1
|
Raterman ST, Wagener FADTG, Zethof J, Cuijpers V, Klaren PHM, Metz JR, Von den Hoff JW. foxe1 mutant zebrafish show indications of a hypothyroid phenotype and increased sensitivity to ethanol for craniofacial malformations. Dev Dyn 2024. [PMID: 39360443 DOI: 10.1002/dvdy.745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 08/13/2024] [Accepted: 08/14/2024] [Indexed: 10/04/2024] Open
Abstract
BACKGROUND FOXE1 mutations in humans are associated with cleft palate and hypothyroidism. We previously developed a foxe1 mutant zebrafish demonstrating mineralization defects in larvae. In the present study, we investigate the thyroid status and skeletal phenotype of adult foxe1 mutants. RESULTS Mutant fish have increased expression of tshβ in the pituitary, and of hepatic dio1 and dio2. In plasma, we found higher Mg levels. Together these findings are indicative of hypothyroidism. We further observed mineralization defects in scales due to enhanced osteoclast activity as measured by increased expression levels of tracp, ctsk, and rankl. Gene-environment interactions in the etiology of FOXE1-related craniofacial abnormalities remain elusive, which prompts the need for models to investigate genotype-phenotype associations. We here investigated whether ethanol exposure increases the risk of developing craniofacial malformations in foxe1 mutant larvae that we compared to wild types. We found in ethanol-exposed mutants an increased incidence of developmental malformations and marked changes in gene expression patterns of cartilage markers (sox9a), apoptotic markers (casp3b), retinoic acid metabolism (cyp26c1), and tissue hypoxia markers (hifaa, hifab). CONCLUSION Taken together, this study shows that the foxe1 mutant zebrafish recapitulates phenotypes associated with FOXE1 mutations in human patients and a clear foxe1-ethanol interaction.
Collapse
Affiliation(s)
- Sophie T Raterman
- Department of Dentistry-Orthodontics and Craniofacial Biology, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Plant & Animal Biology, Radboud Institute for Biological and Environmental Sciences (RIBES), Radboud University, Nijmegen, The Netherlands
| | - Frank A D T G Wagener
- Department of Dentistry-Orthodontics and Craniofacial Biology, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jan Zethof
- Department of Plant & Animal Biology, Radboud Institute for Biological and Environmental Sciences (RIBES), Radboud University, Nijmegen, The Netherlands
| | - Vincent Cuijpers
- Department of Dentistry-Orthodontics and Craniofacial Biology, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Peter H M Klaren
- Department of Plant & Animal Biology, Radboud Institute for Biological and Environmental Sciences (RIBES), Radboud University, Nijmegen, The Netherlands
| | - Juriaan R Metz
- Department of Plant & Animal Biology, Radboud Institute for Biological and Environmental Sciences (RIBES), Radboud University, Nijmegen, The Netherlands
| | - Johannes W Von den Hoff
- Department of Dentistry-Orthodontics and Craniofacial Biology, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
| |
Collapse
|
2
|
Souza TL, da Luz JZ, Barreto LDS, de Oliveira Ribeiro CA, Neto FF. Structure-based modeling to assess binding and endocrine disrupting potential of polycyclic aromatic hydrocarbons in Daniorerio. Chem Biol Interact 2024; 398:111109. [PMID: 38871163 DOI: 10.1016/j.cbi.2024.111109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 06/03/2024] [Accepted: 06/11/2024] [Indexed: 06/15/2024]
Abstract
Environmental contaminants, such as polycyclic aromatic hydrocarbons (PAHs), have raised concerns regarding their potential endocrine-disrupting effects on aquatic organisms, including fish. In this study, molecular docking and molecular dynamics techniques were employed to evaluate the endocrine-disrupting potential of PAHs in zebrafish, as a model organism. A virtual screening with 72 PAHs revealed a correlation between the number of PAH aromatic rings and their binding affinity to proteins involved in endocrine regulation. Furthermore, PAHs with the highest binding affinities for each protein were identified: cyclopenta[cd]pyrene for AR (-9.7 kcal/mol), benzo(g)chrysene for ERα (-11.5 kcal/mol), dibenzo(a,e)pyrene for SHBG (-8.7 kcal/mol), dibenz(a,h)anthracene for StAR (-11.2 kcal/mol), and 2,3-benzofluorene for TRα (-9.8 kcal/mol). Molecular dynamics simulations confirmed the stability of the protein-ligand complexes formed by the PAHs with the highest binding affinities throughout the simulations. Additionally, the effectiveness of the protocol used in this study was demonstrated by the receiver operating characteristic curve (ROC) analysis, which effectively distinguished decoys from true ligands. Therefore, this research provides valuable insights into the endocrine-disrupting potential of PAHs in fish, highlighting the importance of assessing their impact on aquatic ecosystems.
Collapse
Affiliation(s)
- Tugstênio L Souza
- Laboratório de Toxicologia Celular, Departamento de Biologia Celular, Universidade Federal do Paraná, CEP 81531-980, Curitiba, PR, Brazil.
| | - Jessica Zablocki da Luz
- Laboratório de Toxicologia Celular, Departamento de Biologia Celular, Universidade Federal do Paraná, CEP 81531-980, Curitiba, PR, Brazil
| | - Luiza Dos Santos Barreto
- Laboratório de Toxicologia Celular, Departamento de Biologia Celular, Universidade Federal do Paraná, CEP 81531-980, Curitiba, PR, Brazil
| | - Ciro Alberto de Oliveira Ribeiro
- Laboratório de Toxicologia Celular, Departamento de Biologia Celular, Universidade Federal do Paraná, CEP 81531-980, Curitiba, PR, Brazil
| | - Francisco Filipak Neto
- Laboratório de Toxicologia Celular, Departamento de Biologia Celular, Universidade Federal do Paraná, CEP 81531-980, Curitiba, PR, Brazil.
| |
Collapse
|
3
|
Lazcano I, Olvera A, Pech-Pool SM, Sachs L, Buisine N, Orozco A. Differential effects of 3,5-T2 and T3 on the gill regeneration and metamorphosis of the Ambystoma mexicanum (axolotl). Front Endocrinol (Lausanne) 2023; 14:1208182. [PMID: 37492199 PMCID: PMC10364608 DOI: 10.3389/fendo.2023.1208182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 06/01/2023] [Indexed: 07/27/2023] Open
Abstract
Thyroid hormones (THs) regulate tissue remodeling processes during early- and post-embryonic stages in vertebrates. The Mexican axolotl (Ambystoma mexicanum) is a neotenic species that has lost the ability to undergo metamorphosis; however, it can be artificially induced by exogenous administration of thyroxine (T4) and 3,3',5-triiodo-L-thyronine (T3). Another TH derivative with demonstrative biological effects in fish and mammals is 3,5-diiodo-L-thyronine (3,5-T2). Because the effects of this bioactive TH remains unexplored in other vertebrates, we hypothesized that it could be biologically active in amphibians and, therefore, could induce metamorphosis in axolotl. We performed a 3,5-T2 treatment by immersion and observed that the secondary gills were retracted, similar to the onset stage phenotype; however, tissue regeneration was observed after treatment withdrawal. In contrast, T4 and T3 immersion equimolar treatments as well as a four-fold increase in 3,5-T2 concentration triggered complete metamorphosis. To identify the possible molecular mechanisms that could explain the contrasting reversible or irreversible effects of 3,5-T2 and T3 upon gill retraction, we performed a transcriptomic analysis of differential expression genes in the gills of control, 3,5-T2-treated, and T3-treated axolotls. We found that both THs modify gene expression patterns. T3 regulates 10 times more genes than 3,5-T2, suggesting that the latter has a lower affinity for TH receptors (TRs) or that these hormones could act through different TR isoforms. However, both TH treatments regulated different gene sets known to participate in tissue development and cell cycle processes. In conclusion, 3,5-T2 is a bioactive iodothyronine that promoted partial gill retraction but induced full metamorphosis in higher concentrations. Differential effects on gill retraction after 3,5,-T2 or T3 treatment could be explained by the activation of different clusters of genes related with apoptosis, regeneration, and proliferation; in addition, these effects could be initially mediated by TRs that are expressed in gills. This study showed, for the first time, the 3,5,-T2 bioactivity in a neotenic amphibian.
Collapse
Affiliation(s)
- I. Lazcano
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - A. Olvera
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - S. M. Pech-Pool
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - L. Sachs
- UMR PhyMA CNRS, Muséum National d’Histoire Naturelle, Paris, France
| | - N. Buisine
- UMR PhyMA CNRS, Muséum National d’Histoire Naturelle, Paris, France
| | - A. Orozco
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
- Escuela Nacional de Estudios Superiores, Unidad Juriquilla, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| |
Collapse
|
4
|
Lazcano I, Pech-Pool SM, Olvera A, García-Martínez I, Palacios-Pérez S, Orozco A. The importance of thyroid hormone signaling during early development: Lessons from the zebrafish model. Gen Comp Endocrinol 2023; 334:114225. [PMID: 36709002 DOI: 10.1016/j.ygcen.2023.114225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 11/16/2022] [Accepted: 01/23/2023] [Indexed: 01/26/2023]
Abstract
The zebrafish is an optimal experimental model to study thyroid hormone (TH) involvement in vertebrate development. The use of state-of-the-art zebrafish genetic tools available for the study of the effect of gene silencing, cell fate decisions and cell lineage differentiation have contributed to a more insightful comprehension of molecular, cellular, and tissue-specific TH actions. In contrast to intrauterine development, extrauterine embryogenesis observed in zebrafish has facilitated a more detailed study of the development of the hypothalamic-pituitary-thyroid axis. This model has also enabled a more insightful analysis of TH molecular actions upon the organization and function of the brain, the retina, the heart, and the immune system. Consequently, zebrafish has become a trendy model to address paradigms of TH-related functional and biomedical importance. We here compilate the available knowledge regarding zebrafish developmental events for which specific components of TH signaling are essential.
