1
|
Abstract
Iodothyronine deiodinases are enzymes capable of activating and inactivating thyroid hormones (THs) and have an important role in regulating TH action in tissues throughout the body. Three types of deiodinases (D1, D2, and D3) were originally defined based on their biochemical characteristics. Cloning of the first complementary DNAs in the 1990s (Dio1 in rat and dio2 and dio3 in frog) allowed to confirm the existence of 3 distinct enzymes. Over the years, increasing genomic information revealed that deiodinases are present in all chordates, vertebrates, and nonvertebrates and that they can even be found in some mollusks and annelids, pointing to an ancient origin. Research in nonmammalian models has substantially broadened our understanding of deiodinases. In relation to their structure, we discovered for instance that biochemical properties such as inhibition by 6-propyl-2-thiouracil, stimulation by dithiothreitol, and temperature optimum are subject to variation. Data from fish, amphibians, and birds were key in shifting our view on the relative importance of activating and inactivating deiodination pathways and in showing the impact of D2 and D3 not only in local but also whole body T3 availability. They also led to the discovery of new local functions such as the acute reciprocal changes in D2 and D3 in hypothalamic tanycytes upon photostimulation, involved in seasonal rhythmicity. With the present possibilities for rapid and precise gene silencing in any species of interest, comparative research will certainly further contribute to a better understanding of the importance of deiodinases for adequate TH action, also in humans.
Collapse
Affiliation(s)
- Veerle M Darras
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Leuven, Belgium
- Correspondence: Veerle Darras, PhD, Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Naamsestraat 61, PB 2464, B-3000 Leuven, Belgium.
| |
Collapse
|
2
|
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
|
3
|
López-Espíndola D, García-Aldea Á, Gómez de la Riva I, Rodríguez-García AM, Salvatore D, Visser TJ, Bernal J, Guadaño-Ferraz A. Thyroid hormone availability in the human fetal brain: novel entry pathways and role of radial glia. Brain Struct Funct 2019; 224:2103-2119. [PMID: 31165302 DOI: 10.1007/s00429-019-01896-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 05/27/2019] [Indexed: 01/13/2023]
Abstract
Thyroid hormones (TH) are crucial for brain development; their deficiency during neurodevelopment impairs neural cell differentiation and causes irreversible neurological alterations. Understanding TH action, and in particular the mechanisms regulating TH availability in the prenatal human brain is essential to design therapeutic strategies for neurological diseases due to impaired TH signaling during neurodevelopment. We aimed at the identification of cells involved in the regulation of TH availability in the human brain at fetal stages. To this end, we studied the distribution of the TH transporters monocarboxylate transporter 8 (MCT8) and organic anion-transporting polypeptide 1C1 (OATP1C1), as well as the TH-metabolizing enzymes types 2 and 3 deiodinases (DIO2 and DIO3). Paraffin-embedded human brain sections obtained from necropsies of thirteen fetuses from 14 to 38 gestational weeks were analyzed by immunohistochemistry and in situ hybridization. We found these proteins localized along radial glial cells, in brain barriers, in Cajal-Retzius cells, in migrating fibers of the brainstem and in some neurons and glial cells with particular and complex spatiotemporal patterns. Our findings point to an important role of radial glia in controlling TH delivery and metabolism and suggest two additional novel pathways for TH availability in the prenatal human brain: the outer, and the inner cerebrospinal fluid-brain barriers. Based on our data we propose a model of TH availability for neural cells in the human prenatal brain in which several cell types have the ability to autonomously control the required TH content.
Collapse
Affiliation(s)
- Daniela López-Espíndola
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), 28029, Madrid, Spain
- Escuela de Tecnología Médica and Centro de Investigaciones Biomédicas (CIB), Universidad de Valparaíso, Angamos 655, Reñaca, Viña del Mar, Chile
| | - Ángel García-Aldea
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), 28029, Madrid, Spain
| | | | | | - Domenico Salvatore
- Department of Public Health, University of Naples "Federico II", 80133, Naples, Italy
- CEINGE-Biotecnologie Avanzate s.c.a.r.l, 80145, Naples, Italy
| | - Theo J Visser
- Department of Internal Medicine, Erasmus Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Juan Bernal
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), 28029, Madrid, Spain.
- Center for Biomedical Research on Rare Diseases (CIBERER), U708, Madrid, Spain.
| | - Ana Guadaño-Ferraz
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), 28029, Madrid, Spain.
- Center for Biomedical Research on Rare Diseases (CIBERER), U708, Madrid, Spain.
| |
Collapse
|
4
|
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: 20] [Impact Index Per Article: 4.0] [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
|
5
|
Vancamp P, Bourgeois NMA, Houbrechts AM, Darras VM. Knockdown of the thyroid hormone transporter MCT8 in chicken retinal precursor cells hampers early retinal development and results in a shift towards more UV/blue cones at the expense of green/red cones. Exp Eye Res 2018; 178:135-147. [PMID: 30273578 DOI: 10.1016/j.exer.2018.09.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 09/21/2018] [Accepted: 09/27/2018] [Indexed: 12/19/2022]
Abstract
Thyroid hormones (THs) play a crucial role in coordinating brain development in vertebrates. They fine-tune processes like cell proliferation, migration, and differentiation mainly by regulating the transcriptional activity of many essential genes. Regulators of TH availability thereby define the cellular concentration of the bioactive 3,5,3'-triiodothyronine, which binds to nuclear TH receptors. One important regulator, the monocarboxylate transporter 8 (MCT8), facilitates cellular TH uptake and is known to be necessary for correct brain development, but data on its potential role during retinal development is lacking. The retinal cyto-architecture has been conserved throughout vertebrate evolution, and we used the chicken embryo to study the need for MCT8 during retinal development. Its external development allows easy manipulation, and MCT8 is abundantly expressed in the retina from early stages onwards. We induced MCT8 knockdown by electroporating a pRFP-MCT8-RNAi vector into the retinal precursor cells (RPCs) at embryonic day 4 (E4), and studied the consequences for early (E6) and late (E18) retinal development. The empty pRFP-RNAi vector was used as a control. RPC proliferation was reduced at E6. This resulted in cellular hypoplasia and a thinner retina at E18 where mainly photoreceptors and horizontal cells were lost, the two predominant cell types that are born around the stage of electroporation. At E6, differentiation into retinal ganglion cells and amacrine cells was delayed. However, since the proportion of a given cell type within the transfected cell population at E18 was similar in knockdown and controls, the partial loss of some cell types was most-likely due to reduced RPC proliferation and not impaired cell differentiation. Photoreceptors displayed delayed migration at first, but had successfully reached the outer nuclear layer at E18. However, they increasingly differentiated into short wavelength-sensitive cones at the expense of medium/long wavelength-sensitive cones, while the proportion of rods was unaltered. Improperly formed sublaminae in the inner plexiform layer additionally suggested defects in synaptogenesis. Altogether, our data echoes effects of hypothyroidism and the loss of some other regulators of TH availability in the developing zebrafish and rodent retina. Therefore, the expression of MCT8 in RPCs is crucial for adequate TH uptake during cell type-specific events in retinal development.
