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Chang J, Xu Y, Fu Y, Liu J, Jiang D, Pan J, Ouyang H, Liu W, Xu J, Tian Y, Huang Y, Ruan J, Shen X. The dynamic landscape of chromatin accessibility and active regulatory elements in the mediobasal hypothalamus influences the seasonal activation of the reproductive axis in the male quail under long light exposure. BMC Genomics 2024; 25:197. [PMID: 38373887 PMCID: PMC10877898 DOI: 10.1186/s12864-024-10097-5] [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: 09/18/2023] [Accepted: 02/07/2024] [Indexed: 02/21/2024] Open
Abstract
BACKGROUND In cold and temperate zones, seasonal reproduction plays a crucial role in the survival and reproductive success of species. The photoperiod influences reproductive processes in seasonal breeders through the hypothalamic-pituitary-gonadal (HPG) axis, in which the mediobasal hypothalamus (MBH) serves as the central region responsible for transmitting light information to the endocrine system. However, the cis-regulatory elements and the transcriptional activation mechanisms related to seasonal activation of the reproductive axis in MBH remain largely unclear. In this study, an artificial photoperiod program was used to induce the HPG axis activation in male quails, and we compared changes in chromatin accessibility changes during the seasonal activation of the HPG axis. RESULTS Alterations in chromatin accessibility occurred in the mediobasal hypothalamus (MBH) and stabilized at LD7 during the activation of the HPG axis. Most open chromatin regions (OCRs) are enriched mainly in introns and distal intergenic regions. The differentially accessible regions (DARs) showed enrichment of binding motifs of the RFX, NKX, and MEF family of transcription factors that gained-loss accessibility under long-day conditions, while the binding motifs of the nuclear receptor (NR) superfamily and BZIP family gained-open accessibility. Retinoic acid signaling and GTPase-mediated signal transduction are involved in adaptation to long days and maintenance of the HPG axis activation. According to our footprint analysis, three clock-output genes (TEF, DBP, and HLF) and the THRA were the first responders to long days in LD3. THRB, NR3C2, AR, and NR3C1 are the key players associated with the initiation and maintenance of the activation of the HPG axis, which appeared at LD7 and tended to be stable under long-day conditions. By integrating chromatin and the transcriptome, three genes (DIO2, SLC16A2, and PDE6H) involved in thyroid hormone signaling showed differential chromatin accessibility and expression levels during the seasonal activation of the HPG axis. TRPA1, a target of THRB identified by DAP-seq, was sensitive to photoactivation and exhibited differential expression levels between short- and long-day conditions. CONCLUSION Our data suggest that trans effects were the main factors affecting gene expression during the seasonal activation of the HPG axis. This study could lead to further research on the seasonal reproductive behavior of birds, particularly the role of MBH in controlling seasonal reproductive behavior.
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Affiliation(s)
- Jianye Chang
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Yanglong Xu
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Yuting Fu
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Jiaxin Liu
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Danli Jiang
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Jianqiu Pan
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Hongjia Ouyang
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Wenjun Liu
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Jin Xu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510642, China
| | - Yunbo Tian
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Yunmao Huang
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China.
| | - Jue Ruan
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China.
| | - Xu Shen
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China.
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Farasati Far B, Broomand Lomer N, Gharedaghi H, Sahrai H, Mahmoudvand G, Karimi Rouzbahani A. Is beta-carotene consumption associated with thyroid hormone levels? Front Endocrinol (Lausanne) 2023; 14:1089315. [PMID: 37305054 PMCID: PMC10250628 DOI: 10.3389/fendo.2023.1089315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 05/09/2023] [Indexed: 06/13/2023] Open
Abstract
The thyroid hormones play a pivotal role in various physiological processes, including growth, metabolism regulation, and reproduction. While non-modifiable factors are known to impact thyroid function, such as genetics and age, nutritional factors are also important. Diets rich in selenium and iodine are conventionally acknowledged to be beneficial for the production and release of thyroid hormones. Recent studies have suggested a potential link between beta-carotene, a precursor to vitamin A (retinol), and thyroid function. Beta-carotene is known for its antioxidant properties and has been shown to play a role in the prevention of various clinical conditions such as cancer and cardiovascular and neurological diseases. However, its impact on thyroid function is still unclear. Some studies have suggested a positive association between beta-carotene levels and thyroid function, while others have found no significant effect. Conversely, the hormone produced by the thyroid gland, thyroxine, enhances the conversion of beta-carotene to retinol. Furthermore, vitamin A derivatives are being explored as potential therapeutic options for thyroid malignancies. In this review, we highlight the mechanisms through which beta-carotene/retinol and thyroid hormones interact and review the findings of clinical studies examining the association between beta-carotene consumption and thyroid hormone levels. Our review underscores the need for further research to clarify the relationship between beta-carotene and thyroid function.
