulatory proteins, and can be useful in the development of new therapies.
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Affiliation(s)
- Amy B. Cadwallader
- Center for Human Toxicology, University of Utah Department of Pharmacology and Toxicology, 417 Wakara Way Suite 2111, Salt Lake City, UT, U.S.A. 84108
| | - Douglas E. Rollins
- Center for Human Toxicology, University of Utah Department of Pharmacology and Toxicology, 417 Wakara Way Suite 2111, Salt Lake City, UT, U.S.A. 84108
| | - Carol S. Lim
- University of Utah Department of Pharmaceutics and Pharmaceutical Chemistry, 421 Wakara Way Room 318, Salt Lake City, UT, U.S.A. 84108
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Kawata M, Nishi M, Matsuda K, Sakamoto H, Kaku N, Masugi-Tokita M, Fujikawa K, Hirahara-Wada Y, Takanami K, Mori H. Steroid receptor signalling in the brain--lessons learned from molecular imaging. J Neuroendocrinol 2008; 20:673-6. [PMID: 18601688 DOI: 10.1111/j.1365-2826.2008.01727.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Studies with green fluorescent protein (GFP) have revealed the subcellular distribution of many steroid hormone receptors to be much more dynamic than previously thought. Fluorescence resonance energy transfer (FRET) and fluorescence recovery after photobleaching (FRAP) are powerful techniques with which to examine protein-protein interaction and the mobility of tagged proteins, respectively. FRET analysis revealed that steroid treatment (with corticosterone or testosterone) induces direct interaction of the glucocorticoid receptor (GR) and importin alpha in the cytoplasm and that, shortly after nuclear entry, the GR detaches from importin alpha. The mineralocorticoid receptor (MR) and androgen receptor (AR) show the same trafficking. Upon oestradiol treatment, ERalpha and ERbeta in the same cell are relocalised to form a discrete pattern and are localised in the same discrete cluster (subnuclear foci). FRAP analysis showed that nuclear ERalpha and ERbeta are most dynamic and mobile in the absence of the ligand, and that mobility decreases slightly after ligand treatment. Genomic as well as non-genomic actions of steroid hormones influence the cellular function of target tissues spacio-temporally.
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Affiliation(s)
- M Kawata
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kyoto, Japan.
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Agler M, Prack M, Zhu Y, Kolb J, Nowak K, Ryseck R, Shen D, Cvijic ME, Somerville J, Nadler S, Chen T. A high-content glucocorticoid receptor translocation assay for compound mechanism-of-action evaluation. ACTA ACUST UNITED AC 2007; 12:1029-41. [PMID: 17989426 DOI: 10.1177/1087057107309353] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Ligand-induced cytoplasm to nucleus translocation is a critical event in the nuclear receptor (NR) signal transduction cascade. The development of green fluorescent proteins and their color variants fused with NRs, along with the recent developments in automated cellular imaging technologies, has provided unique tools to monitor and quantify the NR translocation events. These technology developments have important implications in the mechanistic evaluation of NR signaling and provide a powerful tool for drug discovery. The unique challenges for developing a robust NR translocation assay include cytotoxicity accompanied with chronic overexpression of NRs, basal translocation induced by serum present in culture medium, and interference from endogenous NRs, as well as subcellular dynamics. The authors have developed a robust assay system for the glucocorticoid receptor (GR) that was applied to a panel of nuclear receptor ligands. Using a high-content imaging system, ligand-induced, dose-dependent GR nuclear translocation was quantified and a correlation with other conventional assays established.
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Affiliation(s)
- Michele Agler
- Bristol-Myers Squibb, Lead Discovery & Profiling, Wallingford, Connecticut 06492, USA.
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Redundant enhancement of mouse constitutive androstane receptor transactivation by p160 coactivator family members. Arch Biochem Biophys 2007; 468:49-57. [PMID: 17950690 DOI: 10.1016/j.abb.2007.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 08/30/2007] [Accepted: 09/02/2007] [Indexed: 11/23/2022]
Abstract
Constitutive androstane receptor (CAR) transactivation is enhanced by p160 coactivators, which include three members, SRC-1, SRC-2, and SRC-3. Each of the p160 coactivators enhanced mouse CAR (mCAR) transactivation of the CYP2B1 phenobarbital (PB)-responsive enhancer in transfected cultured cells and mouse hepatocytes in vivo. The cellular localization of the p160 coactivators in hepatocytes in vivo was not altered by PB treatment, nor did any of the p160 coactivators selectively colocalize with mCAR in the nucleus. Exogenous expression of each p160 coactivator mediated the PB-independent nuclear accumulation of mCAR in hepatocytes in vivo. Induction of Cyp2b10 gene expression by PB was equivalent or greater in mice null for each of the p160 coactivators than in wild type mice. These results indicate that the p160 coactivators are redundant with regard to enhancing CAR-mediated induction of cytochrome P450 genes. SRC-3 alone of the p160 coactivators enhanced CAR transactivation in hepatic cells without PB treatment.