Collapse
Affiliation(s)
- Pieter Vancamp
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, B-3000, Leuven, Belgium
| | - Nele M A Bourgeois
- 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
|
6
|
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
|
7
|
Ruuskanen S, Hsu BY. Maternal Thyroid Hormones: An Unexplored Mechanism Underlying Maternal Effects in an Ecological Framework. Physiol Biochem Zool 2018; 91:904-916. [DOI: 10.1086/697380] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
8
|
Vancamp P, Darras VM. Dissecting the role of regulators of thyroid hormone availability in early brain development: Merits and potential of the chicken embryo model. Mol Cell Endocrinol 2017; 459:71-78. [PMID: 28153797 DOI: 10.1016/j.mce.2017.01.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 01/24/2017] [Accepted: 01/26/2017] [Indexed: 10/20/2022]
Abstract
Thyroid hormones (THs) are important mediators of vertebrate central nervous system (CNS) development, thereby regulating the expression of a wide variety of genes by binding to nuclear TH receptors. TH transporters and deiodinases are both needed to ensure appropriate intracellular TH availability, but the precise function of each of these regulators and their coaction during brain development is only partially understood. Rodent knockout models already provided some crucial insights, but their in utero development severely hampers research regarding the role of TH regulators during early embryonic stages. The establishment of novel gain- and loss-of-function techniques has boosted the position of externally developing non-mammalian vertebrates as research models in developmental endocrinology. Here, we elaborate on the chicken as a model organism to elucidate the function of TH regulators during embryonic CNS development. The fast-developing, relatively big and accessible embryo allows easy experimental manipulation, especially at early stages of brain development. Recent data on the characterisation and spatiotemporal expression pattern of different TH regulators in embryonic chicken CNS have provided the necessary background to dissect the function of each of them in more detail. We highlight some recent advances and important strategies to investigate the role of TH transporters and deiodinases in various CNS structures like the brain barriers, the cerebellum, the retina and the hypothalamus. Exploiting the advantages of this non-classical model can greatly contribute to complete our understanding of the regulation of TH bioavailability throughout embryonic CNS development.
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
|
9
|
Deficiency of the Thyroid Hormone Transporter Monocarboxylate Transporter 8 in Neural Progenitors Impairs Cellular Processes Crucial for Early Corticogenesis. J Neurosci 2017; 37:11616-11631. [PMID: 29109240 DOI: 10.1523/jneurosci.1917-17.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 10/02/2017] [Indexed: 11/21/2022] Open
Abstract
Thyroid hormones (THs) are essential for establishing layered brain structures, a process called corticogenesis, by acting on transcriptional activity of numerous genes. In humans, deficiency of the monocarboxylate transporter 8 (MCT8), involved in cellular uptake of THs before their action, results in severe neurological abnormalities, known as the Allan-Herndon-Dudley syndrome. While the brain lesions predominantly originate prenatally, it remains unclear how and when exactly MCT8 dysfunction affects cellular processes crucial for corticogenesis. We investigated this by inducing in vivo RNAi vector-based knockdown of MCT8 in neural progenitors of the chicken optic tectum, a layered structure that shares many developmental features with the mammalian cerebral cortex. MCT8 knockdown resulted in cellular hypoplasia and a thinner optic tectum. This could be traced back to disrupted cell-cycle kinetics and a premature shift to asymmetric cell divisions impairing progenitor cell pool expansion. Birth-dating experiments confirmed diminished neurogenesis in the MCT8-deficient cell population as well as aberrant migration of both early-born and late-born neuroblasts, which could be linked to reduced reelin signaling and disorganized radial glial cell fibers. Impaired neurogenesis resulted in a reduced number of glutamatergic and GABAergic neurons, but the latter additionally showed decreased differentiation. Moreover, an accompanying reduction in untransfected GABAergic neurons suggests hampered intercellular communication. These results indicate that MCT8-dependent TH uptake in the neural progenitors is essential for early events in corticogenesis, and help to understand the origin of the problems in cortical development and function in Allan-Herndon-Dudley syndrome patients.SIGNIFICANCE STATEMENT Thyroid hormones (THs) are essential to establish the stereotypical layered structure of the human forebrain during embryonic development. Before their action on gene expression, THs require cellular uptake, a process facilitated by the TH transporter monocarboxylate transporter 8 (MCT8). We investigated how and when dysfunctional MCT8 can induce brain lesions associated with the Allan-Herndon-Dudley syndrome, characterized by psychomotor retardation. We used the layered chicken optic tectum to model cortical development, and induced MCT8 deficiency in neural progenitors. Impaired cell proliferation, migration, and differentiation resulted in an underdeveloped optic tectum and a severe reduction in nerve cells. Our data underline the need for MCT8-dependent TH uptake in neural progenitors and stress the importance of local TH action in early development.
Collapse
|
10
|
Delbaere J, Van Herck SLJ, Bourgeois NMA, Vancamp P, Yang S, Wingate RJT, Darras VM. Mosaic Expression of Thyroid Hormone Regulatory Genes Defines Cell Type-Specific Dependency in the Developing Chicken Cerebellum. THE CEREBELLUM 2017; 15:710-725. [PMID: 26559893 DOI: 10.1007/s12311-015-0744-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The cerebellum is a morphologically unique brain structure that requires thyroid hormones (THs) for the correct coordination of key cellular events driving its development. Unravelling the interplay between the multiple factors that can regulate intracellular TH levels is a key step to understanding their role in the regulation of these cellular processes. We therefore investigated the regional/cell-specific expression pattern of TH transporters and deiodinases in the cerebellum using the chicken embryo as a model. In situ hybridisation revealed expression of the TH transporters monocarboxylate transporter 8 (MCT8) and 10 (MCT10), L-type amino acid transporter 1 (LAT1) and organic anion transporting polypeptide 1C1 (OATP1C1) as well as the inactivating type 3 deiodinase (D3) in the fourth ventricle choroid plexus, suggesting a possible contribution of the resulting proteins to TH exchange and subsequent inactivation of excess hormone at the blood-cerebrospinal fluid barrier. Exclusive expression of LAT1 and the activating type 2 deiodinase (D2) mRNA was found at the level of the blood-brain barrier, suggesting a concerted function for LAT1 and D2 in the direct access of active T3 to the developing cerebellum via the capillary endothelial cells. The presence of MCT8 mRNA in Purkinje cells and cerebellar nuclei during the first 2 weeks of embryonic development points to a potential role of this transporter in the uptake of T3 in central neurons. At later stages, together with MCT10, detection of MCT8 signal in close association with the Purkinje cell dendritic tree suggests a role of both transporters in TH signalling during Purkinje cell synaptogenesis. MCT10 was also expressed in late-born cells in the rhombic lip lineage with a clear hybridisation signal in the outer external granular layer, indicating a potential role for MCT10 in the proliferation of granule cell precursors. By contrast, expression of D3 in the first-born rhombic lip-derived population may serve as a buffering mechanism against high T3 levels during early embryonic development, a hypothesis supported by the pattern of expression of a fluorescent TH reporter in this lineage. Overall, this study builds a picture of the TH dependency in multiple cerebellar cell types starting from early embryonic development.