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Affiliation(s)
- Bahareh Farasati Far
- Department of Chemistry, Iran University of Science and Technology, Tehran, Iran
| | | | | | - Hadi Sahrai
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Golnaz Mahmoudvand
- Student Research Committee, Lorestan University of Medical Sciences, Khorramabad, Iran
- USERN Office, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Arian Karimi Rouzbahani
- Student Research Committee, Lorestan University of Medical Sciences, Khorramabad, Iran
- USERN Office, Lorestan University of Medical Sciences, Khorramabad, Iran
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Kubickova B, Martinkova S, Bohaciakova D, Nezvedova M, Liu R, Brozman O, Spáčil Z, Hilscherova K. Effects of all-trans and 9-cis retinoic acid on differentiating human neural stem cells in vitro. Toxicology 2023; 487:153461. [PMID: 36805303 PMCID: PMC10019519 DOI: 10.1016/j.tox.2023.153461] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/02/2023] [Accepted: 02/14/2023] [Indexed: 02/17/2023]
Abstract
Cyanobacterial blooms are known sources of environmentally-occurring retinoid compounds, including all-trans and 9-cis retinoic acids (RAs). The developmental hazard for aquatic organisms has been described, while the implications for human health hazard assessment are not yet sufficiently characterized. Here, we employ a human neural stem cell model that can differentiate in vitro into a mixed culture of neurons and glia. Cells were exposed to non-cytotoxic 8-1000 nM all-trans or 9-cis RA for 9-18 days (DIV13 and DIV22, respectively). Impact on biomarkers was analyzed on gene expression (RT-qPCR) and protein level (western blot and proteomics) at both time points; network patterning (immunofluorescence) on DIV22. RA exposure significantly concentration-dependently increased gene expression of retinoic acid receptors and the metabolizing enzyme CYP26A1, confirming the chemical-specific response of the model. Expression of thyroid hormone signaling-related genes remained mostly unchanged. Markers of neural progenitors/stem cells (PAX6, SOX1, SOX2, NESTIN) were decreased with increasing RA concentrations, though a basal population remained. Neural markers (DCX, TUJ1, MAP2, NeuN, SYP) remained unchanged or were decreased at high concentrations (200-1000 nM). Conversely, (astro-)glial marker S100β was increased concentration-dependently on DIV22. Together, the biomarker analysis indicates an RA-dependent promotion of glial cell fates over neural differentiation, despite the increased abundance of neural protein biomarkers during differentiation. Interestingly, RA exposure induced substantial changes to the cell culture morphology: while low concentrations resulted in a network-like differentiation pattern, high concentrations (200-1000 nM RA) almost completely prevented such network patterning. After functional confirmation for implications in network function, such morphological features could present a proxy for network formation assessment, an apical key event in (neuro-)developmental Adverse Outcome Pathways. The described application of a human in vitro model for (developmental) neurotoxicity to emerging environmentally-relevant retinoids contributes to the evidence-base for the use of differentiating human in vitro models for human health hazard and risk assessment.
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Affiliation(s)
- Barbara Kubickova
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Sarka Martinkova
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Dasa Bohaciakova
- Masaryk University, Faculty of Medicine, Department of Histology and Embryology, Kamenice 3, 62500 Brno, Czech Republic.
| | - Marketa Nezvedova
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Runze Liu
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Ondrej Brozman
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Zdeněk Spáčil
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
| | - Klara Hilscherova
- RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic.
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Lyu Y, Xiu Q, Zuo H, Xu G, Cui X, Sun Z, Mi R, Wu L. Effect of vitamin A on the relationship between maternal thyroid hormones in early pregnancy and fetal growth: A prospective cohort study. Front Nutr 2022; 9:980853. [PMID: 36091237 PMCID: PMC9449534 DOI: 10.3389/fnut.2022.980853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/08/2022] [Indexed: 11/25/2022] Open
Abstract
Background Fetal growth patterns are influenced by maternal thyroid function and vitamin A level during pregnancy. Vitamin A presents interactions with thyroid tissues and hormonal systems. We examined whether vitamin A status modified the associations of maternal thyroid hormones in early pregnancy and fetal growth outcomes among euthyroid pregnant women in a prospective cohort study (n = 637). Methods We performed multiple linear regression and multinomial logistic regression analysis to investigate the effects of thyroid hormones in early pregnancy on fetal growth according to different levels of serum vitamin A based on median value. Results A 1 pmol/L increase in maternal free triiodothyronine (FT3) levels was associated with an increased birth weight of 0.080 kg (p = 0.023) in women with lower maternal vitamin A levels in early pregnancy. Increased maternal free thyroxine (FT4) was associated with decreased odds for both small size for gestational age (SGA) [odds ratios (OR) = 0.66, 95% confidence interval (CI): 0.45–0.95] and large size for gestational age (LGA) (OR = 0.66, 95% CI: 0.45–0.98) in women with higher vitamin A level in early pregnancy after adjustment for maternal prepregnancy body mass index, gestational weight gain, maternal employed, parity, gestational week at sampling, and gestational diabetes mellitus. Conclusions In Chinese pregnant women without overt thyroid dysfunction, maternal FT4 in early pregnancy was positively associated with optimal fetal growth among women with higher serum vitamin A concentrations.
