1
|
Norris DO. Thyroid and reproduction in amphibians and reptiles. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:869-877. [PMID: 37522483 DOI: 10.1002/jez.2737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 08/01/2023]
Abstract
The relationship between the thyroid gland and reproduction in amphibians and reptiles has been studied for more than 100 years. Most studies suggest a positive involvement of thyroid hormones with some aspects of reproduction, but some studies support a negative role for thyroid hormones at certain life stages. Comprehensive studies of gene activation/suppression by thyroid hormones and their absence at various levels of the hypothalamo-pituitary-gonadal axis coupled with observations of adrenocorticoid activity, reproductive performance, and metabolic involvement are needed to understand this complex relationship.
Collapse
Affiliation(s)
- David O Norris
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA
| |
Collapse
|
2
|
Myosho T, Ishibashi A, Fujimoto S, Miyagawa S, Iguchi T, Kobayashi T. Preself-Feeding Medaka Fry Provides a Suitable Screening System for in Vivo Assessment of Thyroid Hormone-Disrupting Potential. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:6479-6490. [PMID: 35475622 DOI: 10.1021/acs.est.1c06729] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Endocrine-disrupting chemicals are assessed based on their physiological potential and their potential associated adverse effects. However, suitable end points for detection of chemicals that interfere with the thyroid hormone (TH) system have not been established in nonmammals, with the exception of amphibian metamorphosis. The aims of the current study were to develop an in vivo screening system using preself-feeding medaka fry (Oryzias latipes) for the detection of TH-disrupting chemicals and elucidate the underlying molecular mechanism. 17α-Ethinylestradiol (EE2: <100 ng/L) did not induce mRNA expression of estrogen-responsive genes, vitellogenins (vtgs) mRNA. Meanwhile, coexposure with thyroxin (T4) induced an increase of vtg expression. TH-disrupting chemicals (thiourea (TU), perfluorooctanoic acid (PFOA), and tetrabromobisphenol A (TBBPA)) significantly suppressed EE2 (1,000 ng/L)-induced vtg1 expression, while T4 rescued their expression as well as that of thyroid hormone receptor α (tRα) and estrogen receptors (esrs). These results were supported by in silico analysis of the 5'-transcriptional regulatory region of these genes. Furthermore, the esr1 null mutant revealed that EE2-induced vtg1 expression requires mainly esr2a and esr2b in a TH-dependent manner in preself-feeding fry. Application of preself-feeding medaka fry as a screening system might help decipher the in vivo mechanisms of action of TH-disrupting molecules, while providing an alternative to the traditional animal model.
Collapse
Affiliation(s)
- Taijun Myosho
- Laboratory of Molecular Reproductive Biology, Institute for Environmental Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
- Graduate School of Integrated Pharmaceutical and Nutrition Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Ayaka Ishibashi
- Graduate School of Integrated Pharmaceutical and Nutrition Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Shingo Fujimoto
- Tropical Biosphere Research Center, University of the Ryukyus, Okinawa 903-0213, Japan
| | - Shinichi Miyagawa
- Faculty of Advanced Engineering, Tokyo University of Science, Tokyo 125-8585, Japan
| | - Taisen Iguchi
- Graduate School of Nanobioscience, Yokohama City University, Yokohama 236-0027, Japan
| | - Tohru Kobayashi
- Laboratory of Molecular Reproductive Biology, Institute for Environmental Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
- Graduate School of Integrated Pharmaceutical and Nutrition Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| |
Collapse
|
3
|
Transcriptome and Methylome Analysis Reveal Complex Cross-Talks between Thyroid Hormone and Glucocorticoid Signaling at Xenopus Metamorphosis. Cells 2021; 10:cells10092375. [PMID: 34572025 PMCID: PMC8468809 DOI: 10.3390/cells10092375] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/31/2021] [Accepted: 09/03/2021] [Indexed: 12/29/2022] Open
Abstract
Background: Most work in endocrinology focus on the action of a single hormone, and very little on the cross-talks between two hormones. Here we characterize the nature of interactions between thyroid hormone and glucocorticoid signaling during Xenopus tropicalis metamorphosis. Methods: We used functional genomics to derive genome wide profiles of methylated DNA and measured changes of gene expression after hormonal treatments of a highly responsive tissue, tailfin. Clustering classified the data into four types of biological responses, and biological networks were modeled by system biology. Results: We found that gene expression is mostly regulated by either T3 or CORT, or their additive effect when they both regulate the same genes. A small but non-negligible fraction of genes (12%) displayed non-trivial regulations indicative of complex interactions between the signaling pathways. Strikingly, DNA methylation changes display the opposite and are dominated by cross-talks. Conclusion: Cross-talks between thyroid hormones and glucocorticoids are more complex than initially envisioned and are not limited to the simple addition of their individual effects, a statement that can be summarized with the pseudo-equation: TH ∙ GC > TH + GC. DNA methylation changes are highly dynamic and buffered from genome expression.
Collapse
|
4
|
Roles of Estrogens in the Healthy and Diseased Oviparous Vertebrate Liver. Metabolites 2021; 11:metabo11080502. [PMID: 34436443 PMCID: PMC8398935 DOI: 10.3390/metabo11080502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 12/12/2022] Open
Abstract
The liver is a vital organ that sustains multiple functions beneficial for the whole organism. It is sexually dimorphic, presenting sex-biased gene expression with implications for the phenotypic differences between males and females. Estrogens are involved in this sex dimorphism and their actions in the liver of several reptiles, fishes, amphibians, and birds are discussed. The liver participates in reproduction by producing vitellogenins (yolk proteins) and eggshell proteins under the control of estrogens that act via two types of receptors active either mainly in the cell nucleus (ESR) or the cell membrane (GPER1). Estrogens also control hepatic lipid and lipoprotein metabolisms, with a triglyceride carrier role for VLDL from the liver to the ovaries during oogenesis. Moreover, the activation of the vitellogenin genes is used as a robust biomarker for exposure to xenoestrogens. In the context of liver diseases, high plasma estrogen levels are observed in fatty liver hemorrhagic syndrome (FLHS) in chicken implicating estrogens in the disease progression. Fishes are also used to investigate liver diseases, including models generated by mutation and transgenesis. In conclusion, studies on the roles of estrogens in the non-mammalian oviparous vertebrate liver have contributed enormously to unveil hormone-dependent physiological and physiopathological processes.