Collapse
Affiliation(s)
- Joke Delbaere
- Laboratory of Comparative Endocrinology, Department of Biology, KU Leuven, Naamsestraat 61, P.O. Box 2464, B-3000, Leuven, Belgium
| | - Stijn L J Van Herck
- Laboratory of Comparative Endocrinology, Department of Biology, KU Leuven, Naamsestraat 61, P.O. Box 2464, B-3000, Leuven, Belgium
| | - Nele M A Bourgeois
- Laboratory of Comparative Endocrinology, Department of Biology, KU Leuven, Naamsestraat 61, P.O. Box 2464, B-3000, Leuven, Belgium
| | - Pieter Vancamp
- Laboratory of Comparative Endocrinology, Department of Biology, KU Leuven, Naamsestraat 61, P.O. Box 2464, B-3000, Leuven, Belgium
| | - Shuo Yang
- Medical Research Council Centre for Developmental Neurobiology, King's College London, London, UK
| | - Richard J T Wingate
- Medical Research Council Centre for Developmental Neurobiology, King's College London, London, UK
| | - Veerle M Darras
- Laboratory of Comparative Endocrinology, Department of Biology, KU Leuven, Naamsestraat 61, P.O. Box 2464, B-3000, Leuven, Belgium.
| |
Collapse
|
11
|
Delbaere J, Vancamp P, Van Herck SLJ, Bourgeois NMA, Green MJ, Wingate RJT, Darras VM. MCT8 deficiency in Purkinje cells disrupts embryonic chicken cerebellar development. J Endocrinol 2017; 232:259-272. [PMID: 27879339 DOI: 10.1530/joe-16-0323] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 11/21/2016] [Indexed: 01/17/2023]
Abstract
Inactivating mutations in the human SLC16A2 gene encoding the thyroid hormone transporter monocarboxylate transporter 8 (MCT8) result in the Allan-Herndon-Dudley syndrome accompanied by severe locomotor deficits. The underlying mechanisms of the associated cerebellar maldevelopment were studied using the chicken as a model. Electroporation of an MCT8-RNAi vector into the cerebellar anlage of a 3-day-old embryo allowed knockdown of MCT8 in Purkinje cell precursors. This resulted in the downregulation of the thyroid hormone-responsive gene RORα and the Purkinje cell-specific differentiation marker LHX1/5 at day 6. MCT8 knockdown also results in a smaller and less complex dendritic tree at day 18 suggesting a pivotal role of MCT8 for cell-autonomous Purkinje cell maturation. Early administration of the thyroid hormone analogue 3,5,3'-triiodothyroacetic acid partially rescued early Purkinje cell differentiation. MCT8-deficient Purkinje cells also induced non-autonomous effects as they led to a reduced granule cell precursor proliferation, a thinner external germinal layer and a loss of PAX6 expression. By contrast, at day 18, the external germinal layer thickness was increased, with an increase in presence of Axonin-1-positive post-mitotic granule cells in the initial stage of radial migration. The concomitant accumulation of presumptive migrating granule cells in the molecular layer, suggests that inward radial migration to the internal granular layer is stalled. In conclusion, early MCT8 deficiency in Purkinje cells results in both cell-autonomous and non-autonomous effects on cerebellar development and indicates that MCT8 expression is essential from very early stages of development, providing a novel insight into the ontogenesis of the Allan-Herndon-Dudley syndrome.
Collapse
Affiliation(s)
- Joke Delbaere
- Laboratory of Comparative EndocrinologyDepartment of Biology, KU Leuven, Leuven, Belgium
| | - Pieter Vancamp
- Laboratory of Comparative EndocrinologyDepartment of Biology, KU Leuven, Leuven, Belgium
| | - Stijn L J Van Herck
- Laboratory of Comparative EndocrinologyDepartment of Biology, KU Leuven, Leuven, Belgium
| | - Nele M A Bourgeois
- Laboratory of Comparative EndocrinologyDepartment of Biology, KU Leuven, Leuven, Belgium
| | - Mary J Green
- Medical Research Council Centre for Developmental NeurobiologyKing's College London, London, UK
| | - Richard J T Wingate
- Medical Research Council Centre for Developmental NeurobiologyKing's College London, London, UK
| | - Veerle M Darras
- Laboratory of Comparative EndocrinologyDepartment of Biology, KU Leuven, Leuven, Belgium
| |
Collapse
|
12
|
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
|
13
|
Henning Y, Szafranski K. Age-Dependent Changes of Monocarboxylate Transporter 8 Availability in the Postnatal Murine Retina. Front Cell Neurosci 2016; 10:205. [PMID: 27616981 PMCID: PMC4999454 DOI: 10.3389/fncel.2016.00205] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 08/15/2016] [Indexed: 12/12/2022] Open
Abstract
The thyroid hormones (TH) triiodothyronine (T3) and its prohormone thyroxine (T4) are crucial for retinal development and function, and increasing evidence points at TH dysregulation as a cause for retinal degenerative diseases. Thus, precise regulation of retinal TH supply is required for proper retinal function, but knowledge on these mechanisms is still fragmentary. Several transmembrane transporters have been described as key regulators of TH availability in target tissues of which the monocarboxylate transporter 8 (MCT8), a high affinity transporter for T4 and T3, plays an essential role in the central nervous system. Moreover, in the embryonic chicken retina, MCT8 is highly expressed, but the postnatal availability of MCT8 in the mammalian retina was not reported to date. In the present study, spatiotemporal retinal MCT8 availability was examined in mice of different age. For this purpose, we quantified expression levels of Mct8 via Real-Time Reverse-Transcriptase PCR in mouse eyecups (C57BL/6) of juvenile and adult age groups. Additionally, age-dependent MCT8 protein levels were quantified via Western blotting and localized via immunofluorescence confocal microscopy. While no difference in Mct8 expression levels could be detected between age groups, MCT8 protein levels in juvenile animals were about two times higher than in adult animals based on Western blot analyses. Immunohistochemical analyses showed that MCT8 immunoreactivity in the eyecup was restricted to the retina and the retinal pigment epithelium. In juvenile mice, MCT8 was broadly observed along the apical membrane of the retinal pigment epithelium, tightly surrounding photoreceptor outer segments. Distinct immunopositive staining was also detected in the inner nuclear layer and the ganglion cell layer. However, in adult specimens, immunoreactivity visibly declined in all layers, which was in line with Western blot analyses. Since MCT8 was abundantly present in juvenile and about twofold lower in adult retinae, our findings suggest a pivotal role of MCT8 especially during postnatal maturation. The present study provides novel insights into age-dependent retinal TH supply, which might help to understand different aspects regarding retinal development, function, and disorders.
