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Janciauskiene S, Lechowicz U, Pelc M, Olejnicka B, Chorostowska-Wynimko J. Diagnostic and therapeutic value of human serpin family proteins. Biomed Pharmacother 2024; 175:116618. [PMID: 38678961 DOI: 10.1016/j.biopha.2024.116618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 04/15/2024] [Accepted: 04/17/2024] [Indexed: 05/01/2024] Open
Abstract
SERPIN (serine proteinase inhibitors) is an acronym for the superfamily of structurally similar proteins found in animals, plants, bacteria, viruses, and archaea. Over 1500 SERPINs are known in nature, while only 37 SERPINs are found in humans, which participate in inflammation, coagulation, angiogenesis, cell viability, and other pathophysiological processes. Both qualitative or quantitative deficiencies or overexpression and/or abnormal accumulation of SERPIN can lead to diseases commonly referred to as "serpinopathies". Hence, strategies involving SERPIN supplementation, elimination, or correction are utilized and/or under consideration. In this review, we discuss relationships between certain SERPINs and diseases as well as putative strategies for the clinical explorations of SERPINs.
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Affiliation(s)
- Sabina Janciauskiene
- Department of Pulmonary and Infectious Diseases and BREATH German Center for Lung Research (DZL), Hannover Medical School, Hannover, Germany; Department of Genetics and Clinical Immunology, National Institute of Tuberculosis and Lung Diseases, 26 Plocka St, Warsaw 01-138, Poland
| | - Urszula Lechowicz
- Department of Genetics and Clinical Immunology, National Institute of Tuberculosis and Lung Diseases, 26 Plocka St, Warsaw 01-138, Poland
| | - Magdalena Pelc
- Department of Genetics and Clinical Immunology, National Institute of Tuberculosis and Lung Diseases, 26 Plocka St, Warsaw 01-138, Poland
| | - Beata Olejnicka
- Department of Pulmonary and Infectious Diseases and BREATH German Center for Lung Research (DZL), Hannover Medical School, Hannover, Germany
| | - Joanna Chorostowska-Wynimko
- Department of Genetics and Clinical Immunology, National Institute of Tuberculosis and Lung Diseases, 26 Plocka St, Warsaw 01-138, Poland.
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2
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Du S, Trakooljul N, Palma-Vera SE, Murani E, Schuler G, Schoen J, Chen S. Regulation of Porcine Oviduct Epithelium Functions via Progesterone and Estradiol Is Influenced by Cortisol. Endocrinology 2022; 164:6767905. [PMID: 36269722 DOI: 10.1210/endocr/bqac176] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Indexed: 01/16/2023]
Abstract
Preimplantation maternal stress, characterized by elevated glucocorticoids (GCs), has been linked to reproductive failures caused by impaired oviduct functionality, which is known to be predominantly regulated by the sex steroids, progesterone (P4) and (17)estradiol (E2). Although steroid receptors share analogous structures and binding preferences, the interaction between GCs and E2/P4 in the oviduct has attracted little attention. Using an air-liquid interface culture model, porcine oviduct epithelial cells were stimulated with single (cortisol, E2, P4) or hormone mixtures (cortisol/E2, cortisol/P4) for 12 hours and 72 hours. Cultures were subsequently assessed for epithelial morphometry, bioelectrical properties, and gene expression responses (steroid hormone signaling, oviductal function, immune response, and apoptosis). Results confirmed the suppressive role of P4 in regulating oviduct epithelium characteristics, which was partially opposed by E2. Besides increasing the ratio of ciliated cells, cortisol antagonized the effect of P4 on epithelial polarity and modified sex steroid-induced changes in transepithelial electrical properties. Both sex steroids affected the glucocorticoid receptor expression, while cortisol downregulated the expression of progesterone receptor. The overall gene expression pattern suggests that sex steroid dominates the cotreatment, but cortisol contributes by altering the gene responses to sex steroids. We conclude that besides its individual action, maternal cortisol interplays with sex steroids at phenotypic and molecular levels in the oviduct epithelium, thereby influencing the microenvironment of gametes and early embryos.
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Affiliation(s)
- Shuaizhi Du
- Institute of Reproductive Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf 18196, Germany
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf 18196, Germany
- Department of Reproduction Biology, Leibniz-Institute for Zoo and Wildlife Research (IZW), Berlin 10315, Germany
| | - Nares Trakooljul
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf 18196, Germany
| | - Sergio E Palma-Vera
- Institute of Reproductive Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf 18196, Germany
- Department of Reproduction Biology, Leibniz-Institute for Zoo and Wildlife Research (IZW), Berlin 10315, Germany
| | - Eduard Murani
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf 18196, Germany
| | - Gerhard Schuler
- Veterinary Clinic for Obstetrics, Gynecology and Andrology, Faculty of Veterinary Medicine, Justus-Liebig-University, Giessen 35392, Germany
| | - Jennifer Schoen
- Institute of Reproductive Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf 18196, Germany
- Department of Reproduction Biology, Leibniz-Institute for Zoo and Wildlife Research (IZW), Berlin 10315, Germany
- Institute of Biotechnology, Technische Universität Berlin, Berlin 13355, Germany
| | - Shuai Chen
- Institute of Reproductive Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf 18196, Germany
- Department of Reproduction Biology, Leibniz-Institute for Zoo and Wildlife Research (IZW), Berlin 10315, Germany
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3
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Toews JNC, Philippe TJ, Hill LA, Dordevic M, Miguelez-Crespo A, Homer NZM, Nixon M, Hammond GL, Viau V. Corticosteroid-binding Globulin (SERPINA6) Establishes Postpubertal Sex Differences in Rat Adrenal Development. Endocrinology 2022; 163:6702154. [PMID: 36112420 DOI: 10.1210/endocr/bqac152] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Indexed: 12/24/2022]
Abstract
Encoded by SerpinA6, plasma corticosteroid-binding globulin (CBG) transports glucocorticoids and regulates their access to cells. We determined how CBG influences plasma corticosterone and adrenal development in rats during the pubertal to adult transition using CRISPR/cas9 to disrupt SerpinA6 gene expression. In the absence of CBG, total plasma corticosterone levels were ∼80% lower in adult rats of both sexes, with a greater absolute reduction in females than in males. Notably, free corticosterone and adrenocorticotropic hormone were comparable between all groups. Between 30 and 90 days of age, wild-type female rats showed increases in adrenal weight and the size of the corticosterone-producing region, the zona fasciculata (zf), in tandem with increases in plasma CBG and corticosterone concentrations, whereas no such changes were observed in males. This sex difference was lost in rats without CBG, such that adrenal growth and zf expansion were similar between sexes. The sex-specific effects of CBG on adrenal morphology were accompanied by remarkable changes in gene expression: ∼40% of the adrenal transcriptome was altered in females lacking CBG, whereas almost no effect was seen in males. Over half of the adrenal genes that normally exhibit sexually dimorphic expression after puberty were similarly expressed in males and females without CBG, including those responsible for cholesterol biosynthesis and mobilization, steroidogenesis, and growth. Rat adrenal SerpinA6 transcript levels were very low or undetectable. Thus, sex differences in adrenal growth, morphology and gene expression profiles that emerge during puberty in rats are dependent on concomitant increases in plasma CBG produced by the liver.