Collapse
|
5
|
Godfrey A, Hooser B, Abdelmoneim A, Sepúlveda MS. Sex-specific endocrine-disrupting effects of three halogenated chemicals in Japanese medaka. J Appl Toxicol 2019; 39:1215-1223. [PMID: 31066087 DOI: 10.1002/jat.3807] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 02/24/2019] [Accepted: 03/11/2019] [Indexed: 12/13/2022]
Abstract
Several halogenated chemicals are found in an array of products that can cause endocrine disruption. Human studies have shown that endocrine responses are sex specific, with females more likely to develop hypothyroidism and males more likely to have reproductive impairment. The objective of this study was to assess sex differences on thyroid and estrogenic effects after exposure of Japanese medaka (Oryzias latipes, SK2MC) to halogenated compounds. This strain is an excellent model for these studies as sex can be determined non-destructively a few hours postfertilization. Medaka embryos were exposed to sublethal concentrations of Tris(1,3-dichloro-2-propyl) phosphate (TDCPP, 0.019 mg/L), perfluorooctanoic acid (PFOA, 4.7 mg/L) and its next generation alternative, perfluorobutyric acid (PFBA, 137 mg/L). Methimazole (inhibits thyroid hormone synthesis) and the thyroid hormone triiodothyronine served as reference controls. Fish were exposed throughout embryo development until 10 days postfertilization. Females displayed significantly larger swim bladders (which are under thyroid hormone control) after exposure to all chemicals with the exception of triiodothyronine, which caused the opposite effect. Females exposed to TDCPP and PFOA had increased expression of vitellogenin and exposure to PFOA upregulated expression of multiple thyroid-related genes. Upregulation of estrogenic-regulated genes after exposure to TDCPP, PFOA and methimazole was only observed in males. Overall, our results suggest that females and males show an estrogenic response when exposed to these halogenated chemicals and that females appear more susceptible to thyroid-induced swim bladder dysfunction compared with males. These results further confirm the importance of considering sex effects when assessing the toxicity of endocrine-disrupting compounds.
Collapse
Affiliation(s)
- Amy Godfrey
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana
| | - Blair Hooser
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana
| | - Ahmed Abdelmoneim
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana.,Department of Veterinary Forensic Medicine & Toxicology, Assiut University, Assiut, Egypt
| | - Maria S Sepúlveda
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana
| |
Collapse
|
6
|
Nelson ER, Habibi HR. Thyroid hormone regulates vitellogenin by inducing estrogen receptor alpha in the goldfish liver. Mol Cell Endocrinol 2016; 436:259-67. [PMID: 27585488 DOI: 10.1016/j.mce.2016.08.045] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 08/27/2016] [Accepted: 08/28/2016] [Indexed: 01/28/2023]
Abstract
Vitellogenin (Vtg) is an egg-yolk precursor protein that is synthesized in the liver of oviparous species and taken up from the circulation by the ovary. It is well known that Vtg is induced by circulating estrogens. However, other endocrine factors that regulate the expression of Vtg are less well characterized; factors that might play significant roles, especially in seasonal spawners such as the goldfish which require increased quantities of Vtg for the development of hundreds of follicles. In this regard, thyroid hormones have been shown to cycle with the reproductive season. Therefore, we hypothesized that the thyroid hormones might influence the synthesis of Vtg. Treatment of female goldfish with triiodothyronine (T3) resulted in increased Vtg, an observation that was absent in males. Furthermore, T3 failed to induce Vtg in cultured hepatocytes of either sex. Interestingly however, T3 consistently up-regulated the expression of the estrogen receptor alpha (ERα). The T3 mediated upregulation of ERα requires the presence of both thyroid receptor (TR) α-1 and TRβ. When goldfish or cultured hepatocytes were treated with T3 followed by estradiol, there was a synergistic increase in Vtg, a response which is dependent on the presence of ERα. Therefore, by upregulating ERα, T3 serves to prime the liver to subsequent stimuli from estradiol. This cross-talk likely reveals an important physiologic mechanism by which thyroid hormones, whose circulating levels are high during early gonadal recrudescence, facilitate the production of large amounts of Vtg required for egg development.
Collapse
Affiliation(s)
- Erik R Nelson
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; University of Illinois Cancer Center, Chicago, IL, USA; Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Research Performed at: The Department of Biological Sciences, University of Calgary, 2500 University Dr. N.W. Calgary, Alberta, T2N 1N4, Canada.
| | - Hamid R Habibi
- Research Performed at: The Department of Biological Sciences, University of Calgary, 2500 University Dr. N.W. Calgary, Alberta, T2N 1N4, Canada
| |
Collapse
|
7
|
Selection of best-performing reference gene products for investigating transcriptional regulation across silvering in the European eel (Anguilla anguilla). Sci Rep 2015; 5:16966. [PMID: 26593703 PMCID: PMC4655329 DOI: 10.1038/srep16966] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 10/22/2015] [Indexed: 12/05/2022] Open
Abstract
The focus of the present study was to set a methodological approach for evaluating molecular mechanisms underlying silvering transformation in the European eel, Anguilla anguilla. Silvering is a tightly controlled process during which eels undergo significant morphological, physiological and behavioral changes, pre-adapting for the oceanic spawning migration. Female eels showing different silver indexes were caught in different seasons in the Comacchio Lagoon (North Adriatic Sea, Italy). Isolated hepatocytes from these eels were selected as the experimental model given the relevant role of these cells in metabolic functions potentially altered during silvering. Expression profiles of 7 candidate reference transcripts were analyzed seeking the most viable and robust strategies for accurate qPCR data normalization during silvering. Stability analysis and further statistical validation identified transcripts encoding the ribosomal proteins L13 and ARP as the appropriate reference genes in studies on A. anguilla through silvering. The identified reference transcripts were further used to evaluate expression profiles of target transcripts encoding the thyroid hormone receptor β (THRβ) and vitellogenin (vtg), known to be involved in silvering processes. To the best of our knowledge, this is the first study comparing THRβ expression in European eels across silvering.
