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Iftikhar A, Islam M, Shepherd S, Jones S, Ellis I. Cancer and Stress: Does It Make a Difference to the Patient When These Two Challenges Collide? Cancers (Basel) 2021; 13:cancers13020163. [PMID: 33418900 PMCID: PMC7825104 DOI: 10.3390/cancers13020163] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/23/2020] [Accepted: 12/28/2020] [Indexed: 02/07/2023] Open
Abstract
Simple Summary Head and neck cancers are the sixth most common cancer in the world. The burden of the disease has remained challenging over recent years despite the advances in treatments of other malignancies. The very use of the word malignancy brings about a stress response in almost all adult patients. Being told you have a tumour is not a word anyone wants to hear. We have embarked on a study which will investigate the effect of stress pathways on head and neck cancer patients and which signalling pathways may be involved. In the future, this will allow clinicians to better manage patients with head and neck cancer and reduce the patients’ stress so that this does not add to their tumour burden. Abstract A single head and neck Cancer (HNC) is a globally growing challenge associated with significant morbidity and mortality. The diagnosis itself can affect the patients profoundly let alone the complex and disfiguring treatment. The highly important functions of structures of the head and neck such as mastication, speech, aesthetics, identity and social interactions make a cancer diagnosis in this region even more psychologically traumatic. The emotional distress engendered as a result of functional and social disruption is certain to negatively affect health-related quality of life (HRQoL). The key biological responses to stressful events are moderated through the combined action of two systems, the hypothalamus–pituitary–adrenal axis (HPA) which releases glucocorticoids and the sympathetic nervous system (SNS) which releases catecholamines. In acute stress, these hormones help the body to regain homeostasis; however, in chronic stress their increased levels and activation of their receptors may aid in the progression of cancer. Despite ample evidence on the existence of stress in patients diagnosed with HNC, studies looking at the effect of stress on the progression of disease are scarce, compared to other cancers. This review summarises the challenges associated with HNC that make it stressful and describes how stress signalling aids in the progression of cancer. Growing evidence on the relationship between stress and HNC makes it paramount to focus future research towards a better understanding of stress and its effect on head and neck cancer.
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Shimba A, Ikuta K. Control of immunity by glucocorticoids in health and disease. Semin Immunopathol 2020; 42:669-680. [PMID: 33219395 DOI: 10.1007/s00281-020-00827-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 11/13/2020] [Indexed: 12/15/2022]
Abstract
Animals receive environmental stimuli from neural signals in order to produce hormones that control immune responses. Glucocorticoids (GCs) are a group of steroid hormones produced in the adrenal cortex and well-known mediators for the nervous and immune systems. GC secretion is induced by circadian rhythm and stress, and plasma GC levels are high at the active phase of animals and under stress condition. Clinically, GCs are used for allergies, autoimmunity, and chronic inflammation, because they have strong anti-inflammatory effects and induce the apoptosis of lymphocytes. Glucocorticoid receptor (GR) acts as a transcription factor and represses the expression of inflammatory cytokines, chemokines, and prostaglandins by binding to its motif, glucocorticoid-response element, or to other transcription factors. In mice, GR suppresses the antigen-stimulated inflammation mediated by macrophages, dendritic cells, and epithelial cells, and impairs cytotoxic immune responses by downregulating interferon-γ production and inhibiting the development of type-1 helper T cells, CD8+ T cells, and natural killer cells. These immune inhibitory effects prevent lethality by excessive inflammation, but at the same time increase the susceptibility to infection and cancer. GCs can also activate the immune system. The circadian cycle of GC secretion controls the diurnal oscillations of the distribution and response of T cells, thus supporting T cell maintenance and effective immune protection against infection. Moreover, several reports have shown that GR has the potential to enhance the activities of Th2, Th17, and immunoglobulin-producing B cells. Stress has two different effects on immune responses: immune suppression to cause mortality by infection and cancer, and excessive immune activation to induce chronic inflammation and autoimmune disease. Consistently, stress-induced GCs strongly suppress cell-mediated immunity and cause viral infection and tumor development. They may also enhance the development of pathogenic helper T cells and cause tissue damage through neural and intestinal inflammation. Past studies have reported the positive and negative effects of GCs on the immune system. These opposing properties of GCs may regulate the immune balance between the responsiveness to antigens and excessive inflammation in steady-state and stress conditions.
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Affiliation(s)
- Akihiro Shimba
- Laboratory of Immune Regulation, Department of Virus Research, Institute for Frontier Life and Medical Sciences, Kyoto University, 53 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan.,Human Health Sciences, Graduate School of Medicine, Kyoto University, 53 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Koichi Ikuta
- Laboratory of Immune Regulation, Department of Virus Research, Institute for Frontier Life and Medical Sciences, Kyoto University, 53 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan.
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A Novel Pathogenic Variant in the N-Terminal Domain of the Glucocorticoid Receptor, Causing Glucocorticoid Resistance. Mol Diagn Ther 2020; 24:473-485. [DOI: 10.1007/s40291-020-00480-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Abstract
The nuclear receptor family of transcription factor proteins mediates endocrine function and plays critical roles in the development, physiology and pharmacology. Malfunctioning nuclear receptors are associated with several disease states. The functional activity of nuclear receptors is regulated by small molecular hormonal and synthetic molecules. Multiple sources of evidence have identified and distinguished between the different allosteric pathways initiated by ligands, DNA and cofactors such as co-activators and co-repressors. Also, these biophysical studies are attempting to determine how these pathways that regulate co-activator and DNA recognition can control gene transcription. Thus, there is a growing interest in determining the genome-scale impact of allostery in nuclear receptors. Today, it is accepted that a detailed understanding of the allosteric regulatory pathways within the nuclear receptor molecular complex will enable the development of efficient drug therapies in the long term.
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Affiliation(s)
- Elias J Fernandez
- Department of Biochemistry & Cellular and Molecular Biology, The University of Tennessee, USA.
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5
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Vispute SG, Bu P, Le Y, Cheng X. Activation of GR but not PXR by dexamethasone attenuated acetaminophen hepatotoxicities via Fgf21 induction. Toxicology 2017; 378:95-106. [PMID: 28088388 DOI: 10.1016/j.tox.2017.01.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 01/05/2017] [Accepted: 01/09/2017] [Indexed: 11/18/2022]
Abstract
Glucocorticoid receptor (GR) signaling is indispensable for cell growth and development, and plays important roles in drug metabolism. Fibroblast growth factor (Fgf) 21, an important regulator of glucose, lipid, and energy metabolism, plays a cytoprotective role by attenuating toxicities induced by chemicals such as dioxins, acetaminophen (APAP), and alcohols. The present study investigates the impact of dexamethasone (DEX)-activated GR on Fgf21 expression and how it affects the progression of APAP-induced hepatotoxicity. Our results showed that DEX dose/concentration- and time-dependently increased Fgf21 mRNA and protein expression in mouse liver as well as cultured mouse and human hepatoma cells. By using PXR-null mouse model, we demonstrated that DEX induced Fgf21 expression by a PXR-independent mechanism. In cultured mouse and human hepatoma cells, inhibition of GR signaling, by RU486 (Mifepristone) or GR silencing using GR-specific siRNA, attenuated DEX-induced Fgf21 expression. In addition, DEX increased luciferase reporter activity driven by the 3.0-kb mouse and human Fgf21/FGF21 gene promoter. Further, ChIP-qPCR assays demonstrated that DEX increased the binding of GR to the specific cis-regulatory elements located in the 3.0-kb mouse and human Fgf21/FGF21 gene promoter. Pretreatment of 2mg/kg DEX ameliorated APAP-induced liver injury in wild-type but not Fgf21-null mice. In conclusion, via GR activation, DEX induced Fgf21 expression in mouse liver and human hepatoma cells.
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Affiliation(s)
- Saurabh G Vispute
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY 11439, USA
| | - Pengli Bu
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY 11439, USA; Department of Biological Sciences, College of Liberal Arts and Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY 11439, USA
| | - Yuan Le
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY 11439, USA
| | - Xingguo Cheng
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY 11439, USA.
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The Interactome of the Glucocorticoid Receptor and Its Influence on the Actions of Glucocorticoids in Combatting Inflammatory and Infectious Diseases. Microbiol Mol Biol Rev 2016; 80:495-522. [PMID: 27169854 DOI: 10.1128/mmbr.00064-15] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Glucocorticoids (GCs) have been widely used for decades as a first-line treatment for inflammatory and autoimmune diseases. However, their use is often hampered by the onset of adverse effects or resistance. GCs mediate their effects via binding to glucocorticoid receptor (GR), a transcription factor belonging to the family of nuclear receptors. An important aspect of GR's actions, including its anti-inflammatory capacity, involves its interactions with various proteins, such as transcription factors, cofactors, and modifying enzymes, which codetermine receptor functionality. In this review, we provide a state-of-the-art overview of the protein-protein interactions (PPIs) of GR that positively or negatively affect its anti-inflammatory properties, along with mechanistic insights, if known. Emphasis is placed on the interactions that affect its anti-inflammatory effects in the presence of inflammatory and microbial diseases.