Collapse
Affiliation(s)
- Yoshiyuki Henning
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen Essen, Germany
| | - Karol Szafranski
- Genome Analysis, Leibniz Institute on Aging - Fritz Lipmann Institute Jena, Germany
| |
Collapse
|
14
|
Bourgeois NMA, Van Herck SLJ, Vancamp P, Delbaere J, Zevenbergen C, Kersseboom S, Darras VM, Visser TJ. Characterization of Chicken Thyroid Hormone Transporters. Endocrinology 2016; 157:2560-74. [PMID: 27070099 DOI: 10.1210/en.2015-2025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Thyroid hormone (TH) transmembrane transporters are key regulators of TH availability in target cells where correct TH signaling is essential for normal development. Although the chicken embryo is a valuable model for developmental studies, the only functionally characterized chicken TH transporter so far is the organic anion transporting polypeptide 1C1 (OATP1C1). We therefore cloned the chicken L-type amino acid transporter 1 (LAT1) and the monocarboxylate transporters 8 (MCT8) and 10 (MCT10), and functionally characterized them, together with OATP1C1, in JEG3, COS1, and DF-1 cells. In addition, we used in situ hybridization to study their mRNA expression pattern during development. MCT8 and OATP1C1 are both high affinity transporters for the prohormone T4, whereas receptor-active T3 is preferably transported by MCT8 and MCT10. The latter one shows lower affinity but has a high Vmax and seems to be especially good at T3 export. Also, LAT1 has a lower affinity for its preferred substrate 3,3'-diiodothyronine. Reverse T3 is transported by all 4 TH transporters and is a good export product for OATP1C1. TH transporters are strongly expressed in eye (LAT1, MCT8, MCT10), pancreas (LAT1, MCT10), kidney, and testis (MCT8). Their extensive expression in the central nervous system, especially at the brain barriers, indicates an important role in brain development. In conclusion, we show TH transport by chicken MCT8, MCT10, and LAT1. Together with OATP1C1, these transporters have functional characteristics similar to their mammalian orthologs and are interesting target genes to further elucidate the role of THs during embryonic development.
Collapse
Affiliation(s)
- Nele M A Bourgeois
- Laboratory of Comparative Endocrinology (N.M.A.B., S.L.J.V.H., P.V., J.D., V.M.D.), Department of Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; and Department of Internal Medicine (C.Z., S.K., T.J.V.), Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands
| | - Stijn L J Van Herck
- Laboratory of Comparative Endocrinology (N.M.A.B., S.L.J.V.H., P.V., J.D., V.M.D.), Department of Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; and Department of Internal Medicine (C.Z., S.K., T.J.V.), Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands
| | - Pieter Vancamp
- Laboratory of Comparative Endocrinology (N.M.A.B., S.L.J.V.H., P.V., J.D., V.M.D.), Department of Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; and Department of Internal Medicine (C.Z., S.K., T.J.V.), Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands
| | - Joke Delbaere
- Laboratory of Comparative Endocrinology (N.M.A.B., S.L.J.V.H., P.V., J.D., V.M.D.), Department of Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; and Department of Internal Medicine (C.Z., S.K., T.J.V.), Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands
| | - Chantal Zevenbergen
- Laboratory of Comparative Endocrinology (N.M.A.B., S.L.J.V.H., P.V., J.D., V.M.D.), Department of Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; and Department of Internal Medicine (C.Z., S.K., T.J.V.), Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands
| | - Simone Kersseboom
- Laboratory of Comparative Endocrinology (N.M.A.B., S.L.J.V.H., P.V., J.D., V.M.D.), Department of Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; and Department of Internal Medicine (C.Z., S.K., T.J.V.), Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands
| | - Veerle M Darras
- Laboratory of Comparative Endocrinology (N.M.A.B., S.L.J.V.H., P.V., J.D., V.M.D.), Department of Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; and Department of Internal Medicine (C.Z., S.K., T.J.V.), Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands
| | - Theo J Visser
- Laboratory of Comparative Endocrinology (N.M.A.B., S.L.J.V.H., P.V., J.D., V.M.D.), Department of Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; and Department of Internal Medicine (C.Z., S.K., T.J.V.), Erasmus University Medical Center, 3015 GE Rotterdam, The Netherlands
| |
Collapse
|
15
|
Alves RN, Gomes AS, Stueber K, Tine M, Thorne MAS, Smáradóttir H, Reinhard R, Clark MS, Rønnestad I, Power DM. The transcriptome of metamorphosing flatfish. BMC Genomics 2016; 17:413. [PMID: 27233904 PMCID: PMC4884423 DOI: 10.1186/s12864-016-2699-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/06/2016] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Flatfish metamorphosis denotes the extraordinary transformation of a symmetric pelagic larva into an asymmetric benthic juvenile. Metamorphosis in vertebrates is driven by thyroid hormones (THs), but how they orchestrate the cellular, morphological and functional modifications associated with maturation to juvenile/adult states in flatfish is an enigma. Since THs act via thyroid receptors that are ligand activated transcription factors, we hypothesized that the maturation of tissues during metamorphosis should be preceded by significant modifications in the transcriptome. Targeting the unique metamorphosis of flatfish and taking advantage of the large size of Atlantic halibut (Hippoglossus hippoglossus) larvae, we determined the molecular basis of TH action using RNA sequencing. RESULTS De novo assembly of sequences for larval head, skin and gastrointestinal tract (GI-tract) yielded 90,676, 65,530 and 38,426 contigs, respectively. More than 57 % of the assembled sequences were successfully annotated using a multi-step Blast approach. A unique set of biological processes and candidate genes were identified specifically associated with changes in morphology and function of the head, skin and GI-tract. Transcriptome dynamics during metamorphosis were mapped with SOLiD sequencing of whole larvae and revealed greater than 8,000 differentially expressed (DE) genes significantly (p < 0.05) up- or down-regulated in comparison with the juvenile stage. Candidate transcripts quantified by SOLiD and qPCR analysis were significantly (r = 0.843; p < 0.05) correlated. The majority (98 %) of DE genes during metamorphosis were not TH-responsive. TH-responsive transcripts clustered into 6 groups based on their expression pattern during metamorphosis and the majority of the 145 DE TH-responsive genes were down-regulated. CONCLUSIONS A transcriptome resource has been generated for metamorphosing Atlantic halibut and over 8,000 DE transcripts per stage were identified. Unique sets of biological processes and candidate genes were associated with changes in the head, skin and GI-tract during metamorphosis. A small proportion of DE transcripts were TH-responsive, suggesting that they trigger gene networks, signalling cascades and transcription factors, leading to the overt changes in tissue occurring during metamorphosis.