Collapse
|
8
|
Bagamasbad P, Denver RJ. Mechanisms and significance of nuclear receptor auto- and cross-regulation. Gen Comp Endocrinol 2011; 170:3-17. [PMID: 20338175 PMCID: PMC2911511 DOI: 10.1016/j.ygcen.2010.03.013] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 03/02/2010] [Accepted: 03/19/2010] [Indexed: 12/14/2022]
Abstract
The number of functional hormone receptors expressed by a cell in large part determines its responsiveness to the hormonal signal. The regulation of hormone receptor gene expression is therefore a central component of hormone action. Vertebrate steroid and thyroid hormones act by binding to nuclear receptors (NR) that function as ligand-activated transcription factors. Nuclear receptor genes are regulated by diverse and interacting intracellular signaling pathways. Nuclear receptor ligands can regulate the expression of the gene for the NR that mediates the hormone's action (autoregulation), thus influencing how a cell responds to the hormone. Autoregulation can be either positive or negative, the hormone increasing or decreasing, respectively, the expression of its own NR. Positive autoregulation (autoinduction) is often observed during postembryonic development, and during the ovarian cycle, where it enhances cellular sensitivity to the hormonal signal to drive the developmental process. By contrast, negative autoregulation (autorepression) may become important in the juvenile and adult for homeostatic negative feedback responses. In addition to autoregulation, a NR can influence the expression other types of NRs (cross-regulation), thus modifying how a cell responds to a different hormone. Cross-regulation by NRs is an important means to temporally coordinate cell responses to a subsequent (different) hormonal signal, or to allow for crosstalk between hormone signaling pathways.
Collapse
Affiliation(s)
- Pia Bagamasbad
- Department of Molecular, Cellular and Developmental Biology, The University of Michigan, Ann Arbor, MI 48109, U.S.A
| | - Robert J. Denver
- Department of Molecular, Cellular and Developmental Biology, The University of Michigan, Ann Arbor, MI 48109, U.S.A
- Department of Ecology and Evolutionary Biology, The University of Michigan, Ann Arbor, MI 48109, U.S.A
| |
Collapse
|
9
|
Pickford DB. Screening chemicals for thyroid-disrupting activity: A critical comparison of mammalian and amphibian models. Crit Rev Toxicol 2010; 40:845-92. [DOI: 10.3109/10408444.2010.494250] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
10
|
Fort DJ, Degitz S, Tietge J, Touart LW. The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Frogs and Its Role in Frog Development and Reproduction. Crit Rev Toxicol 2008; 37:117-61. [PMID: 17364707 DOI: 10.1080/10408440601123545] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Metamorphosis of the amphibian tadpole is a thyroid hormone (TH)-dependent developmental process. For this reason, the tadpole is considered to be an ideal bioassay system to identify disruption of thyroid function by environmental contaminants. Here we provide an in-depth review of the amphibian thyroid system with particular focus on the role that TH plays in metamorphosis. The amphibian thyroid system is similar to that of mammals and other tetrapods. We review the amphibian hypothalamic-pituitary-thyroid (HPT) axis, focusing on thyroid hormone synthesis, transport, and metabolism. We also discuss the molecular mechanisms of TH action, including the role of TH receptors, the actions of TH on organogenesis, and the mechanisms that underlie the pleiotropic actions of THs. Finally, we discuss methods for evaluating thyroid disruption in frogs, including potential sites of action, relevant endpoints, candidate protocols for measuring thyroid axis disruption, and current gaps in our knowledge. The utility of amphibian metamorphosis as a model for evaluating thyroid axis disruption has recently led to the development of a bioassay using Xenopus laevis.
Collapse
Affiliation(s)
- Douglas J Fort
- Fort Environmental Laboratories, Stillwater, Oklahoma 74074, USA.
| | | | | | | |
Collapse
|
11
|
Hogan NS, Crump KL, Duarte P, Lean DRS, Trudeau VL. Hormone cross-regulation in the tadpole brain: developmental expression profiles and effect of T3 exposure on thyroid hormone- and estrogen-responsive genes in Rana pipiens. Gen Comp Endocrinol 2007; 154:5-15. [PMID: 17400220 DOI: 10.1016/j.ygcen.2007.02.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2006] [Revised: 02/10/2007] [Accepted: 02/13/2007] [Indexed: 10/23/2022]
Abstract
During metamorphosis, the tadpole neuroendocrine brain is a major target for the organisational effects of hormones acting via both endocrine feedback mechanisms and local hormone production. While the receptor-mediated actions of thyroid hormones in brain development have been well described, there is evidence that thyroid hormones could also be an important modulator of estrogen action during metamorphosis. To better understand hormone action and potential cross-regulation between thyroid hormone and estrogen, we examined changes in thyroid hormone receptors (TRalpha and TRbeta) and the estrogen receptor (ERalpha) in the brain of Rana pipiens throughout metamorphosis and in response to 48 h waterborne triiodothyronine (T3) exposure (0.5, 5 and 50 nM). We also measured mRNA levels of iodothyronine deiodinase (D2 and D3) and aromatase, key enzymes responsible for local synthesis and availability of thyroid hormones and estrogen, respectively. A real-time PCR strategy targeting these genes was developed using either a fluorescent dual-labelled probe- or SYBR Green I-based method. TRbeta mRNA levels were increased during development and in response to T3 exposure. Deiodinase (D2 and D3) enzymes were differentially regulated during development, but mRNA levels of both were increased with 50 nM T3 exposure. ERalpha and aromatase mRNA levels significantly increased at metamorphic climax, but whereas estrogen receptor alpha mRNA levels were increased by 50 nM T3, aromatase mRNA levels were decreased. These results (1) demonstrate that the developing amphibian brain is an important site for stage-specific thyroid hormone regulation of nuclear receptors and hormone synthesis enzymes and (2) provide the basis for further studies exploring the physiological and functional significance of the cross-regulation between thyroid status and estrogen-sensitive genes in the brain during amphibian metamorphosis.