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7
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Singh N, Taylor K, Mjoli PB, Poolman T, Ray DW, Sommer P. The N-terminal transactivation domain of the glucocorticoid receptor mediates apoptosis of human small cell lung cancer cells. Genes Chromosomes Cancer 2014; 53:999-1007. [DOI: 10.1002/gcc.22209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 07/24/2014] [Indexed: 12/20/2022] Open
Affiliation(s)
- Nimisha Singh
- Division of Genetics; School of Life Sciences, University of KwaZulu-Natal; Durban South Africa
| | - Kerryn Taylor
- Division of Genetics; School of Life Sciences, University of KwaZulu-Natal; Durban South Africa
| | - Phiwokuhle B. Mjoli
- Division of Genetics; School of Life Sciences, University of KwaZulu-Natal; Durban South Africa
| | - Toryn Poolman
- Centre in Endocrinology and Diabetes; Institute of Human Development, University of Manchester; Manchester UK
| | - David W. Ray
- Centre in Endocrinology and Diabetes; Institute of Human Development, University of Manchester; Manchester UK
| | - Paula Sommer
- Division of Genetics; School of Life Sciences, University of KwaZulu-Natal; Durban South Africa
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Vandevyver S, Dejager L, Libert C. Comprehensive overview of the structure and regulation of the glucocorticoid receptor. Endocr Rev 2014; 35:671-93. [PMID: 24937701 DOI: 10.1210/er.2014-1010] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Glucocorticoids are among the most prescribed drugs worldwide for the treatment of numerous immune and inflammatory disorders. They exert their actions by binding to the glucocorticoid receptor (GR), a member of the nuclear receptor superfamily. There are several GR isoforms resulting from alternative RNA splicing and translation initiation of the GR transcript. Additionally, these isoforms are all subject to several transcriptional, post-transcriptional, and post-translational modifications, all of which affect the protein's stability and/or function. In this review, we summarize recent knowledge on the distinct GR isoforms and the processes that generate them. We also review the importance of all known transcriptional, post-transcriptional, and post-translational modifications, including the regulation of GR by microRNAs. Moreover, we discuss the crucial role of the putative GR-bound DNA sequence as an allosteric ligand influencing GR structure and activity. Finally, we describe how the differential composition and distinct regulation at multiple levels of different GR species could account for the wide and diverse effects of glucocorticoids.
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Affiliation(s)
- Sofie Vandevyver
- Inflammation Research Center (S.V., L.D., C.L.), Flanders Institute for Biotechnology, B9052 Ghent, Belgium; and Department of Biomedical Molecular Biology (S.V., L.D., C.L.), Ghent University, B9052 Ghent, Belgium
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Jones C. Bovine Herpes Virus 1 (BHV-1) and Herpes Simplex Virus Type 1 (HSV-1) Promote Survival of Latently Infected Sensory Neurons, in Part by Inhibiting Apoptosis. J Cell Death 2013; 6:1-16. [PMID: 25278776 PMCID: PMC4147773 DOI: 10.4137/jcd.s10803] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
α-Herpesvirinae subfamily members, including herpes simplex virus type 1 (HSV-1) and bovine herpes virus 1 (BHV-1), initiate infection in mucosal surfaces. BHV-1 and HSV-1 enter sensory neurons by cell-cell spread where a burst of viral gene expression occurs. When compared to non-neuronal cells, viral gene expression is quickly extinguished in sensory neurons resulting in neuronal survival and latency. The HSV-1 latency associated transcript (LAT), which is abundantly expressed in latently infected neurons, inhibits apoptosis, viral transcription, and productive infection, and directly or indirectly enhances reactivation from latency in small animal models. Three anti-apoptosis genes can be substituted for LAT, which will restore wild type levels of reactivation from latency to a LAT null mutant virus. Two small non-coding RNAs encoded by LAT possess anti-apoptosis functions in transfected cells. The BHV-1 latency related RNA (LR-RNA), like LAT, is abundantly expressed during latency. The LR-RNA encodes a protein (ORF2) and two microRNAs that are expressed in certain latently infected neurons. Wild-type expression of LR gene products is required for stress-induced reactivation from latency in cattle. ORF2 has anti-apoptosis functions and interacts with certain cellular transcription factors that stimulate viral transcription and productive infection. ORF2 is predicted to promote survival of infected neurons by inhibiting apoptosis and sequestering cellular transcription factors which stimulate productive infection. In addition, the LR encoded microRNAs inhibit viral transcription and apoptosis. In summary, the ability of BHV-1 and HSV-1 to interfere with apoptosis and productive infection in sensory neurons is crucial for the life-long latency-reactivation cycle in their respective hosts.
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Affiliation(s)
- Clinton Jones
- School of Veterinary Medicine and Biomedical Sciences, Nebraska Center for Virology, University of Nebraska, Morrison Life Science Center, Lincoln, NE
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Schlossmacher G, Stevens A, White A. Glucocorticoid receptor-mediated apoptosis: mechanisms of resistance in cancer cells. J Endocrinol 2011; 211:17-25. [PMID: 21602312 DOI: 10.1530/joe-11-0135] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Glucocorticoids (Gcs) are commonly used to treat patients suffering from a wide range of cancers. Their main therapeutic role is based on Gc receptor (GR)-mediated mechanisms that trigger cell death but this varies depending on the cancer type. This review aims to provide an overview of the mechanisms of Gc-induced cell death and more importantly the changes in GR that lead to resistance to Gc treatment in cancer. The three main cancer types, which are susceptible to Gc resistance and therefore loss of Gc-induced apoptotic effects, are acute lymphoblastic leukaemia, osteosarcoma and small-cell lung carcinoma. A common theme is the loss of GR function and/or a downregulation of GR expression which leads to failure of the cell death-inducing effects of Gcs. Loss of GR function is attributed to mutations in the GR gene, and in some cases a dominant-negative effect on any functional GR still present. The downregulation of GR expression can be due to decreased GR promoter activation, increased GR promoter methylation or increased expression of alternative splice isoforms of GR that have decreased transcriptional activity. Understanding the mechanisms behind Gc-triggered apoptosis and the resistance to it in these cancer types will help in further refining treatment regimens for patients and will decrease the chance of relapse caused by Gc-resistant cancer phenotypes.
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Affiliation(s)
- George Schlossmacher
- Endocrinology and Diabetes, Faculty of Life Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester M13 9PT, UK
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11
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Dexamethasone-induced apoptotic mechanisms in myeloma cells investigated by analysis of mutant glucocorticoid receptors. Blood 2008; 112:1338-45. [PMID: 18515658 DOI: 10.1182/blood-2007-11-124156] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanism by which the glucocorticoid (GC) dexamethasone induces apoptosis in multiple myeloma (MM) cells is unknown, although previous work suggests that either transactivation through the glucocorticoid response element (GRE), transrepression of NF-kappaB, phosphorylation of RAFTK (Pyk2), or induction of Bim is important. We studied this question by ectopically expressing mutant glucocorticoid receptors (GRs) in the dexamethasone-resistant MM1R cell line, which has lost its GR. Lentiviral-mediated reexpression of wild-type GR restored GRE transactivation, NF-kappaB transrepression, RAFTK phosphorylation, Bim induction, and dexamethasone-induced apoptosis. We then reexpressed 4 GR mutants, each possessing various molecular effects, into MM1R cells. A perfect correlation was present between induction of GRE transactivation and induction of apoptosis. In contrast, NF-kappaB transrepression and RAFTK phosphorylation were not required for apoptosis. Although not required for dexamethasone-mediated apoptosis, NF-kappaB inhibition achieved by gene transfer suggested that NF-kappaB transrepression could contribute to apoptosis in dexamethasone-treated cells. Dexamethasone treatment of MM1R cells expressing a mutant incapable of inducing apoptosis successfully resulted in RAFTK (Pyk2) phosphorylation and Bim induction indicating the latter GR-mediated events were not sufficient to induce apoptosis. MM1R cells expressing mutant GRs will be helpful in defining the molecular mechanisms of dexamethasone-induced apoptosis of myeloma cells.
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12
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Kumar R, Serrette JM, Khan SH, Miller AL, Thompson EB. Effects of different osmolytes on the induced folding of the N-terminal activation domain (AF1) of the glucocorticoid receptor. Arch Biochem Biophys 2007; 465:452-60. [PMID: 17655821 PMCID: PMC3074928 DOI: 10.1016/j.abb.2007.06.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 06/24/2007] [Accepted: 06/25/2007] [Indexed: 11/25/2022]
Abstract
In order to understand gene regulation by glucocorticoids, it is pivotal to know how the major transactivation domain AF1 of the glucocorticoid receptor (GR) functions. Located in the N-terminal region of the GR, AF1 is quantitatively important for transcriptional regulation, but only in recent years have we begun to understand how AF1 works. This is in part due to the fact that the recombinant AF1 (rAF1) peptide exists as a random ensemble of conformers. Algorithms that predict structure support the view that AF1 is also not well ordered in the holo-GR, and the properties of the amino acids in AF1 suggest that it is intrinsically disordered. However, it is generally believed that intrinsically disordered sequences of the GR AF1 must achieve one or more ordered conformation(s) to carry out transactivation activity. Based on our previous published work and available literature, we hypothesize that a confluence of effects that operate under physiological conditions cause functionally active conformation(s) to form in AF1. We have shown that when rAF1 is incubated in increasing concentrations of a naturally occurring osmolyte trimethylamine-N-oxide (TMAO), the peptide folds into functionally active conformation(s) that selectively binds several critical coregulatory proteins. Because cells contain various organic osmolytes whose effects may be cumulative, and in light of cell-specific effects of GR AF1 action, we tested whether it can be folded by other natural organic osmolytes representative of three classes: certain amino acids (proline), methylamines (sarcosine), and polyols (sorbitol). The osmolyte-induced folding of rAF1 shows greatly increased affinity for specific binding proteins, including TATA box-binding protein (TBP), CREB-binding protein (CBP), and steroid receptor coactivator-1 (SRC-1). Consistent with theory and published data with other proteins, our results show that different osmolytes have differential effects on rAF1 folding. The cell-specific functions of the GR AF1--and by extension the AF1s of other nuclear hormone receptors--may in part be affected by the presence and concentrations of particular osmolytes within a particular cellular environment.
