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Burton DF, Boa-Amponsem OM, Dixon MS, Hopkins MJ, Herbin TA, Toney S, Tarpley M, Rodriguez BV, Fish EW, Parnell SE, Cole GJ, Williams KP. Pharmacological activation of the Sonic hedgehog pathway with a Smoothened small molecule agonist ameliorates the severity of alcohol-induced morphological and behavioral birth defects in a zebrafish model of fetal alcohol spectrum disorder. J Neurosci Res 2022; 100:1585-1601. [PMID: 35014067 PMCID: PMC9271529 DOI: 10.1002/jnr.25008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 12/21/2021] [Accepted: 12/24/2021] [Indexed: 12/17/2022]
Abstract
Ethanol exposure during the early stages of embryonic development can lead to a range of morphological and behavioral differences termed fetal alcohol spectrum disorders (FASDs). In a zebrafish model, we have shown that acute ethanol exposure at 8-10 hr postfertilization (hpf), a critical time of development, produces birth defects similar to those clinically characterized in FASD. Dysregulation of the Sonic hedgehog (Shh) pathway has been implicated as a molecular basis for many of the birth defects caused by prenatal alcohol exposure. We observed in zebrafish embryos that shh expression was significantly decreased by ethanol exposure at 8-10 hpf, while smo expression was much less affected. Treatment of zebrafish embryos with SAG or purmorphamine, small molecule Smoothened agonists that activate Shh signaling, ameliorated the severity of ethanol-induced developmental malformations including altered eye size and midline brain development. Furthermore, this rescue effect of Smo activation was dose dependent and occurred primarily when treatment was given after ethanol exposure. Markers of Shh signaling (gli1/2) and eye development (pax6a) were restored in embryos treated with SAG post-ethanol exposure. Since embryonic ethanol exposure has been shown to produce later-life neurobehavioral impairments, juvenile zebrafish were examined in the novel tank diving test. Our results further demonstrated that in zebrafish embryos exposed to ethanol, SAG treatment was able to mitigate long-term neurodevelopmental impairments related to anxiety and risk-taking behavior. Our results indicate that pharmacological activation of the Shh pathway at specific developmental timing markedly diminishes the severity of alcohol-induced birth defects.
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Affiliation(s)
- Derek F Burton
- Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, Durham, North Carolina, USA
| | - Oswald M Boa-Amponsem
- Integrated Biosciences PhD Program, North Carolina Central University, Durham, North Carolina, USA.,Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, USA
| | - Maria S Dixon
- Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, Durham, North Carolina, USA
| | - Michael J Hopkins
- Department of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina, USA
| | - Te-Andre Herbin
- Department of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina, USA
| | - Shiquita Toney
- Department of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina, USA
| | - Michael Tarpley
- Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, Durham, North Carolina, USA
| | - Blanca V Rodriguez
- Department of Biochemistry, Duke University, Durham, North Carolina, USA
| | - Eric W Fish
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Scott E Parnell
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, USA.,Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Gregory J Cole
- Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, USA.,Department of Biological and Biomedical Sciences, North Carolina Central University, Durham, North Carolina, USA
| | - Kevin P Williams
- Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, Durham, North Carolina, USA.,Department of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina, USA
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Raciti M, Ceccatelli S. Epigenetic mechanisms in developmental neurotoxicity. Neurotoxicol Teratol 2018; 66:94-101. [DOI: 10.1016/j.ntt.2017.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/28/2017] [Accepted: 12/04/2017] [Indexed: 12/28/2022]
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Delov V, Muth-Köhne E, Schäfers C, Fenske M. Transgenic fluorescent zebrafish Tg(fli1:EGFP)y¹ for the identification of vasotoxicity within the zFET. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 150:189-200. [PMID: 24685623 DOI: 10.1016/j.aquatox.2014.03.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 02/12/2014] [Accepted: 03/09/2014] [Indexed: 06/03/2023]
Abstract
The fish embryo toxicity test (FET) is currently one of the most advocated animal alternative tests in ecotoxicology. To date, the application of the FET with zebrafish (zFET) has focused on acute toxicity assessment, where only lethal morphological effects are accounted for. An application of the zFET beyond acute toxicity, however, necessitates the establishment of more refined and quantifiable toxicological endpoints. A valuable tool in this context is the use of gene expression-dependent fluorescent markers that can even be measured in vivo. We investigated the application of embryos of Tg(fli1:EGFP)(y1) for the identification of vasotoxic substances within the zFET. Tg(fli1:EGFP)(y1) fish express enhanced GFP in the entire vasculature under the control of the fli1 promoter, and thus enable the visualization of vascular defects in live zebrafish embryos. We assessed the fli1 driven EGFP-expression in the intersegmental blood vessels (ISVs) qualitatively and quantitatively, and found an exposure concentration related increase in vascular damage for chemicals like triclosan, cartap and genistein. The fluorescence endpoint ISV-length allowed an earlier and more sensitive detection of vasotoxins than the bright field assessment method. In combination with the standard bright field morphological effect assessment, an increase in significance and value of the zFET for a mechanism-specific toxicity evaluation was achieved. This study highlights the benefits of using transgenic zebrafish as convenient tools for identifying toxicity in vivo and to increase sensitivity and specificity of the zFET.