Collapse
Affiliation(s)
- I Lazcano
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Campus Juriquilla, Querétaro 76230, Mexico
| | - S M Pech-Pool
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Campus Juriquilla, Querétaro 76230, Mexico
| | - A Olvera
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Campus Juriquilla, Querétaro 76230, Mexico
| | - I García-Martínez
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Campus Juriquilla, Querétaro 76230, Mexico
| | - S Palacios-Pérez
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Campus Juriquilla, Querétaro 76230, Mexico
| | - A Orozco
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Campus Juriquilla, Querétaro 76230, Mexico; Escuela Nacional de Estudios Superiores, Unidad Juriquilla, Universidad Nacional Autónoma de México (UNAM), Campus Juriquilla, Querétaro 76230, Mexico.
| |
Collapse
|
5
|
Sun C, Chen S. Disease-causing mutations in genes encoding transcription factors critical for photoreceptor development. Front Mol Neurosci 2023; 16:1134839. [PMID: 37181651 PMCID: PMC10172487 DOI: 10.3389/fnmol.2023.1134839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 04/04/2023] [Indexed: 05/16/2023] Open
Abstract
Photoreceptor development of the vertebrate visual system is controlled by a complex transcription regulatory network. OTX2 is expressed in the mitotic retinal progenitor cells (RPCs) and controls photoreceptor genesis. CRX that is activated by OTX2 is expressed in photoreceptor precursors after cell cycle exit. NEUROD1 is also present in photoreceptor precursors that are ready to specify into rod and cone photoreceptor subtypes. NRL is required for the rod fate and regulates downstream rod-specific genes including the orphan nuclear receptor NR2E3 which further activates rod-specific genes and simultaneously represses cone-specific genes. Cone subtype specification is also regulated by the interplay of several transcription factors such as THRB and RXRG. Mutations in these key transcription factors are responsible for ocular defects at birth such as microphthalmia and inherited photoreceptor diseases such as Leber congenital amaurosis (LCA), retinitis pigmentosa (RP) and allied dystrophies. In particular, many mutations are inherited in an autosomal dominant fashion, including the majority of missense mutations in CRX and NRL. In this review, we describe the spectrum of photoreceptor defects that are associated with mutations in the above-mentioned transcription factors, and summarize the current knowledge of molecular mechanisms underlying the pathogenic mutations. At last, we deliberate the outstanding gaps in our understanding of the genotype-phenotype correlations and outline avenues for future research of the treatment strategies.
Collapse
Affiliation(s)
- Chi Sun
- Department of Ophthalmology and Visual Sciences, Washington University in St. Louis, St. Louis, MO, United States
- *Correspondence: Chi Sun,
| | - Shiming Chen
- Department of Ophthalmology and Visual Sciences, Washington University in St. Louis, St. Louis, MO, United States
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO, United States
| |
Collapse
|
6
|
Yadav P, Sarode LP, Gaddam RR, Kumar P, Bhatti JS, Khurana A, Navik U. Zebrafish as an emerging tool for drug discovery and development for thyroid diseases. FISH & SHELLFISH IMMUNOLOGY 2022; 130:53-60. [PMID: 36084888 DOI: 10.1016/j.fsi.2022.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 08/29/2022] [Accepted: 09/01/2022] [Indexed: 12/06/2022]
Abstract
Zebrafish is a useful model for understanding human genetics and diseases and has evolved into a prominent scientific research model. The genetic structure of zebrafish is 70% identical to that of humans. Its small size, low cost, and transparent embryo make it a valuable tool in experimentation. Zebrafish and mammals possess the same molecular mechanism of thyroid organogenesis and development. Thus, thyroid hormone signaling, embryonic development, thyroid-related disorders, and novel genes involved in early thyroid development can all be studied using zebrafish as a model. Here in this review, we emphasize the evolving role of zebrafish as a possible tool for studying the thyroid gland in the context of physiology and pathology. The transcription factors nkx2.1a, pax2a, and hhex which contribute a pivotal role in the differentiation of thyroid primordium are discussed. Further, we have described the role of zebrafish as a model for thyroid cancer, evaluation of defects in thyroid hormone transport, thyroid hormone (TH) metabolism, and as a screening tool to study thyrotoxins. Hence, the present review highlights the role of zebrafish as a novel approach to understand thyroid development and organogenesis.
Collapse
Affiliation(s)
- Poonam Yadav
- Department of Pharmacology, Central University of Punjab, Ghudda, Bathinda, Punjab, India
| | - Lopmudra P Sarode
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, 440033, Maharashtra, India
| | - Ravinder Reddy Gaddam
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, IA, USA
| | - Puneet Kumar
- Department of Pharmacology, Central University of Punjab, Ghudda, Bathinda, Punjab, India
| | - Jasvinder Singh Bhatti
- Department of Human Genetics and Molecular Medicine, School of Health Sciences, Central University of Punjab, Ghudda, Bathinda, Punjab, India
| | - Amit Khurana
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), RWTH Aachen University Hospital, Pauwelsstr. 30, D-52074, Aachen, Germany.
| | - Umashanker Navik
- Department of Pharmacology, Central University of Punjab, Ghudda, Bathinda, Punjab, India.
| |
Collapse
|
7
|
Orije JEMJ, Raymaekers SR, Majumdar G, De Groof G, Jonckers E, Ball GF, Verhoye M, Darras VM, Van der Linden A. Unraveling the Role of Thyroid Hormones in Seasonal Neuroplasticity in European Starlings ( Sturnus vulgaris). Front Mol Neurosci 2022; 15:897039. [PMID: 35836548 PMCID: PMC9275473 DOI: 10.3389/fnmol.2022.897039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 05/30/2022] [Indexed: 11/13/2022] Open
Abstract
Thyroid hormones clearly play a role in the seasonal regulation of reproduction, but any role they might play in song behavior and the associated seasonal neuroplasticity in songbirds remains to be elucidated. To pursue this question, we first established seasonal patterns in the expression of thyroid hormone regulating genes in male European starlings employing in situ hybridization methods. Thyroid hormone transporter LAT1 expression in the song nucleus HVC was elevated during the photosensitive phase, pointing toward an active role of thyroid hormones during this window of possible neuroplasticity. In contrast, DIO3 expression was high in HVC during the photostimulated phase, limiting the possible effect of thyroid hormones to maintain song stability during the breeding season. Next, we studied the effect of hypothyroidism on song behavior and neuroplasticity using in vivo MRI. Both under natural conditions as with methimazole treatment, circulating thyroid hormone levels decreased during the photosensitive period, which coincided with the onset of neuroplasticity. This inverse relationship between thyroid hormones and neuroplasticity was further demonstrated by the negative correlation between plasma T3 and the microstructural changes in several song control nuclei and cerebellum. Furthermore, maintaining hypothyroidism during the photostimulated period inhibited the increase in testosterone, confirming the role of thyroid hormones in activating the hypothalamic-pituitary-gonadal (HPG) axis. The lack of high testosterone levels influenced the song behavior of hypothyroid starlings, while the lack of high plasma T4 during photostimulation affected the myelination of several tracts. Potentially, a global reduction of circulating thyroid hormones during the photosensitive period is necessary to lift the brake on neuroplasticity imposed by the photorefractory period, whereas local fine-tuning of thyroid hormone concentrations through LAT1 could activate underlying neuroplasticity mechanisms. Whereas, an increase in circulating T4 during the photostimulated period potentially influences the myelination of several white matter tracts, which stabilizes the neuroplastic changes. Given the complexity of thyroid hormone effects, this study is a steppingstone to disentangle the influence of thyroid hormones on seasonal neuroplasticity.
Collapse
Affiliation(s)
- Jasmien E. M. J. Orije
- Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Sander R. Raymaekers
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Leuven, Belgium
| | - Gaurav Majumdar
- Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
| | - Geert De Groof
- Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
| | - Elisabeth Jonckers
- Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Gregory F. Ball
- Department of Psychology, Neuroscience and Cognitive Science Program, University of Maryland, College Park, College Park, MD, United States
| | - Marleen Verhoye
- Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Veerle M. Darras
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Leuven, Belgium
| | - Annemie Van der Linden
- Bio-Imaging Lab, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| |
Collapse
|
8
|
Ghimire S, Zhang X, Zhang J, Wu C. Use of Chicken Embryo Model in Toxicity Studies of Endocrine-Disrupting Chemicals and Nanoparticles. Chem Res Toxicol 2022; 35:550-568. [PMID: 35286071 DOI: 10.1021/acs.chemrestox.1c00399] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Lab animals such as mice and rats are widely used in toxicity research of food additive and pharmaceutics, despite the well-recognized research limitation such as the inability to simulate human neurological diseases, faster absorption of chemicals, big variations among species, and high cost when using a large number of animals. The Society of Toxicology's guidance now focuses on minimizing discomfort and distress of lab animals, finding alternative ways to reduce animal number, replacing animals with in vitro models, and complying to the animal welfare policies. The chicken embryonic model can be a better alternative to mice and rats because of its abundant availability and cost-effectiveness. It can be studied in both laboratory and natural environment, with easy manipulation in ovo or in vivo. The objective of this review paper is to evaluate the use of chicken embryonic model in toxicity evaluation for endocrine-disrupting chemicals (EDCs) and nanoparticles (NPs) by different end points to determine more comprehensive toxic responses. The end points include chicken embryonic mortality and hatchability, developmental malformation analysis, hormonal imbalance, physiological changes in endocrine organs, and antiangiogenesis. Major research methodologies using chicken embryos are also summarized to demonstrate their versatile practice and valuable application in modern toxicity evaluation of EDCs and NPs.