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Affiliation(s)
- Yanyu Lyu
- Experiment Center, Capital Institute of Pediatrics, Beijing, China
| | - Qingyong Xiu
- Department of Pediatrics, Beijing Daxing Maternal and Child Care Hospital, Beijing, China
| | - Hanxiao Zuo
- Experiment Center, Capital Institute of Pediatrics, Beijing, China
- School of Public Health, University of Alberta, Edmonton, AB, Canada
| | - Guangfei Xu
- Department of Nutrition, School of Public Health, Nantong University, Nantong, China
| | - Xiaodai Cui
- Experiment Center, Capital Institute of Pediatrics, Beijing, China
| | - Zhenfeng Sun
- Department of Obstetrics, Beijing Daxing Maternal and Child Care Hospital, Beijing, China
| | - Rong Mi
- Department of Neonatology, Children's Hospital of Capital Institute of Pediatrics, Beijing, China
| | - Lijun Wu
- Department of Epidemiology, Capital Institute of Pediatrics, Beijing, China
- *Correspondence: Lijun Wu
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Du ZP, Feng S, Li YL, Li R, Lv J, Ren WQ, Feng QW, Liu P, Wang QN. Di-(2-ethylhexyl) phthalate inhibits expression and internalization of transthyretin in human placental trophoblastic cells. Toxicol Appl Pharmacol 2020; 394:114960. [PMID: 32201330 DOI: 10.1016/j.taap.2020.114960] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/29/2020] [Accepted: 03/18/2020] [Indexed: 11/23/2022]
Abstract
During pregnancy, fetal thyroid hormones (THs) are dependent on maternal placental transport and their physiological level is crucial for normal fetal neurodevelopment. Earlier research has shown that Di-(2-ethylhexyl) phthalate (DEHP) disrupts thyroid function and THs homeostasis in pregnant women and fetuses, and affects placental THs transport. However, the underlying mechanisms are poorly understood. The present study, therefore, aimed to systematically investigate the potential mechanisms of DEHP-induced disruption in the placental THs transport using two human placental trophoblastic cells, HTR-8/SVneo cells and JEG-3 cells. While the exposure of DEHP at the doses of 0-400 μM for 24 h did not affect cell viability, we found reduced consumption of T3 and T4 in the culture medium of HTR-8/Svneo cells treated with DEHP at 400 μM. DEHP treatment did not affect T3 uptake and the expression of monocarboxylate transporters 8 (MCT8) and organic anion transporters 1C1 (OATP1C1). However, DEHP significantly inhibited transthyretin (TTR) internalization, down-regulated TTR, deiodinase 2 (DIO2), and thyroid hormone receptors mRNA expression and protein levels, and up-regulated deiodinase 3 (DIO3) protein levels in a dose-dependent manner. These results indicate that DEHP acts on placental trophoblast cells, inhibits its TTR internalization, down-regulates TTR expression and affects the expression of DIO2, DIO3, and thyroid hormone receptor. These may be the mechanisms by which PAEs affects THs transport through placental.
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Affiliation(s)
- Zhi-Ping Du
- Department of Toxicology, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes/Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China
| | - Shun Feng
- Department of Toxicology, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes/Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China
| | - Yan-Ling Li
- Department of Toxicology, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes/Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China
| | - Rong Li
- Department of Toxicology, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes/Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China
| | - Jia Lv
- Department of Toxicology, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes/Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China
| | - Wen-Qiang Ren
- Department of Toxicology, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes/Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China
| | - Qiang-Wei Feng
- Department of Toxicology, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes/Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China
| | - Ping Liu
- Department of Anatomy, School of Biomedical Sciences, Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
| | - Qu-Nan Wang
- Department of Toxicology, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes/Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, China.
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6
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Groeneweg S, van Geest FS, Peeters RP, Heuer H, Visser WE. Thyroid Hormone Transporters. Endocr Rev 2020; 41:5637505. [PMID: 31754699 DOI: 10.1210/endrev/bnz008] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/07/2019] [Indexed: 02/08/2023]
Abstract
Thyroid hormone transporters at the plasma membrane govern intracellular bioavailability of thyroid hormone. Monocarboxylate transporter (MCT) 8 and MCT10, organic anion transporting polypeptide (OATP) 1C1, and SLC17A4 are currently known as transporters displaying the highest specificity toward thyroid hormones. Structure-function studies using homology modeling and mutational screens have led to better understanding of the molecular basis of thyroid hormone transport. Mutations in MCT8 and in OATP1C1 have been associated with clinical disorders. Different animal models have provided insight into the functional role of thyroid hormone transporters, in particular MCT8. Different treatment strategies for MCT8 deficiency have been explored, of which thyroid hormone analogue therapy is currently applied in patients. Future studies may reveal the identity of as-yet-undiscovered thyroid hormone transporters. Complementary studies employing animal and human models will provide further insight into the role of transporters in health and disease. (Endocrine Reviews 41: 1 - 55, 2020).
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Affiliation(s)
- Stefan Groeneweg
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Ferdy S van Geest
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Robin P Peeters
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Heike Heuer
- Department of Endocrinology, Diabetes and Metabolism, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - W Edward Visser
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
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Balbisi A, AlAmari A, AlSaif F, AlOtaibi H, AlSaif F, AlAmari A, AlDakhil A, AlModayfer A, AlSyefi N. Effect of oral isotretinoin therapy on thyroid function in patients with moderate-to-severe acne vulgaris: A prospective study. JOURNAL OF DERMATOLOGY & DERMATOLOGIC SURGERY 2020. [DOI: 10.4103/jdds.jdds_64_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Draut H, Liebenstein T, Begemann G. New Insights into the Control of Cell Fate Choices and Differentiation by Retinoic Acid in Cranial, Axial and Caudal Structures. Biomolecules 2019; 9:E860. [PMID: 31835881 PMCID: PMC6995509 DOI: 10.3390/biom9120860] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 12/13/2022] Open
Abstract
Retinoic acid (RA) signaling is an important regulator of chordate development. RA binds to nuclear RA receptors that control the transcriptional activity of target genes. Controlled local degradation of RA by enzymes of the Cyp26a gene family contributes to the establishment of transient RA signaling gradients that control patterning, cell fate decisions and differentiation. Several steps in the lineage leading to the induction and differentiation of neuromesodermal progenitors and bone-producing osteogenic cells are controlled by RA. Changes to RA signaling activity have effects on the formation of the bones of the skull, the vertebrae and the development of teeth and regeneration of fin rays in fish. This review focuses on recent advances in these areas, with predominant emphasis on zebrafish, and highlights previously unknown roles for RA signaling in developmental processes.