Collapse
Affiliation(s)
- Natacha S Hogan
- Centre for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, ON., Canada K1N 6N5.
| | | | | | | | | |
Collapse
|
12
|
Amphibian metamorphosis. Dev Biol 2007; 306:20-33. [PMID: 17449026 DOI: 10.1016/j.ydbio.2007.03.021] [Citation(s) in RCA: 311] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 03/09/2007] [Accepted: 03/18/2007] [Indexed: 10/23/2022]
|
13
|
Ohnuma A, Conlon JM, Kawasaki H, Iwamuro S. Developmental and triiodothyronine-induced expression of genes encoding preprotemporins in the skin of Tago's brown frog Rana tagoi. Gen Comp Endocrinol 2006; 146:242-50. [PMID: 16403501 DOI: 10.1016/j.ygcen.2005.11.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Revised: 11/15/2005] [Accepted: 11/25/2005] [Indexed: 11/27/2022]
Abstract
Using RT-PCR, two cDNAs encoding preprotemporins were cloned from a total RNA preparation of the skin of Tago's brown frog Rana tagoi. Preprotemporin-1TGa cDNA directs the synthesis of temporin-1TGa (FLPILGKLLSGIL.NH2) previously isolated from R. tagoi skin. Preprotemporin-1TGb cDNA directs the synthesis of a novel 16-amino-acid-residue peptide (AVDLAKIANKVLSSLF.NH2) that, atypically for members of the temporin family, inhibits the growth of Gram-negative bacteria more effectively than Gram-positive bacteria. Preprotemporin-1TGa mRNA and preprotemporin-1TGb mRNA were not detected in skin prior to the onset of metamorphosis (stage 35) but the levels of the transcripts increased markedly during metamorphosis reaching a maximum at stage 38. Exposure of adult animals to 10(-8) M triiodothyronine (T3) for 72 h enhanced expression of the preprotemporin-1TGb gene (approximately threefold) but did not significantly change the level of expression of the preprotemporin-1TGa gene. Exposure of the animals to 10(-8) M T3 and 10(-6) M bisphenol A, an endocrine disrupting chemical that potently inhibits the action of thyroid hormones (THs), reduced expression of the preprotemporin-1TGb gene by 10-fold and the preprotemporin-1TGa gene by threefold. We propose that T3-stimulated synthesis of antimicrobial peptides is important in protecting the animal against microorganisms, particularly at metamorphosis and during skin moulting, but environmental pollutants can inhibit peptide synthesis and render the animal susceptible to invasion by pathogens.
Collapse
Affiliation(s)
- Aya Ohnuma
- Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
| | | | | | | |
Collapse
|
14
|
Abstract
Thyroid hormone (TH) elicits multiple physiological actions in vertebrates from fish to man. These actions can be divided into two broad categories: those where the hormone regulates developmental processes and those that involve actions in the adult organism. Amphibian metamorphosis is a most dramatic example of extensive morphological, biochemical and cellular changes occurring during post-embryonic development, which is obligatorily initiated and sustained by TH. It is, therefore, an ideal model system to understand the action of the hormone. Each tissue of the frog tadpole responds differently to TH, ranging from altered gene expression, morphogenesis, tissue re-structuring and extensive cell death, according to a developmental programme set in place before the thyroid gland begins to secrete the hormone. The key element determining the response to the hormone is the nuclear thyroid hormone receptor (TR). As in most vertebrates, there are two thyroid hormone receptors, TRalpha and TRbeta, which repress transcription in the absence of the ligand and whose concentration in the tissues is directly modulated by the hormone itself. In Xenopus, biochemical and in situ techniques have shown that the amount of TRbeta mRNA and protein are elevated 50-100 times during TH-induced metamorphic climax. This phenomenon of "autoinduction" of receptor is also seen with developmental or inductive processes regulated by other hormones acting through nuclear receptors. It is possible that receptor upregulation may be a pre-requisite for hormonal response. Recent molecular and cell biological studies have suggested that TRs function as multimeric complexes with other nuclear or chromatin proteins, such as co-repressors and co-activators, to regulate the structure of the chromatin, and thereby determine the transcription of the receptor-specified target gene. There is evidence that this may also be so for thyroid hormone regulated transcription during amphibian metamorphosis.
Collapse
Affiliation(s)
- Jamshed R Tata
- National Institute for Medical Research, Mill Hill, London NW7 2HA, UK.
| |
Collapse
|
15
|
Buchholz DR, Paul BD, Fu L, Shi YB. Molecular and developmental analyses of thyroid hormone receptor function in Xenopus laevis, the African clawed frog. Gen Comp Endocrinol 2006; 145:1-19. [PMID: 16266705 DOI: 10.1016/j.ygcen.2005.07.009] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Revised: 06/23/2005] [Accepted: 07/01/2005] [Indexed: 10/25/2022]
Abstract
The current review focuses on the molecular mechanisms and developmental roles of thyroid hormone receptors (TRs) in gene regulation and metamorphosis in Xenopus laevis and discusses implications for TR function in vertebrate development and diversity. Questions addressed are: (1) what are the molecular mechanisms of gene regulation by TR, (2) what are the developmental roles of TR in mediating the thyroid hormone (TH) signal, (3) what are the roles of the different TR isoforms, and (4) how do changes in these molecular and developmental mechanisms affect evolution? Even though detailed knowledge of molecular mechanisms of TR-mediated gene regulation is available from in vitro studies, relatively little is known about how TR functions in development in vivo. Studies on TR function during frog metamorphosis are leading the way toward bridging the gap between in vitro and in vivo studies. In particular, a dual function model for the role of TR in metamorphosis has been proposed and investigated. In this model, TRs repress genes allowing tadpole growth in the absence of TH during premetamorphosis and activate genes important for metamorphosis when TH is present. Despite the lack of metamorphosis in most other vertebrates, TR has important functions in development across vertebrates. The underlying molecular mechanisms of TR in gene regulation are conserved through evolution, so other mechanisms involving TH-target genes and TH tissue-sensitivity and dependence underlie differences in role of TR across vertebrates. Continued analysis of molecular and developmental roles of TR in X. laevis will provide the basis for understanding how TR functions in gene regulation in vivo across vertebrates and how TR is involved in the generation of evolutionary diversity.
