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Nagpal J, Eachus H, Lityagina O, Ryu S. Optogenetic induction of chronic glucocorticoid exposure in early-life leads to blunted stress-response in larval zebrafish. Eur J Neurosci 2024. [PMID: 38602078 DOI: 10.1111/ejn.16301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 11/29/2023] [Accepted: 02/19/2024] [Indexed: 04/12/2024]
Abstract
Early life stress (ELS) exposure alters stress susceptibility in later life and affects vulnerability to stress-related disorders, but how ELS changes the long-lasting responsiveness of the stress system is not well understood. Zebrafish provides an opportunity to study conserved mechanisms underlying the development and function of the stress response that is regulated largely by the neuroendocrine hypothalamus-pituitary-adrenal/interrenal (HPA/I) axis, with glucocorticoids (GC) as the final effector. In this study, we established a method to chronically elevate endogenous GC levels during early life in larval zebrafish. To this end, we employed an optogenetic actuator, beggiatoa photoactivated adenylyl cyclase, specifically expressed in the interrenal cells of zebrafish and demonstrate that its chronic activation leads to hypercortisolaemia and dampens the acute-stress evoked cortisol levels, across a variety of stressor modalities during early life. This blunting of stress-response was conserved in ontogeny at a later developmental stage. Furthermore, we observe a strong reduction of proopiomelanocortin (pomc)-expression in the pituitary as well as upregulation of fkbp5 gene expression. Going forward, we propose that this model can be leveraged to tease apart the mechanisms underlying developmental programming of the HPA/I axis by early-life GC exposure and its implications for vulnerability and resilience to stress in adulthood.
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Affiliation(s)
- Jatin Nagpal
- University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
- APC Microbiome Ireland and School of Pharmacy and Department of Pharmacology and Therapeutics, University College Cork, Cork, Ireland
| | - Helen Eachus
- Living Systems Institute & Department of Clinical and Biomedical Sciences, University of Exeter, Exeter, UK
| | - Olga Lityagina
- University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
- Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Soojin Ryu
- University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
- Living Systems Institute & Department of Clinical and Biomedical Sciences, University of Exeter, Exeter, UK
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Eachus H, Choi MK, Tochwin A, Kaspareit J, Ho M, Ryu S. Elevated glucocorticoid alters the developmental dynamics of hypothalamic neurogenesis in zebrafish. Commun Biol 2024; 7:416. [PMID: 38580727 PMCID: PMC10997759 DOI: 10.1038/s42003-024-06060-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 03/16/2024] [Indexed: 04/07/2024] Open
Abstract
Exposure to excess glucocorticoid (GC) during early development is implicated in adult dysfunctions. Reduced adult hippocampal neurogenesis is a well-known consequence of exposure to early life stress or elevated GC, however the effects on neurogenesis during development and effects on other brain regions are not well understood. Using an optogenetic zebrafish model, here we analyse the effects of GC exposure on neurogenesis during development in the whole brain. We identify that the hypothalamus is a highly GC-sensitive region where elevated GC causes precocious development. This is followed by failed maturation and early decline accompanied by impaired feeding, growth, and survival. In GC-exposed animals, the developmental trajectory of hypothalamic progenitor cells is strikingly altered, potentially mediated by direct regulation of transcription factors such as rx3 by GC. Our data provide cellular and molecular level insight into GC-induced alteration of the hypothalamic developmental trajectory, a process crucial for health across the life-course.