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Stepien BK, Huttner WB. Transport, Metabolism, and Function of Thyroid Hormones in the Developing Mammalian Brain. Front Endocrinol (Lausanne) 2019; 10:209. [PMID: 31001205 PMCID: PMC6456649 DOI: 10.3389/fendo.2019.00209] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/14/2019] [Indexed: 12/22/2022] Open
Abstract
Ever since the discovery of thyroid hormone deficiency as the primary cause of cretinism in the second half of the 19th century, the crucial role of thyroid hormone (TH) signaling in embryonic brain development has been established. However, the biological understanding of TH function in brain formation is far from complete, despite advances in treating thyroid function deficiency disorders. The pleiotropic nature of TH action makes it difficult to identify and study discrete roles of TH in various aspect of embryogenesis, including neurogenesis and brain maturation. These challenges notwithstanding, enormous progress has been achieved in understanding TH production and its regulation, their conversions and routes of entry into the developing mammalian brain. The endocrine environment has to adjust when an embryo ceases to rely solely on maternal source of hormones as its own thyroid gland develops and starts to produce endogenous TH. A number of mechanisms are in place to secure the proper delivery and action of TH with placenta, blood-brain interface, and choroid plexus as barriers of entry that need to selectively transport and modify these hormones thus controlling their active levels. Additionally, target cells also possess mechanisms to import, modify and bind TH to further fine-tune their action. A complex picture of a tightly regulated network of transport proteins, modifying enzymes, and receptors has emerged from the past studies. TH have been implicated in multiple processes related to brain formation in mammals-neuronal progenitor proliferation, neuronal migration, functional maturation, and survival-with their exact roles changing over developmental time. Given the plethora of effects thyroid hormones exert on various cell types at different developmental periods, the precise spatiotemporal regulation of their action is of crucial importance. In this review we summarize the current knowledge about TH delivery, conversions, and function in the developing mammalian brain. We also discuss their potential role in vertebrate brain evolution and offer future directions for research aimed at elucidating TH signaling in nervous system development.
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Liu YY, Brent GA. Thyroid hormone and the brain: Mechanisms of action in development and role in protection and promotion of recovery after brain injury. Pharmacol Ther 2018; 186:176-185. [PMID: 29378220 DOI: 10.1016/j.pharmthera.2018.01.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Thyroid hormone (TH) is essential for normal brain development and may also promote recovery and neuronal regeneration after brain injury. TH acts predominantly through the nuclear receptors, TH receptor alpha (THRA) and beta (THRB). Additional factors that impact TH action in the brain include metabolism, activation of thyroxine (T4) to triiodothyronine (T3) by the enzyme 5'-deiodinase Type 2 (Dio2), inactivation by the enzyme 5-deiodinase Type 3 (Dio3) to reverse T3 (rT3), which occurs in glial cells, and uptake by the Mct8 transporter in neurons. Traumatic brain injury (TBI) is associated with inflammation, metabolic alterations and neural death. In clinical studies, central hypothyroidism, due to hypothalamic and pituitary dysfunction, has been found in some individuals after brain injury. TH has been shown, in animal models, to be protective for the damage incurred from brain injury and may have a role to limit injury and promote recovery. Although clinical trials have not yet been reported, findings from in vitro and in vivo models inform potential treatment strategies utilizing TH for protection and promotion of recovery after brain injury.
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Affiliation(s)
- Yan-Yun Liu
- Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, United States
| | - Gregory A Brent
- Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, United States.
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Brossaud J, Pallet V, Corcuff JB. Vitamin A, endocrine tissues and hormones: interplay and interactions. Endocr Connect 2017; 6:R121-R130. [PMID: 28720593 PMCID: PMC5551430 DOI: 10.1530/ec-17-0101] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 07/03/2017] [Accepted: 07/18/2017] [Indexed: 12/12/2022]
Abstract
Vitamin A (retinol) is a micronutrient critical for cell proliferation and differentiation. In adults, vitamin A and metabolites such as retinoic acid (RA) play major roles in vision, immune and brain functions, and tissue remodelling and metabolism. This review presents the physiological interactions of retinoids and endocrine tissues and hormonal systems. Two endocrine systems have been particularly studied. In the pituitary, retinoids targets the corticotrophs with a possible therapeutic use in corticotropinomas. In the thyroid, retinoids interfere with iodine metabolism and vitamin A deficiency aggravates thyroid dysfunction caused by iodine-deficient diets. Retinoids use in thyroid cancer appears less promising than expected. Recent and still controversial studies investigated the relations between retinoids and metabolic syndrome. Indeed, retinoids contribute to pancreatic development and modify fat and glucose metabolism. However, more detailed studies are needed before planning any therapeutic use. Finally, retinoids probably play more minor roles in adrenal and gonads development and function apart from their major effects on spermatogenesis.
