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Abstract
Endogenous Cushing's syndrome (CS) is associated with morbidities (diabetes, hypertension, clotting disorders) and shortens life because of infections, pulmonary thromboembolism, and cardiovascular disease. Its clinical presentation is immensely variable, and diagnosis and treatment are often delayed. Thus, there are many opportunities for basic and clinical research leading to better tests, faster diagnosis, and optimized medical treatments. This review focuses on CS caused by excessive adrenocorticotropin (ACTH) production. It describes current concepts of the regulation of ACTH synthesis and secretion by normal corticotropes and mechanisms by which dysregulation occurs in corticotrope (termed "Cushing's disease") and noncorticotrope (so-called ectopic) ACTH-producing tumors. ACTH causes adrenal gland synthesis and pulsatile release of cortisol; the excess ACTH in these forms of CS leads to the hypercortisolism of endogenous CS. Again, the differences between healthy individuals and those with CS are highlighted. The clinical presentations and their use in the interpretation of CS screening tests are described. The tests used for screening and differential diagnosis of CS are presented, along with their relationship to cortisol dynamics, pathophysiology, and negative glucocorticoid feedback regulation in the two forms of ACTH-dependent CS. Finally, several gaps in current understanding are highlighted in the hope of stimulating additional research into this challenging disorder.
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Affiliation(s)
- Lynnette K Nieman
- Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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Zhang D, Damoiseaux R, Babayan L, Rivera-Meza EK, Yang Y, Bergsneider M, Wang MB, Yong WH, Kelly K, Heaney AP. Targeting Corticotroph HDAC and PI3-Kinase in Cushing Disease. J Clin Endocrinol Metab 2021; 106:e232-e246. [PMID: 33000123 PMCID: PMC8921634 DOI: 10.1210/clinem/dgaa699] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 09/28/2020] [Indexed: 12/11/2022]
Abstract
CONTEXT Cushing disease (CD) is a life-threatening disorder. Therapeutic goals include symptom relief, biochemical control, and tumor growth inhibition. Current medical therapies for CD by and large exert no action on tumor growth. OBJECTIVE To identify drugs that inhibit corticotroph tumor adrenocorticotropic hormone (ACTH) secretion and growth. DESIGN High throughput screen employing a novel "gain of signal" ACTH AlphaLISA assay. SETTING Academic medical center. PATIENTS Corticotroph tumor tissues from patients with CD. INTERVENTIONS None. MAIN OUTCOME MEASURES Potent inhibitors of corticotroph tumor ACTH secretion and growth. RESULTS From a kinase inhibitor library, we identified the dual PI3K/HDAC inhibitor CUDC-907 as a potent inhibitor of murine and human corticotroph tumor ACTH secretion (median effective concentration 1-5 nM), and cell proliferation (median inhibitory concentration 5 nM). In an in vivo murine corticotroph tumor xenograft model, orally administered CUDC-907 (300 mg/kg) reduced corticotroph tumor volume (TV [cm3], control 0.17 ± 0.05 vs CUDC-907 0.07 ± 0.02, P < .05) by 65% and suppressed plasma ACTH (ACTH [pg/mL] control 206 ± 27 vs CUDC-907 47 ± 7, P < .05) and corticosterone (corticosterone [ng/mL] control 180 ± 87 vs CUDC-907 27 ± 5, P < .05) levels by 77% and 85% respectively compared with controls. We also demonstrated that CUDC-907 acts through HDAC1/2 inhibition at the proopiomelanocortin transcriptional level combined with its PI3K-mediated inhibition of corticotroph cell viability to reduce ACTH secretion. CONCLUSIONS Given its potent efficacy in in vitro and in vivo models of CD, combined with proven safety and tolerance in clinical trials, we propose CUDC-907 may be a promising therapy for CD.