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Affiliation(s)
- Vera Delov
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Forckenbeckstr. 6, 52074 Aachen, Germany; Institute for Molecular Biotechnology (Biology VII), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
| | - Elke Muth-Köhne
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Auf dem Aberg 1, 57392 Schmallenberg, Germany
| | - Christoph Schäfers
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Auf dem Aberg 1, 57392 Schmallenberg, Germany
| | - Martina Fenske
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Forckenbeckstr. 6, 52074 Aachen, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Auf dem Aberg 1, 57392 Schmallenberg, Germany.
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Chronic cadmium exposure induces transcriptional activation of the Wnt pathway and upregulation of epithelial-to-mesenchymal transition markers in mouse kidney. Toxicol Lett 2010; 198:69-76. [PMID: 20478370 DOI: 10.1016/j.toxlet.2010.05.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 05/05/2010] [Accepted: 05/07/2010] [Indexed: 11/27/2022]
Abstract
The transition metal cadmium (Cd) is an environmental pollutant which damages the kidneys. Chronic Cd exposure may induce renal fibrosis and/or cancer, but the signaling pathways involved are not understood. The Wnt pathway is a key signaling cascade responsible for renal development, fibrosis and cancer. Hence the effect of chronic in vivo Cd exposure (100 mg/l drinking water for 12 weeks) on transcriptional activation of the Wnt pathway and markers of epithelial-to-mesenchymal transition (EMT) was investigated in mouse kidneys. Cd exposure increased kidney Cd content from 0.023+/-0.001 microg/g to 61+/-7 microg/g wet weight (means+/-S.D. of 6-7 animals). This was accompanied by increased expression of Wnt ligands (Wnt3a/6/7a/7b/9a/9b/10a/11), as determined by RT-PCR. The Wnt receptors Frizzled (Fz1/2/4,5,7-10) were also upregulated, as were the co-receptors low-density lipoprotein receptor-related proteins 5/6. Immunoblots with Wnt10a and Fz7 antibodies also revealed increased protein expression induced by Cd exposure. In contrast, Wnt antagonists were largely unaffected. Upregulation of Wnt signaling components induced by Cd was corroborated by increased expression of Wnt target genes, i.e. cell proliferation and survival genes c-Myc, cyclin D1 and the multidrug transporter P-glycoprotein Abcb1b, which promote malignancy. Lastly the EMT markers Twist, fibronectin and collagen I, but not alpha-smooth muscle actin, were also upregulated, suggesting that Cd-induced changes of renal epithelial tissue characteristics towards fibrosis and cancer may be mediated by Wnt signaling.