Collapse
Affiliation(s)
- Ricardo N Alves
- Comparative Endocrinology and Integrative Biology Group, Centro de Ciências do Mar - CCMAR, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Ana S Gomes
- Department of Biology, University of Bergen, 5020, Bergen, Norway
| | - Kurt Stueber
- Max Planck-Genome Centre, Max Planck-Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, D-50829, Köln, Germany
| | - Mbaye Tine
- Max Planck-Genome Centre, Max Planck-Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, D-50829, Köln, Germany.,Current address: Molecular Zoology Laboratory, Department of Zoology, University of Johannesburg, Auckland Park, 2006, South Africa
| | - M A S Thorne
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | | | - Richard Reinhard
- Max Planck-Genome Centre, Max Planck-Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, D-50829, Köln, Germany
| | - M S Clark
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - Ivar Rønnestad
- Department of Biology, University of Bergen, 5020, Bergen, Norway
| | - Deborah M Power
- Comparative Endocrinology and Integrative Biology Group, Centro de Ciências do Mar - CCMAR, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal.
| |
Collapse
|
16
|
Ruuskanen S, Darras VM, Visser ME, Groothuis TGG. Effects of experimentally manipulated yolk thyroid hormone levels on offspring development in a wild bird species. Horm Behav 2016; 81:38-44. [PMID: 27056104 DOI: 10.1016/j.yhbeh.2016.03.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 03/18/2016] [Accepted: 03/19/2016] [Indexed: 10/22/2022]
Abstract
Maternal effects are a crucial mechanism in a wide array of taxa to generate phenotypic variation, thereby affecting offspring development and fitness. Maternally derived thyroid hormones (THs) are known to be essential for offspring development in mammalian and fish models, but have been largely neglected in avian studies, especially in respect to natural variation and an ecological context. We studied, for the first time in a wild species and population, the effects of maternally derived THs on offspring development, behavior, physiology and fitness-related traits by experimental elevation of thyroxine and triiodothyronine in ovo within the physiological range in great tits (Parus major). We found that elevated yolk TH levels had a sex-specific effect on growth, increasing male and decreasing female growth, relative to controls, and this effect was similar throughout the nestling period. Hatching or fledging success, motor coordination behavior, stress reactivity and resting metabolic rate were not affected by the TH treatment. We conclude that natural variation in maternally derived THs may affect some offspring traits in a wild species. As this is the first study on yolk thyroid hormones in a wild species and population, more such studies are needed to investigate its effects on pre-hatching development, and juvenile and adult fitness before generalizations on the importance of maternally derived yolk thyroid hormones can be made. However, this opens a new, interesting avenue for further research in the field of hormone mediated maternal effects.
Collapse
Affiliation(s)
- Suvi Ruuskanen
- Section of Ecology, Department of Biology, University of Turku, Finland; Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.
| | - Veerle M Darras
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Leuven, Belgium.
| | - Marcel E Visser
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.
| | - Ton G G Groothuis
- Groningen Institute of Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.
| |
Collapse
|
17
|
Houbrechts AM, Vergauwen L, Bagci E, Van Houcke J, Heijlen M, Kulemeka B, Hyde DR, Knapen D, Darras VM. Deiodinase knockdown affects zebrafish eye development at the level of gene expression, morphology and function. Mol Cell Endocrinol 2016; 424:81-93. [PMID: 26802877 DOI: 10.1016/j.mce.2016.01.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 01/18/2016] [Accepted: 01/19/2016] [Indexed: 10/22/2022]
Abstract
Retinal development in vertebrates relies extensively on thyroid hormones. Their local availability is tightly controlled by several regulators, including deiodinases (Ds). Here we used morpholino technology to explore the roles of Ds during eye development in zebrafish. Transcriptome analysis at 3 days post fertilization (dpf) revealed a pronounced effect of knockdown of both T4-activating Ds (D1D2MO) or knockdown of T3-inactivating D3 (D3bMO) on phototransduction and retinoid recycling. This was accompanied by morphological defects (studied from 1 to 7 dpf) including reduced eye size, disturbed retinal lamination and strong reduction in rods and all four cone types. Defects were more prominent and persistent in D3-deficient fish. Finally, D3-deficient zebrafish larvae had disrupted visual function at 4 dpf and were less sensitive to a light stimulus at 5 dpf. These data demonstrate the importance of TH-activating and -inactivating Ds for correct zebrafish eye development, and point to D3b as a central player.
Collapse
Affiliation(s)
- Anne M Houbrechts
- Laboratory of Comparative Endocrinology, Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3000, Leuven, Belgium
| | - Lucia Vergauwen
- Zebrafishlab, Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium
| | - Enise Bagci
- Zebrafishlab, Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium; Systemic Physiological & Ecotoxicological Research, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium
| | - Jolien Van Houcke
- Laboratory of Comparative Endocrinology, Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3000, Leuven, Belgium
| | - Marjolein Heijlen
- Laboratory of Comparative Endocrinology, Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3000, Leuven, Belgium
| | - Bernard Kulemeka
- Department of Biological Sciences and Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN, USA
| | - David R Hyde
- Department of Biological Sciences and Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN, USA
| | - Dries Knapen
- Zebrafishlab, Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium
| | - Veerle M Darras
- Laboratory of Comparative Endocrinology, Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3000, Leuven, Belgium.