Collapse
Affiliation(s)
- Daniel R Buchholz
- Section on Molecular Morphogenesis, Laboratory of Gene Regulation and Development, NICHD/NIH, Building 18T, Room 106, Bethesda, MD 20892-5431, USA.
| | | | | | | |
Collapse
|
16
|
Koponen PS, Nieminen P, Mustonen AM, Kukkonen JVK. Postmetamorphic Xenopus laevis shows decreased plasma triiodothyronine concentrations and phosphorylase activity due to subacute phytosterol exposure. CHEMOSPHERE 2004; 57:1683-1689. [PMID: 15519414 DOI: 10.1016/j.chemosphere.2004.07.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2003] [Revised: 06/14/2004] [Accepted: 07/13/2004] [Indexed: 05/24/2023]
Abstract
Postmetamorphic South African clawed frogs (Xenopus laevis) were exposed to a phytosterol mixture (ca. 80% beta-sitosterol and less sitostanol, campesterol, and campestanol) for 14 days at 30 mugl(-1) in a flow-through system. The effects of phytosterols (PS) on the plasma thyroid hormone (T(3) and T(4)), testosterone, leptin-immunoreactive peptide and tissue glycogen concentrations were determined. The following enzyme activities were also analyzed from the liver and muscle: glycogen phosphorylase and lipase, and from the liver only: glucose-6-phosphatase. The plasma T(3) concentration was lower in the PS-exposed female frogs. Both muscle lipase and glycogen phosphorylase activities were also lower in the PS-exposed animals. These results could indicate that the basal metabolic rate and locomotion activity of the frogs were decreased. The effects could not be attributed to the possible estrogenicity of the PS mixture. Further studies will be needed to evaluate the possible significance of these effects.
Collapse
Affiliation(s)
- Petri S Koponen
- Department of Biology, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland.
| | | | | | | |
Collapse
|
17
|
Vasudevan N, Ogawa S, Pfaff D. Estrogen and thyroid hormone receptor interactions: physiological flexibility by molecular specificity. Physiol Rev 2002; 82:923-44. [PMID: 12270948 DOI: 10.1152/physrev.00014.2002] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The influence of thyroid hormone on estrogen actions has been demonstrated both in vivo and in vitro. In transient transfection assays, the effects of liganded thyroid hormone receptors (TR) on transcriptional facilitation by estrogens bound to estrogen receptors (ER) display specificity according to the following: 1) ER isoform, 2) TR isoform, 3) the promoter through which transcriptional facilitation occurs, and 4) cell type. Some of these molecular phenomena may be related to thyroid hormone signaling of seasonal limitations upon reproduction. The various combinations of these molecular interactions provide multiple and flexible opportunities for relations between two major hormonal systems important for neuroendocrine feedbacks and reproductive behaviors.
Collapse
Affiliation(s)
- Nandini Vasudevan
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, New York 10021, USA
| | | | | |
Collapse
|
18
|
Bownes M, Hurd H, Büsgen T, Servay D, Alvis S, Popovic B, Bruce S, Burns I, Rothwell K, Walkinshaw M. Drosophila yolk protein produced in E. coli is accumulated by mosquito ovaries. INSECT MOLECULAR BIOLOGY 2002; 11:487-496. [PMID: 12230547 DOI: 10.1046/j.1365-2583.2002.00357.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Despite similar functions, the yolk proteins of the higher dipteran flies and the vitellogenins found in other insects are unrelated at the sequence level and have evolved from different genes. Both are selectively endocytosed into the ovary via receptors belonging to the LDLR receptor subfamily. We cloned the Drosophila yp1 gene into an E. coli expression vector and showed that the yolk protein produced by E. coli is taken up into ovaries of both Drosophila melanogaster and the malaria mosquito Anopheles gambiae, which normally uses vitellogenin.
Collapse
Affiliation(s)
- M Bownes
- Institute of Cell and Molecular Biology, The University of Edinburgh, Edinburgh, UK.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Warrier SR, Tirumalai R, Subramoniam T. Occurrence of vertebrate steroids, estradiol 17beta and progesterone in the reproducing females of the mud crab Scylla serrata. Comp Biochem Physiol A Mol Integr Physiol 2001; 130:283-94. [PMID: 11544073 DOI: 10.1016/s1095-6433(01)00385-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In crustaceans, vitellogenesis is known to be controlled by eyestalk neuropeptides, biogenic amines, ecdysteroids and a juvenile hormone-like compound, methyl farnesoate. In recent years, the occurrence of vertebrate steroid hormones, estradiol 17beta (E2) and progesterone (PG) has also been reported in a few decapods, although their precise role in female reproduction is yet to be determined. The levels of E2 and PG in the ovary, hepatopancreas and the hemolymph of the red mud crab, Scylla serrata were analyzed in different vitellogenic stages in order to establish a correlation between hormone profile and stages of vitellogenesis. It was observed that the levels of both the steroids increased steeply in the tissues at the onset of vitellogenesis (vitellogenic stage I). Maximum levels of estradiol were present in the hepatopancreas whereas the highest concentration of progesterone was seen in the ovary, suggesting dichotomous roles for these hormones in vitellogenesis. Furthermore, levels of these hormones were estimated in different embryonic stages of the eggs of the sand crab Emerita asiatica and mud crab S. serrata. Their levels fluctuated, following a definite pattern in the different stages, suggesting a possible functional role as morphogenetic hormones. This study, in addition, also reports the presence of E2 and PG on lipovitellin purified from ovary and eggs as well as vitellogenin purified from the hemolymph implicating a role for these lipoproteins as steroid carriers.
Collapse
Affiliation(s)
- S R Warrier
- Department of Zoology, Unit of Invertebrate Reproduction, University of Madras, Guindy Campus, Guindy, Madras-600 025, India
| | | | | |
Collapse
|
20
|
Abstract
The thyroid hormones L-thyroxine and triiodo-L-thyronine have profound effects on postembryonic development of most vertebrates. Analysis of their action in mammals is vitiated by the exposure of the developing foetus to a number of maternal factors which do not allow one to specifically define the role of thyroid hormone (TH) or that of other hormones and factors that modulate its action. Amphibian metamorphosis is obligatorily dependent on TH which can initiate all the diverse physiological manifestations of this postembryonic developmental process (morphogenesis, cell death, re-structuring, etc.) in free-living embryos and larvae of most anurans. This article will first describe the salient features of metamorphosis and its control by TH and other hormones. Emphasis will be laid on the key role played by TH receptor (TR), in particular the phenomenon of TR gene autoinduction, in initiating the developmental action of TH. Finally, it will be argued that the findings on the control of amphibian metamorphosis enhance our understanding of the regulation of postembryonic development by TH in other vertebrate species.