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Affiliation(s)
- Julia N C Toews
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Tristan J Philippe
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Lesley A Hill
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Matthew Dordevic
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Allende Miguelez-Crespo
- British Heart Foundation/University Centre for Cardiovascular Science, University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Natalie Z M Homer
- British Heart Foundation/University Centre for Cardiovascular Science, University of Edinburgh, Edinburgh EH16 4TJ, UK
- Mass Spectrometry Core, Edinburgh Clinical Research Facility, Queen's Medical Research Institute, Edinburgh, UK
| | - Mark Nixon
- British Heart Foundation/University Centre for Cardiovascular Science, University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Geoffrey L Hammond
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Victor Viau
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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4
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Jiang Z, Elsarrag SZ, Duan Q, LaGory EL, Wang Z, Alexanian M, McMahon S, Rulifson IC, Winchester S, Wang Y, Vaisse C, Brown JD, Quattrocelli M, Lin CY, Haldar SM. KLF15 cistromes reveal a hepatocyte pathway governing plasma corticosteroid transport and systemic inflammation. SCIENCE ADVANCES 2022; 8:eabj2917. [PMID: 35263131 PMCID: PMC8906731 DOI: 10.1126/sciadv.abj2917] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 01/13/2022] [Indexed: 05/15/2023]
Abstract
Circulating corticosteroids orchestrate stress adaptation, including inhibition of inflammation. While pathways governing corticosteroid biosynthesis and intracellular signaling are well understood, less is known about mechanisms controlling plasma corticosteroid transport. Here, we show that hepatocyte KLF15 (Kruppel-like factor 15) controls plasma corticosteroid transport and inflammatory responses through direct transcriptional activation of Serpina6, which encodes corticosteroid-binding globulin (CBG). Klf15-deficient mice have profoundly low CBG, reduced plasma corticosteroid binding capacity, and heightened mortality during inflammatory stress. These defects are completely rescued by reconstituting CBG, supporting that KLF15 works primarily through CBG to control plasma corticosterone homeostasis. To understand transcriptional mechanisms, we generated the first KLF15 cistromes using newly engineered Klf153xFLAG mice. Unexpectedly, liver KLF15 is predominantly promoter enriched, including Serpina6, where it binds a palindromic GC-rich motif, opens chromatin, and transactivates genes with minimal associated direct gene repression. Overall, we provide critical mechanistic insight into KLF15 function and identify a hepatocyte-intrinsic transcriptional module that potently regulates systemic corticosteroid transport and inflammation.
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Affiliation(s)
- Zhen Jiang
- Amgen Research, South San Francisco, CA 94080, USA
- Gladstone Institutes, San Francisco, CA 94158, USA
| | - Selma Z. Elsarrag
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Medical Scientist Training Program and Quantitative and Computational Biosciences Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA
| | - Qiming Duan
- Gladstone Institutes, San Francisco, CA 94158, USA
| | | | - Zhe Wang
- Amgen Research, South San Francisco, CA 94080, USA
| | | | - Sarah McMahon
- Gladstone Institutes, San Francisco, CA 94158, USA
- Biomedical Sciences Graduate Program, UCSF School of Medicine, San Francisco, CA 94143, USA
| | | | | | - Yi Wang
- UCSF Diabetes Center and Department of Medicine, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Christian Vaisse
- UCSF Diabetes Center and Department of Medicine, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Jonathan D. Brown
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Mattia Quattrocelli
- Molecular Cardiovascular Biology Division, Heart Institute, Cincinnati Children’s Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Charles Y. Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Kronos Bio Inc., Cambridge, MA 02142, USA
| | - Saptarsi M. Haldar
- Amgen Research, South San Francisco, CA 94080, USA
- Gladstone Institutes, San Francisco, CA 94158, USA
- Cardiology Division, Department of Medicine, UCSF School of Medicine, San Francisco, CA 94143, USA
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5
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Meyer EJ, Spangenberg L, Ramírez MJ, De Sousa SMC, Raggio V, Torpy DJ. CBG Montevideo: A Clinically Novel SERPINA6 Mutation Leading to Haploinsufficiency of Corticosteroid-binding Globulin. J Endocr Soc 2021; 5:bvab115. [PMID: 34308089 PMCID: PMC8294686 DOI: 10.1210/jendso/bvab115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Indexed: 11/22/2022] Open
Abstract
Corticosteroid-binding globulin (CBG) is the main transport protein for cortisol, binding up to 90% in a 1:1 ratio. CBG provides transport of cortisol within the circulation and targeted cortisol tissue delivery. Here, we describe the clinically novel “CBG Montevideo” a SERPINA6 pathogenic variant that results in a 50% reduction in plasma CBG levels. This was associated with low serum total cortisol and clinical features of hypoglycemia, exercise intolerance, chronic fatigue, and hypotension in the proband, a 7-year-old boy, and his affected mother. Previous reports of 9 human CBG genetic variants affecting either CBG concentrations or reduced CBG-cortisol binding properties have outlined symptoms consistent with attenuated features of hypocortisolism, fatigue, and hypotension. Here, however, the presence of hypoglycemia, despite normal circulating free cortisol, suggests a specific role for CBG in effecting glucocorticoid function, perhaps involving cortisol-mediated hepatic glucose homeostasis and cortisol-brain communication.
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Affiliation(s)
- Emily Jane Meyer
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, SA 5000, Australia.,Endocrine and Diabetes Services, The Queen Elizabeth Hospital, Woodville, SA 5011, Australia.,Discipline of Medicine, University of Adelaide, Adelaide, SA 5000, Australia
| | - Lucía Spangenberg
- Bioinformatics Unit, Institut Pasteur de Montevideo, Montevideo, 11400, Uruguay.,Department of Informatics and Computer Science, Universidad Católica del Uruguay, Montevideo, 11600, Uruguay
| | - Maria José Ramírez
- Paediatric Endocrinology, Hospital Británico, Montevideo, 11600, Uruguay.,Paediatric Endocrinology, Centro Hospitalario Pereira Rossell, Montevideo, 11600, Uruguay
| | - Sunita Maria Christina De Sousa
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, SA 5000, Australia.,Discipline of Medicine, University of Adelaide, Adelaide, SA 5000, Australia.,South Australian Adult Genetics Unit, Royal Adelaide Hospital, Adelaide, SA 5000, Australia
| | - Victor Raggio
- Genetics Department, Facultad de Medicina, UDELAR, Montevideo, 11800, Uruguay
| | - David James Torpy
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, SA 5000, Australia.,Discipline of Medicine, University of Adelaide, Adelaide, SA 5000, Australia
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6
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Lin HY, Song G, Lei F, Li D, Qu Y. Avian corticosteroid-binding globulin: biological function and regulatory mechanisms in physiological stress responses. Front Zool 2021; 18:22. [PMID: 33926473 PMCID: PMC8086359 DOI: 10.1186/s12983-021-00409-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 04/19/2021] [Indexed: 12/04/2022] Open
Abstract
Corticosteroid-binding globulin (CBG) is a high-affinity plasma protein that binds glucocorticoids (GCs) and regulates their biological activities. The structural and functional properties of CBG are crucial to understanding the biological actions of GCs in mediating stress responses and the underlying mechanisms. In response to stress, avian CBGs modulate the free and bound fractions of plasma corticosterone (CORT, the main GC), enabling them to mediate the physiological and behavioral responses that are fundamental for balancing the trade-off of energetic investment in reproduction, immunity, growth, metabolism and survival, including adaptations to extreme high-elevation or high-latitude environments. Unlike other vertebrates, avian CBGs substitute for sex hormone-binding globulin (SHBG) in transporting androgens and regulating their bioavailability, since birds lack an Shbg gene. The three-dimensional structures of avian and mammalian CBGs are highly conserved, but the steroid-binding site topographies and their modes of binding steroids differ. Given that CBG serves as the primary transporter of both GCs and reproductive hormones in birds, we aim to review the biological properties of avian CBGs in the context of steroid hormone transportation, stress responses and adaptation to harsh environments, and to provide insight into evolutionary adaptations in CBG functions occurred to accommodate physiological and endocrine changes in birds compared with mammals.