| |
Collapse
|
18
|
Mohácsik P, Füzesi T, Doleschall M, Szilvásy-Szabó A, Vancamp P, Hadadi É, Darras VM, Fekete C, Gereben B. Increased Thyroid Hormone Activation Accompanies the Formation of Thyroid Hormone-Dependent Negative Feedback in Developing Chicken Hypothalamus. Endocrinology 2016; 157:1211-21. [PMID: 26779746 DOI: 10.1210/en.2015-1496] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The hypothalamic-pituitary-thyroid axis is governed by hypophysiotropic TRH-synthesizing neurons located in the hypothalamic paraventricular nucleus under control of the negative feedback of thyroid hormones. The mechanisms underlying the ontogeny of this phenomenon are poorly understood. We aimed to determine the onset of thyroid hormone-mediated hypothalamic-negative feedback and studied how local hypothalamic metabolism of thyroid hormones could contribute to this process in developing chicken. In situ hybridization revealed that whereas exogenous T4 did not induce a statistically significant inhibition of TRH expression in the paraventricular nucleus at embryonic day (E)19, T4 treatment was effective at 2 days after hatching (P2). In contrast, TRH expression responded to T3 treatment in both age groups. TSHβ mRNA expression in the pituitary responded to T4 in a similar age-dependent manner. Type 2 deiodinase (D2) was expressed from E13 in tanycytes of the mediobasal hypothalamus, and its activity increased between E15 and P2 both in the mediobasal hypothalamus and in tanycyte-lacking hypothalamic regions. Nkx2.1 was coexpressed with D2 in E13 and P2 tanycytes and transcription of the cdio2 gene responded to Nkx2.1 in U87 glioma cells, indicating its potential role in the developmental regulation of D2 activity. The T3-degrading D3 enzyme was also detected in tanycytes, but its level was not markedly changed before and after the period of negative feedback acquisition. These findings suggest that increasing the D2-mediated T3 generation during E18-P2 could provide the sufficient local T3 concentration required for the onset of T3-dependent negative feedback in the developing chicken hypothalamus.
Collapse
Affiliation(s)
- P Mohácsik
- Department of Endocrine Neurobiology (P.M., T.F., M.D., A.S.S., É.H., C.F., B.G.), Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary; János Szentágothai PhD School of Neurosciences (P.M., A.S.S.), Semmelweis University, H-1085 Budapest, Hungary; Laboratory of Comparative Endocrinology (P.V., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3001 Leuven, Belgium; and Department of Medicine (C.F.), Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| | - T Füzesi
- Department of Endocrine Neurobiology (P.M., T.F., M.D., A.S.S., É.H., C.F., B.G.), Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary; János Szentágothai PhD School of Neurosciences (P.M., A.S.S.), Semmelweis University, H-1085 Budapest, Hungary; Laboratory of Comparative Endocrinology (P.V., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3001 Leuven, Belgium; and Department of Medicine (C.F.), Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| | - M Doleschall
- Department of Endocrine Neurobiology (P.M., T.F., M.D., A.S.S., É.H., C.F., B.G.), Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary; János Szentágothai PhD School of Neurosciences (P.M., A.S.S.), Semmelweis University, H-1085 Budapest, Hungary; Laboratory of Comparative Endocrinology (P.V., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3001 Leuven, Belgium; and Department of Medicine (C.F.), Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| | - A Szilvásy-Szabó
- Department of Endocrine Neurobiology (P.M., T.F., M.D., A.S.S., É.H., C.F., B.G.), Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary; János Szentágothai PhD School of Neurosciences (P.M., A.S.S.), Semmelweis University, H-1085 Budapest, Hungary; Laboratory of Comparative Endocrinology (P.V., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3001 Leuven, Belgium; and Department of Medicine (C.F.), Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| | - P Vancamp
- Department of Endocrine Neurobiology (P.M., T.F., M.D., A.S.S., É.H., C.F., B.G.), Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary; János Szentágothai PhD School of Neurosciences (P.M., A.S.S.), Semmelweis University, H-1085 Budapest, Hungary; Laboratory of Comparative Endocrinology (P.V., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3001 Leuven, Belgium; and Department of Medicine (C.F.), Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| | - É Hadadi
- Department of Endocrine Neurobiology (P.M., T.F., M.D., A.S.S., É.H., C.F., B.G.), Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary; János Szentágothai PhD School of Neurosciences (P.M., A.S.S.), Semmelweis University, H-1085 Budapest, Hungary; Laboratory of Comparative Endocrinology (P.V., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3001 Leuven, Belgium; and Department of Medicine (C.F.), Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| | - V M Darras
- Department of Endocrine Neurobiology (P.M., T.F., M.D., A.S.S., É.H., C.F., B.G.), Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary; János Szentágothai PhD School of Neurosciences (P.M., A.S.S.), Semmelweis University, H-1085 Budapest, Hungary; Laboratory of Comparative Endocrinology (P.V., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3001 Leuven, Belgium; and Department of Medicine (C.F.), Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| | - C Fekete
- Department of Endocrine Neurobiology (P.M., T.F., M.D., A.S.S., É.H., C.F., B.G.), Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary; János Szentágothai PhD School of Neurosciences (P.M., A.S.S.), Semmelweis University, H-1085 Budapest, Hungary; Laboratory of Comparative Endocrinology (P.V., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3001 Leuven, Belgium; and Department of Medicine (C.F.), Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| | - B Gereben
- Department of Endocrine Neurobiology (P.M., T.F., M.D., A.S.S., É.H., C.F., B.G.), Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Hungary; János Szentágothai PhD School of Neurosciences (P.M., A.S.S.), Semmelweis University, H-1085 Budapest, Hungary; Laboratory of Comparative Endocrinology (P.V., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, KU Leuven, B-3001 Leuven, Belgium; and Department of Medicine (C.F.), Division of Endocrinology, Diabetes, and Metabolism, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| |
Collapse
|
19
|
Préau L, Le Blay K, Saint Paul E, Morvan-Dubois G, Demeneix BA. Differential thyroid hormone sensitivity of fast cycling progenitors in the neurogenic niches of tadpoles and juvenile frogs. Mol Cell Endocrinol 2016; 420:138-51. [PMID: 26628040 DOI: 10.1016/j.mce.2015.11.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 11/21/2015] [Accepted: 11/22/2015] [Indexed: 12/23/2022]
Abstract
Adult neurogenesis occurs in neural stem cell (NSC) niches where slow cycling stem cells give rise to faster cycling progenitors. In the adult mouse NSC niche thyroid hormone, T3, and its receptor TRα act as a neurogenic switch promoting progenitor cell cycle completion and neuronal differentiation. Little is known about whether and how T3 controls proliferation of differentially cycling cells during xenopus neurogenesis. To address this question, we first used Sox3 as a marker of stem cell and progenitor populations and then applied pulse-chase EdU/IdU incorporation experiments to identify Sox3-expressing slow cycling (NSC) and fast cycling progenitor cells. We focused on the lateral ventricle of Xenopus laevis and two distinct stages of development: late embryonic development (pre-metamorphic) and juvenile frogs (post-metamorphic). These stages were selected for their relatively stable thyroid hormone availability, either side of the major dynamic phase represented by metamorphosis. TRα expression was found in both pre and post-metamorphic neurogenic regions. However, exogenous T3 treatment only increased proliferation of the fast cycling Sox3+ cell population in post-metamorphic juveniles, having no detectable effect on proliferation in pre-metamorphic tadpoles. We hypothesised that the resistance of proliferative cells to exogenous T3 in pre-metamorphic tadpoles could be related to T3 inactivation by the inactivating Deiodinase 3 enzyme. Expression of dio3 was widespread in the tadpole neurogenic niche, but not in the juvenile neurogenic niche. Use of a T3-reporter transgenic line showed that in juveniles, T3 had a direct transcriptional effect on rapid cycling progenitors. Thus, the fast cycling progenitor cells in the neurogenic niche of tadpoles and juvenile frogs respond differentially to T3 as a function of developmental stage.