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Hanson ML, Brundage KM, Schafer R, Tou JC, Barnett JB. Prenatal cadmium exposure dysregulates sonic hedgehog and Wnt/beta-catenin signaling in the thymus resulting in altered thymocyte development. Toxicol Appl Pharmacol 2009; 242:136-45. [PMID: 19818801 DOI: 10.1016/j.taap.2009.09.023] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 09/29/2009] [Accepted: 09/30/2009] [Indexed: 11/19/2022]
Abstract
Cadmium (Cd) is both an environmental pollutant and a component of cigarette smoke. Although evidence demonstrates that adult exposure to Cd causes changes in the immune system, there are limited reports in the literature of immunomodulatory effects of prenatal exposure to Cd. The sonic hedgehog (Shh) and Wnt/beta-catenin pathways are required for thymocyte maturation. Several studies have demonstrated that Cd exposure affects these pathways in different organ systems. This study was designed to investigate the effect of prenatal Cd exposure on thymocyte development, and to determine if these effects were linked to dysregulation of Shh and Wnt/beta-catenin pathways. Pregnant C57Bl/6 mice were exposed to an environmentally relevant dose (10 ppm) of Cd throughout pregnancy and effects on the thymus were assessed on the day of birth. Thymocyte phenotype was determined by flow cytometry. A Gli:luciferase reporter cell line was used to measure Shh signaling. Transcription of target genes and translation of key components of both signaling pathways were assessed using real-time RT-PCR and western blot, respectively. Prenatal Cd exposure increased the number of CD4(+) cells and a subpopulation of double-negative cells (DN; CD4(-)CD8(-)), DN4 (CD44(-)CD25(-)). Shh and Wnt/beta-catenin signaling were both decreased in the thymus. Target genes of Shh (Patched1 and Gli1) and Wnt/beta-catenin (c-fos, and c-myc) were affected differentially among thymocyte subpopulations. These findings suggest that prenatal exposure to Cd dysregulates two signaling pathways in the thymus, resulting in altered thymocyte development.
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Affiliation(s)
- Miranda L Hanson
- Department of Microbiology, Immunology and Cell Biology, West Virginia University School of Medicine, PO Box 9177, West Virginia University, Morgantown, WV 26506-9177, USA
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Hen Chow ES, Yu Hui MN, Cheng CW, Cheng SH. Cadmium affects retinogenesis during zebrafish embryonic development. Toxicol Appl Pharmacol 2009; 235:68-76. [DOI: 10.1016/j.taap.2008.11.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 11/10/2008] [Accepted: 11/11/2008] [Indexed: 11/28/2022]
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Hsieh CS, Ko CY, Chen SY, Liu TM, Wu JS, Hu CH, Sun CK. In vivo long-term continuous observation of gene expression in zebrafish embryo nerve systems by using harmonic generation microscopy and morphant technology. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:064041. [PMID: 19123687 DOI: 10.1117/1.3050423] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Gene expression plays an important role in embryo development and organ function. Previous studies have shown that harmonic generation microscopy (HGM) can be used as a fluorescence signal-independent, minimally invasive method with a subcellular 3-D resolution and a penetration depth in the order of millimeters for long-term continuous imaging of vertebrate embryos. We show that it is ideal to combine in vivo HGM with the morphant technology for minimally invasive, long-term continuous observation of gene expression in the nervous system of vertebrate embryos. Since second- and third-harmonic generations (SHG, THG) are virtual-state-transition-based systems that depend only on the structure of the organisms, they are not temporally limited by the expression of the fluorescence proteins. We successfully identified the expression of the zarnt2a and the hif-1alpha, 2alpha, and 3alpha genes in the nervous system of zebrafish embryos with specific knockdown genes by microscopically observing the embryos from the early stages of embryogenesis. The results from a combination of the two different modalities, i.e., SHG microscopy and THG microscopy, successfully revealed the weak cell adhesion, cell apoptosis, nerve formation reduction, and neural tube distortion in the morphant zebrafish embryos.