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Affiliation(s)
- Helen Eachus
- Living Systems Institute & Department of Clinical and Biomedical Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Institute of Health and Neurodevelopment & Aston Pharmacy School, Aston University, Birmingham, B4 7ET, UK
| | - Min-Kyeung Choi
- Living Systems Institute & Department of Clinical and Biomedical Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Anna Tochwin
- Living Systems Institute & Department of Clinical and Biomedical Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Johanna Kaspareit
- Institute of Human Genetics, University Medical Center, Johannes Gutenberg University Mainz, Langenbeckstraße 1, 55131, Mainz, Germany
| | - May Ho
- Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Soojin Ryu
- Living Systems Institute & Department of Clinical and Biomedical Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
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Eachus H, Ryu S. Glucocorticoid effects on the brain: from adaptive developmental plasticity to allostatic overload. J Exp Biol 2024; 227:jeb246128. [PMID: 38449327 PMCID: PMC10949071 DOI: 10.1242/jeb.246128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Exposure to stress during early life may alter the developmental trajectory of an animal by a mechanism known as adaptive plasticity. For example, to enhance reproductive success in an adverse environment, it is known that animals accelerate their growth during development. However, these short-term fitness benefits are often associated with reduced longevity, a phenomenon known as the growth rate-lifespan trade-off. In humans, early life stress exposure compromises health later in life and increases disease susceptibility. Glucocorticoids (GCs) are major stress hormones implicated in these processes. This Review discusses the evidence for GC-mediated adaptive plasticity in development, leading to allostatic overload in later life. We focus on GC-induced effects on brain structure and function, including neurogenesis; highlight the need for longitudinal studies; and discuss approaches to identify molecular mechanisms mediating GC-induced alteration of the brain developmental trajectory leading to adult dysfunctions. Further understanding of how stress and GC exposure can alter developmental trajectories at the molecular and cellular level is of critical importance to reduce the burden of mental and physical ill health across the life course.
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Affiliation(s)
- Helen Eachus
- Living Systems Institute & Department of Clinical and Biomedical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Soojin Ryu
- Living Systems Institute & Department of Clinical and Biomedical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
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Eachus H, Oberski L, Paveley J, Bacila I, Ashton JP, Esposito U, Seifuddin F, Pirooznia M, Elhaik E, Placzek M, Krone NP, Cunliffe VT. Glucocorticoid receptor regulates protein chaperone, circadian clock and affective disorder genes in the zebrafish brain. Dis Model Mech 2023; 16:dmm050141. [PMID: 37525888 PMCID: PMC10565112 DOI: 10.1242/dmm.050141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 07/25/2023] [Indexed: 08/02/2023] Open
Abstract
Glucocorticoid resistance is commonly observed in depression, and has been linked to reduced expression and/or function of the glucocorticoid receptor (NR3C1 in human, hereafter referred to as GR). Previous studies have shown that GR-mutant zebrafish exhibit behavioural abnormalities that are indicative of an affective disorder, suggesting that GR plays a role in brain function. We compared the brain methylomes and brain transcriptomes of adult wild-type and GR-mutant zebrafish, and identified 249 differentially methylated regions (DMRs) that are regulated by GR. These include a cluster of CpG sites within the first intron of fkbp5, the gene encoding the glucocorticoid-inducible heat shock protein co-chaperone Fkbp5. RNA-sequencing analysis revealed that genes associated with chaperone-mediated protein folding, the regulation of circadian rhythm and the regulation of metabolism are particularly sensitive to loss of GR function. In addition, we identified subsets of genes exhibiting GR-regulated transcription that are known to regulate behaviour, and are linked to unipolar depression and anxiety. Taken together, our results identify key biological processes and novel molecular mechanisms through which the GR is likely to mediate responses to stress in the adult zebrafish brain, and they provide further support for the zebrafish GR mutant as a model for the study of affective disorders.