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Everts HB, Sundberg JP, King LE, Ong DE. Immunolocalization of enzymes, binding proteins, and receptors sufficient for retinoic acid synthesis and signaling during the hair cycle. J Invest Dermatol 2007; 127:1593-604. [PMID: 17363914 DOI: 10.1038/sj.jid.5700753] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Retinoic acid (RA) is essential for maintenance of most epithelial tissues. One RA biosynthesis pathway consists of cellular retinol-binding protein (Crbp), retinol dehydrogenase (Dhrs9/eRoldh), retinal dehydrogenase 1-3 (Aldh1a1-3), and cellular RA-binding protein 2 (Crabp2). Previously, we localized Aldh1a2 and Aldh1a3 to both epithelial and mesenchymal cells within the hair follicle throughout the hair cycle. This study expands that observation by examining the complete pathway of RA biosynthesis and signaling via RA receptors alpha, beta, and gamma by immunohistochemistry in C57BL/6J mice wax-stripped to initiate and synchronize the cycle. This pathway of RA biosynthesis and signaling localized to the majority of layers of the hair follicle, sebaceous gland, and interfollicular epidermis in a hair cycle-dependent manner, suggesting that RA biosynthesis within the hair follicle is regulated in both a spatial and temporal manner. This localization pattern also revealed insights into epithelial-mesenchymal interactions and differentiation state differences within the RA biosynthesis and signaling pathway, as well as novel observations on nuclear versus cytoplasmic localization of Crabp2 and RA receptors. This complex pattern of RA biosynthesis and signaling identified by immunolocalization suggests that endogenous RA regulates specific aspects of hair follicle growth, differentiation, and cycling.
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Affiliation(s)
- Helen B Everts
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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16
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Xia J, Kemper B. Subcellular trafficking signals of constitutive androstane receptor: evidence for a nuclear export signal in the DNA-binding domain. Drug Metab Dispos 2007; 35:1489-94. [PMID: 17567731 DOI: 10.1124/dmd.107.016493] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Translocation of constitutive androstane receptor (CAR) from the cytoplasm to the nucleus is induced by phenobarbital-like drugs. Nuclear localization signals (NLSs) and a sequence [xenochemical response signal (XRS)] required for xenobiotic-induced nuclear translocation have been defined in rat and human CAR, but a nuclear export signal (NES) has not been identified. To identify cellular localization signals of CAR, the localization of fragments and mutants of mouse CAR expressed in mouse hepatocytes in vivo was examined. Consistent with other studies, an NLS in the hinge region, a diffuse NLS in the ligand-binding domain, and a cytoplasmic retention sequence were identified, and mutation of the XRS blocked nuclear accumulation both in phenobarbital-treated mice in vivo and in untreated HepG2 cells. Fusing the simian virus 40 NLS to the mutant proteins reversed the localization defect resulting from mutation of the hinge NLS but not that from mutation of the XRS, indicating that the XRS is not simply a novel phenobarbital-responsive NLS. In the DNA-binding domain, a sequence in CAR is conserved with an NES identified in other nuclear receptors. Mutation of two conserved phenylalanines in this sequence resulted in increased nuclear localization of both full-length CAR and a CAR fragment containing the DNA-binding domain. The DNA-binding domain sequence, therefore, may contain an NES, which is consistent with nucleocytoplasmic shuttling of CAR. The results demonstrate that regulation of the cellular localization of CAR is complex, with multiple sequences mediating nuclear import and export and retention in the cytoplasm.