Collapse
Affiliation(s)
- J R Tata
- National Institute for Medical Research, London, UK
| |
Collapse
|
21
|
Crawford K, Vincenti DM. Retinoic acid and thyroid hormone may function through similar and competitive pathways in regenerating axolotls. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1998; 282:724-38. [PMID: 9846384 DOI: 10.1002/(sici)1097-010x(19981215)282:6<724::aid-jez8>3.0.co;2-e] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The objective of this study was to determine whether thyroid hormone (TH) would interfere with retinoic acid (RA), which proximalizes axolotl larvae regenerate limb pattern. RA and TH are ligands for members of the steroid hormone thyroid hormone nuclear binding protein superfamily which form functional homodimers, but may also form stable heterodimers with the RXR protein and may recognize identical DNA sequences. TH alone does not affect limb pattern but induces metamorphosis in regenerating animals. Coinjected animals do not metamorphose, and when compared to RA controls regenerate more proximal and in some cases anteroposterior (AP) and dorsoventral (DV) duplicate limb structures. In addition, the tissues that are normally lost or changed during metamorphosis appear to be sensitized resulting in the formation of (1) new dorsal gill lamellae accompanied by bifurcation and broadening of the original gill lamellae, (2) partial resorption of the tail fin, and (3) changes in eye position and snout morphology. Bifurcation of gill lamellae tips, but not the formation of supernumerary gills, is also observed in animals treated with RA alone. These results indicate that the molecular mechanism of RA and TH function through similar and perhaps competitive pathways.
Collapse
Affiliation(s)
- K Crawford
- Department of Biology, St. Mary's College of Maryland, St. Mary's City 20686, USA
| | | |
Collapse
|
22
|
Tata JR. Amphibian metamorphosis as a model for studying the developmental actions of thyroid hormone. Cell Res 1998; 8:259-72. [PMID: 9934534 DOI: 10.1038/cr.1998.26] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The thyroid hormones L-thyroxine and triiodo-L-thyronine have profound effects on postembryonic development of most vertebrates. Analysis of their action in mammals is vitiated by the exposure of the developing foetus to a number of maternal factors which do not allow one to specifically define the role of thyroid hormone (TH) or that of other hormones and factors that modulate its action. Amphibian metamorphosis is obligatorily dependent on TH which can initiate all the diverse physiological manifestations of this postembryonic developmental process (morphogenesis, cell death, re-structuring, etc.) in free-living embryos and larvae of most anurans. This article will first describe the salient features of metamorphosis and its control by TH and other hormones. Emphasis will be laid on the key role played by TH receptor (TR), in particular the phenomenon of TR gene autoinduction, in initiating the developmental action of TH. Finally, it will be argued that the findings on the control of amphibian metamorphosis enhance our understanding of the regulation of postembryonic development by TH in other vertebrate species.
Collapse
Affiliation(s)
- J R Tata
- National Institute for Medical Research, London, U.K.
| |
Collapse
|
23
|
|
24
|
Rabelo EM, Tata JR. Prolactin inhibits auto- and cross-induction of thyroid hormone and estrogen receptor and vitellogenin genes in adult Xenopus (Amphibia) hepatocytes. ACTA ACUST UNITED AC 1997. [DOI: 10.1590/s0100-84551997000400010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is well known that virtually every tissue of the amphibian larvae is highly sensitive to the mutually antagonistic actions of thyroid hormone (TH) and prolactin (PRL), but it is not known if adult amphibian tissues respond similarly to these two hormones. We have previously shown that very low doses of triiodothyronine (T3) rapidly and strongly potentiate the activation of silent vitellogenin (Vit) genes by estrogen (E2) and the autoinduction of estrogen receptor (ER) transcripts in primary cultures of adult Xenopus hepatocytes. This response to T3 is accompanied by the upregulation of thyroid hormone receptor <FONT FACE="Symbol">b</FONT> (TR<FONT FACE="Symbol">b</FONT>) mRNA. Using Northern blot and RNase protection assays, we now show that ovine PRL added for 12 h along with 2 x 10-9 M T3 will completely prevent potentiation of E2 induction of Vit mRNA in primary cultures of adult Xenopus hepatocytes. PRL also abolished the auto-upregulation of TR<FONT FACE="Symbol">b</FONT> mRNA and the cross-activation of autoinduction of ER mRNA. Thus, we show for the first time that the anti-TH action of PRL that is manifested in Xenopus tadpole tissues during metamorphosis is retained in adult liver, and suggest that the mutually antagonistic actions of the two hormones may be brought about by similar molecular mechanisms in larval and adult amphibian tissues
Collapse
|
25
|
Fairclough L, Tata JR. An immunocytochemical analysis of the expression of thyroid hormone receptor alpha and beta proteins during natural and thyroid hormone-induced metamorphosis in Xenopus. Dev Growth Differ 1997; 39:273-83. [PMID: 9227894 DOI: 10.1046/j.1440-169x.1997.t01-2-00003.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Amphibian metamorphosis is characterized by the upregulation of thyroid hormone receptor (TR) mRNA in all tissues of tadpole during both the natural and thyroid hormone (TH)-induced development. The two TR genes, termed alpha and beta, are members of a large multigene family of nuclear receptors related to the cellular homolog of the oncogene c-erbA. The phenomenon of upregulation is more marked for the beta than the alpha isoform. To determine whether or not the auto-induction of the transcripts is paralleled by that of TR proteins, non-cross-reacting monoclonal antibodies were prepared against Xenopus laevis TR alpha and beta (xTR alpha, beta) in order to analyze immunocytochemically their expression and localization. Three tadpole tissues that exemplify three major consequences of gene re-programing during natural and TH-induced metamorphosis were studied: (i) Liver that undergoes extensive functional switching; (ii) small intestinal epithelium that exhibits substantial cell death prior to major structural and biochemical modifications; and (iii) hind limb-bud as an example of de novo morphogenesis. It was shown that xTR alpha protein is generally more abundant in these tissues, and its expression is developmentally and hormonally less regulated, than is xTR beta. The auto-induction of xTR beta was particularly intense at 5 days after administration of triiodo-thyronine (T3) to both pre-metamorphic (stage 52) tadpoles and at the onset of natural metamorphosis (stage 55). In the developing hind limb-bud at both stages the upregulation of TR beta is topologically restricted, being particularly intense in dense pockets of cells, presumably rich in chondrocytes. It was concluded that the distribution and expression of xTR alpha and beta proteins match partially, but not fully, those of their transcripts during natural and hormone-induced metamorphosis.