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Affiliation(s)
- Cho-Shuen Hsieh
- National Taiwan University, Department of Electrical Engineering, and, Graduate Institute of Photonics and Optoelectronics, Taipei 10617, Taiwan
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Scholz S, Fischer S, Gündel U, Küster E, Luckenbach T, Voelker D. The zebrafish embryo model in environmental risk assessment--applications beyond acute toxicity testing. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2008; 15:394-404. [PMID: 18575912 DOI: 10.1007/s11356-008-0018-z] [Citation(s) in RCA: 395] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 05/27/2008] [Indexed: 05/20/2023]
Abstract
BACKGROUND, AIM, AND SCOPE The use of fish embryos is not regulated by current legislations on animal welfare and is therefore considered as a refinement, if not replacement of animal experiments. Fish embryos represent an attractive model for environmental risk assessment of chemicals since they offer the possibility to perform small-scale, high-throughput analyses. MAIN FEATURES Beyond their application for determining the acute toxicity, fish embryos are also excellent models for studies aimed at the understanding of toxic mechanisms and the indication of possible adverse and long-term effects. Therefore, we have reviewed the scientific literature in order to indicate alternative applications of the fish embryo model with focus on embryos of the zebrafish. RESULTS AND DISCUSSIONS The analysis of the mode of action is important for the risk assessment of environmental chemicals and can assist in indicating adverse and long-term effects. Toxicogenomics present a promising approach to unravel the potential mechanisms. Therefore, we present examples of the use of zebrafish embryos to study the effect of chemicals on gene and protein patterns, and the potential implications of differential expression for toxicity. The possible application of other methods, such as kinase arrays or metabolomic profiling, is also highlighted. Furthermore, we show examples of toxicokinetic studies (bioconcentration, ABC transporters) and discuss limitations that might be caused by the potential barrier function of the chorion. Finally, we demonstrate that biomarkers of endocrine disruption, immune modulation, genotoxicity or chronic toxicity could be used as indicators or predictors of sub-acute and long-term effects. CONCLUSIONS The zebrafish embryo represents a model with an impressive range of possible applications in environmental sciences. Particularly, the adaptation of molecular, system-wide approaches from biomedical research is likely to extend its use in ecotoxicology. RECOMMENDATIONS AND PERSPECTIVES Challenges for future research are (1) the identification of further suitable molecular markers as indicators of the mode of action, (2) the establishment of strong links between (molecular) effects in short-term assays in embryos and long-term (toxic) effects on individuals, (3) the definition of limitations of the model and (4) the development of tests that can be used for regulatory purposes.
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Affiliation(s)
- Stefan Scholz
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany.
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Chow ESH, Hui MNY, Lin CC, Cheng SH. Cadmium inhibits neurogenesis in zebrafish embryonic brain development. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2008; 87:157-169. [PMID: 18342959 DOI: 10.1016/j.aquatox.2008.01.019] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 01/17/2008] [Accepted: 01/25/2008] [Indexed: 05/26/2023]
Abstract
Cadmium is a non-essential heavy metal found abundantly in the environment. Children of women exposed to cadmium during pregnancy display lower motor and perceptual abilities. High cadmium body burden in children is also related to impaired intelligence and lowered school achievement. However, little is known about the molecular and cellular basis of developmental neurotoxicity in the sensitive early life stages of animals. In this study, we explore neurological deficits caused by cadmium during early embryonic stages in zebrafish by examining regionalization of the neural tube, pattern formation and cell fate determination, commitment of proneural genes and induction of neurogenesis. We show that cadmium-treated embryos developed a smaller head with unclear boundaries between the brain subdivisions, particularly in the mid-hindbrain region. Embryos display normal anterior to posterior regionalization; however, the commitment of neural progenitor cells was affected by cadmium. We observe prominent reductions in the expression of several proneuronal genes including ngn1 in cell clusters, zash1a in the developing optic tectum, and zash1b in the telencephalon and tectum. Cadmium-treated embryos also have fewer differentiated neurons and glia in the facial sensory ganglia as indicated by decreased zn-12 expression. Also, a lower transcription level of neurogenic genes, ngn1 and neuroD, is observed in neurons. Our data suggest that cadmium-induced neurotoxicity can be caused by impaired neurogenesis, resulting in markedly reduced neuronal differentiation and axonogenesis.
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Affiliation(s)
- Elly Suk Hen Chow
- Division of Biology, California Institute of Technology, 1200 California Boulevard, Pasadena, CA 91125, USA
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