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Affiliation(s)
- R Kumar
- Department of Internal Medicine, Division of Gastroenterology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-1071, USA.
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Kwok AHY, Wang Y, Wang CY, Leung FC. Cloning of Chicken Glucocorticoid Receptor (GR) and Characterization of its Expression in Pituitary and Extrapituitary Tissues. Poult Sci 2007; 86:423-30. [PMID: 17234861 DOI: 10.1093/ps/86.2.423] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Substantial evidence suggests that glucocorticoids play critical roles in the differentiation of somatotroph and lactotroph in embryonic pituitaries of birds. However, the basic information on the expression of glucocorticoid receptor (GR) in avian species is limited. In this study, the full-length cDNA for chicken GR was cloned from the chicken kidney. It encodes 772 amino acids and shares high homology with that of the human (73%), mouse (73%), rat (71%), rabbit (72%), and trout (51%) sequences. Similar to mammals, chicken GR is widely expressed in all adult tissues being investigated. Among the 12 tissues investigated, relatively high expression of GR was detected in pituitary, muscle, ovary, and kidney using reverse transcription-PCR assay. Using semiquantitative reverse transcription-PCR, GR is shown to be abundantly expressed at a more or less constant level during embryonic pituitary development (from d 8 to 20), supporting the hypothesis that the expression of GR is unlikely to be a limiting factor in initiating the differentiation of somatotroph and lactotroph in embryonic pituitary of birds. Moreover, an abundant expression of GR in the whole embryos at earlier developmental stages (from d 2 to 5) was also detected in the present study, though its physiological relevance remains to be determined.
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Affiliation(s)
- A H Y Kwok
- Department of Zoology, The University of Hong Kong, Hong Kong, China
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Abstract
Glucocorticoids contribute fundamentally to the maintenance of basal and stress-related homeostasis in all higher organisms. The major roles of these steroids in physiology are amply matched by their remarkable contributions to pathology. Glucocorticoid resistance is a rare familial, or sporadic condition characterized by partial end-organ insensitivity to glucocorticoids. The molecular basis of glucocorticoid resistance in several families and sporadic cases has been ascribed to mutations in the human glucocorticoid receptor alpha (hGRalpha) gene, which impair the ability of the receptor to transduce the glucocorticoid signal. Glucocorticoids are crucial for life, and therefore complete glucocorticoid resistance is uncommon. The purpose of this review is to discuss the many structural and functional features of the glucocorticoid receptor and also to evaluate the main clinical and laboratory characteristics of cortisol resistance.
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Affiliation(s)
- Z Orbak
- Ataturk University Faculty of Medicine, Department of Pediatric Endocrinology, Erzurum, 25240, Turkey.
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Tome ME, Johnson DBF, Samulitis BK, Dorr RT, Briehl MM. Glucose 6-phosphate dehydrogenase overexpression models glucose deprivation and sensitizes lymphoma cells to apoptosis. Antioxid Redox Signal 2006; 8:1315-27. [PMID: 16910779 DOI: 10.1089/ars.2006.8.1315] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Glucocorticoids are one component of combined treatment regimens for many types of lymphoma due to their ability to induce apoptosis in lymphoid cells. In WEHI7.2 murine thymic lymphoma cells, altering catalase and glutathione peroxidase activity by transfection or the use of chemical agents modulates the ability of glucocorticoids to induce apoptosis. This suggests that the oxidative stress response is important in determining the glucocorticoid sensitivity of the cells. For glutathione peroxidase and catalase to detoxify reactive oxygen species (ROS), reducing equivalents in the form of nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) are ultimately required. The major source of NADPH in the cell is glucose 6-phosphate dehydrogenase (G6PDH). Therefore, we created G6PDH-overexpressing WEHI7.2 variants to test whether G6PDH activity is a key determinant of glucocorticoid sensitivity in WEHI7.2 cells. G6PDH-overexpressing WEHI7.2 cells were more sensitive to oxidative stress and glucocorticoids. The G6PDH-overexpressing WEHI7.2 variants appeared similar to cells undergoing glucose deprivation with decreased adenosine triphosphate (ATP) synthesis by the mitochondria and increased basal levels of ROS. Overexpression of G6PDH also sensitized the cells to other standard lymphoma chemotherapeutics including cyclophosphamide, doxorubicin, and vincristine. The decreased ATP and elevated ROS due to G6PDH overexpression may be key factors in increasing the sensitivity of the WEHI7.2 cells to lymphoma chemotherapeutics.
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Affiliation(s)
- Margaret E Tome
- Department of Pathology, University of Arizona, Tucson, 85724, USA
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Wang Z, Rong YP, Malone MH, Davis MC, Zhong F, Distelhorst CW. Thioredoxin-interacting protein (txnip) is a glucocorticoid-regulated primary response gene involved in mediating glucocorticoid-induced apoptosis. Oncogene 2006; 25:1903-13. [PMID: 16301999 DOI: 10.1038/sj.onc.1209218] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Glucocorticoid hormones induce apoptosis in lymphoid cells. This process is transcriptionally regulated and requires de novo RNA/protein synthesis. However, the full spectrum of glucocorticoid-regulated genes mediating this cell death process is unknown. Through gene expression profiling we discovered that the expression of thioredoxin-intereacting protein (txnip) mRNA is significantly induced by the glucocorticoid hormone dexamethasone not only in the murine T-cell lymphoma line WEHI7.2, but also in normal mouse thymocytes. This result was confirmed by Northern blot analysis in multiple models of dexamethasone-induced apoptosis. The induction of txnip mRNA by dexamethasone appears to be mediated through the glucocorticoid receptor as it is blocked in the presence of RU486, a glucocorticoid receptor antagonist. Deletion and mutation analysis of the txnip promoter identified a functional glucocorticoid response element in the txnip promoter. Reporter assays demonstrated that this glucocorticoid response element was necessary and sufficient for induction of txnip by dexamethasone. Expression of a GFP-TXNIP fusion protein was sufficient to induce apoptosis in WEHI7.2 cells, and repression of endogenous txnip by RNA interference inhibited dexamethasone-induced apoptosis in WEHI7.2 cells. Together, these findings indicate that txnip is a novel glucocorticoid-induced primary target gene involved in mediating glucocorticoid-induced apoptosis.
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Affiliation(s)
- Z Wang
- Department of Medicine and Pharmacology, Comprehensive Cancer Center, Case Western Reserve University School of Medicine and University Hospitals of Cleveland, Cleveland, OH 44106-7285, USA
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Schmidt S, Rainer J, Ploner C, Presul E, Riml S, Kofler R. Glucocorticoid-induced apoptosis and glucocorticoid resistance: molecular mechanisms and clinical relevance. Cell Death Differ 2005; 11 Suppl 1:S45-55. [PMID: 15243581 DOI: 10.1038/sj.cdd.4401456] [Citation(s) in RCA: 262] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The ability of glucocorticoids (GC) to efficiently kill lymphoid cells has led to their inclusion in essentially all chemotherapy protocols for lymphoid malignancies. This review summarizes recent findings related to the molecular basis of GC-induced apoptosis and GC resistance, and discusses their potential clinical implications. Accumulating evidence suggests that GC may induce cell death via different pathways resulting in apoptotic or necrotic morphologies, depending on the availability/responsiveness of the apoptotic machinery. The former might result from regulation of typical apoptosis genes such as members of the Bcl-2 family, the latter from detrimental GC effects on essential cellular functions possibly perpetuated by GC receptor (GR) autoinduction. Although other possibilities exist, GC resistance might frequently result from defective GR expression, perhaps the most efficient means to target multiple antileukemic GC effects. Numerous novel drug combinations are currently being tested to prevent resistance and improve GC efficacy in the therapy of lymphoid malignancies.