Collapse
Affiliation(s)
- Shweta Ghimire
- University of Delaware, Department of Animal and Food sciences, Newark, Delaware 19716, United States
| | - Xinwen Zhang
- University of Delaware, Department of Animal and Food sciences, Newark, Delaware 19716, United States
| | - Jinglin Zhang
- University of Delaware, Department of Animal and Food sciences, Newark, Delaware 19716, United States
| | - Changqing Wu
- University of Delaware, Department of Animal and Food sciences, Newark, Delaware 19716, United States
| |
Collapse
|
9
|
Lee S, Lee JS, Kho Y, Ji K. Effects of methylisothiazolinone and octylisothiazolinone on development and thyroid endocrine system in zebrafish larvae. JOURNAL OF HAZARDOUS MATERIALS 2022; 425:127994. [PMID: 34915294 DOI: 10.1016/j.jhazmat.2021.127994] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 11/28/2021] [Accepted: 12/02/2021] [Indexed: 06/14/2023]
Abstract
Methylisothiazolinone (MIT) and octylisothiazolinone (OIT) are used as preservatives and biocides to prevent product decay or deterioration. In the present study, developmental toxicity and the effect on the thyroid endocrine system were investigated in zebrafish embryos exposed to MIT and OIT for 96 h. Coagulation was significantly increased when zebrafish embryos were exposed to a concentration of 300 μg/L MIT and ≥ 0.3 μg/L OIT, resulting in a significant decrease in hatchability and larvae survival. The body length in zebrafish larvae exposed to 30 μg/L OIT was significantly shorter than that of the control group. The whole-body levels of triiodothyronine and thyroxine were significantly decreased in larvae exposed to MIT and OIT. Significant upregulation of crh, trh, tshβ, and tshr genes and downregulation of trαa, tg, ttr, and deio2 genes were observed in fish exposed to two isothiazolinones. The expression of dre-miR-193b and dre-miR-499 was significantly increased in zebrafish larvae exposed to MIT and OIT, indicating that epigenetic deregulation of miRNAs modulated genes involved in thyroid hormone regulation. OIT has a higher magnitude of toxicity than MIT, corresponding to the observed changes in thyroid hormones and developmental toxicity.
Collapse
Affiliation(s)
- Sujin Lee
- Department of Environmental Health, Graduate School at Yongin University, Yongin 17092, Republic of Korea
| | - Ji-Su Lee
- Department of Health, Environment and Safety, Eulji University, Seongnam, Gyeonggi 13135, Republic of Korea; National Institute of Environmental Research, Incheon 22689, Republic of Korea
| | - Younglim Kho
- Department of Health, Environment and Safety, Eulji University, Seongnam, Gyeonggi 13135, Republic of Korea
| | - Kyunghee Ji
- Department of Environmental Health, Graduate School at Yongin University, Yongin 17092, Republic of Korea.
| |
Collapse
|
10
|
Cohen A, Popowitz J, Delbridge-Perry M, Rowe CJ, Connaughton VP. The Role of Estrogen and Thyroid Hormones in Zebrafish Visual System Function. Front Pharmacol 2022; 13:837687. [PMID: 35295340 PMCID: PMC8918846 DOI: 10.3389/fphar.2022.837687] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/28/2022] [Indexed: 12/23/2022] Open
Abstract
Visual system development is a highly complex process involving coordination of environmental cues, cell pathways, and integration of functional circuits. Consequently, a change to any step, due to a mutation or chemical exposure, can lead to deleterious consequences. One class of chemicals known to have both overt and subtle effects on the visual system is endocrine disrupting compounds (EDCs). EDCs are environmental contaminants which alter hormonal signaling by either preventing compound synthesis or binding to postsynaptic receptors. Interestingly, recent work has identified neuronal and sensory systems, particularly vision, as targets for EDCs. In particular, estrogenic and thyroidogenic signaling have been identified as critical modulators of proper visual system development and function. Here, we summarize and review this work, from our lab and others, focusing on behavioral, physiological, and molecular data collected in zebrafish. We also discuss different exposure regimes used, including long-lasting effects of developmental exposure. Overall, zebrafish are a model of choice to examine the impact of EDCs and other compounds targeting estrogen and thyroid signaling and the consequences of exposure in visual system development and function.
Collapse
Affiliation(s)
- Annastelle Cohen
- Department of Biology, American University, Washington, DC, WA, United States
| | - Jeremy Popowitz
- Department of Biology, American University, Washington, DC, WA, United States
| | | | - Cassie J. Rowe
- Department of Biology, American University, Washington, DC, WA, United States,Center for Neuroscience and Behavior, American University, Washington, DC, WA, United States
| | - Victoria P. Connaughton
- Department of Biology, American University, Washington, DC, WA, United States,Center for Neuroscience and Behavior, American University, Washington, DC, WA, United States,*Correspondence: Victoria P. Connaughton,
| |
Collapse
|
11
|
Dang Z, Arena M, Kienzler A. Fish toxicity testing for identification of thyroid disrupting chemicals. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 284:117374. [PMID: 34051580 DOI: 10.1016/j.envpol.2021.117374] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/05/2021] [Accepted: 05/12/2021] [Indexed: 05/03/2023]
Abstract
Identification of thyroid disrupting chemicals (TDCs), one of the most studied types of endocrine disruptors (EDs), is required according to EU regulations on industrial chemicals, pesticides, and biocides. Following that requirement, the use of fish as a unique non-mammalian model species for identification of EDs may be warranted. This study summarized and evaluated effects of TDCs on fish thyroid sensitive endpoints including thyroid hormones, thyroid related gene expression, immunostaining for thyroid follicles, eye size and pigmentation, swim bladder inflation as well as effects of TDCs on secondary sex characteristics, sex ratio, growth and reproduction. Changes in thyroid sensitive endpoints may reflect the balanced outcome of different processes of the thyroid cascade. Thyroid sensitive endpoints may also be altered by non-thyroid molecular or endocrine pathways as well as non-specific factors such as general toxicity, development, stress, nutrient, and the environmental factors like temperature and pH. Defining chemical specific effects on thyroid sensitive endpoints is important for identification of TDCs. Application of the AOP (adverse outcome pathway) concept could be helpful for defining critical events needed for testing and identification of TDCs in fish.
Collapse
Affiliation(s)
- ZhiChao Dang
- National Institute for Public Health and the Environment A. van Leeuwenhoeklaan, 93720, BA, Bilthoven, the Netherlands.
| | - Maria Arena
- European Food Safety Authority Via Carlo Magno 1/A, 43126, Parma, Italy
| | - Aude Kienzler
- European Food Safety Authority Via Carlo Magno 1/A, 43126, Parma, Italy
| |
Collapse
|
12
|
Explaining discrepancies in the study of maternal effects: the role of context and embryo. Curr Opin Behav Sci 2020. [DOI: 10.1016/j.cobeha.2020.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
13
|
Deveau C, Jiao X, Suzuki SC, Krishnakumar A, Yoshimatsu T, Hejtmancik JF, Nelson RF. Thyroid hormone receptor beta mutations alter photoreceptor development and function in Danio rerio (zebrafish). PLoS Genet 2020; 16:e1008869. [PMID: 32569302 PMCID: PMC7332105 DOI: 10.1371/journal.pgen.1008869] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 07/02/2020] [Accepted: 05/18/2020] [Indexed: 01/16/2023] Open
Abstract
We investigate mutations in trβ2, a splice variant of thrb, identifying changes in function, structure, and behavior in larval and adult zebrafish retinas. Two N-terminus CRISPR mutants were identified. The first is a 6BP+1 insertion deletion frameshift resulting in a truncated protein. The second is a 3BP in frame deletion with intact binding domains. ERG recordings of isolated cone signals showed that the 6BP+1 mutants did not respond to red wavelengths of light while the 3BP mutants did respond. 6BP+1 mutants lacked optomotor and optokinetic responses to red/black and green/black contrasts. Both larval and adult 6BP+1 mutants exhibit a loss of red-cone contribution to the ERG and an increase in UV-cone contribution. Transgenic reporters show loss of cone trβ2 activation in the 6BP+1 mutant but increase in the density of cones with active blue, green, and UV opsin genes. Antibody reactivity for red-cone LWS1 and LWS2 opsin was absent in the 6BP+1 mutant, as was reactivity for arrestin3a. Our results confirm a critical role for trβ2 in long-wavelength cone development. There are four cone photoreceptors responsible for color vision in zebrafish: red, green, blue, and UV. The thyroid hormone receptor trβ2 is localized in the vertebrate retina. We know that it is necessary for the development of cones expressing long-wavelength-sensitive opsins (red cones), but here we investigate the functional alterations that accompany a loss of trβ2. Our work contributes to the ongoing investigations of retinal development and the involvement of thyroid hormone receptors. As suggested by previous morphological findings, fish became red colorblind when trβ2 was knocked out, and the contributions of the other three cone types shifted. Our work highlights the plasticity of photoreceptor patterning as we see changes in opsin peaks and cone sensitivity, increases in contributions of UV cones, and an attempt at a mosaic pattern in the adult retina, all in the absence of trβ2 and red cones. We now have an increased understanding of mechanisms underlying retinal development.
Collapse
Affiliation(s)
- Ciana Deveau
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, United States of America
- * E-mail:
| | - Xiaodong Jiao
- National Eye Institute, National Institutes of Health, Rockville, Maryland, United States of America
| | - Sachihiro C. Suzuki
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Asha Krishnakumar
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, United States of America
| | | | - J Fielding Hejtmancik
- National Eye Institute, National Institutes of Health, Rockville, Maryland, United States of America
| | - Ralph F. Nelson
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, United States of America
| |
Collapse
|
14
|
Thyroid hormone receptors mediate two distinct mechanisms of long-wavelength vision. Proc Natl Acad Sci U S A 2020; 117:15262-15269. [PMID: 32541022 DOI: 10.1073/pnas.1920086117] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Thyroid hormone (TH) signaling plays an important role in the regulation of long-wavelength vision in vertebrates. In the retina, thyroid hormone receptor β (thrb) is required for expression of long-wavelength-sensitive opsin (lws) in red cone photoreceptors, while in retinal pigment epithelium (RPE), TH regulates expression of a cytochrome P450 enzyme, cyp27c1, that converts vitamin A1 into vitamin A2 to produce a red-shifted chromophore. To better understand how TH controls these processes, we analyzed the phenotype of zebrafish with mutations in the three known TH nuclear receptor transcription factors (thraa, thrab, and thrb). We found that no single TH nuclear receptor is required for TH-mediated induction of cyp27c1 but that deletion of all three (thraa -/- ;thrab -/- ;thrb -/- ) completely abrogates its induction and the resulting conversion of A1- to A2-based retinoids. In the retina, loss of thrb resulted in an absence of red cones at both larval and adult stages without disruption of the underlying cone mosaic. RNA-sequencing analysis revealed significant down-regulation of only five genes in adult thrb -/- retina, of which three (lws1, lws2, and miR-726) occur in a single syntenic cluster. In the thrb -/- retina, retinal progenitors destined to become red cones were transfated into ultraviolet (UV) cones and horizontal cells. Taken together, our findings demonstrate cooperative regulation of cyp27c1 by TH receptors and a requirement for thrb in red cone fate determination. Thus, TH signaling coordinately regulates both spectral sensitivity and sensory plasticity.