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Affiliation(s)
- Hai-Yan Lin
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Gang Song
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Fumin Lei
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Dongming Li
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
| | - Yanhua Qu
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
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7
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Bikle DD. The Free Hormone Hypothesis: When, Why, and How to Measure the Free Hormone Levels to Assess Vitamin D, Thyroid, Sex Hormone, and Cortisol Status. JBMR Plus 2020; 5:e10418. [PMID: 33553985 PMCID: PMC7839820 DOI: 10.1002/jbm4.10418] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/29/2020] [Accepted: 09/22/2020] [Indexed: 12/13/2022] Open
Abstract
The free hormone hypothesis postulates that only the nonbound fraction (the free fraction) of hormones that otherwise circulate in blood bound to their carrier proteins is able to enter cells and exert biologic effects. In this review, I will examine four hormone groups-vitamin D metabolites (especially 25OHD), thyroid hormones (especially thyroxine [T4]), sex steroids (especially testosterone), and glucocorticoids (especially cortisol)-that are bound to various degrees to their respective binding proteins-vitamin D-binding protein (DBP), thyroid-binding globulin (TBG), sex hormone-binding globulin (SHBG), and cortisol-binding globulin (CBG)-for which a strong case can be made that measurement of the free hormone level provides a better assessment of hormonal status than the measurement of total hormonal levels under conditions in which the binding proteins are affected in levels or affinities for the hormones to which they bind. I will discuss the rationale for this argument based on the free hormone hypothesis, discuss potential exceptions to the free hormone hypothesis, and review functions of the binding proteins that may be independent of their transport role. I will then review the complications involved with measuring the free hormone levels and the efforts to calculate those levels based on estimates of binding constants and levels of both total hormone and total binding protein. In this review, the major focus will be on DBP and free 25OHD, but the parallels and differences with the other binding proteins and hormones will be highlighted. Vitamin D and its metabolites, thyroid hormones, sex steroids, and glucocorticoids are transported in blood bound to serum proteins. The tightness of binding varies depending on the hormone and the binding protein such that the percent free varies from 0.03% for T4 and 25OHD to 4% for cortisol with testosterone at 2%. Although the major function of the primary carrier proteins (DBP, TBG, SHBG, and CBG) may be to transport their respective lipophilic hormones within the aqueous media that is plasma, these proteins may have other functions independent of their transport function. For most tissues, these hormones enter the cell as the free hormone presumably by diffusion (the free hormone hypothesis), although a few tissues such as the kidney and reproductive tissues express megalin/cubilin enabling by endocytosis protein-bound hormone to enter the cell. Measuring the free levels of these protein-bound hormones is likely to provide a better measure of the true hormone status than measuring the total levels in situations where the levels and/or affinities of the binding proteins are altered. Methods to measure free hormone levels are problematic as the free levels can be quite low, the methods require separation of bound and free that could disturb the steady state, and the means of separating bound and free are prone to error. Calculation of free levels using existing data for association constants between the hormone and its binding protein are likewise prone to error because of assumptions of linear binding models and invariant association constants, both of which are invalid. © 2020 The Author. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Daniel D Bikle
- Department of Medicine University of California San Francisco USA.,Department of Medicine San Francisco VA Medical Center San Francisco CA USA
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8
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Breuner CW, Beyl HE, Malisch JL. Corticosteroid-binding globulins: Lessons from biomedical research. Mol Cell Endocrinol 2020; 514:110857. [PMID: 32437784 DOI: 10.1016/j.mce.2020.110857] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 04/17/2020] [Accepted: 04/29/2020] [Indexed: 11/19/2022]
Abstract
Glucocorticoids (GCs) circulate in the plasma bound to corticosteroid-binding globulin (CBG). Plasma CBG may limit access of glucocorticoids to tissues (acting as a sponge: the free hormone hypothesis), or may solely serve as a transport molecule, releasing GCs to tissues as the plasma moves through capillaries (the total hormone hypothesis). Both biomedical (focused on human health) and comparative (focused on ecological and evolutionary relevance) studies have worked to incorporate CBG in glucocorticoid physiology, and to understand whether free or total hormone is the biologically active plasma fraction. The biomedical field, however, has been well ahead of the comparative physiologists, and have produced results that can inform comparative research when considering the import of total vs. free plasma hormone. In fact, biomedical studies have made impressive strides regarding the function of CBG in tissues as well as plasma; we, however, focus solely on the plasma functions in this review as this is the primary area of disagreement amongst comparative physiologists. Here we present 5 sets of biomedical studies across genomics, pharmacology, cell culture, whole animal research, and human medicine that strongly support a role for CBG limiting hormone access to tissue. We also discuss three areas of concern across comparative researchers. In contrast to former publications, we are not suggesting that all comparative studies in glucocorticoid physiology must measure CBG, or that only free corticosterone levels are valid. However, we propose that comparative physiologists be aware of biomedical results as they investigate glucocorticoids and interpret how total hormone may or may not impact behavior and physiology of free-living vertebrates.
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Affiliation(s)
- Creagh W Breuner
- Organismal Biology, Ecology, and Evolution, The University of Montana. 32 Campus Drive, HS 104, Missoula, MT, 59801, USA; The Wildlife Biology Program, The University of Montana. 32 Campus Drive, HS 104, Missoula, MT, 59801, USA.
| | - Hannah E Beyl
- The Wildlife Biology Program, The University of Montana. 32 Campus Drive, HS 104, Missoula, MT, 59801, USA
| | - Jessica L Malisch
- Department of Biology, Schaeffer Hall 236, St. Mary's College of Maryland, St. Mary's City, MD, 20686, USA
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9
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Hill LA, Sumer-Bayraktar Z, Lewis JG, Morava E, Thaysen-Andersen M, Hammond GL. N-Glycosylation influences human corticosteroid-binding globulin measurements. Endocr Connect 2019; 8:1136-1148. [PMID: 31307013 PMCID: PMC6686952 DOI: 10.1530/ec-19-0242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 07/15/2019] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Discrepancies in ELISA measurements of human corticosteroid-binding globulin (CBG) using detection monoclonal antibodies that recognize an epitope (9G12) within its reactive center loop (RCL), versus an epitope (12G2) in a different location, have suggested that CBG with a proteolytically cleaved RCL exists in blood samples. We have previously been unable to verify this biochemically, and sought to determine if N-glycosylation differences account for discrepancies in ELISA measurements of CBG. METHODS AND SUBJECTS Molecular biological, biochemical and glycopeptide analyses were used to examine how N-glycosylation at specific sites, including at N347 within the RCL, affect CBG ELISA or steroid-binding capacity assay (BCA) measurements. Plasma from patients with congenital disorders of glycosylation (CDG) was also examined in these assays as examples of N-glycosylation defects. RESULTS We demonstrate that an N-glycan at N347 within the CBG RCL limits the 9G12 antibody from recognizing its epitope, whereas the 12G2 antibody reactivity is unaffected, thereby contributing to discrepancies in ELISA measurements using these two antibodies. Qualitative differences in N-glycosylation at N238 also negatively affect the steroid-binding of CBG in the absence of an N-glycan at N347 caused by a T349A substitution. Desialylation increased both ELISA measurements relative to BCA values. Similarly, plasma CBG levels in both ELISAs were much higher than BCA values in several CDG patients. CONCLUSIONS Plasma CBG measurements are influenced by variations in N-glycosylation. This is important given the increasing number of CDG defects identified recently and because N-glycosylation abnormalities are common in patients with metabolic and liver diseases.
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Affiliation(s)
- Lesley A Hill
- Departments of Cellular and Physiological Sciences and Obstetrics and Gynaecology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Zeynep Sumer-Bayraktar
- School of Life and Environmental Science, Charles Perkins Centre, The University of Sydney, Sydney, New South Wales, Australia
| | - John G Lewis
- Canterbury Health Laboratories, Christchurch, New Zealand
| | - Eva Morava
- Mayo Clinic, Department of Clinical Genomics, CIM, Rochester, Minnesota, USA
| | | | - Geoffrey L Hammond
- Departments of Cellular and Physiological Sciences and Obstetrics and Gynaecology, The University of British Columbia, Vancouver, British Columbia, Canada
- Correspondence should be addressed to G L Hammond:
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10
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Hill LA, Vassiliadi DA, Dimopoulou I, Anderson AJ, Boyle LD, Kilgour AHM, Stimson RH, Machado Y, Overall CM, Walker BR, Lewis JG, Hammond GL. Neutrophil elastase-cleaved corticosteroid-binding globulin is absent in human plasma. J Endocrinol 2019; 240:27-39. [PMID: 30452386 PMCID: PMC6347282 DOI: 10.1530/joe-18-0479] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 09/28/2018] [Indexed: 12/24/2022]
Abstract
Corticosteroid-binding globulin (CBG) transports glucocorticoids in blood and is a serine protease inhibitor family member. Human CBG has a reactive center loop (RCL) which, when cleaved by neutrophil elastase (NE), disrupts its steroid-binding activity. Measurements of CBG levels are typically based on steroid-binding capacity or immunoassays. Discrepancies in ELISAs using monoclonal antibodies that discriminate between intact vs RCL-cleaved CBG have been interpreted as evidence that CBG with a cleaved RCL and low affinity for cortisol exists in the circulation. We examined the biochemical properties of plasma CBG in samples with discordant ELISA measurements and sought to identify RCL-cleaved CBG in human blood samples. Plasma CBG-binding capacity and ELISA values were consistent in arterial and venous blood draining skeletal muscle, liver and brain, as well as from a tissue (adipose) expected to contain activated neutrophils in obese individuals. Moreover, RCL-cleaved CBG was undetectable in plasma from critically ill patients, irrespective of whether their ELISA measurements were concordant or discordant. We found no evidence of RCL-cleaved CBG in plasma using a heat-dependent polymerization assay, and CBG that resists immunoprecipitation with a monoclonal antibody designed to specifically recognize an intact RCL, bound steroids with a high affinity. In addition, mass spectrometry confirmed the absence of NE-cleaved CBG in plasma in which ELISA values were highly discordant. Human CBG with a NE-cleaved RCL and low affinity for steroids is absent in blood samples, and CBG ELISA discrepancies likely reflect structural differences that alter epitopes recognized by specific monoclonal antibodies.