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Affiliation(s)
- S Schmidt
- Tyrolean Cancer Research Institute, Innsbruck, Austria
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Kumar R, Thompson EB. Gene regulation by the glucocorticoid receptor: structure:function relationship. J Steroid Biochem Mol Biol 2005; 94:383-94. [PMID: 15876404 DOI: 10.1016/j.jsbmb.2004.12.046] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Accepted: 12/30/2004] [Indexed: 01/02/2023]
Abstract
The glucocorticoid receptor (GR) belongs to the superfamily of ligand-activated transcription factors, the nuclear hormone receptors. Like other members of the family, the GR possesses a modular structure consisting of three major domains-the N-terminal (NTD), DNA binding (DBD), and ligand binding (LBD). Although the structures of independently expressed GR DBD and LBD are known, the structures of the NTD and of full-length GR are lacking. Both DBD and LBD possess overall globular structures. Not much is known about the structure of the NTD, which contains the powerful AF1/tau1/enh2 transactivation region. Several studies have shown that AF1 region is mostly unstructured and that it can acquire folded functional conformation under certain potentially physiological conditions, namely in the presence of osmolytes, when the GR DBD is bound to glucocorticoid response element (GRE), and when AF1 binds other transcription factor proteins. These conditions are discussed here. The functions of the GR will be fully understood only when its working three-dimensional structure is known. Based on the available data, we propose a model to explain data which are not adequately accounted for in the classical models of GR action. In this review, we summarize and discuss current information on the structure of the GR in the context of its functional aspects, such as protein:DNA and protein:protein interactions. Because of the close similarities in modular organization among the members of the nuclear hormone receptors, the principles discussed here for the GR should be applicable to many other receptors in the family as well.
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Affiliation(s)
- Raj Kumar
- Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1068, USA
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19
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Tome ME, Lutz NW, Briehl MM. Overexpression of catalase or Bcl-2 alters glucose and energy metabolism concomitant with dexamethasone resistance. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1693:57-72. [PMID: 15276325 DOI: 10.1016/j.bbamcr.2004.05.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2003] [Revised: 05/06/2004] [Accepted: 05/07/2004] [Indexed: 10/26/2022]
Abstract
Glucocorticoids induce apoptosis in lymphocytes by causing the release of cytochrome c into the cytosol; however, the events in the signaling phase between translocation of the steroid-receptor complex to the nucleus and the release of cytochrome c have not been elucidated. Previously, we found that, in response to steroid treatment, WEHI7.2 mouse thymic lymphoma cells overexpressing catalase (CAT38) show delayed apoptosis (delayed cytochrome c release) compared to the parental cells, while Bcl-2 overexpressing cells (Hb12) are protected from steroid-induced apoptosis. In lymphocytes, glucocorticoid treatment decreases glucose uptake. Both glucose deprivation and the attendant ATP drop are known inducers of apoptosis. Therefore, we used (31)P and (1)H NMR spectroscopy to compare metabolic profiles of WEHI7.2, CAT38 and Hb12 cells in the presence and absence of dexamethasone to determine: (1) whether glucocorticoid effects on glucose metabolism contribute to the mechanism of steroid-induced apoptosis; and (2) whether catalase or Bcl-2 overexpression altered metabolism thereby providing a mechanism of steroid resistance. Loss of mitochondrial hexokinase activity was correlated to the induction of apoptosis in WEHI7.2 and CAT38 cells. CAT38 and Hb12 cells have an altered basal metabolism which includes increases in hexokinase activity, lactate production when subcultured into new medium, use of mitochondria for ATP production and potentially increased glutaminolysis. These data suggest that: (1) glucocorticoid effects on glucose metabolism may contribute to the mechanism of steroid-induced lymphocyte apoptosis; and (2) the altered metabolism seen in catalase and Bcl-2 overexpressing cells may contribute to both the steroid resistance and increased tumorigenicity of these variants.
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Affiliation(s)
- Margaret E Tome
- Department of Pathology, University of Arizona, P.O. Box 245043, Tucson, AZ 85724, USA.
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20
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Chen R, Valencia I, Zhong F, McColl KS, Roderick HL, Bootman MD, Berridge MJ, Conway SJ, Holmes AB, Mignery GA, Velez P, Distelhorst CW. Bcl-2 functionally interacts with inositol 1,4,5-trisphosphate receptors to regulate calcium release from the ER in response to inositol 1,4,5-trisphosphate. ACTA ACUST UNITED AC 2004; 166:193-203. [PMID: 15263017 PMCID: PMC2172311 DOI: 10.1083/jcb.200309146] [Citation(s) in RCA: 314] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs) are channels responsible for calcium release from the endoplasmic reticulum (ER). We show that the anti-apoptotic protein Bcl-2 (either wild type or selectively localized to the ER) significantly inhibited InsP3-mediated calcium release and elevation of cytosolic calcium in WEHI7.2 T cells. This inhibition was due to an effect of Bcl-2 at the level of InsP3Rs because responses to both anti-CD3 antibody and a cell-permeant InsP3 ester were decreased. Bcl-2 inhibited the extent of calcium release from the ER of permeabilized WEHI7.2 cells, even at saturating concentrations of InsP3, without decreasing luminal calcium concentration. Furthermore, Bcl-2 reduced the open probability of purified InsP3Rs reconstituted into lipid bilayers. Bcl-2 and InsP3Rs were detected together in macromolecular complexes by coimmunoprecipitation and blue native gel electrophoresis. We suggest that this functional interaction of Bcl-2 with InsP3Rs inhibits InsP3R activation and thereby regulates InsP3-induced calcium release from the ER.
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Affiliation(s)
- Rui Chen
- Department of Medicine, Comprehensive Cancer Center, Case Western Reserve University and University Hospitals of Cleveland, OH 44106, USA
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21
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Ohta K, Okoshi R, Wakabayashi M, Sato Y, Kizaki H. MODULATION OF DEXAMETHASONE-INDUCED THYMOCYTE APOPTOSIS BY HEAT-SHOCK PROTEIN 90-BINDING AGENTS. THE BULLETIN OF TOKYO DENTAL COLLEGE 2004; 45:1-8. [PMID: 15346879 DOI: 10.2209/tdcpublication.45.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Heat-shock protein 90 (HSP90) is known to affect a variety of cellular activities. The present study showed that the HSP90-binding agents, geldanamycin, herbimycin A and radicicol, inhibited the murine thymocyte apoptosis induced by dexamethasone and was accompanied by the inhibition of the reduction of the mitochondrial transmembrane potential (delta psi m). HSP90-binding agents did not inhibit etoposide-induced apoptosis. The inhibition of dexamethasone-induced apoptosis was in part due to the interference of HSP90 with the glucocorticoid receptor, resulting in the inhibition of nuclear translocation of the receptor. The expression of inositol 1,4,5-triphosphate receptors, which were shown to be involved in dexamethasone-induced apoptosis, did not participate in the inhibition of apoptosis.
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Affiliation(s)
- Kazumasa Ohta
- Department of Biochemistry, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan
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22
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Tome ME, Lutz NW, Briehl MM. Overexpression of catalase or Bcl-2 delays or prevents alterations in phospholipid metabolism during glucocorticoid-induced apoptosis in WEHI7.2 cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2003; 1642:149-62. [PMID: 14572898 DOI: 10.1016/j.bbamcr.2003.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Dexamethasone-treated WEHI7.2 mouse thymoma cells readily undergo apoptosis. WEHI7.2 variants that overexpress catalase (CAT38) or Bcl-2 (Hb12) show a delay or lack of apoptosis, respectively, when treated with dexamethasone. This is accompanied by a delay or lack of cytochrome c release from the mitochondria suggesting that alterations in the signaling phase of apoptosis are responsible for the observed resistance. Because membranes are a rich source of signaling molecules, we have used 31P NMR spectroscopy to compare phospholipids and their metabolites in WEHI7.2, CAT38 and Hb12 cells after dexamethasone treatment. Increased lysophosphatidylcholine (lysoPtdC) content accompanied phosphatidylserine (PtdS) externalization in the WEHI7.2 cells. Both changes were delayed in CAT38 cells suggesting phosphatidylcholine (PtdC) metabolites may play a role in steroid-induced apoptotic signaling. The steroid-resistant Hb12 cells showed a dramatic increase in glycerophosphocholine (GPC) content, suggesting increased phospholipid turnover may contribute to the anti-apoptotic mechanism of Bcl-2.
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Affiliation(s)
- Margaret E Tome
- Department of Pathology, University of Arizona, PO Box 254043, Tucson, AZ 85724, USA
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23
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Gametchu B, Watson CS. Correlation of membrane glucocorticoid receptor levels with glucocorticoid-induced apoptotic competence using mutant leukemic and lymphoma cells lines. J Cell Biochem 2003; 87:133-46. [PMID: 12244567 DOI: 10.1002/jcb.10288] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We have studied the presence and functional implications of membrane glucocorticoid receptor (mGR) in several wild type (WT) and mutant mouse lymphoid cell lines (nuclear transfer decrease, NT(-); nuclear transfer increase, NT(i); and receptorless, R(-)). Direct fluorescent antibody staining revealed large aggregates of mGR-specific fluorescing antigens in the plasma membrane of the WT and mGR-enriched (mGR(++)) S-49 cells. While R(-) cells totally lacked mGR, this receptor level was low in NT(-) and NT(i) groups. FACS analysis corroborated these results, showing a approximately 4-10-fold difference between the highest mGR levels (mGR(++)) and the R(-) and NT(i) cells. Membrane extracts were analyzed for mGR by immunoblotting. Multiple receptor forms, ranging in M(r) from 94,000 to > 200,000, were observed in the WT cells, while only smaller peptides (85,000-94,000) were found in NT(-) cells. No detectable immunoreactive bands were identified in either membrane or cytosol immunoprecipitates of NT(i) and R(-) cell groups. Within 48 h post dexamethasone exposure > 98% of WT and mGR(++) S-49 cells underwent apoptosis, compared to 0-30% in the mutant cells, albeit the total receptor number is two to three times higher in NT(i) compared to WT. These results suggest a better correlation between the quantity and quality of mGRs (rather than total cellular GRs) and the ability of glucocorticoids (GCs) to lyse lymphoid cells.