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Affiliation(s)
- Helen Eachus
- School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
- Department of Oncology and Metabolism, Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Lara Oberski
- School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
- Department of Oncology and Metabolism, Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Jack Paveley
- School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
- Department of Oncology and Metabolism, Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Irina Bacila
- Department of Oncology and Metabolism, Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - John-Paul Ashton
- School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Umberto Esposito
- School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Fayaz Seifuddin
- Bioinformatics and Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Building 12, 12 South Drive, Bethesda, MD 20892, USA
| | - Mehdi Pirooznia
- Bioinformatics and Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Building 12, 12 South Drive, Bethesda, MD 20892, USA
| | - Eran Elhaik
- School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Marysia Placzek
- School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Nils P. Krone
- Department of Oncology and Metabolism, Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
- Department of Medicine III, University Hospital Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Vincent T. Cunliffe
- School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
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Eachus H, Ryu S, Placzek M, Wood J. Zebrafish as a model to investigate the CRH axis and interactions with DISC1. Curr Opin Endocr Metab Res 2022; 26:100383. [PMID: 36632608 PMCID: PMC9823094 DOI: 10.1016/j.coemr.2022.100383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Release of corticotropin-releasing hormone (CRH) from CRH neurons activates the hypothalamo-pituitary-adrenal (HPA) axis, one of the main physiological stress response systems. Complex feedback loops operate in the HPA axis and understanding the neurobiological mechanisms regulating CRH neurons is of great importance in the context of stress disorders. In this article, we review how in vivo studies in zebrafish have advanced knowledge of the neurobiology of CRH neurons. Disrupted-in-schizophrenia 1 (DISC1) mutant zebrafish have blunted stress responses and can be used to model human stress disorders. We propose that DISC1 influences the development and functioning of CRH neurons as a mechanism linking DISC1 to psychiatric disorders.
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Affiliation(s)
- Helen Eachus
- Living Systems Institute and College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Soojin Ryu
- Living Systems Institute and College of Medicine and Health, University of Exeter, Exeter, United Kingdom
- Institute of Human Genetics, University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Marysia Placzek
- School of Biosciences and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Jonathan Wood
- Sheffield Institute for Translational Neuroscience and Department of Neuroscience, University of Sheffield, Sheffield, United Kingdom
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Eachus H, Choi MK, Ryu S. The Effects of Early Life Stress on the Brain and Behaviour: Insights From Zebrafish Models. Front Cell Dev Biol 2021; 9:657591. [PMID: 34368117 PMCID: PMC8335398 DOI: 10.3389/fcell.2021.657591] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 04/20/2021] [Indexed: 01/27/2023] Open
Abstract
The early life period represents a window of increased vulnerability to stress, during which exposure can lead to long-lasting effects on brain structure and function. This stress-induced developmental programming may contribute to the behavioural changes observed in mental illness. In recent decades, rodent studies have significantly advanced our understanding of how early life stress (ELS) affects brain development and behaviour. These studies reveal that ELS has long-term consequences on the brain such as impairment of adult hippocampal neurogenesis, altering learning and memory. Despite such advances, several key questions remain inadequately answered, including a comprehensive overview of brain regions and molecular pathways that are altered by ELS and how ELS-induced molecular changes ultimately lead to behavioural changes in adulthood. The zebrafish represents a novel ELS model, with the potential to contribute to answering some of these questions. The zebrafish offers some important advantages such as the ability to non-invasively modulate stress hormone levels in a whole animal and to visualise whole brain activity in freely behaving animals. This review discusses the current status of the zebrafish ELS field and its potential as a new ELS model.