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Affiliation(s)
- Lesley A Hill
- Departments of Cellular and Physiological Sciences and Obstetrics and Gynaecology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Dimitra A Vassiliadi
- Endocrine Unit, Second Department of Internal Medicine-Research Institute and Diabetes Center, Attiko University Hospital, Athens, Greece
| | - Ioanna Dimopoulou
- Endocrine Unit, Second Department of Internal Medicine-Research Institute and Diabetes Center, Attiko University Hospital, Athens, Greece
| | - Anna J Anderson
- BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Luke D Boyle
- BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Alixe H M Kilgour
- BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Roland H Stimson
- BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Yoan Machado
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher M Overall
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Brian R Walker
- BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - John G Lewis
- Canterbury Health Laboratories, Christchurch, New Zealand
| | - Geoffrey L Hammond
- Departments of Cellular and Physiological Sciences and Obstetrics and Gynaecology, The University of British Columbia, Vancouver, British Columbia, Canada
- Correspondence should be addressed to G L Hammond:
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11
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Corticosteroid-binding globulin, induced in testicular Leydig cells by perfluorooctanoic acid, promotes steroid hormone synthesis. Arch Toxicol 2018; 92:2013-2025. [DOI: 10.1007/s00204-018-2207-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/25/2018] [Indexed: 12/19/2022]
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12
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Meyer EJ, Nenke MA, Lewis JG, Torpy DJ. Corticosteroid-binding globulin: acute and chronic inflammation. Expert Rev Endocrinol Metab 2017; 12:241-251. [PMID: 30058887 DOI: 10.1080/17446651.2017.1332991] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Corticosteroid-binding globulin (CBG) is the principal transport protein for cortisol binding 80% in a 1:1 ratio. Since its discovery in 1958, CBG's primary function has been considered to be cortisol transport within the circulation. More recent data indicate a cortisol tissue delivery function, particularly at inflammatory sites. CBG's structure as a non-inhibitory serine protease inhibitor allows allosteric structural change after reactive central loop (RCL) cleavage by neutrophil elastase (NE) and RCL insertion into CBG's protein core. Transition from the high to low affinity CBG form reduces cortisol-binding. Areas covered: In acute systemic inflammation, high affinity CBG (haCBG) is depleted proportionate to sepsis severity, with lowest levels seen in non-survivors. Conversely, in chronic inflammation, CBG cleavage is paradoxically reduced in proportion to disease severity, implying impaired targeted delivery of cortisol. CBG's structure allows thermosensitive release of bound cortisol, by reversible partial insertion of the RCL and loosening of CBG:cortisol binding. Recent studies indicate a significant frequency of function-altering single nucleotide polymorphisms of the SERPINA6 gene which may be important in population risk of inflammatory disease. Expert commentary: Further exploration of CBG in inflammatory disease may offer new avenues for treatment based on the model of optimal cortisol tissue delivery.
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Affiliation(s)
- Emily J Meyer
- a Endocrine and Metabolic Unit , Royal Adelaide Hospital , Adelaide , Australia
- b Discipline of Medicine , University of Adelaide , Adelaide , Australia
| | - Marni A Nenke
- a Endocrine and Metabolic Unit , Royal Adelaide Hospital , Adelaide , Australia
- b Discipline of Medicine , University of Adelaide , Adelaide , Australia
| | - John G Lewis
- c Steroid & Immunobiochemistry Laboratory , Canterbury Health Laboratories , Christchurch , New Zealand
| | - David J Torpy
- a Endocrine and Metabolic Unit , Royal Adelaide Hospital , Adelaide , Australia
- b Discipline of Medicine , University of Adelaide , Adelaide , Australia
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13
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Hammond GL. Plasma steroid-binding proteins: primary gatekeepers of steroid hormone action. J Endocrinol 2016; 230:R13-25. [PMID: 27113851 PMCID: PMC5064763 DOI: 10.1530/joe-16-0070] [Citation(s) in RCA: 186] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 04/22/2016] [Indexed: 12/11/2022]
Abstract
Biologically active steroids are transported in the blood by albumin, sex hormone-binding globulin (SHBG), and corticosteroid-binding globulin (CBG). These plasma proteins also regulate the non-protein-bound or 'free' fractions of circulating steroid hormones that are considered to be biologically active; as such, they can be viewed as the 'primary gatekeepers of steroid action'. Albumin binds steroids with limited specificity and low affinity, but its high concentration in blood buffers major fluctuations in steroid concentrations and their free fractions. By contrast, SHBG and CBG play much more dynamic roles in controlling steroid access to target tissues and cells. They bind steroids with high (~nM) affinity and specificity, with SHBG binding androgens and estrogens and CBG binding glucocorticoids and progesterone. Both are glycoproteins that are structurally unrelated, and they function in different ways that extend beyond their transportation or buffering functions in the blood. Plasma SHBG and CBG production by the liver varies during development and different physiological or pathophysiological conditions, and abnormalities in the plasma levels of SHBG and CBG or their abilities to bind steroids are associated with a variety of pathologies. Understanding how the unique structures of SHBG and CBG determine their specialized functions, how changes in their plasma levels are controlled, and how they function outside the blood circulation provides insight into how they control the freedom of steroids to act in health and disease.
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Affiliation(s)
- Geoffrey L Hammond
- Departments of Cellular & Physiological Sciences and Obstetrics & GynaecologyUniversity of British Columbia, Vancouver, British Columbia, Canada
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14
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Kwon SG, Hwang JH, Park DH, Kim TW, Kang DG, Kang KH, Kim IS, Ha J, Kim CW. Effects of a non-synonymous CBG gene single nucleotide polymorphism (SNP) on meat-quality traits in Berkshire pigs. CANADIAN JOURNAL OF ANIMAL SCIENCE 2016. [DOI: 10.1139/cjas-2015-0074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Corticosteroid-binding globulin (CBG) is a plasma transport protein that has glucocorticoid-binding activity. In the present study, we identified CBG gene expression in several tissues of four pig breeds: Berkshire, Duroc, Landrace, and Yorkshire. Expression of CBG mRNA was detected in the liver of all four breeds, and was the highest in Berkshire pigs. We also found single nucleotide polymorphisms (SNPs) in the CBG gene from Berkshire pigs, including SNP c.919G>A, which corresponds to 307G>R. We analyzed the relationships between this CBG variant and various meat-quality traits. The SNP was significantly associated with backfat thickness, post-mortem pH24h, meat color [CIE a* (redness), CIE b* (yellowness)], water-holding capacity, fat content, moisture content, protein content, cooking loss, and shear force. However, the effects differed by gender: the values were significantly associated with almost all traits in gilts, whereas only cooking loss and shear force were shown significantly in barrows. The variant G allele was associated with decreases in backfat thickness, post-mortem pH24h, CIE a*, fat content, and cooking loss, but with increases in CIE b*, water-holding capacity, moisture content, protein content, and shear force. Because the general correlation between meat-quality traits were not validated in the present study, we suggest that certain SNP might be used in the restrictive application to distinguish meat-quality traits.