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Affiliation(s)
- Dongyun Zhang
- Department of Medicine, University of California, David Geffen School of Medicine, Los Angeles, California
| | - Robert Damoiseaux
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Lilit Babayan
- Department of Medicine, University of California, David Geffen School of Medicine, Los Angeles, California
| | | | - Yingying Yang
- Department of Medicine, University of California, David Geffen School of Medicine, Los Angeles, California
| | - Marvin Bergsneider
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Marilene B Wang
- Department of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, California
| | - William H Yong
- Department of Pathology and Lab Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Kathleen Kelly
- Department of Pathology and Lab Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Anthony P Heaney
- Correspondence and Reprint Requests: Anthony P. Heaney, Department of Medicine, University of California, David Geffen School of Medicine, Los Angeles, CA, USA. E-mail:
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Nuclear Receptors as Regulators of Pituitary Corticotroph Pro-Opiomelanocortin Transcription. Cells 2020; 9:cells9040900. [PMID: 32272677 PMCID: PMC7226830 DOI: 10.3390/cells9040900] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 03/29/2020] [Accepted: 04/01/2020] [Indexed: 12/16/2022] Open
Abstract
The hypothalamic–pituitary–adrenal (HPA) axis plays a critical role in adaptive stress responses and maintaining organism homeostasis. The pituitary corticotroph is the central player in the HPA axis and is regulated by a plethora of hormonal and stress related factors that synergistically interact to activate and temper pro-opiomelanocortin (POMC) transcription, to either increase or decrease adrenocorticotropic hormone (ACTH) production and secretion as needed. Nuclear receptors are a family of highly conserved transcription factors that can also be induced by various physiologic signals, and they mediate their responses via multiple targets to regulate metabolism and homeostasis. In this review, we summarize the modulatory roles of nuclear receptors on pituitary corticotroph cell POMC transcription, describe the unique and complex role these factors play in hypothalamic–pituitary–adrenal axis (HPA) regulation and discuss potential therapeutic targets in disease states.
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Kruse MS, Suarez LG, Coirini H. LXR activation increases the expression of GnRH AND αMSH in the rat hypothalamus in vivo. Neurosci Lett 2018; 664:20-27. [DOI: 10.1016/j.neulet.2017.11.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 10/11/2017] [Accepted: 11/07/2017] [Indexed: 11/25/2022]
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Lu J, Chatain GP, Bugarini A, Wang X, Maric D, Walbridge S, Zhuang Z, Chittiboina P. Histone Deacetylase Inhibitor SAHA Is a Promising Treatment of Cushing Disease. J Clin Endocrinol Metab 2017; 102:2825-2835. [PMID: 28505327 PMCID: PMC5546859 DOI: 10.1210/jc.2017-00464] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 05/05/2017] [Indexed: 02/01/2023]
Abstract
CONTEXT Remission failure following transsphenoidal surgery in Cushing disease (CD) from pituitary corticotroph tumors (CtTs) remains clinically challenging. Histone deacetylase inhibitors (HDACis) are antitumor drugs approved for clinical use, with the potential to affect adrenocorticotropin hormone (ACTH) hypersecretion by inhibiting pro-opiomelanocortin (POMC) transcription. OBJECTIVE Testing the efficacy of suberoylanilide hydroxamic acid (SAHA) on human and murine ACTH-secreting tumor (AtT-20) cells. DESIGN Cell viability, ACTH secretion (enzyme-linked immunosorbent assay), apoptosis, and gene expression profile were investigated on AtT-20 cells. In vivo efficacy was examined in an athymic nude mouse AtT-20 xenograft model. SAHA efficacy against human-derived corticotroph tumor (hCtT) (n = 8) was tested in vitro. SETTING National Institutes of Health. INTERVENTION SAHA (0.5 to 8 µM). MAIN OUTCOME MEASURES AtT-20 and hCtT cell survival, in vitro/invivo ACTH measurements. RESULTS SAHA (1 µM) reduced AtT-20 viability to 75% at 24 hours, 43% at 48 hours (analysis of variance; P = 0.002). Apoptosis was confirmed with elevated BAX/Bcl2 ratio and FACS. Intriguingly, early (3-hour) significant decline (70%; P < 0.0001) of secreted ACTH and diminished POMC transcription was observed with SAHA (1 µM). Microarray analysis revealed a direct association between liver X receptor alpha (LXRα) and POMC expression. Accordingly, SAHA reduced LXRα in AtT-20 cells but not in normal murine corticotrophs. Xenografted nude-mice tumor involution (126 ± 33/160 ± 35 vs 337 ± 49 mm3; P = 0.0005) was observed with 5-day intraperitoneal SAHA, with reversal of elevated ACTH (P < 0.0001). SAHA did not affect serum ACTH in nontumor mice. Lastly, we confirmed that SAHA (1 µM/24 h) decreased hCtT survival (78.92%; P = 0.0007) and ACTH secretion (83.64%; P = 0.03). CONCLUSION Our findings demonstrate SAHA's efficacy in reducing survival and ACTH secretion in AtT-20 and hCtT cells, providing a potential intervention for recurrent/unremitting CD.