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Affiliation(s)
- Jun Xia
- Department of Cell and Development Biology, University of Illinois at Urbana-Champaign, 524 Burrill Hall, 407 S. Goodwin Ave., Urbana, IL 61801, USA
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Dey N, De PK, Wang M, Zhang H, Dobrota EA, Robertson KA, Durden DL. CSK controls retinoic acid receptor (RAR) signaling: a RAR-c-SRC signaling axis is required for neuritogenic differentiation. Mol Cell Biol 2007; 27:4179-97. [PMID: 17325034 PMCID: PMC1900023 DOI: 10.1128/mcb.01352-06] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Herein, we report the first evidence that c-SRC is required for retinoic acid (RA) receptor (RAR) signaling, an observation that suggests a new paradigm for this family of nuclear hormone receptors. We observed that CSK negatively regulates RAR functions required for neuritogenic differentiation. CSK overexpression inhibited RA-mediated neurite outgrowth, a result which correlated with the inhibition of the SFK c-SRC. Consistent with an extranuclear effect of CSK on RAR signaling and neurite outgrowth, CSK overexpression blocked the downstream activation of RAC1. The conversion of GDP-RAC1 to GTP-RAC1 parallels the activation of c-SRC as early as 15 min following all-trans-retinoic acid treatment in LA-N-5 cells. The cytoplasmic colocalization of c-SRC and RARgamma was confirmed by immunofluorescence staining and confocal microscopy. A direct and ligand-dependent binding of RAR with SRC was observed by surface plasmon resonance, and coimmunoprecipitation studies confirmed the in vivo binding of RARgamma to c-SRC. Deletion of a proline-rich domain within RARgamma abrogated this interaction in vivo. CSK blocked the RAR-RA-dependent activation of SRC and neurite outgrowth in LA-N-5 cells. The results suggest that transcriptional signaling events mediated by RA-RAR are necessary but not sufficient to mediate complex differentiation in neuronal cells. We have elucidated a nongenomic extranuclear signal mediated by the RAR-SRC interaction that is negatively regulated by CSK and is required for RA-induced neuronal differentiation.
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Affiliation(s)
- Nandini Dey
- Section of Pediatric Hematology/Oncology, Department of Pediatrics, Aflac Cancer Center and Blood Disorders Services, Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA 30022, USA
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18
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Plant KE, Everett DM, Gordon Gibson G, Lyon J, Plant NJ. Transcriptomic and phylogenetic analysis of Kpna genes: a family of nuclear import factors modulated in xenobiotic-mediated liver growth. Pharmacogenet Genomics 2006; 16:647-58. [PMID: 16906019 DOI: 10.1097/01.fpc.0000220570.82842.4d] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES We have identified a member of the karyopherin (importin) alpha family of nuclear import factors as being modulated in rat liver following exposure to the hypolipidaemic and liver growth agent Wy-14,643. To examine the hypothetical role of this protein family as a checkpoint in receptor-mediated signalling, we characterized the rat karyopherin alpha (Kpna) gene family and present cDNA sequences and gene structures for all six rat Kpna genes. Further, we have assembled a comprehensive panel of Kpna coding regions from a range of metazoa, which we have subjected to phylogenetic analysis: This represents by far the most complete phylogenetic study of metazoan karyopherins, including several evolutionary intermediates not previously examined. The phylogeny reveals three Kpna subfamilies with distinct, conserved gene structures, shedding light on the evolutionary origins of this multigene family in metazoa. METHODS AND RESULTS Using quantitative PCR, we have analysed Kpna transcript levels in 44 rat tissues; Kpna transcripts show a wide variation in their distribution both in absolute and relative terms, suggestive of specialized roles for each member. We also demonstrate that Kpna genes are regulated in rat liver and isolated hepatocytes in a xenobiotic-specific manner for a number of chemically distinct liver growth agents. CONCLUSIONS In light of the crucial role of nuclear import in mediating the genomic changes elicited through nuclear receptor activation, we postulate that changes in the levels of specific karyopherins alpha during xenobiotic-mediated liver growth represent an important component of the cellular response to the external stimuli that trigger these events.