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Affiliation(s)
- Helen Eachus
- Living Systems Institute and College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Min-Kyeung Choi
- Living Systems Institute and College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Soojin Ryu
- Living Systems Institute and College of Medicine and Health, University of Exeter, Exeter, United Kingdom.,Institute of Human Genetics, University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany
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Eachus H, Zaucker A, Oakes JA, Griffin A, Weger M, Güran T, Taylor A, Harris A, Greenfield A, Quanson JL, Storbeck KH, Cunliffe VT, Müller F, Krone N. Genetic Disruption of 21-Hydroxylase in Zebrafish Causes Interrenal Hyperplasia. Endocrinology 2017; 158:4165-4173. [PMID: 28938470 PMCID: PMC5711382 DOI: 10.1210/en.2017-00549] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 09/07/2017] [Indexed: 11/23/2022]
Abstract
Congenital adrenal hyperplasia is a group of common inherited disorders leading to glucocorticoid deficiency. Most cases are caused by 21-hydroxylase deficiency (21OHD). The systemic consequences of imbalanced steroid hormone biosynthesis due to severe 21OHD remains poorly understood. Therefore, we developed a zebrafish model for 21OHD, which focuses on the impairment of glucocorticoid biosynthesis. A single 21-hydroxylase gene (cyp21a2) is annotated in the zebrafish genome based on sequence homology. Our in silico analysis of the 21-hydroxylase (Cyp21a2) protein sequence suggests a sufficient degree of similarity for the usage of zebrafish cyp21a2 to model aspects of human 21OHD in vivo. We determined the spatiotemporal expression patterns of cyp21a2 by whole-mount in situ hybridization and reverse transcription polymerase chain reaction throughout early development. Early cyp21a2 expression is restricted to the interrenal gland (zebrafish adrenal counterpart) and the brain. To further explore the in vivo consequences of 21OHD we created several cyp21a2 null-allele zebrafish lines by using a transcription activator-like effector nuclease genomic engineering strategy. Homozygous mutant zebrafish larvae showed an upregulation of the hypothalamic-pituitary-interrenal (HPI) axis and interrenal hyperplasia. Furthermore, Cyp21a2-deficient larvae had a typical steroid profile, with reduced concentrations of cortisol and increased concentrations of 17-hydroxyprogesterone and 21-deoxycortisol. Affected larvae showed an upregulation of the HPI axis and interrenal hyperplasia. Downregulation of the glucocorticoid-responsive genes pck1 and fkbp5 indicated systemic glucocorticoid deficiency. Our work demonstrates the crucial role of Cyp21a2 in glucocorticoid biosynthesis in zebrafish larvae and establishes an in vivo model allowing studies of systemic consequences of altered steroid hormone synthesis.
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Affiliation(s)
- Helen Eachus
- Department of Biomedical Science, The Bateson Centre, Sheffield S10 2TN, United Kingdom
| | - Andreas Zaucker
- Centre for Endocrinology, Diabetes, and Metabolism, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - James A. Oakes
- Department of Biomedical Science, The Bateson Centre, Sheffield S10 2TN, United Kingdom
- Academic Unit of Child Health, Department of Oncology and Metabolism, University of Sheffield, Sheffield S10 2TG, United Kingdom
| | - Aliesha Griffin
- Centre for Endocrinology, Diabetes, and Metabolism, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Meltem Weger
- Centre for Endocrinology, Diabetes, and Metabolism, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Tülay Güran
- Centre for Endocrinology, Diabetes, and Metabolism, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Angela Taylor
- Centre for Endocrinology, Diabetes, and Metabolism, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Abigail Harris
- Mammalian Genetics Unit, Medical Research Council, Harwell Institute, Oxfordshire OX11 0RD, United Kingdom
| | - Andy Greenfield
- Mammalian Genetics Unit, Medical Research Council, Harwell Institute, Oxfordshire OX11 0RD, United Kingdom
| | - Jonathan L. Quanson
- Department of Biochemistry, Stellenbosch University, Stellenbosch, Matieland 7602, South Africa
| | - Karl-Heinz Storbeck
- Department of Biochemistry, Stellenbosch University, Stellenbosch, Matieland 7602, South Africa
| | - Vincent T. Cunliffe
- Department of Biomedical Science, The Bateson Centre, Sheffield S10 2TN, United Kingdom
| | - Ferenc Müller
- Institute of Cancer and Genomic Sciences, University of Birmingham, College of Medical and Dental Sciences, Birmingham B15 2TT, United Kingdom
| | - Nils Krone
- Department of Biomedical Science, The Bateson Centre, Sheffield S10 2TN, United Kingdom
- Academic Unit of Child Health, Department of Oncology and Metabolism, University of Sheffield, Sheffield S10 2TG, United Kingdom