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Affiliation(s)
- Jie Lu
- Neurosurgery Unit for Pituitary and Inheritable Diseases, National Institute of Neurologic Diseases and Stroke, Bethesda, Maryland 20892
| | - Grégoire P. Chatain
- Neurosurgery Unit for Pituitary and Inheritable Diseases, National Institute of Neurologic Diseases and Stroke, Bethesda, Maryland 20892
| | - Alejandro Bugarini
- Surgical Neurology Branch, National Institute of Neurologic Diseases and Stroke, Bethesda, Maryland 20892
| | - Xiang Wang
- Surgical Neurology Branch, National Institute of Neurologic Diseases and Stroke, Bethesda, Maryland 20892
| | - Dragan Maric
- Flow Cytometry Core Facility, National Institute of Neurologic Diseases and Stroke, Bethesda, Maryland 20892
| | - Stuart Walbridge
- Surgical Neurology Branch, National Institute of Neurologic Diseases and Stroke, Bethesda, Maryland 20892
| | - Zhengping Zhuang
- Surgical Neurology Branch, National Institute of Neurologic Diseases and Stroke, Bethesda, Maryland 20892
| | - Prashant Chittiboina
- Neurosurgery Unit for Pituitary and Inheritable Diseases, National Institute of Neurologic Diseases and Stroke, Bethesda, Maryland 20892
- Surgical Neurology Branch, National Institute of Neurologic Diseases and Stroke, Bethesda, Maryland 20892
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Once and for all, LXRα and LXRβ are gatekeepers of the endocrine system. Mol Aspects Med 2016; 49:31-46. [DOI: 10.1016/j.mam.2016.04.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 03/08/2016] [Accepted: 04/10/2016] [Indexed: 01/08/2023]
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Effects of RXR Agonists on Cell Proliferation/Apoptosis and ACTH Secretion/Pomc Expression. PLoS One 2015; 10:e0141960. [PMID: 26714014 PMCID: PMC4695086 DOI: 10.1371/journal.pone.0141960] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Accepted: 10/15/2015] [Indexed: 12/11/2022] Open
Abstract
Various retinoid X receptor (RXR) agonists have recently been developed, and some of them have shown anti-tumor effects both in vivo and in vitro. However, there has been no report showing the effects of RXR agonists on Cushing’s disease, which is caused by excessive ACTH secretion in a corticotroph tumor of the pituitary gland. Therefore, we examined the effects of synthetic RXR pan-agonists HX630 and PA024 on the proliferation, apoptosis, ACTH secretion, and pro-opiomelanocortin (Pomc) gene expression of murine pituitary corticotroph tumor AtT20 cells. We demonstrated that both RXR agonists induced apoptosis dose-dependently in AtT20 cells, and inhibited their proliferation at their higher doses. Microarray analysis identified a significant gene network associated with caspase 3 induced by high dose HX630. On the other hand, HX630, but not PA024, inhibited Pomc transcription, Pomc mRNA expression, and ACTH secretion dose-dependently. Furthermore, we provide new evidence that HX630 negatively regulates the Pomc promoter activity at the transcriptional level due to the suppression of the transcription factor Nur77 and Nurr1 mRNA expression and the reduction of Nur77/Nurr1 heterodimer recruiting to the Pomc promoter region. We also demonstrated that the HX630-mediated suppression of the Pomc gene expression was exerted via RXRα. Furthermore, HX630 inhibited tumor growth and decreased Pomc mRNA expression in corticotroph tumor cells in female nude mice in vivo. Thus, these results indicate that RXR agonists, especially HX630, could be a new therapeutic candidate for Cushing’s disease.