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Affiliation(s)
- Bahiru Gametchu
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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24
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Meintières S, Nesslany F, Pallardy M, Marzin D. Detection of ghost cells in the standard alkaline comet assay is not a good measure of apoptosis. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2003; 41:260-269. [PMID: 12717781 DOI: 10.1002/em.10156] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The single cell gel electrophoresis assay, or Comet assay, is a powerful tool for measurement of DNA strands breaks, oxidative damage, and alkali labile sites, and the assay was recently modified to detect DNA cross-links. It has also been proposed as a measure of apoptosis since apoptotic cells are suspected to result in total migration of the DNA from the nucleus into the tail. Cells with this appearance are called ghost cells, clouds, hedgehogs, or NDCN (nondetectable cell nuclei). The aim of this study was to determine if ghost cells can be used to measure apoptosis in the standard alkaline comet assay. To answer this question, we made use of two cell lines: CTLL-2 cells that can enter apoptosis upon addition of apoptosis stimuli or IL-2 deprivation, and CTLL-2 bcl2 cells that are protected from apoptosis due to the overexpression of the apoptosis inhibitor gene bcl2. The two cell lines were treated with cytotoxins (nongenotoxic apoptosis inducers, nongenotoxic necrotic agents) or genotoxins. They were also subjected to growth factor withdrawal, which induced apoptosis in the CTLL-2 cell line. The level of apoptosis was measured by the Annexin V-FITC method in parallel with performing the Comet assay. The results obtained in the two cell lines suggest that apoptotic or necrotic death does not correlate well with the detection of ghost cells, presumably because these cells are lost upon electrophoresis. A variant of the alkaline Comet assay that was performed without electrophoresis (halo method) was able to efficiently detect cells undergoing apoptosis, but it was unable to clearly distinguish between apoptosis and genotoxic damage.
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Affiliation(s)
- Sophie Meintières
- Laboratoire de Toxicologie Génétique, Institut Pasteur de Lille, Lille, France
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25
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Planey SL, Derfoul A, Steplewski A, Robertson NM, Litwack G. Inhibition of glucocorticoid-induced apoptosis in 697 pre-B lymphocytes by the mineralocorticoid receptor N-terminal domain. J Biol Chem 2002; 277:42188-96. [PMID: 12194973 DOI: 10.1074/jbc.m205085200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The glucocorticoid and mineralocorticoid receptors (GR and MR) share considerable structural and functional homology and bind as homodimers to hormone-response elements. We have shown previously that MR and GR can form heterodimers that inhibit transcription from a glucocorticoid (GC)-responsive gene and that this inhibition was mediated by the N-terminal domain (NTD) of MR. In this report, we examined the effect of NTD-MR on GC-induced apoptosis in the GC-sensitive pre-B lymphoma cell line, 697. In GC-treated 697 cells, we demonstrated that stable expression of NTD-MR blocks apoptosis and inhibits proteolytic processing of pro-caspases-3, -8, and -9 and poly(ADP-ribose) polymerase. Importantly, gel shift and immunoprecipitation analyses revealed a direct association between the GR and amino acids 203-603 of NTD-MR. We observed down-regulation of c-Myc and of the anti-apoptotic proteins Bcl-2 and Bfl-1 as well as high levels of the pro-apoptotic proteins Bax and Bid. Conversely, cells stably expressing NTD-MR exhibited increased expression of Bcl-2 and Bfl-1 and diminished levels of Bid and Bax. These data provide a potential mechanism for the observed inhibition of cytochrome c and Smac release from the mitochondria of NTD-MR cells and resultant resistance to GC-induced apoptosis. Thus, NTD-MR may mediate GC effects through heterodimerization with GR and ensuing inhibition of GC-regulated gene transcription.
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Affiliation(s)
- Sonia L Planey
- Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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26
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Heeley RP, Rusconi SG, Sutcliffe RG, Kenyon CJ. Mutations flanking the polyglutamine repeat in the modulatory domain of rat glucocorticoid receptor lead to an increase in affinity for hormone. Endocr Res 2002; 28:217-29. [PMID: 12489571 DOI: 10.1081/erc-120015060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A polyglutamine repeat in the N-terminus of the rat glucocorticoid receptor shows polymorphism, with variants of Q2RQ5, Q2RQ15-21. We investigated whether these natural polymorphisms affect receptor function, and whether alleles with polyglutamine repeats shorter than Q2RQ5, between Q2RQ6-14, or longer than Q2RQ21 are not found naturally because they encode a dysfunctional receptor. Ligand binding and transactivation properties of sets of natural (Q2RQ5-Q2RQ21) and artificial (Q4-Q80) alleles were compared following expression in CV-1 cells. The sequence of artificial alleles at sites flanking the repeat region was altered slightly to facilitate cloning. Western blotting showed that all constructs expressed GR protein in CV-1 cells. When co-expressed with an MMTV-lacZ reporter plasmid, all GR proteins were shown to be transcriptionally active in the presence of hormone. Scatchard analysis of ligand binding curves showed that affinities for dexamethasone and corticosterone were not affected by variation in the polyglutamine repeat either the natural or artificial sets of alleles. However, affinities were greater for the artificial compared with the natural alleles (2-3-fold for dexametasone, p < 0.001; and 4-fold for corticosterone,p < 0.001). These differences provide evidence of a direct or indirect interaction within GR between the ligand binding domain and residues flanking the polyglutamine repeat of the N-terminal domain.
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Affiliation(s)
- Robert P Heeley
- Molecular Medicine Centre, University of Edinburgh, Edinburgh, EH4 2XU, UK
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27
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Baehrecke EH. Steroid regulation of programmed cell death during Drosophila development. Cell Death Differ 2000; 7:1057-62. [PMID: 11139278 DOI: 10.1038/sj.cdd.4400753] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Steroid hormones play an important role in the regulation of numerous physiological responses, but the mechanisms that enable these systemic signals to trigger specific cell changes remain poorly characterized. Recent studies of Drosophila illustrate several important features of steroid-regulated programmed cell death. A single steroid hormone activates both cell differentiation and cell death in different tissues and at multiple stages during development. While several steroid-regulated genes are required for cell execution, most of these genes function in both cell differentiation and cell death, and require more specific factors to kill cells. Genes that regulate apoptosis during Drosophila embryogenesis are induced by steroids in dying cells later in development. These apoptosis genes likely function downstream of hormone-induced factors to serve a more direct role in the death response. This article reviews the current knowledge of steroid signaling and the regulation of programmed cell death during development of Drosophila.
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Affiliation(s)
- E H Baehrecke
- Center for Agricultural Biotechnology, University of Maryland Biotechnology Institute, College Park, Maryland, MD 20742, USA.
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28
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Farkas R, Mechler BM. The timing of drosophila salivary gland apoptosis displays an l(2)gl-dose response. Cell Death Differ 2000; 7:89-101. [PMID: 10713724 DOI: 10.1038/sj.cdd.4400621] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
During Drosophila metamorphosis, larval tissues, such as the salivary glands, are histolysed whereas imaginal tissues differentiate into adult structures forming at eclosion a fly-shaped adult. Inactivation of the lethal(2)giant larvae (l(2)gl) gene encoding the cytoskeletal associated p127 protein, causes malignant transformation of brain neuroblasts and imaginal disc cells with developmental arrest at the larval-pupal transition phase. At this stage, p127 is expressed in wild-type salivary glands which become fully histolysed 12 - 13 h after pupariation. By contrast to wild-type, administration of 20-hydroxyecdsone to l(2)gl-deficient salivary glands is unable to induce histolysis, although it releases stored glue granules and gives rise to a nearly normal pupariation chromosome puffing, indicating that p127 is required for salivary gland apoptosis. To unravel the l(2)gl function in this tissue we used transgenic lines expressing reduced ( approximately 0.1) or increased levels of p127 (3.0). Here we show that the timing of salivary gland histolysis displays an l(2)gl-dose response. Reduced p127 expression delays histolysis whereas overexpression accelerates this process without affecting the duration of third larval instar, prepupal and pupal development. Similar l(2)gl-dependence is noticed in the timing of expression of the cell death genes reaper, head involution defective and grim, supporting the idea that p127 plays a critical role in the implementation of ecdysone-triggered apoptosis. These experiments show also that the timing of salivary gland apoptosis can be manipulated without affecting normal development and provide ways to investigate the nature of the components specifically involved in the apoptotic pathway of the salivary glands.