Collapse
|
15
|
Han CR, Holmsen E, Carrington B, Bishop K, Zhu YJ, Starost M, Meltzer P, Sood R, Liu P, Cheng SY. Generation of Novel Genetic Models to Dissect Resistance to Thyroid Hormone Receptor α in Zebrafish. Thyroid 2020; 30:314-328. [PMID: 31952464 PMCID: PMC7047097 DOI: 10.1089/thy.2019.0598] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Background: Patients with mutations of the thyroid hormone receptor alpha (THRA) gene show resistance to thyroid hormone alpha (RTHα). No amendable mouse models are currently available to elucidate deleterious effects of TRα1 mutants during early development. Zebrafish with transient suppressed expression by morpholino knockdown and ectopic expression of TRα1 mutants in the embryos have been reported. However, zebrafish with germline transmittable mutations have not been reported. The stable expression of thra mutants from embryos to adulthood facilitated the study of molecular actions of TRα1 mutants during development. Methods: In contrast to human and mice, the thra gene is duplicated in zebrafish, thraa, and thrab. Using CRISPR/Cas9-mediated targeted mutagenesis, we created dominant negative mutations in the two duplicated thra genes. We comprehensively analyzed the molecular and phenotypic characteristics of mutant fish during development. Results: Adult and juvenile homozygous thrab 1-bp ins (m/m) mutants exhibited severe growth retardation, but adult homozygous thraa 8-bp ins (m/m) mutants had very mild growth impairment. Expression of the growth hormone (gh1) and insulin-like growth factor 1 was markedly suppressed in homozygous thrab 1-bp ins (m/m) mutants. Decreased messenger RNA and protein levels of triiodothyronine-regulated keratin genes and inhibited keratinocyte proliferation resulted in hypoplasia of the epidermis in adult and juvenile homozygous thrab 1-bp ins (m/m) mutants, but not homozygous thraa 8-bp ins (m/m) mutants. RNA-seq analysis showed that homozygous thrab 1-bp ins (m/m) mutation had global impact on the functions of the adult pituitary. However, no morphological defects nor any changes in the expression of gh1 and keratin genes were observed in the embryos and early larvae. Thus, mutations of either the thraa or thrab gene did not affect initiation of embryogenesis. But the mutation of the thrab gene, but not the thraa gene, is detrimental in postlarval growth and skin development. Conclusions: The thra duplicated genes are essential to control temporal coordination in postlarval growth and development in a tissue-specific manner. We uncovered novel functions of the duplicated thra genes in zebrafish in development. These mutant zebrafish could be used as a model for further analysis of TRα1 mutant actions and for rapid screening of therapeutics for RTHα.
Collapse
Affiliation(s)
- Cho Rong Han
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Erik Holmsen
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Blake Carrington
- Zebrafish Core, Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Kevin Bishop
- Zebrafish Core, Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Yuelin Jack Zhu
- Laboratory of Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Matthew Starost
- Division of Veterinary Resources, Diagnostic and Research Services Branch, National Institutes of Health, Bethesda, Maryland
| | - Paul Meltzer
- Laboratory of Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Raman Sood
- Zebrafish Core, Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Paul Liu
- Zebrafish Core, Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Sheue-yann Cheng
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
- Address correspondence to: Sheue-yann Cheng, PhD, Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Room 5128, Bethesda, MD 20892-4264
| |
Collapse
|
16
|
Gothié J, Vancamp P, Demeneix B, Remaud S. Thyroid hormone regulation of neural stem cell fate: From development to ageing. Acta Physiol (Oxf) 2020; 228:e13316. [PMID: 31121082 PMCID: PMC9286394 DOI: 10.1111/apha.13316] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/10/2019] [Accepted: 05/17/2019] [Indexed: 12/13/2022]
Abstract
In the vertebrate brain, neural stem cells (NSCs) generate both neuronal and glial cells throughout life. However, their neuro‐ and gliogenic capacity changes as a function of the developmental context. Despite the growing body of evidence on the variety of intrinsic and extrinsic factors regulating NSC physiology, their precise cellular and molecular actions are not fully determined. Our review focuses on thyroid hormone (TH), a vital component for both development and adult brain function that regulates NSC biology at all stages. First, we review comparative data to analyse how TH modulates neuro‐ and gliogenesis during vertebrate brain development. Second, as the mammalian brain is the most studied, we highlight the molecular mechanisms underlying TH action in this context. Lastly, we explore how the interplay between TH signalling and cell metabolism governs both neurodevelopmental and adult neurogenesis. We conclude that, together, TH and cellular metabolism regulate optimal brain formation, maturation and function from early foetal life to adult in vertebrate species.
Collapse
Affiliation(s)
- Jean‐David Gothié
- Department of Neurology & Neurosurgery Montreal Neurological Institute & Hospital, McGill University Montreal Quebec Canada
| | - Pieter Vancamp
- CNRS UMR 7221 Muséum National d’Histoire Naturelle Paris France
| | | | - Sylvie Remaud
- CNRS UMR 7221 Muséum National d’Histoire Naturelle Paris France
| |
Collapse
|
17
|
Wu L, Ru H, Ni Z, Zhang X, Xie H, Yao F, Zhang H, Li Y, Zhong L. Comparative thyroid disruption by o,p'-DDT and p,p'-DDE in zebrafish embryos/larvae. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 216:105280. [PMID: 31518776 DOI: 10.1016/j.aquatox.2019.105280] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 08/14/2019] [Accepted: 08/18/2019] [Indexed: 06/10/2023]
Abstract
1,1-Trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl) ethane (o,p'-DDT) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE) cause thyroid disruption, but the underlying mechanisms of these disturbances in fish remain unclear. To explore the potential mechanisms of thyroid dysfunction caused by o,p'-DDT and p,p'-DDE, thyroid hormone and gene expression levels in the hypothalamic-pituitary-thyroid (HPT) axis were measured, and the developmental toxicity were recorded in zebrafish larvae. Zebrafish embryos/larvae were exposed to o,p'-DDT (0, 0.28, 2.8, and 28 nM; or 0, 0.1, 1, and 10 μg/L) and p,p'-DDE (0, 1.57, 15.7, and 157 nM; or 0, 0.5, 5, and 50 μg/L) for 7 days. The genes related to thyroid hormone synthesis (crh, tshβ, tg, nis and tpo) and thyroid development (nkx2.1 and pax8) were up-regulated in both the o,p'-DDT and p,p'-DDE exposure groups. Zebrafish embryos/larvae exposed to o,p'-DDT showed significantly increased total whole-body T4 and T3 levels, with the expression of ugt1ab and dio3 being significantly down-regulated. However, the p,p'-DDE exposure groups showed significantly lowered whole-body total T4 and T3 levels, which were associated with up-regulation and down-regulation expression of the expression of dio2 and ugt1ab, respectively. Interestingly, the ratio of T3 to T4 was significantly decreased in the o,p'-DDT (28 nM) and p,p'-DDE (157 nM) exposure groups, suggesting an impairment of thyroid function. In addition, reduced survival rates and body lengths and increased malformation rates were recorded after treatment with either o,p'-DDT or p,p'-DDE. In summary, our study indicates that the disruption of thyroid states was different in response to o,p'-DDT and p,p'-DDE exposure in zebrafish larvae.
Collapse
Affiliation(s)
- Luyin Wu
- Observation Station for Fishery Resource and Environment in Upper-Middle Reaches of Yangtze River (Ministry of Agriculture), Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Huijun Ru
- Observation Station for Fishery Resource and Environment in Upper-Middle Reaches of Yangtze River (Ministry of Agriculture), Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Zhaohui Ni
- Observation Station for Fishery Resource and Environment in Upper-Middle Reaches of Yangtze River (Ministry of Agriculture), Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Xiaoxin Zhang
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Huaxiao Xie
- Observation Station for Fishery Resource and Environment in Upper-Middle Reaches of Yangtze River (Ministry of Agriculture), Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Fan Yao
- Observation Station for Fishery Resource and Environment in Upper-Middle Reaches of Yangtze River (Ministry of Agriculture), Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China
| | - He Zhang
- State Key Laboratory of Optometry, Ophthalmology, and Visual Science, School of Optometry and Ophthalmology and the Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325003, China
| | - Yunfeng Li
- Observation Station for Fishery Resource and Environment in Upper-Middle Reaches of Yangtze River (Ministry of Agriculture), Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China.
| | - Liqiao Zhong
- Observation Station for Fishery Resource and Environment in Upper-Middle Reaches of Yangtze River (Ministry of Agriculture), Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China.
| |
Collapse
|
18
|
Vancamp P, Houbrechts AM, Darras VM. Insights from zebrafish deficiency models to understand the impact of local thyroid hormone regulator action on early development. Gen Comp Endocrinol 2019; 279:45-52. [PMID: 30244055 DOI: 10.1016/j.ygcen.2018.09.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/05/2018] [Accepted: 09/18/2018] [Indexed: 12/23/2022]
Abstract
Thyroid hormones (THs) stimulate and coordinate a wide range of processes to ensure normal development, mainly by binding of the most active TH 3,5,3'-triiodothyronine (T3) to nuclear receptors resulting in changes in gene transcription. Local TH action is monitored at three distinct levels by different types of regulators: transmembrane transporters (TH influx and efflux), deiodinases (TH activation and inactivation) and nuclear receptors (TH signalling). Since TH regulators are strongly conserved among vertebrate species, the externally and rapidly developing zebrafish (Danio rerio) has become one of the favourite models to study their role in TH-dependent development. Most regulators are expressed in zebrafish from early stages in development in a dynamic and tissue-specific pattern. Transient or permanent disruption of a given regulator severely perturbs development of multiple organs. These zebrafish deficiency models help to explain why, next to overall hypo-/hyperthyroidism, inactivating mutations in the genes encoding TH regulators such as MCT8 and THRA/B have irreversible adverse effects on human development. Zebrafish are also increasingly used as a high-throughput model to assess the toxicity of various xenobiotics and their impact on development. While adverse effects on TH metabolism and gene expression have been shown, information on direct interaction with TH regulators is scarce, albeit essential to fully understand their mechanism of action. For the future, the combination of novel gene silencing tools, fluorescent reporter lines and (single-cell) transcriptomics holds promise for new zebrafish models to further elucidate the role of each TH regulator in vertebrate development.