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Affiliation(s)
- Kathryn E Plant
- School of Biomedical and Molecular Sciences, University of Surrey, Guildford, GU2 7XH, UK
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19
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Wu Y, Kawate H, Ohnaka K, Nawata H, Takayanagi R. Nuclear compartmentalization of N-CoR and its interactions with steroid receptors. Mol Cell Biol 2006; 26:6633-55. [PMID: 16914745 PMCID: PMC1592818 DOI: 10.1128/mcb.01534-05] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The repression mechanisms by the nuclear receptor corepressor (N-CoR) of steroid hormone receptor (SHR)-mediated transactivation were examined. Yellow fluorescent protein (YFP)-N-CoR was distributed as intranuclear discrete dots, while coexpression of androgen receptor (AR), glucocorticoid receptor alpha, and estrogen receptor alpha ligand-dependently triggered redistribution of YFP-N-CoR. In fluorescence recovery after photobleaching analysis, mobility of the N-CoR was reduced by 5alpha-dihydrotestosterone (DHT)-bound AR. The middle region of N-CoR mostly contributed to the interaction with agonist-bound SHRs and the suppression of their transactivation function. N-CoR impaired the DHT-induced N-C interaction of AR, and the impaired interaction was dose-dependently recovered by coexpression of SRC-1 and CBP. N-CoR also impaired the intranuclear complete (distinct) focus formation of SHRs. Coexpression of SRC-1 or CBP released YFP-N-CoR or endogenous N-CoR from incomplete foci and simultaneously recovered complete foci of AR-green fluorescent protein. These results indicate that the relative ratio of coactivators and corepressors determines the conformational equilibrium between transcriptionally active and inactive SHRs in the presence of agonists. The intranuclear foci formed by agonist-bound SHRs were completely destroyed by actinomycin D and alpha-amanitin, indicating that the focus formation does not precede the transcriptional activation. The focus formation may reflect the accumulation of SHR/coactivator complexes released from the transcriptionally active sites and thus be a mirror of transcriptionally active complex formation.
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Affiliation(s)
- Yin Wu
- Department of Geriatric Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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20
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Corry GN, Underhill DA. Subnuclear compartmentalization of sequence-specific transcription factors and regulation of eukaryotic gene expression. Biochem Cell Biol 2005; 83:535-47. [PMID: 16094457 DOI: 10.1139/o05-062] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
To date, the majority of the research regarding eukaryotic transcription factors has focused on characterizing their function primarily through in vitro methods. These studies have revealed that transcription factors are essentially modular structures, containing separate regions that participate in such activities as DNA binding, protein-protein interaction, and transcriptional activation or repression. To fully comprehend the behavior of a given transcription factor, however, these domains must be analyzed in the context of the entire protein, and in certain cases the context of a multiprotein complex. Furthermore, it must be appreciated that transcription factors function in the nucleus, where they must contend with a variety of factors, including the nuclear architecture, chromatin domains, chromosome territories, and cell-cycle-associated processes. Recent examinations of transcription factors in the nucleus have clarified the behavior of these proteins in vivo and have increased our understanding of how gene expression is regulated in eukaryotes. Here, we review the current knowledge regarding sequence-specific transcription factor compartmentalization within the nucleus and discuss its impact on the regulation of such processes as activation or repression of gene expression and interaction with coregulatory factors.
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Affiliation(s)
- Gareth N Corry
- Department of Medical Genetics, University of Alberta, Edmonton, Canada
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21
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Kawate H, Wu Y, Ohnaka K, Tao RH, Nakamura KI, Okabe T, Yanase T, Nawata H, Takayanagi R. Impaired nuclear translocation, nuclear matrix targeting, and intranuclear mobility of mutant androgen receptors carrying amino acid substitutions in the deoxyribonucleic acid-binding domain derived from androgen insensitivity syndrome patients. J Clin Endocrinol Metab 2005; 90:6162-9. [PMID: 16118342 DOI: 10.1210/jc.2005-0179] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Recent imaging studies revealed that androgen receptor (AR) is ligand-dependently translocated from the cytoplasm into the nucleus and forms intranuclear fine foci. In this study, we examined whether intracellular dynamics of mutant ARs detected in two androgen insensitivity syndrome (AIS) patients was impaired. OBJECTIVE ARs with mutations in the DNA-binding domain were functionally characterized and compared with the wild-type AR. PATIENTS In a complete AIS patient (subject 1), cysteine residue 579 in the first zinc finger motif of AR was substituted for phenylalanine (AR-C579F). Another mutation (AR-F582Y) was found in a partial AIS patient (subject 2). RESULTS AR-F582Y retained less than 10% of the transactivation activity of the wild-type AR, whereas no ligand-dependent transactivation was detected for AR-C579F. Image analyses of the receptors fused to green fluorescent protein showed that the wild-type AR was ligand-dependently translocated into the nucleus in which it formed fine subnuclear foci. Surprisingly, after the addition of dihydrotestosterone, the two mutant ARs initially formed large cytoplasmic dots, many of which were found to be close to mitochondria by electron microscopy. Subsequently, a part of the ligand-bound mutant ARs gradually entered the nucleus to form a smaller number of larger dots, compared with the wild-type AR. Fluorescence recovery after photobleaching analysis revealed that the intranuclear mobility of the mutant ARs decreased, compared with that of the wild-type AR. CONCLUSIONS These results suggest that the abnormal translocation, localization, and mobility of the mutant ARs may be the cause of AIS in these subjects.