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Affiliation(s)
- R Farkas
- Department of Developmental Genetics, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
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29
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Yagi J, Dianzani U, Kato H, Okamoto T, Katsurada T, Buonfiglio D, Miyoshi-Akiyama T, Uchiyama T. Identification of a New Type of Invariant Vα14+ T Cells and Responsiveness to a Superantigen, Yersinia pseudotuberculosis- Derived Mitogen. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.6.3083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
We examined the expression of the H4 T cell activation marker in thymic T cell subpopulations and found that TCR-αβ+ CD4+ thymic T cells are segregated into three subpopulations based upon H4 levels. Thymic T cells with either no or low H4 expression differentiate via the mainstream differentiation pathway in the thymus. H4int thymic T cells, which express a skewed Vβ repertoire of Vβ2, -7, and -8 in their TCRs, show the phenotype of NKT cells: CD44high, Ly6Chigh, NK1.1+, and TCR-αβlow. H4high thymic T cells also show a skewed Vβ repertoire, Vβ2, -7, and -8, and predominantly express an invariant Vα14-Jα281+ α-chain in their TCRs but constitute a distinct population in that they are CD44int, Ly6C−, NK1.1−, and TCR-αβhigh. Thus, invariant Vα14+ thymic T cells consist of ordinary NKT cells and a new type of T cell population. Vβ7+ and Vβ8.1+ invariant Vα14+ thymic T cells are present in DBA/2 mice, which carry mammary tumor virus-7-encoded superantigens, in comparable levels to those in BALB/c mice. Furthermore, Vβ7+ invariant Vα14+ thymic T cells in DBA/2 mice are in the immunologically responsive state, and Yersinia pseudotuberculosis-derived mitogen-induced Vβ7+ invariant Vα14+ thymic T cell blasts from DBA/2 and BALB/c mice exhibited equally enhanced responses upon restimulation with Y. pseudotuberculosis-derived mitogen. Thus, invariant Vα14+ thymic T cells that escape negative selection in DBA/2 mice contain T cells as functionally mature as those in BALB/c mice.
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Affiliation(s)
| | - Umberto Dianzani
- § Laboratory of Immunology, Department of Medical Science, A. Avogadro University of Eastern Piedmont, Novara, Italy
| | | | | | | | - Donatella Buonfiglio
- § Laboratory of Immunology, Department of Medical Science, A. Avogadro University of Eastern Piedmont, Novara, Italy
| | | | - Takehiko Uchiyama
- *Microbiology and Immunology and
- ‡ Institute of Laboratory Animals, Tokyo Women’s Medical University, Tokyo, Japan; and
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30
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Andréau K, Lemaire C, Souvannavong V, Adam A. Induction of apoptosis by dexamethasone in the B cell lineage. IMMUNOPHARMACOLOGY 1998; 40:67-76. [PMID: 9776480 DOI: 10.1016/s0162-3109(98)00034-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The susceptibility to induction of apoptosis by the synthetic glucocorticoid, dexamethasone (Dex), was analysed at different stages of B cell maturation. Cells of the 70Z/3 pre-B cell line, expressing cytoplasmic mu chains, and LPS-stimulated 70Z/3 cells, expressing surface IgM, were used as a model of differentiation of pre-B cells into immature B cells. Cell proliferation and cell cycle progression were similarly inhibited by Dex (100 nM) in both naive 70Z/3 pre-B cells and in LPS-stimulated 70Z/3 cells. In contrast, Dex failed to affect apoptosis of naive 70Z/3 cells while it increased that of LPS-stimulated 70Z/3 cells. Splenic mature B lymphocytes were highly susceptible to Dex-induced apoptosis since subphysiological doses (5 nM) increased the frequency of apoptotic cells to more than 80%. On the other hand, the treatment of B lymphocytes with LPS, which led to proliferation and differentiation into immunoblasts, decreased the susceptibility to Dex-induced apoptosis. These effects were mediated by the glucocorticoid receptor since they were abrogated by the RU 486 antagonist. The response of B cells to glucocorticoids is thus dependent on their stage of differentiation.
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Affiliation(s)
- K Andréau
- Institut de Biochimie, CNRS ERS 0571, Université Paris-Sud, Orsay, France.
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31
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McColl KS, He H, Zhong H, Whitacre CM, Berger NA, Distelhorst CW. Apoptosis induction by the glucocorticoid hormone dexamethasone and the calcium-ATPase inhibitor thapsigargin involves Bc1-2 regulated caspase activation. Mol Cell Endocrinol 1998; 139:229-38. [PMID: 9705090 DOI: 10.1016/s0303-7207(98)00051-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The requirement for caspases (ICE-like proteases) were investigated in mediating apoptosis of WEHI7.2 mouse lymphoma cells in response to two death inducers with different mechanisms of action, the glucocorticoid hormone dexamethasone (DX) and the calcium-ATPase inhibitor thapsigargin (TG). Apoptosis induction by these agents followed different kinetics, and was closely correlated with in vivo activation of caspase-3 (CPP32/Yama/Apopain) and cleavage of the caspase target protein poly(ADP-ribose) polymerase (PARP). Caspase activation and PARP cleavage were inhibited by Bcl-2 overexpression. Cell extracts from DX- and TG-treated cells cleaved the in vitro synthesized baculovirus p35 ICE-like protease target, producing 25 and 10 kDa fragments. p35 cleavage was inhibited by mutating the active site aspartic acid to alanine, and by a panel of protease inhibitors that inhibit caspase-3-like proteases, including iodoacetamide, N-ethylmaleimide, and Ac-DEVD-cho. Treatment of cells in vivo with two cell permeant peptide fluoromethylketone inhibitors of caspase activity, Z-VAD-fmk and Z-DEVD-fmk, inhibited DX- and TG-induced apoptotic nuclear changes and maintained plasma membrane integrity, whereas the cathepsin inhibitor, Z-FA-fmk, and two calpain inhibitors failed to inhibit apoptosis. An unexpected observation was that due to the delayed time course of DX-induced apoptosis, optimal preservation of plasma membrane integrity was achieved by adding caspase inhibitors beginning 8 h after DX addition. In summary, the findings indicate that two diverse apoptosis-inducing signals converge into a common Bcl-2-regulated pathway that leads to caspase activation and apoptosis.
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Affiliation(s)
- K S McColl
- Department of Medicine, Case Western Reserve University/Ireland Cancer Center, Cleveland, OH 44106-4937, USA
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32
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Role of Calcium in Glucocorticosteroid-Induced Apoptosis of Thymocytes and Lymphoma Cells: Resurrection of Old Theories by New Findings. Blood 1998. [DOI: 10.1182/blood.v91.3.731] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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33
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Role of Calcium in Glucocorticosteroid-Induced Apoptosis of Thymocytes and Lymphoma Cells: Resurrection of Old Theories by New Findings. Blood 1998. [DOI: 10.1182/blood.v91.3.731.731_731_734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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34
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Jiang C, Baehrecke EH, Thummel CS. Steroid regulated programmed cell death during Drosophila metamorphosis. Development 1997; 124:4673-83. [PMID: 9409683 DOI: 10.1242/dev.124.22.4673] [Citation(s) in RCA: 283] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During insect metamorphosis, pulses of the steroid hormone 20-hydroxyecdysone (ecdysone) direct the destruction of obsolete larval tissues and their replacement by tissues and structures that form the adult fly. We show here that larval midgut and salivary gland histolysis are stage-specific steroid-triggered programmed cell death responses. Dying larval midgut and salivary gland cell nuclei become permeable to the vital dye acridine orange and their DNA undergoes fragmentation, indicative of apoptosis. Furthermore, the histolysis of these tissues can be inhibited by ectopic expression of the baculovirus anti-apoptotic protein p35, implicating a role for caspases in the death response. Coordinate stage-specific induction of the Drosophila death genes reaper (rpr) and head involution defective (hid) immediately precedes the destruction of the larval midgut and salivary gland. In addition, the diap2 anti-cell death gene is repressed in larval salivary glands as rpr and hid are induced, suggesting that the death of this tissue is under both positive and negative regulation. Finally, diap2 is repressed by ecdysone in cultured salivary glands under the same conditions that induce rpr expression and trigger programmed cell death. These studies indicate that ecdysone directs the death of larval tissues via the precise stage- and tissue-specific regulation of key death effector genes.
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Affiliation(s)
- C Jiang
- Howard Hughes Medical Institute, Department of Human Genetics, University of Utah, Salt Lake City 84112, USA
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35
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Werman A, Hollenberg A, Solanes G, Bjorbaek C, Vidal-Puig AJ, Flier JS. Ligand-independent activation domain in the N terminus of peroxisome proliferator-activated receptor gamma (PPARgamma). Differential activity of PPARgamma1 and -2 isoforms and influence of insulin. J Biol Chem 1997; 272:20230-5. [PMID: 9242701 DOI: 10.1074/jbc.272.32.20230] [Citation(s) in RCA: 214] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear hormone receptor superfamily, and is an important regulator of adipogenesis and adipocyte gene expression. PPARgamma exists as two isoforms, PPARgamma1 and PPARgamma2, that differ only in their N termini. Both isoforms are activated by ligands that include the antidiabetic thiazoladinedione drugs and 15-deoxy-Delta12, 14-prostaglandin J2, and potential differences in their function have yet to be described. We report that, in addition to a ligand-activated transcriptional activity, when studied under conditions of ligand depletion, intact PPARgamma has a ligand-independent activation domain. To identify the basis for this ligand-independent activation, we used GAL4-PPARgamma chimeric expression constructs and UAS-TK-LUC in CV1 cells and isolated rat adipocytes. In both cell systems, isolated PPARgamma1 and PPARgamma2 N termini have activation domains, and the activation function of PPARgamma2 is 5-6-fold greater than that of PPARgamma1. Insulin enhances the transcriptional effect mediated by both PPARgamma1 and PPARgamma2 N-terminal domains. These data demonstrate that 1) PPARgamma has an N-terminal (ligand-independent) activation domain; 2) PPARgamma1 and PPARgamma2 N termini have distinct activation capacities; and 3) insulin can potentiate the activity of the N-terminal domain of PPARgamma.