Collapse
Affiliation(s)
- Pieter Vancamp
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, B-3000 Leuven, Belgium
| | - Anne M Houbrechts
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, B-3000 Leuven, Belgium
| | - Veerle M Darras
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, B-3000 Leuven, Belgium.
| |
Collapse
|
19
|
Shkil F, Siomava N, Voronezhskaya E, Diogo R. Effects of hyperthyroidism in the development of the appendicular skeleton and muscles of zebrafish, with notes on evolutionary developmental pathology (Evo-Devo-Path). Sci Rep 2019; 9:5413. [PMID: 30931985 PMCID: PMC6443675 DOI: 10.1038/s41598-019-41912-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 03/20/2019] [Indexed: 12/17/2022] Open
Abstract
The hypothalamus-pituitary-thyroid (HPT) axis plays a crucial role in the metabolism, homeostasis, somatic growth and development of teleostean fishes. Thyroid hormones regulate essential biological functions such as growth and development, regulation of stress, energy expenditure, tissue compound, and psychological processes. Teleost thyroid follicles produce the same thyroid hormones as in other vertebrates: thyroxin (T4) and triiodothyronine (T3), making the zebrafish a very useful model to study hypo- and hyperthyroidism in other vertebrate taxa, including humans. Here we investigate morphological changes in T3 hyperthyroid cases in the zebrafish to better understand malformations provoked by alterations of T3 levels. In particular, we describe musculoskeletal abnormalities during the development of the zebrafish appendicular skeleton and muscles, compare our observations with those recently done by us on the normal developmental of the zebrafish, and discuss these comparisons within the context of evolutionary developmental pathology (Evo-Devo-Path), including human pathologies.
Collapse
Affiliation(s)
- Fedor Shkil
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow, 119334, Russia
- Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, pr. Leninskii 33, Moscow, 119071, Russia
| | - Natalia Siomava
- Department of Anatomy, Howard University College of Medicine, 520W Street NW, 20059, Washington, DC, USA
| | - Elena Voronezhskaya
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow, 119334, Russia
| | - Rui Diogo
- Department of Anatomy, Howard University College of Medicine, 520W Street NW, 20059, Washington, DC, USA.
| |
Collapse
|
20
|
Darras VM. The Role of Maternal Thyroid Hormones in Avian Embryonic Development. Front Endocrinol (Lausanne) 2019; 10:66. [PMID: 30800099 PMCID: PMC6375826 DOI: 10.3389/fendo.2019.00066] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 01/24/2019] [Indexed: 12/21/2022] Open
Abstract
During avian embryonic development, thyroid hormones (THs) coordinate the expression of a multitude of genes thereby ensuring that the correct sequence of cell proliferation, differentiation and maturation is followed in each tissue and organ. Although THs are needed from the start of development, the embryonic thyroid gland only matures around mid-incubation in precocial birds and around hatching in altricial species. Therefore, maternal THs deposited in the egg yolk play an essential role in embryonic development. They are taken up by the embryo throughout its development, from the first day till hatching, and expression of TH regulators such as distributor proteins, transporters, and deiodinases in the yolk sac membrane provide the tools for selective metabolism and transport starting from this level. TH receptors and regulators of local TH availability are expressed in avian embryos in a dynamic and tissue/cell-specific pattern from the first stages studied, as shown in detail in chicken. Maternal hyperthyroidism via TH supplementation as well as injection of THs into the egg yolk increase TH content in embryonic tissues while induction of maternal hypothyroidism by goitrogen treatment results in a decrease. Both increase and decrease of maternal TH availability were shown to alter gene expression in early chicken embryos. Knockdown of the specific TH transporter monocarboxylate transporter 8 at early stages in chicken cerebellum, optic tectum, or retina allowed to reduce local TH availability, interfering with gene expression and confirming that development of the central nervous system (CNS) is highly dependent on maternal THs. While some of the effects on cell proliferation, migration and differentiation seem to be transient, others result in persistent defects in CNS structure. In addition, a number of studies in both precocial and altricial birds showed that injection of THs into the yolk at the start of incubation influences a number of parameters in posthatch performance and fitness. In conclusion, the data presently available clearly indicate that maternal THs play an important role in avian embryonic development, but how exactly their influence on cellular and molecular processes in the embryo is linked to posthatch fitness needs to be further explored.
Collapse
|
21
|
Vancamp P, Darras VM. From zebrafish to human: A comparative approach to elucidate the role of the thyroid hormone transporter MCT8 during brain development. Gen Comp Endocrinol 2018; 265:219-229. [PMID: 29183795 DOI: 10.1016/j.ygcen.2017.11.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/24/2017] [Accepted: 11/24/2017] [Indexed: 02/07/2023]
Abstract
Monocarboxylate transporter 8 (MCT8) facilitates transmembrane transport of thyroid hormones (THs) ensuring their action on gene expression during vertebrate neurodevelopment. A loss of MCT8 in humans results in severe psychomotor deficits associated with the Allan-Herndon-Dudley Syndrome (AHDS). However, where and when exactly a lack of MCT8 causes the neurological manifestations remains unclear because of the varying expression pattern of MCT8 between specific brain regions and cells. Here, we elaborate on the animal models that have been generated to elucidate the mechanisms underlying MCT8-deficient brain development. The absence of a clear neurological phenotype in Mct8 knockout mice made it clear that a single species would not suffice. The evolutionary conservation of TH action on neurodevelopment as well as the components regulating TH signalling however offers the opportunity to answer different aspects of MCT8 function in brain development using different vertebrate species. Moreover, the plethora of tools for genome editing available today facilitates gene silencing in these animals as well. Studies in the recently generated mct8-deficient zebrafish and Mct8/Oatp1c1 double knockout mice have put forward the current paradigm of impaired TH uptake at the level of the blood-brain barrier during peri- and postnatal development as being the main pathophysiological mechanism of AHDS. RNAi vector-based, cell-specific induction of MCT8 knockdown in the chicken embryo points to an additional function of MCT8 at the level of the neural progenitors during early brain development. Future studies including also additional in vivo models like Xenopus or in vitro approaches such as induced pluripotent stem cells will continue to help unravelling the exact role of MCT8 in developmental events. In the end, this multispecies approach will lead to a unifying thesis regarding the cellular and molecular mechanisms responsible for the neurological phenotype in AHDS patients.
Collapse
Affiliation(s)
- Pieter Vancamp
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, B-3000 Leuven, Belgium
| | - Veerle M Darras
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, B-3000 Leuven, Belgium.
| |
Collapse
|
22
|
Anyetei-Anum CS, Roggero VR, Allison LA. Thyroid hormone receptor localization in target tissues. J Endocrinol 2018; 237:R19-R34. [PMID: 29440347 PMCID: PMC5843491 DOI: 10.1530/joe-17-0708] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 02/12/2018] [Indexed: 12/28/2022]
Abstract
The thyroid hormone receptors, TRα1, TRβ1 and other subtypes, are members of the nuclear receptor superfamily that mediate the action of thyroid hormone signaling in numerous tissues to regulate important physiological and developmental processes. Their most well-characterized role is as ligand-dependent transcription factors; TRs bind thyroid hormone response elements in the presence or absence of thyroid hormone to facilitate the expression of target genes. Although primarily residing in the nucleus, TRα1 and TRβ1 shuttle rapidly between the nucleus and cytoplasm. We have identified multiple nuclear localization signals and nuclear export signals within TRα1 and TRβ1 that interact with importins and exportins, respectively, to mediate translocation across the nuclear envelope. More recently, enigmatic cytoplasmic functions have been ascribed to other TR subtypes, expanding the diversity of the cellular response to thyroid hormone. By integrating data on localization signal motifs, this review provides an overview of the complex interplay between TR's dynamic transport pathways and thyroid hormone signaling activities. We examine the variation in TR subtype response to thyroid hormone signaling, and what is currently known about regulation of the variety of tissue-specific localization patterns, including targeting to the nucleus, the mitochondria and the inner surface of the plasma membrane.
Collapse
Affiliation(s)
| | - Vincent R Roggero
- Department of BiologyCollege of William and Mary, Williamsburg, Virginia, USA
| | - Lizabeth A Allison
- Department of BiologyCollege of William and Mary, Williamsburg, Virginia, USA
| |
Collapse
|
23
|
Abstract
In recent years, the zebrafish has become a powerful model not only for the developmental biology studies, but also for genetic analyses and drug screenings, mostly thanks to the ease with which its embryos can be manipulated and to its translucent body, which allows in vivo imaging. In this chapter, we will provide an overview of the current knowledge about the role of thyroid hormone receptors during zebrafish embryonic development. Moreover, we will explore the methodologies applied to zebrafish biology to knock down a gene of interest and to analyze in vivo the molecular mechanisms of the mutated receptors.
Collapse
Affiliation(s)
- Federica Marelli
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Lab of Endocrine and Metabolic Research, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Luca Persani
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.