Collapse
Affiliation(s)
- L Préau
- UMR CNRS 7221, Evolution des Régulations Endocriniennes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, Paris, 75231, France
| | - K Le Blay
- UMR CNRS 7221, Evolution des Régulations Endocriniennes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, Paris, 75231, France
| | - E Saint Paul
- UMR CNRS 7221, Evolution des Régulations Endocriniennes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, Paris, 75231, France
| | - G Morvan-Dubois
- UMR CNRS 7221, Evolution des Régulations Endocriniennes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, Paris, 75231, France
| | - B A Demeneix
- UMR CNRS 7221, Evolution des Régulations Endocriniennes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, Paris, 75231, France.
| |
Collapse
|
20
|
Van Herck SLJ, Delbaere J, Bourgeois NMA, McAllan BM, Richardson SJ, Darras VM. Expression of thyroid hormone transporters and deiodinases at the brain barriers in the embryonic chicken: Insights into the regulation of thyroid hormone availability during neurodevelopment. Gen Comp Endocrinol 2015; 214:30-9. [PMID: 25745816 DOI: 10.1016/j.ygcen.2015.02.021] [Citation(s) in RCA: 34] [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: 10/03/2014] [Revised: 01/28/2015] [Accepted: 02/06/2015] [Indexed: 02/02/2023]
Abstract
Thyroid hormones (THs) are key regulators in the development of the vertebrate brain. Therefore, TH access to the developing brain needs to be strictly regulated. The brain barriers separate the central nervous system from the rest of the body and impose specific transport mechanisms on the exchange of molecules between the general circulation and the nervous system. As such they form ideal structures for regulating TH exchange between the blood and the brain. To investigate the mechanism by which the developing brain regulates TH availability, we investigated the ontogenetic expression profiles of TH transporters, deiodinases and the TH distributor protein transthyretin (TTR) at the brain barriers during embryonic and early postnatal development using the chicken as a model. In situ hybridisation revealed expression of the TH transporters monocarboxylate transporter 8 (MCT8) and 10 (MCT10), organic anion transporting polypeptide 1C1 (OATP1C1) and L-type amino acid transporter 1 (LAT1) and the inactivating type 3 deiodinase (D3) in the choroid plexus which forms the blood-cerebrospinal fluid barrier. This was confirmed by quantitative PCR which additionally indicated strongly increasing expression of TTR as well as detectable expression of the activating type 2 deiodinase (D2) and the (in)activating type 1 deiodinase (D1). In the brain capillaries forming the blood-brain barrier in situ hybridisation showed exclusive expression of LAT1 and D2. The combined presence of LAT1 and D2 in brain capillaries suggests that the blood-brain barrier forms the main route for receptor-active T3 uptake into the embryonic chicken brain. Expression of multiple transporters, deiodinases and TTR in the choroid plexus indicates that the blood-cerebrospinal fluid barrier is also important in regulating early TH availability. The impact of these barrier systems can be deduced from the clear difference in T3 and T4 levels as well as the T3/T4 ratio between the developing brain and the general circulation. We conclude that the tight regulation of TH exchange at the brain barriers from early embryonic stages is one of the factors needed to allow the brain to develop within a relative microenvironment.
Collapse
Affiliation(s)
- Stijn L J Van Herck
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, Leuven, Belgium
| | - Joke Delbaere
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, Leuven, Belgium
| | - Nele M A Bourgeois
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, Leuven, Belgium
| | - Bronwyn M McAllan
- The University of Sydney, Physiology, School of Medical Sciences, and Bosch Institute, Sydney, Australia
| | | | - Veerle M Darras
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, Leuven, Belgium.
| |
Collapse
|
21
|
Abstract
Most of our knowledge on the mechanisms of thyroid hormone (TH) dependent brain development is based on clinical observations and animal studies of maternal/fetal hypothyroidism. THs play an essential role in brain development and hormone deficiency during critical phases in fetal life may lead to severe and permanent brain damage. Maternal hypothyroidism is considered the most common cause of fetal TH deficiency, but the problem may also arise in the fetus. In the case of congenital hypothyroidism due to defects in fetal thyroid gland development or hormone synthesis, clinical symptoms at birth are often mild as a result of compensatory maternal TH supply. TH transporters (THTs) and deiodinases (Ds) are important regulators of intracellular triiodothyronine (T3) availability and therefore contribute to the control of thyroid receptors (TRs)-dependent CNS development and early embryonic life. Defects in fetal THTs or Ds may have more impact on fetal brain since they can result in intracellular T3 deficiency despite sufficient maternal TH supply. One clear example is the recent discovery of mutations in the TH transporter (monocarboxylate transporter 8; MCT8) that could be linked to a syndrome of severe and non reversible psychomotor retardation. Even mild and transient changes in maternal TH levels can directly affect and alter the gene expression profile, and thus disturb fetal brain development. Animal studies are needed to increase our understanding of the exact role of THTs and Ds in prenatal brain development.