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Eachus H, Bright C, Cunliffe VT, Placzek M, Wood JD, Watt PJ. Disrupted-in-Schizophrenia-1 is essential for normal hypothalamic-pituitary-interrenal (HPI) axis function. Hum Mol Genet 2017; 26:1992-2005. [PMID: 28334933 PMCID: PMC5437527 DOI: 10.1093/hmg/ddx076] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 02/23/2017] [Indexed: 02/01/2023] Open
Abstract
Psychiatric disorders arise due to an interplay of genetic and environmental factors, including stress. Studies in rodents have shown that mutants for Disrupted-In-Schizophrenia-1 (DISC1), a well-accepted genetic risk factor for mental illness, display abnormal behaviours in response to stress, but the mechanisms through which DISC1 affects stress responses remain poorly understood. Using two lines of zebrafish homozygous mutant for disc1, we investigated behaviour and functioning of the hypothalamic-pituitary-interrenal (HPI) axis, the fish equivalent of the hypothalamic-pituitary-adrenal (HPA) axis. Here, we show that the role of DISC1 in stress responses is evolutionarily conserved and that DISC1 is essential for normal functioning of the HPI axis. Adult zebrafish homozygous mutant for disc1 show aberrant behavioural responses to stress. Our studies reveal that in the embryo, disc1 is expressed in neural progenitor cells of the hypothalamus, a conserved region of the vertebrate brain that centrally controls responses to environmental stressors. In disc1 mutant embryos, proliferating rx3+ hypothalamic progenitors are not maintained normally and neuronal differentiation is compromised: rx3-derived ff1b+ neurons, implicated in anxiety-related behaviours, and corticotrophin releasing hormone (crh) neurons, key regulators of the stress axis, develop abnormally, and rx3-derived pomc+ neurons are disorganised. Abnormal hypothalamic development is associated with dysfunctional behavioural and neuroendocrine stress responses. In contrast to wild type siblings, disc1 mutant larvae show altered crh levels, fail to upregulate cortisol levels when under stress and do not modulate shoal cohesion, indicative of abnormal social behaviour. These data indicate that disc1 is essential for normal development of the hypothalamus and for the correct functioning of the HPA/HPI axis.
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Affiliation(s)
- Helen Eachus
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.,The Bateson Centre, Department of Biomedical Science, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Charlotte Bright
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Vincent T Cunliffe
- The Bateson Centre, Department of Biomedical Science, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Marysia Placzek
- The Bateson Centre, Department of Biomedical Science, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Jonathan D Wood
- The Bateson Centre, Department of Biomedical Science, Firth Court, Western Bank, Sheffield S10 2TN, UK.,Sheffield Institute for Translational Neuroscience, Department of Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Penelope J Watt
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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Muthu V, Eachus H, Ellis P, Brown S, Placzek M. Rx3 and Shh direct anisotropic growth and specification in the zebrafish tuberal/anterior hypothalamus. Development 2016; 143:2651-63. [PMID: 27317806 PMCID: PMC4958342 DOI: 10.1242/dev.138305] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/03/2016] [Indexed: 12/11/2022]
Abstract
In the developing brain, growth and differentiation are intimately linked. Here, we show that in the zebrafish embryo, the homeodomain transcription factor Rx3 coordinates these processes to build the tuberal/anterior hypothalamus. Analysis of rx3 chk mutant/rx3 morphant fish and EdU pulse-chase studies reveal that rx3 is required to select tuberal/anterior hypothalamic progenitors and to orchestrate their anisotropic growth. In the absence of Rx3 function, progenitors accumulate in the third ventricular wall, die or are inappropriately specified, the shh(+) anterior recess does not form, and its resident pomc(+), ff1b(+) and otpb(+) Th1(+) cells fail to differentiate. Manipulation of Shh signalling shows that Shh coordinates progenitor cell selection and behaviour by acting as an on-off switch for rx3 Together, our studies show that Shh and Rx3 govern formation of a distinct progenitor domain that elaborates patterning through its anisotropic growth and differentiation.
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Affiliation(s)
- Victor Muthu
- The Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Helen Eachus
- The Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - Pam Ellis
- The Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - Sarah Brown
- The Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - Marysia Placzek
- The Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
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