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Affiliation(s)
- Seul Gi Kwon
- Swine Science and Technology Center, Gyeongnam National University of Science and Technology, Jinju 660-758, South Korea
| | - Jung Hye Hwang
- Swine Science and Technology Center, Gyeongnam National University of Science and Technology, Jinju 660-758, South Korea
| | - Da Hye Park
- Swine Science and Technology Center, Gyeongnam National University of Science and Technology, Jinju 660-758, South Korea
| | - Tae Wan Kim
- Swine Science and Technology Center, Gyeongnam National University of Science and Technology, Jinju 660-758, South Korea
| | - Deok Gyeong Kang
- Swine Science and Technology Center, Gyeongnam National University of Science and Technology, Jinju 660-758, South Korea
| | - Kyung Hee Kang
- Swine Science and Technology Center, Gyeongnam National University of Science and Technology, Jinju 660-758, South Korea
| | - Il-Suk Kim
- Department of Animal Resources Technology, Gyeongnam National University of Science and Technology, Gyeongnam 660-758, South Korea
| | - Jeongim Ha
- Swine Science and Technology Center, Gyeongnam National University of Science and Technology, Jinju 660-758, South Korea
| | - Chul Wook Kim
- Swine Science and Technology Center, Gyeongnam National University of Science and Technology, Jinju 660-758, South Korea
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15
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Bae YJ, Kratzsch J. Corticosteroid-binding globulin: modulating mechanisms of bioavailability of cortisol and its clinical implications. Best Pract Res Clin Endocrinol Metab 2015; 29:761-72. [PMID: 26522460 DOI: 10.1016/j.beem.2015.09.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Corticosteroid-binding globulin (CBG) is the principal transport protein of glucocorticoids. Approximately 80-90% of serum cortisol binds to CBG with high affinity and only about 5% of cortisol remain unbound and is considered biologically active. CBG seems to modulate and influence the bioavailability of cortisol to local tissues. In this review, we will discuss physicochemical properties of CBG and structure of CBG in the mechanisms of binding and release of cortisol. This review describes several factors affecting CBG functions, such as genetic factors or temperature. Furthermore, clinical implications of CBG abnormalities and the measurement of CBG and its use for assessment of free cortisol levels are described in this review.
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Affiliation(s)
- Yoon Ju Bae
- Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University of Leipzig, Paul-List Strasse 13-15, D-04103, Leipzig, Germany.
| | - Juergen Kratzsch
- Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University of Leipzig, Paul-List Strasse 13-15, D-04103, Leipzig, Germany
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16
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Molenaar N, Groeneveld ABJ, de Jong MFC. Three calculations of free cortisol versus measured values in the critically ill. Clin Biochem 2015; 48:1053-8. [PMID: 26169244 DOI: 10.1016/j.clinbiochem.2015.07.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/03/2015] [Accepted: 07/08/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVES To investigate the agreement between the calculated free cortisol levels according to widely applied Coolens and adjusted Södergård equations with measured levels in the critically ill. DESIGN AND METHODS A prospective study in a mixed intensive care unit. We consecutively included 103 patients with treatment-insensitive hypotension in whom an adrenocorticotropic hormone (ACTH) test (250μg) was performed. Serum total and free cortisol (equilibrium dialysis), corticosteroid-binding globulin and albumin were assessed. Free cortisol was estimated by the Coolens method (C) and two adjusted Södergård (S1 and S2) equations. Bland Altman plots were made. RESULTS The bias for absolute (t=0, 30 and 60min after ACTH injection) cortisol levels was 38, -24, 41nmol/L when the C, S1 and S2 equations were used, with 95% limits of agreement between -65-142, -182-135, and -57-139nmol/L and percentage errors of 66, 85, and 64%, respectively. Bias for delta (peak-baseline) cortisol was 14, -31 and 16nmol/L, with 95% limits of agreement between -80-108, -157-95, and -74-105nmol/L, and percentage errors of 107, 114, and 100% for C, S1 and S2 equations, respectively. CONCLUSIONS Calculated free cortisol levels have too high bias and imprecision to allow for acceptable use in the critically ill.
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Affiliation(s)
- Nienke Molenaar
- Department of Surgery, University Medical Center Groningen, 9700 RB Groningen, The Netherlands
| | - A B Johan Groeneveld
- Department of Intensive Care, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Margriet F C de Jong
- Department of Nephrology, University Medical Center Groningen, 9700 RB Groningen, The Netherlands.
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Genome wide association identifies common variants at the SERPINA6/SERPINA1 locus influencing plasma cortisol and corticosteroid binding globulin. PLoS Genet 2014; 10:e1004474. [PMID: 25010111 PMCID: PMC4091794 DOI: 10.1371/journal.pgen.1004474] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 05/15/2014] [Indexed: 11/30/2022] Open
Abstract
Variation in plasma levels of cortisol, an essential hormone in the stress response, is associated in population-based studies with cardio-metabolic, inflammatory and neuro-cognitive traits and diseases. Heritability of plasma cortisol is estimated at 30–60% but no common genetic contribution has been identified. The CORtisol NETwork (CORNET) consortium undertook genome wide association meta-analysis for plasma cortisol in 12,597 Caucasian participants, replicated in 2,795 participants. The results indicate that <1% of variance in plasma cortisol is accounted for by genetic variation in a single region of chromosome 14. This locus spans SERPINA6, encoding corticosteroid binding globulin (CBG, the major cortisol-binding protein in plasma), and SERPINA1, encoding α1-antitrypsin (which inhibits cleavage of the reactive centre loop that releases cortisol from CBG). Three partially independent signals were identified within the region, represented by common SNPs; detailed biochemical investigation in a nested sub-cohort showed all these SNPs were associated with variation in total cortisol binding activity in plasma, but some variants influenced total CBG concentrations while the top hit (rs12589136) influenced the immunoreactivity of the reactive centre loop of CBG. Exome chip and 1000 Genomes imputation analysis of this locus in the CROATIA-Korcula cohort identified missense mutations in SERPINA6 and SERPINA1 that did not account for the effects of common variants. These findings reveal a novel common genetic source of variation in binding of cortisol by CBG, and reinforce the key role of CBG in determining plasma cortisol levels. In turn this genetic variation may contribute to cortisol-associated degenerative diseases. Cortisol is a steroid hormone from the adrenal glands that is essential in the response to stress. Most cortisol in blood is bound to corticosteroid binding globulin (CBG). Diseases causing cortisol deficiency (Addison's disease) or excess (Cushing's syndrome) are life-threatening. Variations in plasma cortisol have been associated with cardiovascular and psychiatric diseases and their risk factors. To dissect the genetic contribution to variation in plasma cortisol, we formed the CORtisol NETwork (CORNET) consortium and recruited collaborators with suitable samples from more than 15,000 people. The results reveal that the major genetic influence on plasma cortisol is mediated by variations in the binding capacity of CBG. This is determined by differences in the circulating concentrations of CBG and also in the immunoreactivity of its ‘reactive centre loop’, potentially influencing not only binding affinity for cortisol but also the stability of CBG and hence the tissue delivery of cortisol. These findings provide the first evidence for a common genetic effect on levels of this clinically important hormone, suggest that differences in CBG between individuals are biologically important, and pave the way for further research to dissect causality in the associations of plasma cortisol with common diseases.
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Lee SR, Kim HK, Song IS, Youm J, Dizon LA, Jeong SH, Ko TH, Heo HJ, Ko KS, Rhee BD, Kim N, Han J. Glucocorticoids and their receptors: insights into specific roles in mitochondria. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2013; 112:44-54. [PMID: 23603102 DOI: 10.1016/j.pbiomolbio.2013.04.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/03/2013] [Accepted: 04/08/2013] [Indexed: 12/27/2022]
Abstract
Glucocorticoids (GCs) affect most physiological systems and are the most frequently used drugs for multiple disorders and organ transplantation. GC functions depend on a balance between circulating GC and cytoplasmic glucocorticoid receptor II (GR). Mitochondria individually enclose circular, double-stranded DNA that is expressed and replicated in response to nuclear-encoded factors imported from the cytoplasm. Fine-tuning and response to cellular demands should be coordinately regulated by the nucleus and mitochondria; thus mitochondrial-nuclear interaction is vital to optimal mitochondrial function. Elucidation of the direct and indirect effects of steroids, including GCs, on mitochondria is an important and emerging field of research. Mitochondria may also be under GC control because GRs are present in mitochondria, and glucocorticoid response elements (GREs) reside in the mitochondrial genome. Therefore, mitochondrial gene expression can be regulated by GCs via at least two different mechanisms: direct action on mitochondrial DNA and oxidative phosphorylation (OXPHOS) genes, or by an indirect effect through interaction with nuclear genes. In this review, we outline possible mechanisms of regulation of mitochondrial genes in response to GCs in view of translocation of the GR into mitochondria and the possible regulation of OXPHOS genes by GREs in the mitochondrial genome.