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Affiliation(s)
- Hisaya Kawate
- Department of Geriatric Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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22
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Tanaka M, Nishi M, Morimoto M, Sugimoto T, Kawata M. Imaging analysis of mineralocorticoid receptor and importins in single living cells by using GFP color variants. Cell Tissue Res 2005; 320:447-53. [PMID: 15846517 DOI: 10.1007/s00441-004-0984-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2004] [Accepted: 08/10/2004] [Indexed: 11/27/2022]
Abstract
Mineralocorticoid receptor (MR) is a ligand-dependent transcription factor involved in gene regulation in association with another corticosteroid receptor, glucocorticoid receptor. In the absence of ligand, MR resides both in the cytoplasm and in the nucleus. Agonists increase the number of MRs residing in the nucleus. Importins are docking proteins for karyopherin-mediated binding of substrate in a nuclear import pathway. To investigate the interactions between MR and importins, we analyzed the subcellular distribution of MR and importins in response to ligand in living COS-1 cells, which do not express endogenous MR, by using fusion proteins labeled with different spectral variants of green fluorescent protein. In the cells coexpressing fluorescent protein-tagged (FP)-MR and FP-importin alpha, the proteins simultaneously moved into the nucleus from the cytoplasm upon activation with ligand treatment. In the cells coexpressing FP-MR and FP-importin beta, FP-MR moved into the nucleus from the cytoplasm, but the distribution of FP-importin beta was little changed upon ligand treatment. Analysis of a mutant of MR, in which nuclear localization signal (NLS) is inactivated, demonstrated that the intact NLS is necessary for the trafficking of MR related to importin alpha. This is the first visual evidence of the nuclear import of MR in association with importin alpha in single living cells.
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Affiliation(s)
- Masayuki Tanaka
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kawaramachi Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
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23
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Arun KHS, Kaul CL, Ramarao P. Green fluorescent proteins in receptor research: An emerging tool for drug discovery. J Pharmacol Toxicol Methods 2005; 51:1-23. [PMID: 15596111 DOI: 10.1016/j.vascn.2004.07.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2003] [Accepted: 07/27/2004] [Indexed: 01/20/2023]
Abstract
In the last five years, green fluorescent protein (GFP) has emerged from being a mere curiosity to become a reliable tool for molecular pharmacological research. GFP produces an intense and stable green fluorescence noncatalytically by absorbing blue light maximally at 395 nm and emitting green light with a peak at 509 nm. It consists of 238 amino acids and its molecular mass is 27-30 kDa. GFP fluorescence occurs without cofactors and this property allows GFP fluorescence to be utilised in nonnative organisms, wherein it can be used as a reporter. This use of GFP permits real-time analysis of receptor dynamics. The emitted fluorescence can be used as a nontoxic marker and detected using fluorescence-activated cell sorting (FACS), thus avoiding any staining procedure, expensive mRNA analysis or hazardous radiolabeled binding assays. The potential value of GFP has also been recognized in orphan receptor research, where various GFP-tagged therapeutic proteins have been constructed in an attempt to identify the endogenous ligand(s). These chimeric proteins have been used to determine the site and time course of receptor expression and to relate receptor dynamics with therapeutic outcome. The preparation of new GFP constructs for identifying germ layer cells (endodermal, ectodermal, and mesodermal), as well as neuronal, haematopoietic, endothelial, and cartilage cells, has provided a useful battery of tissue/receptor-specific screening assays for new chemical entities. Genetically engineered cells with GFP expression have provided a valuable tool for automated analysis, and can be adapted for high-throughput systems. GFP is being increasingly utilised for the study of receptor dynamics, where, having already proved beneficial, it will likely continue to contribute towards the search for new classes of drugs, as well as to "de-orphaning" orphan receptors.