Collapse
Affiliation(s)
- R G Ahmed
- Division of Anatomy and Embryology, Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
| |
Collapse
|
22
|
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]
|
23
|
Préau L, Fini JB, Morvan-Dubois G, Demeneix B. Thyroid hormone signaling during early neurogenesis and its significance as a vulnerable window for endocrine disruption. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:112-21. [PMID: 24980696 DOI: 10.1016/j.bbagrm.2014.06.015] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/14/2014] [Accepted: 06/20/2014] [Indexed: 12/11/2022]
Abstract
The essential roles of thyroid hormone (TH) in perinatal brain development have been known for decades. More recently, many of the molecular mechanisms underlying the multiple effects of TH on proliferation, differentiation, migration, synaptogenesis and myelination in the developing nervous system have been elucidated. At the same time data from both epidemiological studies and animal models have revealed that the influence of thyroid signaling on development of the nervous system, extends to all periods of life, from early embryogenesis to neurogenesis in the adult brain. This review focuses on recent insights into the actions of TH during early neurogenesis. A key concept is that, in contrast to the previous ideas that only the unliganded receptor was implicated in these early phases, a critical role of the ligand, T3, is increasingly recognized. These findings are considered in the light of increasing knowledge of cell specific control of T3 availability as a function of deiodinase activity and transporter expression. These requirements for TH in the early stages of neurogenesis take on new relevance given the increasing epidemiological data on adverse effects of TH lack in early pregnancy on children's neurodevelopmental outcome. These ideas lead logically into a discussion on how the actions of TH during the first phases of neurogenesis can be potentially disrupted by gestational iodine lack and/or chemical pollution. This article is part of a Special Issue entitled: Nuclear receptors in animal development.
Collapse
Affiliation(s)
- Laetitia Préau
- UMR CNRS 7221, Evolution des Régulations Endocriniennes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, 75231 Paris, France
| | - Jean Baptiste Fini
- UMR CNRS 7221, Evolution des Régulations Endocriniennes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, 75231 Paris, France
| | - Ghislaine Morvan-Dubois
- UMR CNRS 7221, Evolution des Régulations Endocriniennes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, 75231 Paris, France
| | - Barbara Demeneix
- UMR CNRS 7221, Evolution des Régulations Endocriniennes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, 75231 Paris, France.
| |
Collapse
|
24
|
Wirth EK, Schweizer U, Köhrle J. Transport of thyroid hormone in brain. Front Endocrinol (Lausanne) 2014; 5:98. [PMID: 25009532 PMCID: PMC4067591 DOI: 10.3389/fendo.2014.00098] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 06/07/2014] [Indexed: 12/13/2022] Open
Abstract
Thyroid hormone (TH) transport into the brain is not only pivotal for development and differentiation, but also for maintenance and regulation of adult central nervous system (CNS) function. In this review, we highlight some key factors and structures regulating TH uptake and distribution. Serum TH binding proteins play a major role for the availability of TH since only free hormone concentrations may dictate cellular uptake. One of these proteins, transthyretin is also present in the cerebrospinal fluid (CSF) after being secreted by the choroid plexus. Entry routes into the brain like the blood-brain-barrier (BBB) and the blood-CSF-barrier will be explicated regarding fetal and adult status. Recently identified TH transmembrane transporters (THTT) like monocarboxylate transporter 8 (Mct8) play a major role in uptake of TH across the BBB but as well in transport between cells like astrocytes and neurons within the brain. Species differences in transporter expression will be presented and interference of TH transport by endogenous and exogenous compounds including endocrine disruptors and drugs will be discussed.
Collapse
Affiliation(s)
- Eva K. Wirth
- Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Ulrich Schweizer
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Josef Köhrle
- Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
- *Correspondence: Josef Köhrle, Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, Berlin 13353, Germany e-mail:
| |
Collapse
|
25
|
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
|
26
|
Van Herck SLJ, Geysens S, Bald E, Chwatko G, Delezie E, Dianati E, Ahmed RG, Darras VM. Maternal transfer of methimazole and effects on thyroid hormone availability in embryonic tissues. J Endocrinol 2013; 218:105-15. [PMID: 23608220 DOI: 10.1530/joe-13-0089] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Methimazole (MMI) is an anti-thyroid drug used in the treatment of chronic hyperthyroidism. There is, however, some debate about its use during pregnancy as MMI is known to cross the mammalian placenta and reach the developing foetus. A similar problem occurs in birds, where MMI is deposited in the egg and taken up by the developing embryo. To investigate whether maternally derived MMI can have detrimental effects on embryonic development, we treated laying hens with MMI (0.03% in drinking water) and measured total and reduced MMI contents in the tissues of hens and embryos at different stages of development. In hens, MMI was selectively increased in the thyroid gland, while its levels in the liver and especially brain remained relatively low. Long-term MMI treatment induced a pronounced goitre with a decrease in thyroxine (T₄) content but an increase in thyroidal 3,5,3'-triiodothyronine (T₃) content. This resulted in normal T₃ levels in tissues except in the brain. In chicken embryos, MMI levels were similar in the liver and brain. They gradually decreased during development but always remained above those in the corresponding maternal tissues. Contrary to the situation in hens, T₄ availability was only moderately affected in embryos. Peripheral T₃ levels were reduced in 14-day-old embryos but normal in 18-day-old embryos, while brain T₃ content was decreased at all embryonic stages tested. We conclude that all embryonic tissues are exposed to relatively high doses of MMI and its oxidised metabolites. The effect of maternal MMI treatment on embryonic thyroid hormone availability is most pronounced for brain T₃ content, which is reduced throughout the embryonic development period.
Collapse
Affiliation(s)
- Stijn L J Van Herck
- Laboratory of Comparative Endocrinology, Department of Biology, KU Leuven, Naamsestraat 61, PB 2464, B-3000 Leuven, Belgium
| | | | | | | | | | | | | | | |
Collapse
|
27
|
|
28
|
Vatine GD, Zada D, Lerer-Goldshtein T, Tovin A, Malkinson G, Yaniv K, Appelbaum L. Zebrafish as a model for monocarboxyl transporter 8-deficiency. J Biol Chem 2012; 288:169-80. [PMID: 23161551 DOI: 10.1074/jbc.m112.413831] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Allan-Herndon-Dudley syndrome (AHDS) is a severe psychomotor retardation characterized by neurological impairment and abnormal thyroid hormone (TH) levels. Mutations in the TH transporter, monocarboxylate transporter 8 (MCT8), are associated with AHDS. MCT8 knock-out mice exhibit impaired TH levels; however, they lack neurological defects. Here, the zebrafish mct8 gene and promoter were isolated, and mct8 promoter-driven transgenic lines were used to show that, similar to humans, mct8 is primarily expressed in the nervous and vascular systems. Morpholino-based knockdown and rescue experiments revealed that MCT8 is strictly required for neural development in the brain and spinal cord. This study shows that MCT8 is a crucial regulator during embryonic development and establishes the first vertebrate model for MCT8 deficiency that exhibits a neurological phenotype.
Collapse
Affiliation(s)
- Gad David Vatine
- Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
| | | | | | | | | | | | | |
Collapse
|