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Mengeling BJ, Furlow JD. Pituitary specific retinoid-X receptor ligand interactions with thyroid hormone receptor signaling revealed by high throughput reporter and endogenous gene responses. Toxicol In Vitro 2015; 29:1609-18. [PMID: 26096596 DOI: 10.1016/j.tiv.2015.06.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 05/26/2015] [Accepted: 06/18/2015] [Indexed: 11/25/2022]
Abstract
Disruption of thyroid hormone (TH) signaling can compromise vital processes both during development and in the adult. We previously reported on high-throughput screening experiments for man-made TH disruptors using a stably integrated line of rat pituitary cells, GH3.TRE-Luc, in which a thyroid hormone receptor (TR) response element drives luciferase (Luc) expression. In these experiments, several retinoid/rexinoid compounds activated the reporter. Here we show that all-trans and 13-cis retinoic acid appear to function through the heterodimer partners of TRs, retinoid-X receptors (RXRs), as RXR antagonists abrogated retinoid-induced activation. The retinoids also induced known endogenous TR target genes, showing good correlation with Luc activity. Synthetic RXR-specific agonists significantly activated all tested TR target genes, but interestingly, retinoid/rexinoid activation was more consistent between genes than the extent of T3-induced activation. In contrast, the retinoids neither activated the Luc reporter construct in transient transfection assays in the human hepatocarcinoma cell line HuH7, nor two of the same T3-induced genes examined in pituitary cells. These data demonstrate the suitability and sensitivity of GH3.TRE-Luc cells for screening chemical compound libraries for TH disruption and suggest that the extent of disruption can vary on a cell type and gene-specific bases, including an underappreciated contribution by RXRs.
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Affiliation(s)
- Brenda J Mengeling
- Department of Neurobiology, Physiology and Behavior, 1 Shields Avenue, University of California Davis, Davis, CA 95616, United States
| | - J David Furlow
- Department of Neurobiology, Physiology and Behavior, 1 Shields Avenue, University of California Davis, Davis, CA 95616, United States.
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Antihyperglycemic mechanism of metformin occurs via the AMPK/LXRα/POMC pathway. Sci Rep 2015; 5:8145. [PMID: 25634597 PMCID: PMC4311245 DOI: 10.1038/srep08145] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 01/09/2015] [Indexed: 01/27/2023] Open
Abstract
Metformin is a first-line drug for treating type 2 diabetes. Although metformin is known to phosphorylate AMP-activated protein kinase (AMPK), it is unclear how the glucose-lowering effect of metformin is related to AMPK activation. The aim of this study was to identify the urinary endogenous metabolites affected by metformin and to identify the novel underlying molecular mechanisms related to its anti-diabetic effect. Fourteen healthy male subjects were orally administered metformin (1000 mg) once. First morning urine samples were taken before and after administration to obtain metabolomic data. We then further investigated the anti-diabetic mechanism of metformin in vitro and in vivo. The fluctuation of the metabolite cortisol indicated that the neuroendocrine system was involved in the anti-diabetic effect of metformin. Actually we found that metformin induced AMPK/liver X receptor α (LXRα) phosphorylation, followed by pro-opiomelanocortin (POMC) suppression in rat pituitary cells. We confirmed this result by administering metformin in an animal study. Given that cortisol stimulates gluconeogenesis, we propose the anti-hyperglycemic effect of metformin is attributed to reduced POMC/adrenocorticotropic hormone (ACTH)/cortisol levels following AMPK/LXRα phosphorylation in the pituitaries.
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Freitas J, Miller N, Mengeling BJ, Xia M, Huang R, Houck K, Rietjens IMCM, Furlow JD, Murk AJ. Identification of thyroid hormone receptor active compounds using a quantitative high-throughput screening platform. Curr Chem Genom Transl Med 2014; 8:36-46. [PMID: 24772387 PMCID: PMC3999704 DOI: 10.2174/2213988501408010036] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Revised: 12/09/2013] [Accepted: 12/12/2013] [Indexed: 02/02/2023] Open
Abstract
To adapt the use of GH3.TRE-Luc reporter gene cell line for a quantitative high-throughput screening (qHTS)
platform, we miniaturized the reporter gene assay to a 1536-well plate format. 1280 chemicals from the Library of Pharmacologically
Active Compounds (LOPAC) and the National Toxicology Program (NTP) 1408 compound collection
were analyzed to identify potential thyroid hormone receptor (TR) agonists and antagonists. Of the 2688 compounds
tested, eight scored as potential TR agonists when the positive hit cut-off was defined at ≥10% efficacy, relative to maximal
triiodothyronine (T3) induction, and with only one of those compounds reaching ≥20% efficacy. One common class of
compounds positive in the agonist assays were retinoids such as all-trans retinoic acid, which are likely acting via the retinoid-X receptor, the heterodimer partner with the TR. Five potential TR antagonists were identified, including the antiallergy
drug tranilast and the anxiolytic drug SB 205384 but also some cytotoxic compounds like 5-fluorouracil. None of
the inactive compounds were structurally related to T3, nor had been reported elsewhere to be thyroid hormone disruptors,
so false negatives were not detected. None of the low potency (>100µM) TR agonists resembled T3 or T4, thus these may
not bind directly in the ligand-binding pocket of the receptor. For TR agonists, in the qHTS, a hit cut-off of ≥20% efficacy
at 100 µM may avoid identification of positives with low or no physiological relevance. The miniaturized GH3.TRE-Luc
assay offers a promising addition to the in vitro test battery for endocrine disruption, and given the low percentage of
compounds testing positive, its high-throughput nature is an important advantage for future toxicological screening.