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Affiliation(s)
- K H S Arun
- Cardiovascular and Receptorology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, Phase-X, Sector 67, S.A.S. Nagar (Mohali)-160 062, Punjab, India
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24
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Menendez JA, Oza BP, Atlas E, Verma VA, Mehmi I, Lupu R. Inhibition of tumor-associated fatty acid synthase activity antagonizes estradiol- and tamoxifen-induced agonist transactivation of estrogen receptor (ER) in human endometrial adenocarcinoma cells. Oncogene 2004; 23:4945-58. [PMID: 15094777 DOI: 10.1038/sj.onc.1207476] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Overexpression of the lipogenic enzyme fatty acid synthase (FAS) is a common molecular feature in subsets of sex-steroid-related tumors including endometrium and breast carcinomas that are associated with poor prognosis. Pharmacological inhibition of tumor-associated FAS hyperactivity is under investigation as a chemotherapeutic target. We examined the effects of the mycotoxin cerulenin (a covalent FAS inactivator), and the novel small compound C75 (a slow-binding FAS inhibitor) on estradiol (E2)- and tamoxifen (TAM)-stimulated ER-driven molecular responses in Ishikawa cells, an in vitro model of well-differentiated human endometrial carcinoma. We evaluated the effects of FAS inhibition on E2- and TAM-induced estrogen receptor (ER) transcriptional activity by using transient cotransfection assays with an estrogen-response element reporter construct (ERE-Luciferase). Antiestrogenic effects of cerulenin and C75 were observed by dose-dependent inhibition of E2-stimulated ERE-dependent transcription, whereas FAS inhibitors did not significantly increase the levels of ERE transcriptional activity in the absence of E2. Moreover, pharmacological blockade of FAS activity completely abolished TAM-stimulated ERE activity. To address the reliability of transient transfection assays, the effects of FAS inhibitors on E2-inducible gene products were evaluated. FAS blockade induced a dose-dependent decrease in E2-inducible alkaline phosphatase activity. E2-stimulated accumulation of progesterone receptor (PR) and HER-2/neu oncogene was abolished in the presence of FAS blockers. FAS inhibition also resulted in a marked downregulation of E2-stimulated ERalpha expression, and noticeably impaired E2-induced ERalpha nuclear accumulation. A dose-dependent decrease in cell proliferation and cell viability was observed after FAS blockade. A Cell Death ELISA, detecting DNA fragmentation, demonstrated that FAS inhibitors stimulated apoptosis of Ishikawa cells. The analysis of critical E2- and TAM-related cell cycle proteins revealed an increase of both the expression and the nuclear accumulation of cyclin-dependent kinase inhibitors p21WAF1/CIP1 and p27Kip1 following FAS inhibition. To rule out non-FAS cerulenin- and C75-related effects, we finally monitored ER signaling after silencing of FAS gene expression using the highly sequence-specific mechanism of RNA interference (RNAi). The concentrations of E2 and TAM inducing half-maximal ERE activity (EC50) dramatically increased (>100 times) in FAS RNAi-transfected Ishikawa cells. Moreover, depletion of FAS by RNAi also caused loss of ERalpha expression, downregulation of PR, and accumulation of p21WAF1/CIP1 and p27Kip1 in E2-stimulated Ishikawa cells. If chemically stable FAS inhibitors or cell-selective vector systems able to deliver RNAi targeting FAS gene demonstrate systemic anticancer effects in vivo, our results render FAS as a novel target for the prevention and treatment of endometrial carcinoma.