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Affiliation(s)
- Julie Brossaud
- J Brossaud, Nuclear Medicine, University hospital of Bordeaux, Pessac, France
| | - Veronique Pallet
- V Pallet, NutriNeurO-INRA 1286 - Université Bdx 2, University of Bordeaux, Bordeaux, 33076 BORDEAUX , France
| | - Jean-Benoit Corcuff
- J Corcuff, Nuclear Medicine, University hospital of Bordeaux, Pessac, 33604, France
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Comptour A, Rouzaire M, Belville C, Bouvier D, Gallot D, Blanchon L, Sapin V. Nuclear retinoid receptors and pregnancy: placental transfer, functions, and pharmacological aspects. Cell Mol Life Sci 2016; 73:3823-37. [PMID: 27502420 PMCID: PMC11108506 DOI: 10.1007/s00018-016-2332-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 08/04/2016] [Indexed: 10/21/2022]
Abstract
Animal models of vitamin A (retinol) deficiency have highlighted its crucial role in reproduction and placentation, whereas an excess of retinoids (structurally or functionally related entities) can cause toxic and teratogenic effects in the embryo and foetus, especially in the first trimester of human pregnancy. Knock-out experimental strategies-targeting retinoid nuclear receptors RARs and RXRs have confirmed that the effects of vitamin A are mediated by retinoic acid (especially all-trans retinoic acid) and that this vitamin is essential for the developmental process. All these data show that the vitamin A pathway and metabolism are as important for the well-being of the foetus, as they are for that of the adult. Accordingly, during this last decade, extensive research on retinoid metabolism has yielded detailed knowledge on all the actors in this pathway, spurring the development of antagonists and agonists for therapeutic and research applications. Natural and synthetic retinoids are currently used in clinical practice, most often on the skin for the treatment of acne, and as anti-oncogenic agents in acute promyelocytic leukaemia. However, because of the toxicity and teratogenicity of retinoids during pregnancy, their pharmacological use needs a sound knowledge of their metabolism, molecular aspects, placental transfer, and action.
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Affiliation(s)
- Aurélie Comptour
- EA7281, Retinoids, Reproduction Developmental Diseases, School of Medicine, Clermont Université, Université d'Auvergne, 63000, Clermont-Ferrand, France
| | - Marion Rouzaire
- EA7281, Retinoids, Reproduction Developmental Diseases, School of Medicine, Clermont Université, Université d'Auvergne, 63000, Clermont-Ferrand, France
| | - Corinne Belville
- EA7281, Retinoids, Reproduction Developmental Diseases, School of Medicine, Clermont Université, Université d'Auvergne, 63000, Clermont-Ferrand, France
- GReD, Clermont Université, Université d'Auvergne, 63000, Clermont-Ferrand, France
| | - Damien Bouvier
- EA7281, Retinoids, Reproduction Developmental Diseases, School of Medicine, Clermont Université, Université d'Auvergne, 63000, Clermont-Ferrand, France
- Biochemistry and Molecular Biology Department, CHU Clermont-Ferrand, 63000, Clermont-Ferrand, France
| | - Denis Gallot
- EA7281, Retinoids, Reproduction Developmental Diseases, School of Medicine, Clermont Université, Université d'Auvergne, 63000, Clermont-Ferrand, France
- Obstetrics and Gynecology Department, CHU Clermont-Ferrand, 63000, Clermont-Ferrand, France
| | - Loïc Blanchon
- EA7281, Retinoids, Reproduction Developmental Diseases, School of Medicine, Clermont Université, Université d'Auvergne, 63000, Clermont-Ferrand, France
| | - Vincent Sapin
- EA7281, Retinoids, Reproduction Developmental Diseases, School of Medicine, Clermont Université, Université d'Auvergne, 63000, Clermont-Ferrand, France.
- Biochemistry and Molecular Biology Department, CHU Clermont-Ferrand, 63000, Clermont-Ferrand, France.
- Laboratoire de Biochimie Médicale, 4R3, Faculté de Médecine, 28 Place Henri-Dunant, BP38, 63001, Clermont-Ferrand Cedex, France.
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Ectopic cross-talk between thyroid and retinoic acid signaling: A possible etiology for spinal neural tube defects. Gene 2015; 573:254-60. [DOI: 10.1016/j.gene.2015.07.048] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 05/20/2015] [Accepted: 07/14/2015] [Indexed: 12/17/2022]
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Zibara K, El-Zein A, Joumaa W, El-Sayyad M, Mondello S, Kassem N. Thyroxine transfer from cerebrospinal fluid into choroid plexus and brain is affected by brefeldin A, low sodium, BCH, and phloretin, in ventriculo-cisternal perfused rabbits. Front Cell Dev Biol 2015; 3:60. [PMID: 26484343 PMCID: PMC4586509 DOI: 10.3389/fcell.2015.00060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/14/2015] [Indexed: 01/16/2023] Open
Abstract
Background: Thyroxine (T4) hormone is synthesized by the thyroid gland and then released into the systemic circulation where it binds to a number of proteins. Dysfunction in T4 transport mechanisms has been demonstrated in multiple central nervous system (CNS) diseases including Alzheimer's disease. In the presence of different compounds that inhibit potential T4 transport mechanisms, this study investigated the transfer of T4 from cerebrospinal fluid (CSF) into Choroid Plexus (CP) and other brain tissues. The compounds used were brefeldin A, low sodium artificial CSF (aCSF), BCH, phloretin, and taurocholate (TA). Methods: Radiolabeled T4 (125I-T4) was perfused continuously into the CSF and was assessed in several brain compartments with reference molecule 14C-mannitol and blue dextran, using the in vivo ventriculo-cisternal perfusion (V-C) technique in the rabbit. The aCSF containing the drug of interest was infused after 1 h of perfusion. Drugs were applied independently to the aCSF after 1 h of control perfusion. Results: Of interest, in presence of low sodium or BCH, the percentage recovery of 125I-T4, was increased compared to controls, with concomitant increase in T4 clearance. Conversely, brefeldin A, phloretin, and TA did not exert any significant effect on the recovery and clearance of 125I-T4 assessed in aCSF. On the other hand, the uptake of 125I-T4 into CP was raised by 18 fold compared to controls in the presence of brefeldin A. In addition, low sodium, BCH, or phloretin alone, enhanced the uptake of 125I-T4 by almost 3-fold, whereas TA did not show any significant effect. Finally, the uptake and distribution of 125I-T4 into other brain regions including ependymal region (ER) and caudate putamen (CAP) were significantly higher than in controls. Conclusion: Our study suggests the involvement of different mechanisms for the transfer of 125I-T4 from CSF into CP and other brain regions. This transfer may implicate sodium-dependent mechanisms, amino acid “L” system, or organic anion transporting polypeptide (OATP).