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Affiliation(s)
- Jaime Freitas
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands ; Group of Cell Activation and Gene Expression, Institute for Molecular and Cellular Biology, University of Porto, Porto, Portugal
| | - Nicole Miller
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Brenda J Mengeling
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis 95616, USA
| | - Menghang Xia
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Ruili Huang
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Keith Houck
- National Center for Computational Toxicology, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands
| | - J David Furlow
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis 95616, USA
| | - Albertinka J Murk
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands ; Subdepartment of Environmental Technology, Wageningen University, and Wageningen-IMARES, Axis Z (Building number 118), Room TT.1.100, Bornse Weilanden 96708, WG Wageningen, The Netherlands
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Parikh M, Patel K, Soni S, Gandhi T. Liver X Receptor: A Cardinal Target for Atherosclerosis and Beyond. J Atheroscler Thromb 2014. [DOI: 10.5551/jat.19778] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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Ishida E, Hashimoto K, Okada S, Satoh T, Yamada M, Mori M. Thyroid hormone receptor and liver X receptor competitively up-regulate human selective Alzheimer’s disease indicator-1 gene expression at the transcriptional levels. Biochem Biophys Res Commun 2013; 432:513-8. [DOI: 10.1016/j.bbrc.2013.02.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 02/04/2013] [Indexed: 10/27/2022]
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Evans JF, Islam S, Urade Y, Eguchi N, Ragolia L. The lipocalin-type prostaglandin D2 synthase knockout mouse model of insulin resistance and obesity demonstrates early hypothalamic-pituitary-adrenal axis hyperactivity. J Endocrinol 2013; 216:169-80. [PMID: 23151358 DOI: 10.1530/joe-12-0275] [Citation(s) in RCA: 14] [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: 02/05/2023]
Abstract
Obesity and diabetes are closely associated with hyperactivation of the hypothalamic-pituitary-adrenal (HPA) axis. In this study, the diet-induced obese C57BL/6 mouse was used to test the hypothesis that chronically elevated metabolic parameters associated with the development of obesity such as cholesterol and glucose can aggravate basal HPA axis activity. Because the lipocalin-type prostaglandin D(2) synthase (L-PGDS) knockout (KO) mouse is a model of accelerated insulin resistance, glucose intolerance, and obesity, it was further hypothesized that HPA activity would be greater in this model. Starting at 8 weeks of age, the L-PGDS KO and C57BL/6 mice were maintained on a low-fat or high-fat diet. After 20 or 37 weeks, fasting metabolic parameters and basal HPA axis hormones were measured and compared between genotypes. Correlation analyses were performed to identify associations between obesity-related chronic metabolic changes and changes in the basal activity of the HPA axis. Our results have identified strong positive correlations between total cholesterol, LDL-cholesterol, glucose, and HPA axis hormones that increase with age in the C57BL/6 mice. These data confirm that obesity-related elevations in cholesterol and glucose can heighten basal HPA activity. Additionally, the L-PGDS KO mice show early elevations in HPA activity with no age-related changes relative to the C57BL/6 mice.