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Affiliation(s)
- Sung-Ryul Lee
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, 633-165 Gaegeum-Dong, Busanjin-Gu, 613-735 Busan, Republic of Korea
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19
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Interstitial cortisol obtained by microdialysis in mechanically ventilated septic patients: Correlations with total and free serum cortisol. J Crit Care 2013; 28:158-65. [DOI: 10.1016/j.jcrc.2012.07.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 06/06/2012] [Accepted: 07/04/2012] [Indexed: 01/13/2023]
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20
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Gardill BR, Vogl MR, Lin HY, Hammond GL, Muller YA. Corticosteroid-binding globulin: structure-function implications from species differences. PLoS One 2012; 7:e52759. [PMID: 23300763 PMCID: PMC3530532 DOI: 10.1371/journal.pone.0052759] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 11/20/2012] [Indexed: 11/18/2022] Open
Abstract
Corticosteroid-binding globulin (CBG) transports glucocorticoids and progesterone in the blood and thereby modulates the tissue availability of these hormones. As a member of the serine protease inhibitor (SERPIN) family, CBG displays a reactive center loop (RCL) that is targeted by proteinases. Cleavage of the RCL is thought to trigger a SERPIN-typical stressed-to-relaxed (S-to-R) transition that leads to marked structural rearrangements and a reduced steroid-binding affinity. To characterize structure-function relationships in CBG we studied various conformational states of E. coli-produced rat and human CBG. In the 2.5 Å crystal structure of human CBG in complex with progesterone, the RCL is cleaved at a novel site that differs from the known human neutrophil elastase recognition site. Although the cleaved RCL segment is five residues longer than anticipated, it becomes an integral part of β-sheet A as a result of the S-to-R transition. The atomic interactions observed between progesterone and CBG explain the lower affinity of progesterone in comparison to corticosteroids. Surprisingly, CD measurements in combination with thermal unfolding experiments show that rat CBG fails to undergo an S-to-R transition upon proteolytic cleavage of the RCL hinting that the S-to-R transition observed in human CBG is not a prerequisite for CBG function in rat. This observation cautions against drawing general conclusions about molecular mechanisms by comparing and merging structural data from different species.
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Affiliation(s)
- Bernd R. Gardill
- Department of Biology, Lehrstuhl für Biotechnik, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Michael R. Vogl
- Department of Biology, Lehrstuhl für Biotechnik, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Hai-Yan Lin
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Geoffrey L. Hammond
- Department of Obstetrics and Gynecology, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yves A. Muller
- Department of Biology, Lehrstuhl für Biotechnik, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
- * E-mail:
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21
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Perogamvros I, Ray DW, Trainer PJ. Regulation of cortisol bioavailability--effects on hormone measurement and action. Nat Rev Endocrinol 2012; 8:717-27. [PMID: 22890008 DOI: 10.1038/nrendo.2012.134] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Routine assessment of the hypothalamic-pituitary-adrenal axis relies on the measurement of total serum cortisol levels. However, most cortisol in serum is bound to corticosteroid-binding globulin (CBG) and albumin, and changes in the structure or circulating levels of binding proteins markedly affect measured total serum cortisol levels. Furthermore, high-affinity binding to CBG is predicted to affect the availability of cortisol for the glucocorticoid receptor. CBG is a substrate for activated neutrophil elastase, which cleaves the binding protein and results in the release of cortisol at sites of inflammation, enhancing its tissue-specific anti-inflammatory effects. Further tissue-specific modulation of cortisol availability is conferred by corticosteroid 11β-dehydrogenase. Direct assessment of tissue levels of bioavailable cortisol is not clinically practicable and measurement of total serum cortisol levels is of limited value in clinical conditions that alter prereceptor glucocorticoid bioavailability. Bioavailable cortisol can, however, be measured indirectly at systemic, extracellular tissue and cell levels, using novel techniques that have provided new insight into the transport, metabolism and biological action of glucocorticoids. A more physiologically informative approach is, therefore, now possible in the assessment of the hypothalamic-pituitary-adrenal axis, which could prove useful in clinical practice.
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Affiliation(s)
- Ilias Perogamvros
- Endocrine Sciences Research Group, School of Medicine, University of Manchester, A. V. Hill Building, Oxford Road, Manchester M13 9PT, UK.
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Hill LA, Vassiliadi DA, Simard M, Pavlaki A, Perogamvros I, Hadjidakis D, Hammond GL. Two different corticosteroid-binding globulin variants that lack cortisol-binding activity in a greek woman. J Clin Endocrinol Metab 2012; 97:4260-7. [PMID: 22948765 DOI: 10.1210/jc.2012-2467] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
BACKGROUND Corticosteroid-binding globulin (CBG), encoded by SERPINA6, is the principal plasma binding protein for cortisol. Most nonsynonymous single-nucleotide polymorphisms that alter the production or function of CBG occur rarely, and their clinical significance remains obscure. METHODS Serum and DNA were obtained from a Greek woman with low morning cortisol levels and from family members. SERPINA6 exons were sequenced, and serum CBG was measured by ELISA and cortisol-binding capacity assay. Recombinant CBG variants were produced for detailed functional studies. RESULTS A novel heterozygous c.1282G>C transversion in exon 5 of SERPINA6, resulting in a p.Trp393Ser (W371S) substitution, was identified in the proband, who was also heterozygous for single-nucleotide polymorphisms encoding the CBG Lyon (D367N) and CBG A224S variants. The proband had no measurable plasma cortisol-binding activity despite a CBG level of 273 nm by ELISA. She inherited CBG W371S from her mother whose plasma cortisol-binding capacity was approximately 50% lower than the CBG measurements by ELISA (314 nm). The proband's father and four children were heterozygous for CBG D367N; their CBG levels by ELISA were normal, but corresponding cortisol-binding capacity measurements were 50% lower. Pedigree analysis revealed that W371S segregates with A224 and that D367N and W371S segregate separately. Recombinant CBG D367N and CBG W371S had no measureable cortisol-binding activity. CONCLUSION A new CBG Athens (W371S) variant that lacks cortisol-binding activity has been identified in a carrier of the cortisol-binding deficient CBG Lyon (D367N) variant. Analyses of CBG levels in this pedigree illustrate how immunoassays fail to accurately reflect cortisol-binding activity.
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Affiliation(s)
- L A Hill
- Endocrine Unit, Attikon University Hospital, Athens University Medical School, Second Department of Internal Medicine-Research Institute and Diabetes Center, 1 Rimini Street, Haidari, Athens 12462, Greece.
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Lee SR, Kim HK, Youm JB, Dizon LA, Song IS, Jeong SH, Seo DY, Ko KS, Rhee BD, Kim N, Han J. Non-genomic effect of glucocorticoids on cardiovascular system. Pflugers Arch 2012; 464:549-59. [PMID: 23001133 DOI: 10.1007/s00424-012-1155-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 09/05/2012] [Indexed: 01/01/2023]
Abstract
Glucocorticoids (GCs) are essential steroid hormones for homeostasis, development, metabolism, and cognition and possess anti-inflammatory and immunosuppressive actions. Since glucocorticoid receptor II (GR) is nearly ubiquitous, chronic activation or depletion of GCs leads to dysfunction of diverse organs, including the heart and blood vessels, resulting predominantly from changes in gene expression. Most studies, therefore, have focused on the genomic effects of GC to understand its related pathophysiological manifestations. The nongenomic effects of GCs clearly differ from well-known genomic effects, with the former responding within several minutes without the need for protein synthesis. There is increasing evidence that the nongenomic actions of GCs influence various physiological functions. To develop a GC-mediated therapeutic target for the treatment of cardiovascular disease, understanding the genomic and nongenomic effects of GC on the cardiovascular system is needed. This article reviews our current understanding of the underlying mechanisms of GCs on cardiovascular diseases and stress, as well as how nongenomic GC signaling contributes to these conditions. We suggest that manipulation of GC action based on both GC and GR metabolism, mitochondrial impact, and the action of serum- and glucocorticoid-dependent kinase 1 may provide new information with which to treat cardiovascular diseases.