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Affiliation(s)
- Kazem Zibara
- ER045, PRASE, Faculty of Sciences-I, Lebanese University Beirut, Lebanon ; Department of Biology, Faculty of Sciences-I, Lebanese University Beirut, Lebanon
| | - Ali El-Zein
- ER045, PRASE, Faculty of Sciences-I, Lebanese University Beirut, Lebanon ; Physics Department, Faculty of Sciences, Lebanese University Beirut, Lebanon
| | - Wissam Joumaa
- Department of Biology, Faculty of Sciences-I, Lebanese University Beirut, Lebanon
| | | | | | - Nouhad Kassem
- ER045, PRASE, Faculty of Sciences-I, Lebanese University Beirut, Lebanon ; Department of Pharmacology and Therapeutics, Institute of Pharmaceutical Science, King's College London London, UK
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15
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Silencing of murine transthyretin and retinol binding protein genes has distinct and shared behavioral and neuropathologic effects. Neuroscience 2014; 275:352-64. [DOI: 10.1016/j.neuroscience.2014.06.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/06/2014] [Accepted: 06/07/2014] [Indexed: 01/03/2023]
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Expression of organic anion transporting polypeptide 1c1 and monocarboxylate transporter 8 in the rat placental barrier and the compensatory response to thyroid dysfunction. PLoS One 2014; 9:e96047. [PMID: 24763672 PMCID: PMC3999103 DOI: 10.1371/journal.pone.0096047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 04/02/2014] [Indexed: 01/21/2023] Open
Abstract
Thyroid hormones (THs) must pass from mother to fetus for normal fetal development and require the expression of placental TH transporters. We investigate the compensatory effect of placental organic anion transporting polypeptide 1c1 (Oatp1c1) and monocarboxylate transporter 8 (Mct8) on maternal thyroid dysfunction. We describe the expressions of these two transporters in placental barriers and trophoblastic cell populations in euthyroidism and thyroid dysfunction resulting from differential iodine nutrition at gestation day (GD) 16 and 20, that is, before and after the onset of fetal thyroid function. Immunohistochemistry revealed that in the blood-placenta barrier, these two TH transporters were strongly expressed in the villous interstitial substance and were weakly expressed in trophoblast cells. Levels of Oatp1c1 protein obviously increased in the placental fetal portion during maternal thyroid deficiency at GD16. Under maternal thyroid deficiency after the production of endogenous fetal TH, quantitative PCR analysis revealed down-regulation of Oatp1c1 occurred along with up-regulation of Mct8 in trophoblast cell populations isolated by laser capture microdissection (LCM); this was consistent with the protein levels in the fetal portion of the placenta. In addition, decreased D3 mRNA at GD16 and increased D2 mRNA on two gestational days were observed in trophoblast cells with thyroid dysfunction. However, levels of Oatp1c1 mRNA at GD16 and D3 mRNA at GD20 were too low to be detectable in trophoblast cells. In conclusion, placental Oatp1c1 plays an essential compensatory role when the transplacental passage of maternal THs is insufficient at the stage before the fetal TH production. In addition, the coordinated effects of Oatp1c1, Mct8, D2 and D3 in the placental barrier may regulate both transplacental TH passage and the development of trophoblast cells during thyroid dysfunction throughout the pregnancy.
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Fu J, Refetoff S, Dumitrescu AM. Inherited defects of thyroid hormone-cell-membrane transport: review of recent findings. Curr Opin Endocrinol Diabetes Obes 2013; 20:434-40. [PMID: 23974772 PMCID: PMC4061907 DOI: 10.1097/01.med.0000432531.03233.ad] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW This review summarizes the most significant findings over the last year regarding human and animal models deficient in thyroid hormone cell-membrane transporters (THCMTs). Although several THCMTs have been modelled in genetically engineered mice, the only THCMT defect known in humans is that caused by mutations in the monocarboxylate transporter 8 (MCT8) gene. RECENT FINDINGS The importance of several amino acid residues has been assessed in vitro to further our understanding on the structure-function of the MCT8. The administration of the thyromimetic compound, diiodothyropropionic acid, has been tested in patients with MCT8 gene mutations, following studies of its use in mice. Another thyroid hormone analogue, 3,3',5,5'-tetraiodothyroacetic acid, was tested in Mct8-deficient mice. The phenotypes of L-type aminoacid transporter 2 and organic anion transporting polypeptide 1C1 deficiencies have been studied in mouse models. Mct8/organic anion transporting polypeptide 1C1 double knockout mice have been shown to manifest neurodevelopmental deficits. Zebrafish is emerging as another vertebrate model that may be useful to study the role of Mct8 in brain development. SUMMARY Studies on the pathogenesis and therapy of MCT8 deficiency are in progress, and new vertebrate models that are suitable to study the neurological consequences of the syndrome are being explored.