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Affiliation(s)
- A Werman
- Department of Medicine, Division of Endocrinology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA
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36
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Affiliation(s)
- C W Distelhorst
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4937, USA
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Perrin-Wolff M, Mishal Z, Bertoglio J, Pallardy M. Position 16 of the steroid nucleus modulates glucocorticoid-induced apoptosis at the transcriptional level in murine T-lymphocytes. Biochem Pharmacol 1996; 52:1469-76. [PMID: 8937459 DOI: 10.1016/s0006-2952(96)00385-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Synthetic glucocorticoids (GCs), which possess a different radical substituted in position 16 of the steroid nucleus structure, display various antiproliferative activities on activated lymphoid cells. We analysed this structure-function relationship between dexamethasone (DEX; methyl group in position 16 alpha) and beta-methasone (BM; methyl group in position 16 beta) with regard to two important aspects of GC activity, namely the activation of transcription and induction of apoptosis in IL-2-dependent murine lymphoid cells. DEX induced a higher percentage of apoptotic viable cells compared to BM. This structure-activity relationship was not related to differences in cytosolic glucocorticoid receptor (GR) affinity or kinetics of apoptosis. However, DEX was more efficient than BM in inducing transcriptional activation of an MMTV-CAT plasmid in transiently transfected CTLL-2 cells. In addition, DEX was more potent in inhibiting AP-1 DNA-binding activity compared to BM. These results suggest that the configuration in position 16 may influence the potency of GCs to induce apoptosis in lymphoid cells, mainly by modulating GR-induced transcription.
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Affiliation(s)
- M Perrin-Wolff
- Immunotoxicologie et Cancérogènese, CJF INSERM 93-01 Faculté de Pharmacie Paris-Sud, Châtenay-Malabry, France
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Chamberlain NL, Whitacre DC, Miesfeld RL. Delineation of two distinct type 1 activation functions in the androgen receptor amino-terminal domain. J Biol Chem 1996; 271:26772-8. [PMID: 8900157 DOI: 10.1074/jbc.271.43.26772] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Based on the finding that some transcription factors contain multiple transcriptional regulatory activities, we constructed a panel of rat androgen receptor (AR) mutants containing small internal deletions and point mutations within the amino-terminal region of the receptor. Trans-activation assays in CV-1 cells using AR-responsive reporter genes were performed and led to the identification of two noncontiguous trans-activation regions in the AR amino terminus. One of these regions, termed activator function 1a (AF-1a) is a highly-conserved 14-amino acid segment that is predicted to form a beta-turn followed by an acidic amphipathic alpha-helix. Point mutagenesis within AF-1a revealed that two adjacent hydrophobic residues were required for full AR trans-activation function, as arginine substitutions resulted in a 60% reduction in transcriptional activity. A second amino-terminal region was also identified and has been designated AF-1b. Deletion of the 65-amino acid AF-1b segment, which contains numerous glutamate and aspartate residues, caused a 55% decrease in trans-activation function. An AF-1a/AF-1b double mutant retains less than 10% trans-activation function compared with wild-type AR, suggesting that AF-1a and AF-1b may each contribute separately to maximal AR activity. To determine whether AF-1a and AF-1b play a role in AR-mediated trans-repression of AP-1 function, we tested single and double AF-1a/AF-1b mutants in a transient trans-repression assay. Our results showed that neither AF-1a nor AF-1b was required for AP-1 trans-repression, demonstrating that AR-mediated trans-repression and trans-activation are discrete functions.
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Affiliation(s)
- N L Chamberlain
- Department of Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
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Rasmuson-Lestander A, Ekström K. Genetic and molecular analysis of a set of unstable white mutants in Drosophila melanogaster. Genetica 1996; 98:179-92. [PMID: 8976064 DOI: 10.1007/bf00121365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Two related unstable mutants at the white locus of Drosophila melanogaster show different interactions with the zeste1 mutant: one mutated white gene becomes repressed in males, whereas the other is unaffected by z1. By use of Southern blot techniques and by constructing genomic lambda-libraries, molecular analyses of the white regions of these two strains were performed. The results showed a single difference at a site 2.5 kb (kilobases) downstream of the white transcription unit. In both strains, FB (foldback) elements were integrated at this site, but the repressed strain also harboured a 4 kb NOF (Nofretete) element. No other restriction site polymorphisms between the two strains were observed within a 120 kb region surrounding the white gene. The extent of twelve white deletions and twelve white transpositions deriving from these unstable strains was analysed by in situ hybridisation and Southern blot techniques. The results revealed that the distal breakpoint of all aberrations coincided with the insertion site of the mobile elements, but that the centromere proximal breakpoints varied. The mechanisms for the instability and the interaction with the zeste1 mutant are discussed.
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40
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Abstract
Since mammalian cardiac myocytes essentially rely on aerobic energy metabolism, it has been assumed that cardiocytes die in a catastrophic breakdown of cellular homeostasis (i.e. necrosis), if oxygen supply remains below a critical limit. Recent observations, however, indicate that a process of gene-directed cellular suicide (i.e. apoptosis) is activated in terminally differentiated cardiocytes of the adult mammalian heart by ischemia and reperfusion, and by cardiac overload as well. Apoptosis or programmed cell death is an actively regulated process of cellular self destruction, which requires energy and de novo gene expression, and which is directed by an inborn genetic program. The final result of this program is the fragmentation of nuclear DNA into typical 'nucleosomal ladders', while the functional integrity of the cell membrane and of other cellular organelles is still maintained. The critical step in this regulated apoptotic DNA fragmentation is the proteolytic inactivation of poly-[ADP-ribose]-polymerase (PARP) by a group of cysteine proteases with some structural homologies to interleukin-1 beta-converting enzyme (ICE-related proteases [IRPs] such as apopain, yama and others). PARP catalyzes the ADP-ribosylation of nuclear proteins at the sites of spontaneous DNA strand breaks and thereby facilitates the repair of this DNA damage. IRP-mediated destruction of PARP, the 'supervisor of the genome', can be induced by activation of membrane receptors (e.g. FAS or APOI) and other signals, and is inhibited by activation of 'anti-death genes' (e.g. bcl-2). Overload-triggered myocyte apoptosis appears to contribute to the transition to cardiac failure, which can be prevented by therapeutic hemodynamic unloading. In myocardial ischemia, the activation of the apoptotic program in cardiocytes does not exclude their final destiny to catastrophic necrosis with release of cytosolic enzymes, but might be considered as an adaptive process in hypoperfused ventricular zones, sacrificing some jeopardized myocytes to regulated apoptosis, which may be less arrhythmogenic than necrosis with the primary disturbance of membrane function.
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Affiliation(s)
- H J Brömme
- Institute of Pathophysiology, Martin Luther University Halle-Wittenberg, Germany
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Ashwell JD, King LB, Vacchio MS. Cross-talk between the T cell antigen receptor and the glucocorticoid receptor regulates thymocyte development. Stem Cells 1996; 14:490-500. [PMID: 8888490 DOI: 10.1002/stem.140490] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The fate of an immature thymocyte, life or death, is largely determined by the ligand-specificity of its T cell antigen receptor (TCR). The default pathway for thymocytes bearing TCRs with subthreshold avidity for self-antigens is death (death by neglect). Thymocytes bearing TCRs with high avidity for self also undergo apoptosis (negative selection). Those thymocytes with intermediate avidities, or that perhaps recognize self-peptides that have partial agonist or antagonist properties, survive and differentiate into mature immunocompetent T cells (positive selection). How TCR avidity is interpreted as a "rescue" signal or a death signal is unknown. Based upon a T cell hybridoma model, our laboratory proposed that glucocorticoids, which themselves are potent inducers of thymocyte apoptosis, antagonize TCR-mediated thymocyte deletion and allow positive selection to occur. In fact, epithelial cells in the thymus proved to be a source of steroid production, and interference with steroid synthesis in fetal thymic organ culture resulted in a greatly enhanced sensitivity of thymocytes to TCR-mediated apoptosis. Transgenic mice with reduced glucocorticoid receptor (GR) levels were produced by tissue-specific expression of GR antisense. Thymocytes in these mice had high levels of spontaneous apoptosis, and were exquisitely sensitive to deletion induced by cross-linking the TCR. Moreover, there was a very large (> or = 90%) loss of CD4+CD8+ thymocytes, signifying a block at the CD4-CD8- to CD4+CD8+ transition, perhaps due to apoptosis of cells upon engagement of the pre-TCR in the absence of an antagonizing glucocorticoid stimulus. The molecular mechanism of the antagonism is currently being investigated. These data indicate that there is cross-talk in thymocytes between the TCR and glucocorticoid signaling pathways resulting in apoptosis, and that locally produced steroids, in a paracrine fashion, participate in setting the TCR avidity thresholds that determine whether developing thymocytes survive or die, and therefore help to mold the antigen-specific T cell repertoire.