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Affiliation(s)
- Sung Ryul Lee
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, 633-165 Gaegeum-Dong, Busanjin-Gu, Busan, Korea
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24
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Li Y, Wu L, Lei J, Zhu C, Wang H, Yu X, Lin H. Single nucleotide polymorphisms in the human corticosteroid-binding globulin promoter alter transcriptional activity. SCIENCE CHINA-LIFE SCIENCES 2012; 55:699-708. [PMID: 22932886 DOI: 10.1007/s11427-012-4365-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 08/01/2012] [Indexed: 12/16/2022]
Abstract
Corticosteroid-binding globulin (CBG) is a high-affinity plasma protein that transports glucocorticoids and progesterone. Others and we have reported non-synonymous single nucleotide polymorphisms (SNPs) that influence CBG production or steroid-binding activity. However, no promoter polymorphisms affecting the transcription of human CBG gene (Cbg) have been reported. In the present study we investigated function implications of six promoter SNPs, including -26 C/G, -54 C/T, -144 G/C, -161 A/G, -205 C/A, and -443/-444 AG/-, five of which are located within the first 205 base pairs of 5'-flanking region and close to the highly conserved footprinted elements, TATA-box, or CCAAT-box. Luciferase reporter assays demonstrated that basal activity of the promoter carrying -54 T or -161 G was significantly enhanced. The first three polymorphisms, -26 C/G, -54 C/T, and -144 G/C located close to the putative hepatic nuclear factor (HNF) 1 binding elements, altered the transactivation effect of HNF1β. We also found a negative promoter response to dexamethasone-activated glucocorticoid receptor (GR) α, although none of the SNPs affected its transrepression function. Our results suggest that human Cbg -26 C/G, -54 C/T, -144 G/C, and -161 A/G promoter polymorphisms alter transcriptional activity, and further studies are awaited to explore their association with physiological and pathological conditions.
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Affiliation(s)
- Yue Li
- Department of Biochemistry and Molecular Biology, College of Basic Medical Science, Harbin Medical University, Harbin, 150081, China
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25
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Marathe CS, Torpy DJ. A role for corticosteroid-binding globulin variants in stress-related disorders. Expert Rev Endocrinol Metab 2012; 7:301-308. [PMID: 30780848 DOI: 10.1586/eem.12.20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Primary stress-related diseases such as chronic fatigue syndrome, fibromyalgia or chronic widespread pain have been associated with altered activity of the hypothalamic-pituitary-adrenal axis due to measured relative hyper- or hypo-cortisolism in basal or experimentally stimulated states. A hereditary risk to development of these diseases has been proposed. Corticosteroid-binding globulin (CBG), a plasma transport vehicle for cortisol, may play a more active role in the hypothalamic-pituitary-adrenal axis. Chronically altered hypothalamic-pituitary-adrenal axis has been associated with common medical problems. Hypocortisolism has been observed in kindred studies of rare mutations of the SERPIN A6 (CBG) gene and more common SERPIN A6 polymorphisms associated with reduced CBG levels or CBG:cortisol-binding affinity. Over the last decade, studies of five different CBG gene mutations in humans, human genetic associations and transgenic mouse models have suggested that CBG may have hitherto unexpected roles in modulation of the stress response. Naturally occurring CBG variants may alter susceptibility to disorders associated with chronic stress and relative hypocortisolism. On the other hand, hypercortisolism has been linked with Cushing's disease and metabolic syndrome and CBG gene polymorphisms have been linked to obesity in animal models. In this article, we look at the evidence suggesting a role for CBG in stress-related disorders, focusing particularly on CBG gene polymorphisms and chronic pain/fatigue syndromes.
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Affiliation(s)
- Chinmay S Marathe
- a Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
| | - David J Torpy
- b Endocrine & Metabolic Unit, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia.
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Abstract
CONTEXT Corticosteroid-binding globulin (CBG; SERPIN A6) gene mutations are rare; only four mutations have been described, often in association with fatigue and chronic pain, albeit with incomplete penetrance. PATIENT We report a kindred with a novel SERPINA6 mutation. The proband, a 9-yr-old male, had excessive postexertional fatigue, weakness, and migraine. MAIN OUTCOME MEASURES AND RESULTS Investigations revealed low morning and ACTH-stimulated peak cortisol levels. SERPIN A6 sequencing detected a novel exon 2 single base deletion (c.13delC) leading to a frameshift generating a stop codon within the signal peptide coding region (p.Leu5CysfsX26) and 50% reduced CBG levels in heterozygotes. The patient's father and two sisters share the mutation. Symptom expression within the family may have been modified by a polymorphic CBG allele (c.735G>T). Exogenous hydrocortisone had no effect on the fatigue. CONCLUSION This report documents the fifth CBG gene mutation in humans and the second causing major effects on CBG levels. Individuals with low CBG levels may be misdiagnosed as having secondary hypocortisolism. The association with fatigue and idiopathic pain is again noted and may relate to altered stress system function. Variability of the phenotype may relate to other genetic variations of the CBG gene or environmental factors.
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Affiliation(s)
- D J Torpy
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, North Terrace, Adelaide 5000, South Australia, Australia.
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Cizza G, Bernardi L, Smirne N, Maletta R, Tomaino C, Costanzo A, Gallo M, Lewis JG, Geracitano S, Grasso MB, Potenza G, Monteleone C, Brancati G, Ho JT, Torpy DJ, Bruni AC. Clinical manifestations of highly prevalent corticosteroid-binding globulin mutations in a village in southern Italy. J Clin Endocrinol Metab 2011; 96:E1684-93. [PMID: 21795453 PMCID: PMC3200236 DOI: 10.1210/jc.2011-1321] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
CONTEXT Corticosteroid-binding globulin (CBG) is the binding protein for cortisol. Rare kindreds with CBG mutations reducing CBG levels or altering binding affinity have been described, along with clinical manifestations encompassing fatigue, chronic pain, and hypotension. The largest kindred, exhibiting two mutations (null and Lyon) were Australian immigrants from Italy. OBJECTIVE Our objective was to determine the prevalence of the null/Lyon mutations in the village where the original null/Lyon family emigrated and compare subjects with and without CBG mutations, without previous knowledge of their mutation status. DESIGN, SETTING, AND PARTICIPANTS We conducted a survey field study that included 495 adult residents. MAIN OUTCOMES We assessed clinical history, CBG mutation analysis, plasma CBG, salivary cortisol, body mass index, waist circumference, blood pressure, and the Krupp fatigue scale. RESULTS Eighteen of 495 participants (3.6%, seven males and 11 females) had one of two function-altering CBG mutations. All were heterozygous for the null (n = 6) or Lyon mutations (n = 12). Of 12 Lyon participants (four males and eight females), eight (two males and six females) had chronic widespread pain and five osteoarthritis with associated pain (one male and four females). Of six null participants (three males and three females), three (one male and two females) had chronic pain and four osteoarthritis with associated pain (two males and two females). CONCLUSIONS A high combined prevalence (3.6%) of these two CBG mutations was detected. The presence of either mutation conferred a propensity to chronic pain. In other communities, individuals with the same genetic background complain more of fatigue than pain, suggesting an environmental effect on the phenotype. These findings, combined with animal CBG gene knockout and human CBG single-nucleotide polymorphism haplotype studies, suggest that CBG influences the endocrine and neurobehavioral response to stress, including the development of pain/fatigue syndromes.
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Affiliation(s)
- Giovanni Cizza
- National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA.