Collapse
Affiliation(s)
- L Fairclough
- Division of Developmental Biochemistry, MRC National Institute for Medical Research, London, UK
| | | |
Collapse
|
26
|
Ulisse S, Iwamura S, Tata JR. Differential responses to ligands of overexpressed thyroid hormone and retinoid X receptors in a Xenopus cell line and in vivo. Mol Cell Endocrinol 1997; 126:17-24. [PMID: 9027359 DOI: 10.1016/s0303-7207(96)03965-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In an attempt to explain the contrasting patterns of expression of Xenopus thyroid hormone (xTR) and retinoid X (xRXR) receptor genes and to extend our understanding of the role of heterodimerization of these receptors during amphibian metamorphosis, we have investigated the response to their respective ligands of cells in which xTR and xRXR were overexpressed. Results obtained with two separate approaches are now described. In the first, 3,3'5-triiodothyronine (t3) was found to strongly upregulate xTR beta mRNA in XTC-2 cells, but not of xTR alpha or xRXR alpha mRNAs, while xRXR gamma transcripts could not be detected. 9-cis-retinoic acid (9-cis-RA) did not substantially influence the expression of any of these four receptor genes. When transcription from three different thyroid response elements (TREs) (a palindromic TREpal, an inverted repeat +6 [F2] and a direct repeat +4[DR+4] as present in the promoter of xTR beta gene) was measured in XTC-2 cells in which xTR beta and xRXR alpha were overexpressed, only T3 upregulated transcription while 9-cis-RA, alone or together with T3, was ineffective. 9-cis-RA however enhanced transcription from an RXR responsive element (RXR-RE). THe second approach involved overexpression of xTR beta and xRXR alpha in premetamorphic Xenopus tadpole tail muscle followed by measuring the response of the tails to T3 in organ culture. After validating the microinjection/culture procedure histochemically, we found that T3 enhanced transcription from the xTR beta DR +4 TRE in tails in which xTR beta was overexpressed but the overexpression of xRXR alpha failed to modify this response. It is concluded that in both XTC cells and tadpole tails, overexpressed xRXR fails to modify the enhanced transcriptional response of endogenous and overexpressed xTR beta to T3 and that exogenous 9-cis-RA is ineffective.
Collapse
Affiliation(s)
- S Ulisse
- Division of Developmental Biochemistry, National Institute for Medical Research, Mill Hill London, UK
| | | | | |
Collapse
|
27
|
Hormonal Signaling and Amphibian Metamorphosis. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1566-3116(08)60039-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
28
|
Tata JR. Amphibian metamorphosis: An exquisite model for hormonal regulation of postembryonic development in vertebrates. Dev Growth Differ 1996. [DOI: 10.1046/j.1440-169x.1996.t01-2-00001.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
29
|
Puzianowska-Kuznicka M, Shi YB. Nuclear factor I as a potential regulator during postembryonic organ development. J Biol Chem 1996; 271:6273-82. [PMID: 8626421 DOI: 10.1074/jbc.271.11.6273] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Nuclear factor I (NFI) family members are transcription factors that are believed to also participate in DNA replication. We have cloned two Xenopus laevis NFIs that are up-regulated by thyroid hormone. They are 84-95% identical to their counterparts in birds and mammals. In contrast, the two Xenopus NFIs are much less homologous to each other, sharing only 58% homology, which largely resides in the DNA binding domain at the amino terminus. However, both NFIs can bind to a consensus NFI binding site and activate the transcription of a promoter bearing the site. Northern blot reveals that both NFI genes are regulated in tissue- and developmental stage-dependent manners. They are first activated, independently of thyroid hormone, to low levels at stages 23/24, around the onset of larval organogenesis. After stage 54, their mRNA levels are dramatically upregulated by endogenous thyroid hormone, and high levels of their expression correlate with organ-specific metamorphosis. Furthermore, gel mobility shift assay indicates that the NFI proteins are present in different organs and that their levels are regulated similarly to the mRNA levels. These results strongly suggest that NFIs play important roles during postembryonic organ development, in contrast to the general belief that NFIs are ubiquitous factors.
Collapse
Affiliation(s)
- M Puzianowska-Kuznicka
- Laboratory of Molecular Embryology, NICHD, National Institutes of Health, Bethesda, Maryland 20892-5430, USA
| | | |
Collapse
|
30
|
Iwamuro S, Tata JR. Contrasting patterns of expression of thyroid hormone and retinoid X receptor genes during hormonal manipulation of Xenopus tadpole tail regression in culture. Mol Cell Endocrinol 1995; 113:235-43. [PMID: 8674831 DOI: 10.1016/0303-7207(95)03634-j] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The precocious induction of amphibian metamorphosis is an ideal system for analyzing the developmental action of TH, while the hormonal activation of tadpole tail regression offers the further advantage of studying programmed cell death. One of the striking features of thyroid hormone (TH)-induced tail regression (as with morphogenetic responses of all tadpole tissues) in Xenopus is the rapid autoinduction of TRbeta gene, but it is not known how TH would affect the expression of the genes encoding TR's heterodimeric partner, retinoid X receptor (RXR). Here we first show that the synthetic glucocorticoid dexamethasone (Dex) potentiates and prolactin (PRL) suppresses, 3,3',5-triiodothyronine (T3)-induced regression of pre-metamorphic Xenopus tadpole tails in organ culture. T3 strongly upregulated (11-35-fold) the concentration of Xenopus TRbeta (xTRbeta) mRNA in these cultures while downregulating by 50% that of Xenopus RXRgamma (xRXRgamma) mRNA in the same samples of tail RNA. DEX and PRL enhanced or diminished the T3-regulated expression of these two transcripts, respectively, which parallels their other effects in whole tadpoles or cultured tails. The contrasting effects of the three hormones on the steady-state levels of xTRbeta and XRXRgamma mRNAs were time- and dose-dependent. T3 and DEX also strongly upregulated the transcription of xTRbeta gene transfected into Xenopus XTC-2 cells but PRL failed to prevent this autoinduction. The actions of these three hormones involved in amphibian metamorphosis, as judged by the expression of xTRbeta and xRXRgamma genes, reveal a new facet of hormonal interplay underlying their developmental actions.