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Affiliation(s)
- Jiao Fu
- Department of Medicine, The University of Chicago, Chicago, Illinois, USA
| | - Samuel Refetoff
- Departments of Medicine, Pediatrics and Genetics, The University of Chicago, Chicago, Illinois, USA
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Vatine GD, Zada D, Lerer-Goldshtein T, Tovin A, Malkinson G, Yaniv K, Appelbaum L. Zebrafish as a model for monocarboxyl transporter 8-deficiency. J Biol Chem 2012; 288:169-80. [PMID: 23161551 DOI: 10.1074/jbc.m112.413831] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Allan-Herndon-Dudley syndrome (AHDS) is a severe psychomotor retardation characterized by neurological impairment and abnormal thyroid hormone (TH) levels. Mutations in the TH transporter, monocarboxylate transporter 8 (MCT8), are associated with AHDS. MCT8 knock-out mice exhibit impaired TH levels; however, they lack neurological defects. Here, the zebrafish mct8 gene and promoter were isolated, and mct8 promoter-driven transgenic lines were used to show that, similar to humans, mct8 is primarily expressed in the nervous and vascular systems. Morpholino-based knockdown and rescue experiments revealed that MCT8 is strictly required for neural development in the brain and spinal cord. This study shows that MCT8 is a crucial regulator during embryonic development and establishes the first vertebrate model for MCT8 deficiency that exhibits a neurological phenotype.
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Affiliation(s)
- Gad David Vatine
- Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
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20
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Abstract
Our understanding of thyroid hormone action has been substantially altered by recent clinical observations of thyroid signaling defects in syndromes of hormone resistance and in a broad range of conditions, including profound mental retardation, obesity, metabolic disorders, and a number of cancers. The mechanism of thyroid hormone action has been informed by these clinical observations as well as by animal models and has influenced the way we view the role of local ligand availability; tissue and cell-specific thyroid hormone transporters, corepressors, and coactivators; thyroid hormone receptor (TR) isoform-specific action; and cross-talk in metabolic regulation and neural development. In some cases, our new understanding has already been translated into therapeutic strategies, especially for treating hyperlipidemia and obesity, and other drugs are in development to treat cardiac disease and cancer and to improve cognitive function.
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Affiliation(s)
- Gregory A Brent
- Department of Medicine, VA Greater Los Angeles Healthcare System, David Geffen School of Medicine at UCLA, Los Angeles, CA 90073, USA.
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21
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Schweizer U, Köhrle J. Function of thyroid hormone transporters in the central nervous system. Biochim Biophys Acta Gen Subj 2012; 1830:3965-73. [PMID: 22890106 DOI: 10.1016/j.bbagen.2012.07.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 07/12/2012] [Accepted: 07/30/2012] [Indexed: 01/24/2023]
Abstract
BACKGROUND Iodothyronines are charged amino acid derivatives that cannot passively cross a phospholipid bilayer. Transport of thyroid hormones across plasma membranes is mediated by integral membrane proteins belonging to several gene families. These transporters therefore allow or limit access of thyroid hormones into brain. Since thyroid hormones are essential for brain development and cell differentiation, it is expected that genetic deficiency of such transporters would result in neurodevelopmental derangements. SCOPE OF REVIEW We introduce concepts of thyroid hormone transport into the brain and into brain cells. Important thyroid hormone transmembrane transporters are presented along with their expression patterns in different brain cell types. A focus is placed on monocarboxylate transporter 8 (MCT8) which has been identified as an essential thyroid hormone transporter in humans. Mutations in MCT8 underlie one of the first described X-linked mental retardation syndromes, the Allan-Herndon-Dudley syndrome. MAJOR CONCLUSIONS Thyroid hormone transporter molecules are expressed in a developmental and cell type-specific pattern. Any thyroid hormone molecule has to cross consecutively the luminal and abluminal membranes of the capillary endothelium, enter astrocytic foot processes, and leave the astrocyte through the plasma membrane to finally cross another plasma membrane on its way towards its target nucleus. GENERAL SIGNIFICANCE We can expect more transporters being involved in or contributing to in neurodevelopmental or neuropsychiatric disease. Due to their expression in cellular components regulating the hypothalamus-pituitary-thyroid axis, mutations and polymorphisms are expected to impact on negative feedback regulation and hormonal setpoints. This article is part of a Special Issue entitled Thyroid hormone signalling.