- Lab of Endocrine and Metabolic Research, IRCCS Istituto Auxologico Italiano, Milan, Italy.
| |
Collapse
|
24
|
Raymaekers SR, Darras VM. Thyroid hormones and learning-associated neuroplasticity. Gen Comp Endocrinol 2017; 247:26-33. [PMID: 28390960 DOI: 10.1016/j.ygcen.2017.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/30/2017] [Accepted: 04/03/2017] [Indexed: 12/11/2022]
Abstract
Thyroid hormones (THs) are crucial for brain development and maturation in all vertebrates. Especially during pre- and perinatal development, disruption of TH signaling leads to a multitude of neurological deficits. Many animal models provided insight in the role of THs in brain development, but specific data on how they affect the brain's ability to learn and adapt depending on environmental stimuli are rather limited. In this review, we focus on a number of learning processes like spatial learning, fear conditioning, vocal learning and imprinting behavior and on how abnormal TH signaling during development shapes subsequent performance. It is clear from multiple studies that TH deprivation leads to defects in learning on all fronts, and interestingly, changes in local expression of the TH activator deiodinase type 2 seem to have an important role. Taking into account that THs are regulated in a very space-specific manner, there is thus increasing pressure to investigate more local TH regulators as potential factors involved in neuroplasticity. As these learning processes are also important for proper adult human functioning, further elucidating the role of THs in developmental neuroplasticity in various animal models is an important field for advancing both fundamental and applied knowledge on human brain function.
Collapse
Affiliation(s)
- Sander R Raymaekers
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Naamsestraat 61, 3000 Leuven, Belgium
| | - Veerle M Darras
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Naamsestraat 61, 3000 Leuven, Belgium.
| |
Collapse
|
25
|
Raymaekers SR, Verbeure W, Ter Haar SM, Cornil CA, Balthazart J, Darras VM. A dynamic, sex-specific expression pattern of genes regulating thyroid hormone action in the developing zebra finch song control system. Gen Comp Endocrinol 2017; 240:91-102. [PMID: 27693816 DOI: 10.1016/j.ygcen.2016.09.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/19/2016] [Accepted: 09/28/2016] [Indexed: 01/19/2023]
Abstract
The zebra finch (Taeniopygia guttata) song control system consists of several series of interconnected brain nuclei that undergo marked changes during ontogeny and sexual development, making it an excellent model to study developmental neuroplasticity. Despite the demonstrated influence of hormones such as sex steroids on this phenomenon, thyroid hormones (THs) - an important factor in neural development and maturation - have not been studied in this regard. We used in situ hybridization to compare the expression of TH transporters, deiodinases and receptors between both sexes during all phases of song development in male zebra finch. Comparisons were made in four song control nuclei: Area X, the lateral magnocellular nucleus of the anterior nidopallium (LMAN), HVC (used as proper name) and the robust nucleus of the arcopallium (RA). Most genes regulating TH action are expressed in these four nuclei at early stages of development. However, while general expression levels decrease with age, the activating enzyme deiodinase type 2 remains highly expressed in Area X, HVC and RA in males, but not in females, until 90days post-hatch (dph), which marks the end of sensorimotor learning. Furthermore, the L-type amino acid transporter 1 and TH receptor beta show elevated expression in male HVC and RA respectively compared to surrounding tissue until adulthood. Differences compared to surrounding tissue and between sexes for the other TH regulators were minor. These developmental changes are accompanied by a strong local increase in vascularization in the male RA between 20 and 30dph but not in Area X or HVC. Our results suggest that local regulation of TH signaling is an important factor in the development of the song control nuclei during the song learning phase and that TH activation by DIO2 is a key player in this process.
Collapse
Affiliation(s)
- Sander R Raymaekers
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Naamestraat 61, 3000 Leuven, Belgium
| | - Wout Verbeure
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Naamestraat 61, 3000 Leuven, Belgium
| | - Sita M Ter Haar
- Research Group in Behavioral Neuroendocrinology, GIGA Neurosciences, ULg, Avenue Hippocrate 15, 4000 Liège, Belgium
| | - Charlotte A Cornil
- Research Group in Behavioral Neuroendocrinology, GIGA Neurosciences, ULg, Avenue Hippocrate 15, 4000 Liège, Belgium
| | - Jacques Balthazart
- Research Group in Behavioral Neuroendocrinology, GIGA Neurosciences, ULg, Avenue Hippocrate 15, 4000 Liège, Belgium
| | - Veerle M Darras
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Naamestraat 61, 3000 Leuven, Belgium.
| |
Collapse
|
26
|
Hsu BY, Dijkstra C, Darras VM, de Vries B, Groothuis TGG. Maternal thyroid hormones enhance hatching success but decrease nestling body mass in the rock pigeon (Columba livia). Gen Comp Endocrinol 2017; 240:174-181. [PMID: 27793722 DOI: 10.1016/j.ygcen.2016.10.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 10/20/2016] [Accepted: 10/24/2016] [Indexed: 11/22/2022]
Abstract
Thyroid hormones (THs) - triiodothyronine (T3) and thyroxine (T4) - are essential for embryonic development in vertebrates. All vertebrate embryos are exposed to THs from maternal origin. As maternal TH levels are known to be essential to embryonic development, the natural variation of maternal THs probably represents a pathway of maternal effects that can modify offspring phenotype. However, potential fitness consequences of variation of maternal TH exposure within the normal physiological range and without confounding effects of the mother have never been experimentally investigated. We experimentally manipulated the levels of yolk T3 and T4 within the physiological range in a species in which the embryo develops outside the mother's body, the Rock Pigeon (Columba livia) eggs. Making use of the natural difference of yolk testosterone between the two eggs of pigeon clutches, we were also able to investigate the potential interaction between THs and testosterone. Elevated yolk TH levels enhanced embryonic development and hatching success, and reduced body mass but not tarsus length between day 14 and fledging. The yolk hormones increased plasma T4 concentrations in females but reduced it in males, in line with the effect on metabolic rate at hatching. Plasma concentrations of T3 and testosterone were not significantly affected. The effects of treatment did not differ between eggs with high or low testosterone levels. Our data indicate that natural variation in maternal yolk TH levels affects offspring phenotype and embryonic survival, potentially influencing maternal and chick fitness.
Collapse
Affiliation(s)
- Bin-Yan Hsu
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
| | - Cor Dijkstra
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Veerle M Darras
- Laboratory of Comparative Endocrinology, Section of Animal Physiology and Neurobiology, KU Leuven, Naamsestraat 61, B-3000 Leuven, Belgium
| | - Bonnie de Vries
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Ton G G Groothuis
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| |
Collapse
|
27
|
Vogeler S, Bean TP, Lyons BP, Galloway TS. Dynamics of nuclear receptor gene expression during Pacific oyster development. BMC DEVELOPMENTAL BIOLOGY 2016; 16:33. [PMID: 27680968 PMCID: PMC5041327 DOI: 10.1186/s12861-016-0129-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 08/11/2016] [Indexed: 12/30/2022]
Abstract
BACKGROUND Nuclear receptors are a highly conserved set of ligand binding transcription factors, with essential roles regulating aspects of vertebrate and invertebrate biology alike. Current understanding of nuclear receptor regulated gene expression in invertebrates remains sparse, limiting our ability to elucidate gene function and the conservation of developmental processes across phyla. Here, we studied nuclear receptor expression in the early life stages of the Pacific oyster, Crassostrea gigas, to identify at which specific key stages nuclear receptors are expressed RESULTS: We used quantitative RT-PCR to determine the expression profiles of 34 nuclear receptors, revealing three developmental key stages, during which nuclear receptor expression is dynamically regulated: embryogenesis, mid development from gastrulation to trochophore larva, and late larval development prior to metamorphosis. Clustering of nuclear receptor expression patterns demonstrated that transcriptional regulation was not directly related to gene phylogeny, suggesting closely related genes may have distinct functions. Expression of gene homologs of vertebrate retinoid receptors suggests participation in organogenesis and shell-formation, as they are highly expressed at the gastrulation and trochophore larval initial shell formation stages. The ecdysone receptor homolog showed high expression just before larval settlement, suggesting a potential role in metamorphosis. CONCLUSION Throughout early oyster development nuclear receptors exhibited highly dynamic expression profiles, which were not confined by gene phylogeny. These results provide fundamental information on the presence of nuclear receptors during key developmental stages, which aids elucidation of their function in the developmental process. This understanding is essential as ligand sensing nuclear receptors can be disrupted by xenobiotics, a mode of action through which anthropogenic environmental pollutants have been found to mediate effects.
Collapse
Affiliation(s)
- Susanne Vogeler
- School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD UK
- Centre for Environment, Fisheries and Aquaculture Science, Cefas Weymouth Laboratory, Barrack Road, Weymouth, DT4 8UB UK
| | - Tim P. Bean
- Centre for Environment, Fisheries and Aquaculture Science, Cefas Weymouth Laboratory, Barrack Road, Weymouth, DT4 8UB UK
| | - Brett P. Lyons
- Centre for Environment, Fisheries and Aquaculture Science, Cefas Weymouth Laboratory, Barrack Road, Weymouth, DT4 8UB UK
| | - Tamara S. Galloway
- School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD UK
| |
Collapse
|
28
|
Técher R, Houde M, Verreault J. Associations between organohalogen concentrations and transcription of thyroid-related genes in a highly contaminated gull population. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 545-546:289-298. [PMID: 26747993 DOI: 10.1016/j.scitotenv.2015.12.110] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/22/2015] [Accepted: 12/22/2015] [Indexed: 06/05/2023]
Abstract
A number of studies have reported altered circulating thyroid hormone levels in birds exposed either in controlled settings or in their natural habitat to ubiquitous organohalogen compounds including organochlorines (OCs) and polybrominated diphenyl ether (PBDE) flame retardants. However, limited attention has been paid to underlying homeostatic mechanisms in wild birds such as changes in the expression of genes in the hypothalamic-pituitary-thyroid (HPT) axis. The objective of the present study was to investigate the relationships between hepatic concentrations of major organohalogens (PBDEs and OCs), and circulating thyroid hormone (free and total thyroxine (T4) and triiodothyronine (T3)) levels and transcription of 14 thyroid-related genes in three tissues (thyroid, brain, and liver) of an urban-adapted bird exposed to high organohalogen concentrations in the Montreal area (QC, Canada), the ring-billed gull (Larus delawarensis). Positive correlations were found between liver concentrations of several polychlorinated biphenyls (PCBs), PBDEs as well as chlordanes and total plasma T4 levels. Hepatic concentrations of several PBDEs were negatively correlated with mRNA levels of deiodinase type 3, thyroid peroxidase, and thyroid hormone receptor β (TRβ) in the thyroid gland. Liver PCB (deca-CB) correlated positively with mRNA levels of sodium-iodide symporter and TRα. In brain, concentrations of most PBDEs were positively correlated with mRNA levels of organic anion transporter protein 1C1 and transthyretin, while PCBs positively correlated with expression of TRα and TRβ as well as deiodinase type 2. These multiple correlative linkages suggest that organohalogens operate through several mechanisms (direct or compensatory) involving gene transcription, thus potentially perturbing the HPT axis of this highly organohalogen-contaminated ring-billed gull population.