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Affiliation(s)
- Jodi F Evans
- Biomedical Research Core, Winthrop University Hospital, 222 Station Plaza North, Suite 505-B, Mineola, New York 11501, USA
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Kruse MS, Rey M, Vega MC, Coirini H. Alterations of LXRα and LXRβ expression in the hypothalamus of glucose-intolerant rats. J Endocrinol 2012; 215:51-8. [PMID: 22836489 DOI: 10.1530/joe-12-0088] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Liver X receptor (LXR) α and β are nuclear receptors that are crucial for the regulation of carbohydrate and lipid metabolism. Activation of LXRs in the brain facilitates cholesterol clearance and improves cognitive deficits, thus they are considered as promising drug targets to treat diseases such as atherosclerosis and Alzheimer's disease. Nevertheless, little is known about the function and localization of LXRs in the brain. Here, we studied the expression of LXR in the brains of rats that received free access to 10% (w/v) fructose group (FG) in their beverages or water control drinks (control group (CG)). After 6 weeks rats in the FG presented with hypertriglyceridemia, hyperinsulinemia, and became glucose intolerant, suggesting a progression toward type 2 diabetes. We found that hypothalamic LXR expression was altered in fructose-fed rats. Rats in the FG presented with a decrease in LXRβ levels while showing an increase in LXRα expression in the hypothalamus but not in the hippocampus, cerebellum, or neocortex. Moreover, both LXRα and β expression correlated negatively with insulin and triglyceride levels. Interestingly, LXRβ showed a negative correlation with the area under the curve during the glucose tolerance test in the CG and a positive correlation in the FG. Immunocytochemistry revealed that the paraventricular and ventromedial nuclei express mainly LXRα whereas the arcuate nucleus expresses LXRβ. Both LXR immunosignals were found in the median preoptic area. This is the first study showing a relationship between glucose and lipid homeostasis and the expression of LXRs in the hypothalamus, suggesting that LXRs may trigger neurochemical and neurophysiological responses for the control of food intake and energy expenditure through these receptors.
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Affiliation(s)
- María Sol Kruse
- Laboratorio de Neurobiología, Instituto de Biología y Medicina Experimental, Vuelta de Obligado 2490, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
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Salman ED, He D, Runge-Morris M, Kocarek TA, Falany CN. Site-directed mutagenesis of human cytosolic sulfotransferase (SULT) 2B1b to phospho-mimetic Ser348Asp results in an isoform with increased catalytic activity. J Steroid Biochem Mol Biol 2011; 127:315-23. [PMID: 21855633 PMCID: PMC3220804 DOI: 10.1016/j.jsbmb.2011.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 06/29/2011] [Accepted: 07/26/2011] [Indexed: 10/17/2022]
Abstract
Human SULT2B1b is distinct from other SULT isoforms due to the presence of unique amino (N)- and carboxy (C)-terminal peptides. Using site-directed mutagenesis, it was determined that phosphorylation of Ser348 was associated with nuclear localization. To investigate the effects of this phosphorylation of Ser348 on activity and cellular localization, an in silico molecular mimic was generated by mutating Ser348 to an Asp. The Asp residue mimics the shape and charge of a phospho-Ser and homology models of SULT2B1b-phospho-S348 and SULT2B1b-S348D suggest a similar significant structural rearrangement in the C-terminal peptide. To evaluate the functional consequences of this post-translational modification and predicted rearrangement, 6His-SULT2B1b-S348D was synthesized, expressed, purified and characterized. The 6His-SULT2B1b-S348D has a specific activity for DHEA sulfation ten-fold higher than recombinant 6His-SULT2B1b (209.6 and 21.8pmolmin(-1)mg(-1), respectively). Similar to native SULT2B1b, gel filtration chromatography showed SULT2B1b-S348D was enzymatically active as a homodimer. Stability assays comparing SULT2B1b and SUL2B1b-S348 demonstrated that SULT2B1b is 60% less thermostable than SULT2B1b-348D. The increased stability and sulfation activity allowed for better characterization of the sulfation kinetics for putative substrates as well as the determination of dissociation constants that were difficult to obtain with wild-type (WT) 6His-SULT2B1b. The K(D)s for DHEA and PAPS binding to 6His-SULT2B1b-S348D were 650±7nM and 265±4nM, respectively, whereas K(D)s for binding of substrates to the WT enzyme could not be determined. Characterization of the molecular mimic SULT2B1b-S348D provides a better understanding for the role of the unique structure of SULT2B1b and its effect on sulfation activity, and has allowed for improved kinetic characterization of the SULT2B1b enzyme.