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Affiliation(s)
- Javier A Menendez
- Department of Medicine, Evanston Northwestern Healthcare Research Institute, Evanston, IL 60201, USA
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25
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Jang ER, Lim SJ, Lee ES, Jeong G, Kim TY, Bang YJ, Lee JS. The histone deacetylase inhibitor trichostatin A sensitizes estrogen receptor α-negative breast cancer cells to tamoxifen. Oncogene 2003; 23:1724-36. [PMID: 14676837 DOI: 10.1038/sj.onc.1207315] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Many cases of breast cancer show loss of estrogen receptor (ER) alpha expression, which leads to unresponsiveness to antihormonal treatment even though there is no loss of the structurally and biochemically similar ER beta. ER activity is positively and negatively regulated by transcriptional regulators such as histone deacetylase (HDAC), which is known to be a negative ER regulator. Here, we evaluated using ER beta as an alternative target for tamoxifen therapy by treating ER alpha-negative, beta-positive breast cancer cells with the HDAC inhibitor trichostatin A (TSA), and testing whether tamoxifen responsiveness increased following upregulation of ER beta. TSA enhanced the overall ER transcriptional activity in these cells, as visualized by estrogen response element-regulated reporter and the expression of progesterone receptor, a known ER target, without ER alpha restoration. Additionally, TSA induced the expression and nuclear translocation of ER beta but not alpha, suggesting that these actions leading to increase of ER transcriptional activity are mediated through ER beta rather than alpha. Furthermore, following treatment with TSA, the formerly unresponsive MDA-MB-231 and Hs578T breast cancer cells became responsive to tamoxifen. However, reduction of ER beta expression by short interfering RNA abrogated this TSA-induced sensitization effect in these cells. Together, these results show that the HDAC inhibitor TSA sensitized ER alpha-negative, antihormone-unresponsive breast cancer cells to tamoxifen treatment possibly by upregulating ER beta activity.
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MESH Headings
- Active Transport, Cell Nucleus/drug effects
- Antineoplastic Agents, Hormonal/pharmacology
- Antineoplastic Agents, Hormonal/therapeutic use
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Cell Line, Tumor
- Estrogen Antagonists/pharmacology
- Estrogen Antagonists/therapeutic use
- Estrogen Receptor alpha
- Estrogen Receptor beta
- Female
- Gene Expression Regulation, Neoplastic/drug effects
- HeLa Cells
- Histone Deacetylase Inhibitors
- Histone Deacetylases/metabolism
- Humans
- Hydroxamic Acids/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Neoplasm/genetics
- RNA, Neoplasm/metabolism
- Receptors, Estrogen/deficiency
- Receptors, Estrogen/metabolism
- Receptors, Progesterone/metabolism
- Response Elements/genetics
- Tamoxifen/pharmacology
- Tamoxifen/therapeutic use
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Affiliation(s)
- Eun Ryoung Jang
- Research Institute and Hospital, National Cancer Center, 411-764, Republic of Korea
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26
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Le HT, Schaldach CM, Firestone GL, Bjeldanes LF. Plant-derived 3,3'-Diindolylmethane is a strong androgen antagonist in human prostate cancer cells. J Biol Chem 2003; 278:21136-45. [PMID: 12665522 DOI: 10.1074/jbc.m300588200] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
3,3'-Diindolylmethane (DIM) is a major digestive product of indole-3-carbinol, a potential anticancer component of cruciferous vegetables. Our results indicate that DIM exhibits potent antiproliferative and antiandrogenic properties in androgen-dependent human prostate cancer cells. DIM suppresses cell proliferation of LNCaP cells and inhibits dihydrotestosterone (DHT) stimulation of DNA synthesis. These activities were not produced in androgen-independent PC-3 cells. Moreover, DIM inhibited endogenous PSA transcription and reduced intracellular and secreted PSA protein levels induced by DHT in LNCaP cells. Also, DIM inhibited, in a concentration-dependent manner, the DHT-induced expression of a prostate-specific antigen promoter-regulated reporter gene construct in transiently transfected LNCaP cells. Similar effects of DIM were observed in PC-3 cells only when these cells were co-transfected with a wild-type androgen receptor expression plasmid. Using fluorescence imaging with green fluorescent protein androgen receptor and Western blot analysis, we demonstrated that DIM inhibited androgen-induced androgen receptor (AR) translocation into the nucleus. Results of receptor binding assays indicated further that DIM is a strong competitive inhibitor of DHT binding to the AR. Results of structural modeling studies showed that DIM is remarkably similar in conformational geometry and surface charge distribution to an established synthetic AR antagonist, although the atomic compositions of the two substances are quite different. Taken together with our published reports of the estrogen agonist activities of DIM, the present results establish DIM as a unique bifunctional hormone disrupter. To our knowledge, DIM is the first example of a pure androgen receptor antagonist from plants.
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Affiliation(s)
- Hien T Le
- Department of Nutritional Sciences and Toxicology, The University of California, Berkeley, California 94720-3104, USA.