Collapse
Affiliation(s)
- Romy Técher
- Centre de recherche en toxicologie de l'environnement (TOXEN), Département des sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montreal, QC H3C 3P8, Canada.
| | - Magali Houde
- Environment Canada, St. Lawrence Centre, 105 McGill Street, Montreal, QC H2Y 2E7, Canada.
| | - Jonathan Verreault
- Centre de recherche en toxicologie de l'environnement (TOXEN), Département des sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montreal, QC H3C 3P8, Canada.
| |
Collapse
|
29
|
Hsu BY, Dijkstra C, Darras VM, de Vries B, Groothuis TGG. Maternal adjustment or constraint: differential effects of food availability on maternal deposition of macro-nutrients, steroids and thyroid hormones in rock pigeon eggs. Ecol Evol 2016; 6:397-411. [PMID: 26843926 PMCID: PMC4729257 DOI: 10.1002/ece3.1845] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 10/21/2015] [Indexed: 11/09/2022] Open
Abstract
In oviparous species like birds, eggs provide the direct environment in which embryos are developing. Mothers may adjust different egg components in different ways in reaction to environmental cues either to adjust offspring development or because of constraints. In this study, we investigated the effects of food quality and quantity before and during egg laying on three different aspects of egg quality: macro‐nutrients (egg and yolk mass), androgens (testosterone and androstenedione), and thyroid hormones (3,5,3′‐triiodothyronine, T3 and l‐thyroxine, T4), using the rock pigeon (Columba livia). As expected, egg and yolk mass were significantly reduced for the eggs laid under the poor‐food condition, indicating a maternal trade‐off between offspring and self in allocating important resources. We did not find any significant change in yolk testosterone or their within‐clutch pattern over the laying sequence. This is consistent with the fact that, in contrast with nutrients, these hormones are not costly to produce, but does not support the hypothesis that they play a role in adjusting brood size to food conditions. In contrast, we found that T3 levels were higher in the egg yolks under the poor‐food condition whereas the total T4 content was lower. This change could be related to the fact that iodine, the critical constituent of thyroid hormones, might be a limiting factor in the production of this hormone. Given the knowledge that food restriction usually lead to reduction of circulating T3 levels, our results suggested that avian mothers can independently regulate its concentrations in their eggs from their own circulation. The study demonstrates that environmentally induced maternal effects via the egg can be a result of a combination of constrained resources and unconstrained signals and that thyroid hormones might be an interesting case of both. Therefore, this hormone and the interplay of different maternal effects on the offspring phenotype deserve much more attention.
Collapse
Affiliation(s)
- Bin-Yan Hsu
- Behavioural Biology Groningen Institute for Evolutionary Life Sciences University of Groningen Groningen The Netherlands
| | - Cor Dijkstra
- Behavioural Biology Groningen Institute for Evolutionary Life Sciences University of Groningen Groningen The Netherlands
| | - Veerle M Darras
- Comparative Endocrinology Section of Animal Physiology and Neurobiology KU Leuven Leuven Belgium
| | - Bonnie de Vries
- Behavioural Biology Groningen Institute for Evolutionary Life Sciences University of Groningen Groningen The Netherlands
| | - Ton G G Groothuis
- Behavioural Biology Groningen Institute for Evolutionary Life Sciences University of Groningen Groningen The Netherlands
| |
Collapse
|
30
|
Macaulay LJ, Chen A, Rock KD, Dishaw LV, Dong W, Hinton DE, Stapleton HM. Developmental toxicity of the PBDE metabolite 6-OH-BDE-47 in zebrafish and the potential role of thyroid receptor β. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2015; 168:38-47. [PMID: 26433919 PMCID: PMC4618599 DOI: 10.1016/j.aquatox.2015.09.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 09/14/2015] [Accepted: 09/15/2015] [Indexed: 05/13/2023]
Abstract
6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE-47) is both a polybrominated diphenyl ether (PBDE) flame retardant metabolite and a marine natural product. It has been identified both as a neurotoxicant in cell-based studies and as a developmental toxicant in zebrafish. However, hydroxylated PBDE metabolites are also considered thyroid hormone disruptors due to their structural similarity to endogenous thyroid hormones. The purpose of this study was to evaluate the effects of 6-OH-BDE-47 on a developmental pathway regulated by thyroid hormones in zebrafish. Morphological measurements of development (head trunk angle, otic vesicle length, and eye pigmentation) were recorded in embryos at 30h post fertilization (hpf) and detailed craniofacial morphology was examined in 4 day old larvae using cartilage staining. Exposure to 6-OH-BDE-47 resulted in severe developmental delays. A 100nM concentration resulted in a 26% decrease in head trunk angle, a 54% increase in otic vesicle length, and a 42% decrease in eye pigmentation. Similarly, altered developmental morphology was observed following thyroid receptor β morpholino knockdown, exposure to the thyroid hormone triiodothyronine (T3) or to thyroid disrupting chemicals (TDC; iopanoic acid and propylthiouracil). The threshold for lower jaw deformities and craniofacial cartilage malformations was at doses greater than 50nM. Of interest, these developmental delays and effects were rescued by microinjection of TRβ mRNA during the 1-2 cell stage. These data indicate that OH-BDEs can adversely affect early life development of zebrafish and suggest they may be impacting thyroid hormone regulation in vivo through downregulation of the thyroid hormone receptor.
Collapse
Affiliation(s)
- Laura J Macaulay
- Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
| | - Albert Chen
- Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
| | - Kylie D Rock
- Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
| | - Laura V Dishaw
- Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
| | - Wu Dong
- Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
| | - David E Hinton
- Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
| | | |
Collapse
|
31
|
Comparative analysis of goitrogenic effects of phenylthiourea and methimazole in zebrafish embryos. Reprod Toxicol 2015; 57:10-20. [DOI: 10.1016/j.reprotox.2015.04.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 04/19/2015] [Accepted: 04/29/2015] [Indexed: 11/24/2022]
|
32
|
Darras VM, Houbrechts AM, Van Herck SL. Intracellular thyroid hormone metabolism as a local regulator of nuclear thyroid hormone receptor-mediated impact on vertebrate development. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:130-41. [DOI: 10.1016/j.bbagrm.2014.05.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/17/2014] [Accepted: 05/07/2014] [Indexed: 01/13/2023]
|
33
|
Park HG, Yeo MK. Metabolic gene expression profiling of Zebrafish embryos exposed to silver nanocolloids and nanotubes. Mol Cell Toxicol 2015. [DOI: 10.1007/s13273-014-0045-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
34
|
Zada D, Tovin A, Lerer-Goldshtein T, Vatine GD, Appelbaum L. Altered behavioral performance and live imaging of circuit-specific neural deficiencies in a zebrafish model for psychomotor retardation. PLoS Genet 2014; 10:e1004615. [PMID: 25255244 PMCID: PMC4177677 DOI: 10.1371/journal.pgen.1004615] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 07/18/2014] [Indexed: 11/28/2022] Open
Abstract
The mechanisms and treatment of psychomotor retardation, which includes motor and cognitive impairment, are indefinite. The Allan-Herndon-Dudley syndrome (AHDS) is an X-linked psychomotor retardation characterized by delayed development, severe intellectual disability, muscle hypotonia, and spastic paraplegia, in combination with disturbed thyroid hormone (TH) parameters. AHDS has been associated with mutations in the monocarboxylate transporter 8 (mct8/slc16a2) gene, which is a TH transporter. In order to determine the pathophysiological mechanisms of AHDS, MCT8 knockout mice were intensively studied. Although these mice faithfully replicated the abnormal serum TH levels, they failed to exhibit the neurological and behavioral symptoms of AHDS patients. Here, we generated an mct8 mutant (mct8−/−) zebrafish using zinc-finger nuclease (ZFN)-mediated targeted gene editing system. The elimination of MCT8 decreased the expression levels of TH receptors; however, it did not affect the expression of other TH-related genes. Similar to human patients, mct8−/− larvae exhibited neurological and behavioral deficiencies. High-throughput behavioral assays demonstrated that mct8−/− larvae exhibited reduced locomotor activity, altered response to external light and dark transitions and an increase in sleep time. These deficiencies in behavioral performance were associated with altered expression of myelin-related genes and neuron-specific deficiencies in circuit formation. Time-lapse imaging of single-axon arbors and synapses in live mct8−/− larvae revealed a reduction in filopodia dynamics and axon branching in sensory neurons and decreased synaptic density in motor neurons. These phenotypes enable assessment of the therapeutic potential of three TH analogs that can enter the cells in the absence of MCT8. The TH analogs restored the myelin and axon outgrowth deficiencies in mct8−/− larvae. These findings suggest a mechanism by which MCT8 regulates neural circuit assembly, ultimately mediating sensory and motor control of behavioral performance. We also propose that the administration of TH analogs early during embryo development can specifically reduce neurological damage in AHDS patients. In a wide range of brain disorders, mutations in specific genes cause alterations in the development and function of neural circuits that ultimately affect behavior. A major challenge is to uncover the mechanism and provide treatment which is capable of preventing brain damage. Allan-Herndon-Dudley syndrome (AHDS) is a severe psychomotor retardation characterized by intellectual disabilities, neurological impairment and abnormal thyroid hormone (TH) levels. Mutations in the TH transporter MCT8 are associated with AHDS. Mice that lack the MCT8 protein exhibited impaired TH levels, as is the case in human patients; however, they lack neurological defects. Here, we generated an mct8 mutant (mct8−/−) zebrafish, which exhibited neurological and behavioral deficiencies and mimics pathological conditions of AHDS patients. The zebrafish is a simple transparent vertebrate and its nervous system is conserved with mammals. Time-lapse live imaging of single axons and synapses, and video-tracking of behavior revealed deficiencies in neural circuit assembly, which are associated with disturbed sleep and altered locomotor activity. In addition, since the mct8−/− larvae provides a highthroughput platform for testing therapeutic drugs, we showed that TH analogs can recover neurological deficiencies in an animal model for psychomotor retardation.