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Affiliation(s)
- Ulrich Schweizer
- Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
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22
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Smith VE, Read ML, Turnell AS, Sharma N, Lewy GD, Fong JCW, Seed RI, Kwan P, Ryan G, Mehanna H, Chan SY, Darras VM, Boelaert K, Franklyn JA, McCabe CJ. PTTG-binding factor (PBF) is a novel regulator of the thyroid hormone transporter MCT8. Endocrinology 2012; 153:3526-36. [PMID: 22535767 DOI: 10.1210/en.2011-2030] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Within the basolateral membrane of thyroid follicular epithelial cells, two transporter proteins are central to thyroid hormone (TH) biosynthesis and secretion. The sodium iodide symporter (NIS) delivers iodide from the bloodstream into the thyroid, and after TH biosynthesis, monocarboxylate transporter 8 (MCT8) mediates TH secretion from the thyroid gland. Pituitary tumor-transforming gene-binding factor (PBF; PTTG1IP) is a protooncogene that is up-regulated in thyroid cancer and that binds NIS and modulates its subcellular localization and function. We now show that PBF binds MCT8 in vitro, eliciting a marked shift in MCT8 subcellular localization and resulting in a significant reduction in the amount of MCT8 at the plasma membrane as determined by cell surface biotinylation assays. Colocalization and interaction between PBF and Mct8 was also observed in vivo in a mouse model of thyroid-specific PBF overexpression driven by a bovine thyroglobulin (Tg) promoter (PBF-Tg). Thyroidal Mct8 mRNA and protein expression levels were similar to wild-type mice. Critically, however, PBF-Tg mice demonstrated significantly enhanced thyroidal TH accumulation and reduced TH secretion upon TSH stimulation. Importantly, Mct8-knockout mice share this phenotype. These data show that PBF binds and alters the subcellular localization of MCT8 in vitro, with PBF overexpression leading to an accumulation of TH within the thyroid in vivo. Overall, these studies identify PBF as the first protein to interact with the critical TH transporter MCT8 and modulate its function in vivo. Furthermore, alongside NIS repression, PBF may thus represent a new regulator of TH biosynthesis and secretion.
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Affiliation(s)
- V E Smith
- School of Clinical and Experimental Medicine, Institute for Biomedical Research, University of Birmingham, Birmingham, B15 2TT, United Kingdom
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Abstract
PURPOSE OF REVIEW To discuss the recent advances on thyroid hormone transport in the brain. A special attention is paid to the X-linked thyroid hormone cell transport (THCT) defect (also known as the Allan-Herndon-Dudley syndrome), caused by mutations of the specific thyroid hormone transporter MCT8 gene. RECENT FINDINGS MCT8 is involved in thyroid hormone transport in the brain. MRI of patients with THCT defect showed myelination delays, probably related to impaired thyroid hormone action on oligodendrocytes. MCT8 is also expressed in the thyroid and has an important role in thyroid hormone secretion. The altered circulating concentrations of thyroid hormone in the patients are partly because of impaired secretion and altered peripheral metabolism. Increased deiodinase activity is important in the pathophysiology of the syndrome. High D1 activity in liver and kidney increases T4 and rT3 deiodination, and contributes to the increased serum T3. High D2 activity in the brain contributes to compensate the deficient T3 transport by increasing local T3 production. SUMMARY Patients with suspected X-linked leukoencephalopathy should be screened for MCT8 gene mutations. Research on the brain pathophysiology of the THCT defect should focus on the specific role of Mct8 on oligodendrocytes and myelination.
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Affiliation(s)
- Juan Bernal
- Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.
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Chan SY, Martín-Santos A, Loubière LS, González AM, Stieger B, Logan A, McCabe CJ, Franklyn JA, Kilby MD. The expression of thyroid hormone transporters in the human fetal cerebral cortex during early development and in N-Tera-2 neurodifferentiation. J Physiol 2011; 589:2827-45. [PMID: 21486766 DOI: 10.1113/jphysiol.2011.207290] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Associations of neurological impairment with mutations in the thyroid hormone (TH) transporter, MCT8, and with maternal hypothyroxinaemia, suggest that THs are crucial for human fetal brain development. It has been postulated that TH transporters regulate the cellular supply of THs within the fetal brain during development. This study describes the expression of TH transporters in the human fetal cerebral cortex (7–20 weeks gestation) and during retinoic acid induced neurodifferentiation of the human N-Tera-2 (NT2) cell line, in triiodothyronine (T3) replete and T3-depleted media. Compared with adult cortex, mRNAs encoding OATP1A2, OATP1C1, OATP3A1 variant 2, OATP4A1, LAT2 and CD98 were reduced in fetal cortex at different gestational ages, whilst mRNAs encoding MCT8, MCT10, OATP3A1 variant 1 and LAT1 were similar. From the early first trimester, immunohistochemistry localised MCT8 and MCT10 to the microvasculature and to undifferentiated CNS cells. With neurodifferentiation, NT2 cells demonstrated declining T3 uptake, accompanied by reduced expressions of MCT8, LAT1, CD98 and OATP4A1. T3 depletion significantly reduced MCT10 and LAT2 mRNA expression at specific time points during neurodifferentiation but there were no effects upon T3 uptake, neurodifferentiation marker expression or neurite lengths and branching. MCT8 repression also did not affect NT2 neurodifferentiation. In conclusion, many TH transporters are expressed in the human fetal cerebral cortex from the first trimester, which could regulate cellular TH supply during early development. However, human NT2 neurodifferentiation is not dependent upon T3 or MCT8 and there were no compensatory changes to promote T3 uptake in a T3-depleted environment.
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Affiliation(s)
- S-Y Chan
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Floor 3, Birmingham Women's Hospital, Edgbaston, Birmingham B15 2TG, UK.
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