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27
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Pozzan T, Mongillo M, Rudolf R. The Theodore Bücher lecture. Investigating signal transduction with genetically encoded fluorescent probes. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:2343-52. [PMID: 12755688 DOI: 10.1046/j.1432-1033.2003.03615.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ca2+ and cAMP are ubiquitous second messengers in eukaryotes and control numerous physiological responses ranging from fertilization to cell death induction. To distinguish between these different responses, their subtle regulation in time, space and amplitude is needed. Therefore, the characterization of the signalling process requires measurement of second messengers with tools of precise localization, high dynamic range and as little disturbance of cell physiology as possible. Recently, fluorescent proteins of marine jellyfish have given rise to a set of genetically encoded biosensors which fulfil these criteria and which have already led to important new insights into the subcellular handling of Ca2+ and cAMP. The use of these probes in combination with new microscopical methods such as two-photon microscopy now enables researchers to study second messenger signalling in intact tissues. In this review, the genetically encoded measurement probes and their origin are briefly introduced and some recent insights into the spatio-temporal complexity of both Ca2+ and cAMP signalling obtained with these tools are discussed.
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Affiliation(s)
- Tullio Pozzan
- Department of Biomedical Sciences, CNR Institute of Neurosciences, University of Padua, and Venetian Institute for Molecular Medicine, Padua, Italy.
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28
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Dufour JM, Vo MN, Bhattacharya N, Okita J, Okita R, Kim KH. Peroxisome proliferators disrupt retinoic acid receptor alpha signaling in the testis. Biol Reprod 2003; 68:1215-24. [PMID: 12606456 DOI: 10.1095/biolreprod.102.010488] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Peroxisome proliferators include a diverse group of chemicals, some of which have been demonstrated to be testicular toxicants. However, the mechanism by which peroxisome proliferators, such as phthalates, cause testicular damage is not clear. It is known that retinoic acid receptor alpha (RARalpha) and its retinoic acid ligand, the acid form of vitamin A, are required for spermatogenesis. It has been demonstrated that the absence of RARalpha gene or vitamin A in the animal leads to testis degeneration and sterility. Therefore, any compound that disrupts the action of vitamin A in the testis could potentially be damaging to male fertility. The current investigation examined a novel hypothesis that a mechanism of degeneration by peroxisome proliferators in the testis is due, in part, to disruption of the critical RARalpha signaling pathway. We show that peroxisome proliferators were able to disrupt the retinoic acid-induced nuclear localization of RARalpha and the retinoic acid-stimulated increase in transcriptional activity of a retinoic acid-responsive reporter gene in Sertoli cells. Concomitantly, peroxisome proliferators increased the nuclear localization of PPARalpha and the transcriptional activity of a peroxisome proliferator-responsive reporter gene in these cells. These results indicate that peroxisome proliferators can indeed shift the balance of nuclear localization for RARalpha and PPARalpha, resulting in deactivation of the critical RARalpha transcriptional activity in Sertoli cells.
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Affiliation(s)
- Jannette M Dufour
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
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29
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Tyagi RK. Dynamics of subcellular compartmentalization of steroid receptors in living cells as a strategic screening method to determine the biological impact of suspected endocrine disruptors. Med Hypotheses 2003; 60:501-4. [PMID: 12615508 DOI: 10.1016/s0306-9877(02)00442-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Although a number of screening methods being used for identifying potential endocrine disruptors have generated a wealth of information, a search for alternative combination of methods is still needed to overcome experimental artefacts. There are no generally accepted or validated screening methods for monitoring and studying impact of environmental endocrine disruptors. Also, no single assay can accurately predict all the deleterious effects of endocrine disruptors. For this reason various environmental protection agencies, mainly European and US, have urged that a battery of tests in current use need to be designed to assess their adequacy in detecting the effects of endocrine disruptors. Some details about endocrine disruptors and screening programs can be found at http://www.epa.gov/scipoly/oscpendo/whatis.htm. Several studies in recent years have used fusion proteins between steroid receptors (estrogen, androgen, progesterone, etc.) and green fluorescent protein (GFP) that can serve as an alternative potent screening method to study intracellular dynamics of receptors in living cells. An approach employing nucleocytoplasmic trafficking of steroid receptors as a parameter in response to potential xenobiotic chemicals in living cells may prove to be promising in terms of being direct, fast, reliable, simple and inexpensive.
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Affiliation(s)
- Rakesh Kumar Tyagi
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, Special Centre for Molecular Medicine, New Delhi, India.
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