Collapse
Affiliation(s)
- David Zada
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel
| | - Adi Tovin
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel
| | - Tali Lerer-Goldshtein
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel
| | - Gad David Vatine
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel
- Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Lior Appelbaum
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel
- * E-mail:
| |
Collapse
|
35
|
Bhumika S, Darras VM. Role of thyroid hormones in different aspects of nervous system regeneration in vertebrates. Gen Comp Endocrinol 2014; 203:86-94. [PMID: 24681191 DOI: 10.1016/j.ygcen.2014.03.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 03/08/2014] [Accepted: 03/11/2014] [Indexed: 12/19/2022]
Abstract
Spontaneous functional recovery from injury in the adult human nervous system is rare and trying to improve recovery remains a clinical challenge. Nervous system regeneration is a complicated sequence of events involving cell death or survival, cell proliferation, axon extension and remyelination, and finally reinnervation and functional recovery. Successful recovery depends on the cell-specific and time-dependent activation and repression of a wide variety of growth factors and guidance molecules. Thyroid hormones (THs), well known for their regulatory role in neurodevelopment, have recently emerged as important modulators of neuroregeneration. This review focuses on the endogenous changes in the proteins regulating TH availability and action in different cell types of the adult mammalian nervous system during regeneration as well as the impact of TH supplementation on the consecutive steps in this process. It also addresses possible differences in TH involvement between different vertebrate classes, early or late developmental stages and peripheral or central nervous system. The available data show that THs are able to stimulate many signaling pathways necessary for successful neurogeneration. They however also suggest that supplementation with T4 and/or T3 may have beneficial or detrimental influences depending on the dose and more importantly on the specific phase of the regeneration process.
Collapse
Affiliation(s)
- Stitipragyan Bhumika
- Laboratory of Comparative Endocrinology, Division Animal Physiology and Neurobiology, Biology Department, KU Leuven, B-3000 Leuven, Belgium
| | - Veerle M Darras
- Laboratory of Comparative Endocrinology, Division Animal Physiology and Neurobiology, Biology Department, KU Leuven, B-3000 Leuven, Belgium.
| |
Collapse
|
36
|
|
37
|
Van Herck SLJ, Geysens S, Delbaere J, Darras VM. Regulators of thyroid hormone availability and action in embryonic chicken brain development. Gen Comp Endocrinol 2013; 190:96-104. [PMID: 23707378 DOI: 10.1016/j.ygcen.2013.05.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 05/10/2013] [Accepted: 05/13/2013] [Indexed: 11/21/2022]
Abstract
Thyroid hormones (THs) are crucial elements in vertebrate brain development. They exert their action mainly through binding of 3,5,3'-triiodothyronine (T3) to nuclear receptors that directly influence the expression of TH-regulated genes. Intracellular TH action is therefore dependent on both the availability of T3 and its receptors. TH uptake in cells is regulated by specific TH transporters and local activation and inactivation is regulated by deiodinases. This review provides an overview of the general expression pattern of TH transporters, deiodinases and receptors during embryonic chicken brain development and compares it to the situation in mammals. It is clear that THs and their regulators are present in the embryonic brain from the early stages of development, long before the onset of embryonic thyroid gland functioning. The mechanism of TH uptake across the brain barriers during development is only partly understood. At the developing blood-brain-barrier expression of the TH-activating type 2 deiodinase is closely associated with the blood vessels, but contrary to the situation in (adult) mammals no expression of MCT8 or OATP1C1 TH transporters is found at that level in the developing chicken. At the blood-cerebrospinal fluid-barrier co-expression of the TH-inactivating type 3 deiodinase and MCT8 and OATP1C1 is found in birds and mammals. These comparative data show overlapping patterns, pointing to general mechanisms, but also indicate specific interspecies differences that may help to understand species-specific responses to regulator gene knockout/mutation.
Collapse
Affiliation(s)
- Stijn L J Van Herck
- Laboratory of Comparative Endocrinology, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, B-3000 Leuven, Belgium.
| | | | | | | |
Collapse
|
38
|
Sechman A. The role of thyroid hormones in regulation of chicken ovarian steroidogenesis. Gen Comp Endocrinol 2013; 190:68-75. [PMID: 23631902 DOI: 10.1016/j.ygcen.2013.04.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 04/01/2013] [Accepted: 04/04/2013] [Indexed: 10/26/2022]
Abstract
In all vertebrates, including birds, the normal development of the ovary and ovarian follicles is under the regulatory influence of hormones produced by the reproductive axis. In recent years, it has become clear that in birds an adequate level of thyroid hormones (THs), i.e. thyroxine (T4) and triiodothyronine (T3), in blood circulation is of primary importance for normal female reproductive functions. In avian species, characterized by seasonal reproduction, THs are involved in the photoperiodic regulation of reproduction acting at the mediobasal hypothalamus. In domestic fowl, where the seasonality of reproduction has been eliminated, the role of THs in ovarian function is not fully elucidated. Recent studies have revealed that ovarian follicles of the laying hen express mRNAs of TH nuclear receptors (TRα and TRβ0) as well as integrin (αVβ3) plasma membrane receptors, indicating genomic and nongenomic action of THs in the chicken ovary. In vivo experiments carried out on laying hens have showed that the bolus injection of T3 decreases levels of luteinizing hormone (LH) and estradiol (E2) in blood, and a hyperthyroid state evoked by administration of T3 for few days diminishes LH, E2 and progesterone (P4) levels, reduces the weight of the ovary, induces atresia of preovulatory follicles and eventually causes stoppage of egg laying. In vitro studies have demonstrated that T3 decreases E2 secretion from white nonhierarchical follicles and the theca layer of yellow preovulatory follicles, while on the other hand, it elevates P4 production from the granulosa layer of these follicles. These effects have been associated with steroidogenic enzyme expression and cyclic AMP synthesis. This review summarizes the current knowledge concerning the role of THs in regulation of steroidogenesis in chicken ovarian follicles.
Collapse
Affiliation(s)
- Andrzej Sechman
- Department of Animal Physiology and Endocrinology, University of Agriculture in Krakow, Al. Mickiewicza 24/28, 30-059 Krakow, Poland.
| |
Collapse
|
39
|
Heijlen M, Houbrechts AM, Darras VM. Zebrafish as a model to study peripheral thyroid hormone metabolism in vertebrate development. Gen Comp Endocrinol 2013; 188:289-96. [PMID: 23603432 DOI: 10.1016/j.ygcen.2013.04.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 04/08/2013] [Accepted: 04/10/2013] [Indexed: 11/21/2022]
Abstract
To unravel the role of thyroid hormones (THs) in vertebrate development it is important to have suitable animal models to study the mechanisms regulating TH availability and activity. Zebrafish (Danio rerio), with its rapidly and externally developing transparent embryo has been a widely used model in developmental biology for some time. To date many of the components of the zebrafish thyroid axis have been identified, including the TH transporters MCT8, MCT10 and OATP1C1, the deiodinases D1, D2 and D3, and the receptors TRα and TRβ. Their structure and function closely resemble those of higher vertebrates. Interestingly, due to a whole genome duplication in the early evolution of ray-finned fishes, zebrafish possess two genes for D3 (dio3 and dio3a) and for TRα (thraa and thrab). Transcripts of all identified genes are present during embryonic development and several of them show dynamic spatio-temporal distribution patterns. Transient morpholino-knockdown of D2, D3 or MCT8 expression clearly disturbs embryonic development, confirming the importance of each of these regulators during early life stages. The recently available tools for targeted stable gene knockout will further increase the value of zebrafish to study the role of peripheral TH metabolism in pre- and post-hatch/post-natal vertebrate development.
Collapse
Affiliation(s)
- Marjolein Heijlen
- Laboratory of Comparative Endocrinology, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, B-3000 Leuven, Belgium.
| | | | | |
Collapse
|
40
|
Van Herck SLJ, Geysens S, Delbaere J, Tylzanowski P, Darras VM. Expression profile and thyroid hormone responsiveness of transporters and deiodinases in early embryonic chicken brain development. Mol Cell Endocrinol 2012; 349:289-97. [PMID: 22120204 DOI: 10.1016/j.mce.2011.11.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 10/21/2011] [Accepted: 11/12/2011] [Indexed: 10/15/2022]
Abstract
We used the chick embryo to study the mechanisms regulating intracellular TH availability in developing brain. TH-transporters OATP1C1 and MCT8, and deiodinases D1, D2, and D3 were expressed in a region-specific way, well before the onset of endogenous TH secretion. Between day 4 and 10 of development MCT8 and D2 mRNA levels increased, while OATP1C1 and D3 mRNA levels decreased. D2 and D3 mRNAs were translated into active protein, while no D1 activity was detectable. Injection of THs into the yolk 24h before sampling increased TH levels in the brain and resulted in decreased OATP1C1 and increased MCT8 expression in 4-day-old embryos. A compensatory response in deiodinase activity was only observed at day 8. We conclude that THs are active in the early embryonic brain and TH-transporters and deiodinases can regulate their availability. However, the absence of clear compensatory mechanisms at day 4 makes the brain more vulnerable for changes in maternal TH supply.
Collapse
Affiliation(s)
- Stijn L J Van Herck
- Laboratory of Comparative Endocrinology, Animal Physiology and Neurobiology Section, Department of Biology, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | | | | | | | | |
Collapse
|