Collapse
Affiliation(s)
- S Iwamuro
- Division of Developmental Biochemistry, National Institute for Medical Research, Mill Hill, London, UK
| | | |
Collapse
|
31
|
Abstract
Although cell death has long been recognized to be a significant element in the process of embryonic morphogenesis, its relationships to differentiation and its mechanisms are only now becoming apparent. This new appreciation has come about not only through advances in the understanding of cell death in parallel immunological and pathological situations, but also through progress in developmental genetics which has revealed the roles played by death in the cell lineages of invertebrate embryos. In this review, we discuss programmed cell death as it is understood in developmental situations, and its relationship to apoptosis. We describe the morphological and biochemical features of apoptosis, and some methods for its detection in tissues. The occurrence of programmed cell death during invertebrate development is reviewed, as well as selected examples in vertebrate development. In particular, we discuss cell death in the early vertebrate embryo, in limb development, and in the nervous system.
Collapse
Affiliation(s)
- E J Sanders
- Department of Physiology, University of Alberta, Edmonton, Canada
| | | |
Collapse
|
32
|
Yamauchi K, Tata JR. Purification and characterization of a cytosolic thyroid-hormone-binding protein (CTBP) in Xenopus liver. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 225:1105-12. [PMID: 7957201 DOI: 10.1111/j.1432-1033.1994.1105b.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A variety of cytosolic thyroid-hormone-binding proteins with different characteristics have previously been reported. Here, we first describe the thyroid-hormone-binding characteristics of adult Xenopus liver cytosol, then a novel procedure for purifying cytosolic thyroid-hormone-binding protein (CTBP) from Xenopus liver (xCTBP). The procedure consists of combining preparative isoelectrofocusing, FPLC cation-exchange chromatography, HPLC hydrophobic-interaction chromatography and ultraviolet light cross-linking of 125I-labeled 3,3'5-triiodo-L-thyronine (T3). The isolated xCTBP thus prepared retained all the characteristics of the major thyroid- hormone-(TH)-binding component of the unfractionated cytosol. It is a monomeric protein of approximately 59 kDa with an isoelectric point of 7.0 +/- 0.1, binds T3 with a higher affinity than its analogs with a Kd of approximately 9 nM, and is sensitive to sulfhydryl agents but not to NADPH. In several respects, xCTBP differs from most CTBP-like preparations from other sources described hitherto. Microsequencing of a 23-amino-acid peptide generated from xCTBP by cyanogen bromide digestion revealed 92-100% identity of a 23-amino-acid sequence of several mammalian (amino acids 236-258) and avian (amino acids 245-267) cytosolic aldehyde dehydrogenases (ALDH); xCTBP also exhibited significant similarity of amino acid composition with rat ALDH. This novel finding of sequence identity between a CTBP and ALDH, and the diversity of CTBPs from different sources, suggest that a variety of cytosolic proteins, depending on the species and tissue, can function as thyroid-hormone-binding proteins.
Collapse
Affiliation(s)
- K Yamauchi
- Laboratory of Developmental Biochemistry, National Institute for Medical Research, London, England
| | | |
Collapse
|
33
|
Ulisse S, Tata JR. Thyroid hormone and glucocorticoid independently regulate the expression of estrogen receptor in male Xenopus liver cells. Mol Cell Endocrinol 1994; 105:45-53. [PMID: 7821717 DOI: 10.1016/0303-7207(94)90034-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Earlier studies from our laboratory had shown that triiodothyronine (T3) strongly potentiates the activation by estradiol (E2) of silent vitellogenin (Vit) genes and the autoinduction of estrogen receptor (ER) mRNA in primary cultures of male Xenopus hepatocytes (Rabelo and Tata, 1993). It was, however, not known if T3, or other hormones, could up-regulate ER mRNA in the absence of exogenous E2. We now show that T3 and dexamethasone (Dex), but not progesterone and testosterone, directly induce ER mRNA within 4 h by separate pathways, at doses compatible with the Kd values of their receptors. This induction of ER mRNA is accompanied by a marked enhancement of the activation of the silent Vit B1 gene if E2 is added by 12 h after T3 and Dex, thus suggesting an elevated level of functional ER induced by the two hormones. This conclusion was supported by a higher rate of transcription from an estrogen response element (ERE)-tk-CAT construct transfected into cultured hepatocytes pre-treated with T3 and Dex before incubation with estrogen. Our findings emphasize the importance of hormonal interplay via auto- and cross-regulation of nuclear hormone receptors.
Collapse
Affiliation(s)
- S Ulisse
- Laboratory of Developmental Biochemistry, National Institute for Medical Research, Mill Hill, London, UK
| | | |
Collapse
|
34
|
Abstract
Whereas crossregulation of nuclear receptors has been known for some time, recently several examples of autoregulation have been described, especially during development and specific gene expression. In this review, I discuss both these phenomena, based on some studies from our laboratory on amphibian metamorphosis and egg protein gene expression. These include autoinduction of estrogen receptor (ER) accompanying egg protein gene expression in adult and larval Xenopus; autoinduction of thyroid hormone receptor (TR) during metamorphosis and in adult Xenopus; crossregulation by triiodothyronine (T(3)) and dexamethasone of autoinduction of ER; and inhibition by PRL of autoinduction and crossinduction of TR and ER genes. A dual receptor threshold model to explain the interplay between T(3), estrogen and PRL is presented and its significance to the general question of nuclear receptor autoregulation and crossregulation during development is also discussed.
Collapse
Affiliation(s)
- J R Tata
- The Laboratory of Developmental Biochemistry, National Institute for Medical Research, The Ridgeway, London NW7 1AA, England
| |
Collapse
|