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Affiliation(s)
- J D Ashwell
- Laboratory of Immune Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20852, USA
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42
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Grimm LM, Goldberg AL, Poirier GG, Schwartz LM, Osborne BA. Proteasomes play an essential role in thymocyte apoptosis. EMBO J 1996; 15:3835-44. [PMID: 8670888 PMCID: PMC452071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cell death in many different organisms requires the activation of proteolytic cascades involving cytosolic proteases. Here we describe a novel requirement in thymocyte cell death for the 20S proteasome, a highly conserved multicatalytic protease found in all eukaryotes. Specific inhibitors of proteasome function blocked cell death induced by ionizing radiation, glucocorticoids or phorbol ester. In addition to inhibiting apoptosis, these signals prevented the cleavage of poly(ADP-ribose) polymerase that accompanies many cell deaths. Since overall rates of protein degradation were not altered significantly during cell death in thymocytes, these results suggest that the proteasome may either degrade regulatory protein(s) that normally inhibit the apoptotic pathway or may proteolytically activate protein(s) than promote cell death.
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Affiliation(s)
- L M Grimm
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA
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43
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Abstract
The regulation of cell proliferation and the selection against autoreactive cells in the lymphoid system both occur through the induction of apoptosis. Many of the signals that induce apoptosis in lymphocytes are now well defined. Interactions between Fas and its ligand have emerged as a major mechanism for the deletion of activated peripheral T cells and autoreactive B cells. Although the signal-transduction pathway leading from engagement of Fas to apoptosis is not entirely clear, significant advances have been made recently. There has also been progress in the elucidation of the mechanisms that regulate apoptosis in the immune system.
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Affiliation(s)
- B A Osborne
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst 01003, USA.
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King LB, Vacchio MS, Dixon K, Hunziker R, Margulies DH, Ashwell JD. A targeted glucocorticoid receptor antisense transgene increases thymocyte apoptosis and alters thymocyte development. Immunity 1995; 3:647-56. [PMID: 7584154 DOI: 10.1016/1074-7613(95)90135-3] [Citation(s) in RCA: 135] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The exquisite sensitivity of thymocytes to steroid-induced apoptosis, the steroidogenic potential of thymic epithelial cells, and the ability of steroid synthesis inhibitors to enhance antigen-specific deletion of thymocytes in fetal thymic organ cultures suggest a role for glucocorticoids in thymocyte development. To address this further, transgenic mice that express antisense transcripts to the glucocorticoid receptor (GR) specifically in immature thymocytes were generated. The consequent hyporesponsiveness of thymocytes to glucocorticoids was accompanied by a reduction in thymic size, primarily owing to a decrease in the number of CD4+CD8+ cells. While an enhanced susceptibility to T cell receptor (TCR)-mediated apoptosis appeared to be partially responsible for this reduction, thymocyte loss could also be detected before thymocytes progressed to the CD4+CD8+ TCR alpha beta-expressing stage. These results suggest that glucocorticoids are necessary for survival and maturation of thymocytes, and are consistent with a role for steroids in both the transition from CD4-CD8- to CD4+CD8+ cells and the survival of CD4+CD8+ cells stimulated via the TCR.
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Affiliation(s)
- L B King
- Laboratory of Immune Cell Biology, National Cancer Institute, National Institutes of Health Bethesda, Maryland 20892, USA
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45
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Abstract
Steroid hormones play major roles in regulation in growth, development, homeostasis, and cell death. Together with other hormones and growth factors, steroids regulate both the function and cellular composition of organs throughout the body. In this article we will discuss the mechanisms of steroid hormone regulated apoptosis. Emphasis will be placed on the effect of glucocorticoids on lymphoid cells.
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Affiliation(s)
- R B Evans-Storms
- National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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46
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47
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Rundlett SE, Miesfeld RL. Quantitative differences in androgen and glucocorticoid receptor DNA binding properties contribute to receptor-selective transcriptional regulation. Mol Cell Endocrinol 1995; 109:1-10. [PMID: 7789609 DOI: 10.1016/0303-7207(95)03477-o] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Androgen receptor (AR) and glucocorticoid receptor (GR) belong to the same subfamily of steroid/nuclear receptors and have been shown to bind qualitatively to the same hormone response element (HRE) DNA sequences. Despite this similarity in target gene recognition, AR and GR have differential affects on the transcriptional regulation of genes containing both simple and complex HRE control regions. Using HREs from the mouse mammary tumor virus (MMTV), tyrosine aminotransferase (TAT), prostatein (C3) or sex-limited protein (SLP) genes, linked to the thymidine kinase promoter, we found receptor-selective differences in the ability of rat AR and rat GR to induce transcription of these various reporter genes. Since AR and GR have a 20% amino acid sequence difference in their DNA binding domains (DBDs), which could result in altered DNA binding affinities, we measured the ability of purified AR and GR DBDs to bind selectively and with high affinity to these HRE sequences in vitro. Gel shift mobility assays showed that the GR DBD had a higher affinity for a consensus HRE than did the AR DBD, and quantitative DNase I footprinting revealed that AR and GR DBDs bound to the MMTV, TAT, C3 and SLP HREs with different affinities. It was found that AR had a dissociation constant (Kd) that was 2-3 times higher than GR on the TAT, C3 and SLP HREs and that the Kd of AR for the C3 and SLP HREs differed by an order of magnitude (43 nM and 460 nM, respectively). Taken together, these data suggest that amino acid differences in the AR and GR DBDs contribute to altered receptor-DNA interactions, however it is likely that non-receptor factors are involved in further modulating receptor-selective DNA binding and transactivation functions.
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Affiliation(s)
- S E Rundlett
- Department of Molecular and Cellular Biology, University of Arizona, Tucson 85721, USA
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Chapman MS, Qu N, Pascoe S, Chen WX, Apostol C, Gordon D, Miesfeld RL. Isolation of differentially expressed sequence tags from steroid-responsive cells using mRNA differential display. Mol Cell Endocrinol 1995; 108:R1-7. [PMID: 7758820 DOI: 10.1016/0303-7207(95)03481-l] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Transcriptional control of steroid-regulated gene networks by nuclear receptor proteins results in the coordinate expression of a limited number of target genes. Although much is known about the structure and function of steroid receptors, relatively few cell-specific steroid-regulated genes have been isolated and characterized. In this paper we describe results using mRNA differential display reverse transcriptase PCR (DDPCR) to identify and isolate short cDNA sequence tags from thymocyte and prostate cells under various hormone conditions. Using this technique we have isolated several differentially expressed sequence tags (DESTs) from the mouse thymocyte cell line WEHI 7.2. Two of these DESTs, GIG10 and GIG18, are rapidly induced by dexamethasone within 2 h of treatment. GIG10 is a novel sequence and GIG18 is the mouse homologue of a human expressed sequence tag isolated from activated B lymphocytes. We also used DDPCR to isolate DESTs from androgen-modulated rat ventral prostate tissue, one of which we characterized and found to correspond to the 3' end of prostatic spermine binding protein mRNA, a known androgen-regulated gene. Modifications of the original DDPCR protocol, which we found can potentially decrease the frequency of isolating false-positive DESTs, are described and the merits of DDPCR, relative to other differential cDNA cloning strategies, are discussed.
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Affiliation(s)
- M S Chapman
- Department of Biochemistry, University of Arizona, Tucson 85724, USA
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49
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Coucouvanis EC, Martin GR, Nadeau JH. Genetic approaches for studying programmed cell death during development of the laboratory mouse. Methods Cell Biol 1995; 46:387-440. [PMID: 7609658 DOI: 10.1016/s0091-679x(08)61937-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- E C Coucouvanis
- Department of Anatomy, University of California at San Francisco 94143, USA
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50
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Cole TJ, Blendy JA, Monaghan AP, Schmid W, Aguzzi A, Schütz G. Molecular genetic analysis of glucocorticoid signaling during mouse development. Steroids 1995; 60:93-6. [PMID: 7792824 DOI: 10.1016/0039-128x(94)00009-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Glucocorticoids are important in a number of developmental processes in mammals around birth. The pathway of gluconeogenesis is activated in liver shortly after birth due to the combined effects of glucocorticoids and glucagon. We have defined the essential cis-regulatory elements directing hormone-dependent liver-specific expression of the gene for tyrosine aminotransferase, a key gluconeogenic enzyme. The hormone response elements synergize with cell-type specific elements. In the case of glucocorticoids, the glucocorticoid-dependent enhancer is composed of the glucocorticoid response element and binding sites for liver cell-enriched transcription factors, in particular hepatocyte nuclear factor-3. The dependence of the respective enhancer motifs on each other restricts the hormonal activation of the tyrosine aminotransferase gene in liver in response to a hormonal signal. To further understand the role of glucocorticoid signaling via the type II glucocorticoid receptor (GR) in the perinatal period and earlier during development, we have studied the expression of the mouse GR gene. Expression of the gene is controlled by at least three promoters, one of which is only active in T-lymphocytes. Expression of GR mRNA has been detected as early as day 9.5 of mouse development. To specifically address the role of glucocorticoid signaling via the GR during development, we have disrupted the GR gene by homologous recombination in mouse embryonic stem cells. The majority of GR mutants die shortly after birth and analysis so far has revealed defects in lung, liver, and adrenal function.
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Affiliation(s)
- T J Cole
- Division Molecular Biology of the Cell I, German Cancer Research Center, Heidelberg
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