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Qian X, Droste SK, Gutièrrez-Mecinas M, Collins A, Kersanté F, Reul JMHM, Linthorst ACE. A rapid release of corticosteroid-binding globulin from the liver restrains the glucocorticoid hormone response to acute stress. Endocrinology 2011; 152:3738-48. [PMID: 21828178 PMCID: PMC3722548 DOI: 10.1210/en.2011-1008] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A strict control of glucocorticoid hormone responses to stress is essential for health. In blood, glucocorticoid hormones are for the largest part bound to corticosteroid-binding globulin (CBG), and just a minor fraction of hormone is free. Only free glucocorticoid hormone is able to exert biological effects, but little is known about its regulation during stress. We found, using a dual-probe in vivo microdialysis method, that in rats, the forced-swim stress-induced rise in free corticosterone (its major glucocorticoid hormone) is strikingly similar in the blood and in target compartments such as the subcutaneous tissue and the brain. However, in all compartments, the free corticosterone response was delayed by 20-30 min as compared with the total corticosterone response in the blood. We discovered that CBG is the key player in this delay. Swim stress evoked a fast (within 5 min) and profound rise in CBG protein and binding capacity in the blood through a release of the protein from the liver. Thus, the increase in circulating CBG levels after stress restrains the rise in free corticosterone concentrations for approximately 20 min in the face of mounting total hormone levels in the circulation. The stress-induced increase in CBG seems to be specific for moderate and strong stressors. Both restraint stress and forced swimming caused an increase in circulating CBG, whereas its levels were not affected by mild novelty stress. Our data uncover a new, highly dynamic role for CBG in the regulation of glucocorticoid hormone physiology after acute stress.
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Affiliation(s)
- Xiaoxiao Qian
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, University of Bristol, Bristol BS1 3NY, United Kingdom
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Perogamvros I, Kayahara M, Trainer PJ, Ray DW. Serum regulates cortisol bioactivity by corticosteroid-binding globulin-dependent and independent mechanisms, as revealed by combined bioassay and physicochemical assay approaches. Clin Endocrinol (Oxf) 2011; 75:31-8. [PMID: 21521274 DOI: 10.1111/j.1365-2265.2011.04003.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
CONTEXT Corticosteroid-binding globulin (CBG) is the principal carrier of natural glucocorticoids in the circulation, and we hypothesized that it modulates glucocorticoid bioactivity (GBA). Alterations in CBG, the presence of noncortisol, naturally occurring glucocorticoids and the use of potent, synthetic glucocorticoids, all make it difficult to assess adrenal activity in-vivo; these problems can be addressed by a glucocorticoid bioassay. DESIGN AND SUBJECTS A bioassay was developed for serum GBA and a physicochemical ultrafiltration-liquid chromatography-tandem mass spectrometry assay for free serum cortisol (FreeF). We studied individuals homozygous and heterozygous for a nonfunctioning CBG variant (CBG G237V) and healthy controls. RESULTS FreeF concentrations were similar in healthy controls, and those with absent functional CBG, but surprisingly we found low GBA in CBG null individuals. This may suggest that CBG delivers cortisol to target cells. However, further experiments revealed that dilution of serum in the bioassay caused release of cortisol from CBG, resulting in elevated GBA measurements in all but the CBG G237V homozygotes. Furthermore, we identified a specific and potent inhibitory effect of high concentration serum on glucocorticoid sensitivity of the recipient cells used in the bioassay. Analysis of inflammatory synovial fluid, a filtrate of serum with lower CBG concentration, revealed elevated free cortisol compared to noninflammatory synovial fluid, a change not attributable to interconversion between cortisol and cortisone. CONCLUSIONS Our findings reveal that dilution of CBG enhances cortisol release, and so bioactivity, and also that serum potently induces glucocorticoid resistance in target cells.
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Affiliation(s)
- I Perogamvros
- Department of Endocrinology, Christie HospitalEndocrine Sciences Research Group, University of Manchester, Manchester, UK
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New insights into corticosteroid-binding globulin and glucocorticoid delivery. Neuroscience 2011; 180:1-8. [DOI: 10.1016/j.neuroscience.2011.02.053] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 02/08/2011] [Accepted: 02/19/2011] [Indexed: 12/23/2022]
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Qi X, Loiseau F, Chan WL, Yan Y, Wei Z, Milroy LG, Myers RM, Ley SV, Read RJ, Carrell RW, Zhou A. Allosteric modulation of hormone release from thyroxine and corticosteroid-binding globulins. J Biol Chem 2011; 286:16163-73. [PMID: 21325280 PMCID: PMC3091225 DOI: 10.1074/jbc.m110.171082] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The release of hormones from thyroxine-binding globulin (TBG) and corticosteroid-binding globulin (CBG) is regulated by movement of the reactive center loop in and out of the β-sheet A of the molecule. To investigate how these changes are transmitted to the hormone-binding site, we developed a sensitive assay using a synthesized thyroxine fluorophore and solved the crystal structures of reactive loop cleaved TBG together with its complexes with thyroxine, the thyroxine fluorophores, furosemide, and mefenamic acid. Cleavage of the reactive loop results in its complete insertion into the β-sheet A and a substantial but incomplete decrease in binding affinity in both TBG and CBG. We show here that the direct interaction between residue Thr(342) of the reactive loop and Tyr(241) of the hormone binding site contributes to thyroxine binding and release following reactive loop insertion. However, a much larger effect occurs allosterically due to stretching of the connecting loop to the top of the D helix (hD), as confirmed in TBG with shortening of the loop by three residues, making it insensitive to the S-to-R transition. The transmission of the changes in the hD loop to the binding pocket is seen to involve coherent movements in the s2/3B loop linked to the hD loop by Lys(243), which is, in turn, linked to the s4/5B loop, flanking the thyroxine-binding site, by Arg(378). Overall, the coordinated movements of the reactive loop, hD, and the hormone binding site allow the allosteric regulation of hormone release, as with the modulation demonstrated here in response to changes in temperature.
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Affiliation(s)
- Xiaoqiang Qi
- Department of Biochemistry, Nanjing University, Nanjing, China
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Perogamvros I, Aarons L, Miller AG, Trainer PJ, Ray DW. Corticosteroid-binding globulin regulates cortisol pharmacokinetics. Clin Endocrinol (Oxf) 2011; 74:30-6. [PMID: 21054475 DOI: 10.1111/j.1365-2265.2010.03897.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Corticosteroid-binding globulin (CBG) is the principal carrier for cortisol in the circulation. Variations in CBG-binding capacity are predicted to alter total serum cortisol disposition, but free serum cortisol is believed to be unaffected. Unbound cortisol pharmacokinetics (PK) have not been studied in the context of CBG changes. We aimed to assess the regulation of cortisol PK by CBG. DESIGN AND SUBJECTS Women on oestrogens [oral contraceptive pill, (OCP)], patients homozygous for a nonfunctioning CBG variant (CBG null) and healthy controls (HV) were studied before and after IV and oral administration of hydrocortisone 20 mg. MEASUREMENTS PK parameters were studied for total serum cortisol (SerF), free serum cortisol (FreeF) and cortisone (FreeE), and salivary cortisol (SalF) and cortisone (SalE): area under the curve (AUC), clearance (CL), half-life and volume of distribution (V(d)). RESULTS Following IV hydrocortisone, AUC and half-life of SerF were significantly higher in the OCP group and lower in the CBG null. SerF CL and V(d) were significantly lower in the OCP group and increased in the CBG null, compared to HV. PK parameters for FreeF and the salivary biomarkers were not different between the CBG null and HV, although OCP patients still had higher AUC compared to HV and prolonged half-life. These findings were confirmed following oral hydrocortisone, but concentration-time profiles were highly heterogeneous and SalF interpretation was problematic because of oral contamination. CONCLUSIONS We have demonstrated that CBG has a distinct effect on cortisol PK. When CBG binding is disrupted, FreeF retains normal PK characteristics, although CBG null patients lack a CBG-bound pool of readily releasable cortisol. Women on oestrogens may have altered free serum cortisol kinetics and thus may be potentially overexposed to glucocorticoids.
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Affiliation(s)
- I Perogamvros
- Department of Endocrinology, Christie Hospital, Manchester Academic Health Science Centre, UK
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