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Affiliation(s)
- Emily D. Salman
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Dongning He
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Melissa Runge-Morris
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48201
| | - Thomas A. Kocarek
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48201
| | - Charles N. Falany
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294
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Pecori Giraldi F, Cassarino F, Pagliardini L, Asnaghi V, Cavagnini F. The human POMC gene promoter: where do we stand? J Endocrinol Invest 2011; 34:454-60. [PMID: 21464606 DOI: 10.1007/bf03346713] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Proopiomelanocortin (POMC) is crucial for several life-essential functions and its regulation has been studied extensively in the past decades. The first studies provided the framework for POMC promoter activity, namely the identification for the major response elements contained in the promoter, e.g., the glucocorticoid response element, the Nur response element, while subsequent studies showed the importance of cooperation and interplay between transcription factors to achieve optimal promoter activity. The involvement of constitutive repressors of POMC transcription, such as Bmp4, provided the latest clues to our understanding of POMC promoter activity. This increased knowledge benefits the clinician as it allows genetic testing and early recognition of patients with congenital ACTH deficiency due to mutations in TPIT and paves the way to new medical treatments in Cushing's disease. The present review will illustrate the current standing on regulation of the human POMC promoter, focusing on its activity in corticotropes.
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Hashimoto K, Matsumoto S, Ishida E, Miura A, Horiguchi K, Ozawa A, Shibusawa N, Satoh T, Yamada M, Yamada S, Mori M. Liver X receptor-α/β expression ratio is increased in ACTH-secreting pituitary adenomas. Neurosci Lett 2011; 494:34-7. [PMID: 21356276 DOI: 10.1016/j.neulet.2011.02.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2010] [Revised: 02/05/2011] [Accepted: 02/18/2011] [Indexed: 02/07/2023]
Abstract
The liver X receptors (LXR-α and -β) are nuclear oxysterol receptors that play pivotal roles in regulating the expression of genes involved in cholesterol transport and metabolism. Recently, several groups have reported that the LXRs also regulate adrenal steroidogenesis. In the previous report, we demonstrated that LXR-α is dominantly expressed in the pituitary and that LXR-α positively regulates the proopiomelanocortin (POMC) gene promoter at the transcriptional level. In this report, we evaluated the expression levels of LXR-α and -β gene in the human pituitary tumor. Even though LXR-α mRNA levels are not significantly increased in ACTH-secreting adenomas, LXR-α/β expression ratio is significantly higher than other pituitary tumors including normal pituitaries. Furthermore, in At-T20 cells, which express POMC gene, overexpression of LXR-β decreased POMC gene promoter activities. Thus, we concluded that LXR-α/β gene expression ratio is a critical factor to activate POMC gene expression in ACTH-secreting pituitary adenomas.
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Affiliation(s)
- Koshi Hashimoto
- Department of Medicine and Molecular Science, Graduate School of Medicine, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8511, Gunma, Japan.
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Abstract
Chronic liver inflammation after murine bile duct ligation could evolve according to three interrelated phenotypes, which would have different metabolic, functional and histologic characteristics. Liver injury secondary to extrahepatic cholestasis would induce an early ischemic-reperfusion phenotype with cholangiocyte depolarization, abnormal ion transport, hypometabolism with anaerobic glycolysis and hepatocytic apoptosis. This phenotype, in turn, could trigger the switch to a leukocytic phenotype by the cholangiocytes, with an intense anaplerotic activity, hypermetabolism, extracellular matrix degradation and moderated proliferation to create a pseudotissue with metabolic autonomy and paracrine functions. In the long-term cholestasis-drive tumorigenesis, the tumorous tissue would principally consist of cholangiocyte parenchyma, with an impressive biosynthetic activity through the tricarboxylic cell cycle. In terms of the tumorous stroma, made up by fibroplasia and angiogenesis, it would favor the tumor trophism. In conclusion, the great intensity and persistence in the expression of these phenotypes by the cholestatic cholangiocyte would favor chronic inflammatory tumorigenesis.
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Shridas P, Bailey WM, Boyanovsky BB, Oslund RC, Gelb MH, Webb NR. Group X secretory phospholipase A2 regulates the expression of steroidogenic acute regulatory protein (StAR) in mouse adrenal glands. J Biol Chem 2010; 285:20031-9. [PMID: 20421306 DOI: 10.1074/jbc.m109.090423] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We developed C57BL/6 mice with targeted deletion of group X secretory phospholipase A(2) (GX KO). These mice have approximately 80% higher plasma corticosterone concentrations compared with wild-type (WT) mice under both basal and adrenocorticotropic hormone (ACTH)-induced stress conditions. This increased corticosterone level was not associated with increased circulating ACTH or a defect in the hypothalamic-pituitary axis as evidenced by a normal response to dexamethasone challenge. Primary cultures of adrenal cells from GX KO mice exhibited significantly increased corticosteroid secretion compared with WT cells. Conversely, overexpression of GX secretory phospholipase A(2) (sPLA(2)), but not a catalytically inactive mutant form of GX sPLA(2), significantly reduced steroid production 30-40% in Y1 mouse adrenal cell line. This effect was reversed by the sPLA(2) inhibitor, indoxam. Silencing of endogenous M-type receptor expression did not restore steroid production in GX sPLA(2)-overexpressing Y1 cells, ruling out a role for this sPLA(2) receptor in this regulatory process. Expression of steroidogenic acute regulatory protein (StAR), the rate-limiting protein in corticosteroid production, was approximately 2-fold higher in adrenal glands of GX KO mice compared with WT mice, whereas StAR expression was suppressed in Y1 cells overexpressing GX sPLA(2). Results from StAR-promoter luciferase reporter gene assays indicated that GX sPLA(2) antagonizes StAR promoter activity and liver X receptor-mediated StAR promoter activation. In summary, GX sPLA(2) is expressed in mouse adrenal glands and functions to negatively regulate corticosteroid synthesis, most likely by negatively regulating StAR expression.
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Affiliation(s)
- Preetha Shridas
- Graduate Center for Nutritional Sciences, the Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, Kentucky 40536, USA
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Finn DA, Beckley EH, Kaufman KR, Ford MM. Manipulation of GABAergic steroids: Sex differences in the effects on alcohol drinking- and withdrawal-related behaviors. Horm Behav 2010; 57:12-22. [PMID: 19615369 PMCID: PMC2813380 DOI: 10.1016/j.yhbeh.2009.07.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 07/02/2009] [Accepted: 07/07/2009] [Indexed: 12/16/2022]
Abstract
Alcoholism is a complex disorder that represents an important contributor to health problems worldwide and that is difficult to encompass with a single preclinical model. Additionally, alcohol (ethanol) influences the function of many neurotransmitter systems, with the interaction at gamma-aminobutyric acid(A) (GABA(A)) receptors being integral for ethanol's reinforcing and several withdrawal-related effects. Given that some steroid derivatives exert rapid membrane actions as potent positive modulators of GABA(A) receptors and exhibit a similar pharmacological profile to that of ethanol, studies in the laboratory manipulated GABAergic steroid levels and determined the impact on ethanol's rewarding- and withdrawal-related effects. Manipulations focused on the progesterone metabolite allopregnanolone (ALLO), since it is the most potent endogenous GABAergic steroid identified. The underlying hypothesis is that fluctuations in GABAergic steroid levels (and the resultant change in GABAergic inhibitory tone) alter sensitivity to ethanol, leading to changes in the positive motivational or withdrawal-related effects of ethanol. This review describes results that emphasize sex differences in the effects of ALLO and the manipulation of its biosynthesis on alcohol reward-versus withdrawal-related behaviors, with females being less sensitive to the modulatory effects of ALLO on ethanol-drinking behaviors but more sensitive to some steroid manipulations on withdrawal-related behaviors. These findings imply the existence of sex differences in the sensitivity of GABA(A) receptors to GABAergic steroids within circuits relevant to alcohol reward versus withdrawal. Thus, sex differences in the modulation of GABAergic neurosteroids may be an important consideration in understanding and developing therapeutic interventions in alcoholics.
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Affiliation(s)
- Deborah A Finn
- Department of Veterans Affairs Medical Research, Portland, OR 97239, USA.
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He J, Cheng Q, Xie W. Minireview: Nuclear receptor-controlled steroid hormone synthesis and metabolism. Mol Endocrinol 2009; 24:11-21. [PMID: 19762543 DOI: 10.1210/me.2009-0212] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Steroid hormones are essential in normal physiology whereas disruptions in hormonal homeostasis represent an important etiological factor for many human diseases. Steroid hormones exert most of their functions through the binding and activation of nuclear hormone receptors (NRs or NHRs), a superfamily of DNA-binding and often ligand-dependent transcription factors. In recent years, accumulating evidence has suggested that NRs can also regulate the biosynthesis and metabolism of steroid hormones. This review will focus on the recent progress in our understanding of the regulatory role of NRs in hormonal homeostasis and the implications of this regulation in physiology and diseases.
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Affiliation(s)
- Jinhan He
- Center for Pharmacogenetics, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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