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Korzh V. Development of the brain ventricular system from a comparative perspective. Clin Anat 2023; 36:320-334. [PMID: 36529666 DOI: 10.1002/ca.23994] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
The brain ventricular system (BVS) consists of brain ventricles and channels filled with cerebrospinal fluid (CSF). Disturbance of CSF flow has been linked to scoliosis and neurodegenerative diseases, including hydrocephalus. This could be due to defects of CSF production by the choroid plexus or impaired CSF movement over the ependyma dependent on motile cilia. Most vertebrates have horizontal body posture. They retain additional evolutionary innovations assisting CSF flow, such as the Reissner fiber. The causes of hydrocephalus have been studied using animal models including rodents (mice, rats, hamsters) and zebrafish. However, the horizontal body posture reduces the effect of gravity on CSF flow, which limits the use of mammalian models for scoliosis. In contrast, fish swim against the current and experience a forward-to-backward mechanical force akin to that caused by gravity in humans. This explains the increased popularity of the zebrafish model for studies of scoliosis. "Slit-ventricle" syndrome is another side of the spectrum of BVS anomalies. It develops because of insufficient inflation of the BVS. Recent advances in zebrafish functional genetics have revealed genes that could regulate the development of the BVS and CSF circulation. This review will describe the BVS of zebrafish, a typical teleost, and vertebrates in general, in comparative perspective. It will illustrate the usefulness of the zebrafish model for developmental studies of the choroid plexus (CP), CSF flow and the BVS.
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Affiliation(s)
- Vladimir Korzh
- International Institute of Molecular and Cell Biology, Warsaw, Poland
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2
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Neuromasts and Olfactory Organs of Zebrafish Larvae Represent Possible Sites of SARS-CoV-2 Pseudovirus Host Cell Entry. J Virol 2022; 96:e0141822. [PMID: 36448804 PMCID: PMC9769390 DOI: 10.1128/jvi.01418-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the acute respiratory disease coronavirus disease 2019 (COVID-19), which has resulted in millions of deaths globally. Here, we explored the mechanism of host cell entry of a luciferase-ZsGreen spike (SARS-CoV-2)-pseudotyped lentivirus using zebrafish embryos/larvae as an in vivo model. Successful pseudovirus entry was demonstrated via the expression of the luciferase (luc) gene, which was validated by reverse transcription-PCR (RT-PCR). Treatment of larvae with chloroquine (a broad-spectrum viral inhibitor that blocks membrane fusion) or bafilomycin A1 (a specific inhibitor of vacuolar proton ATPases, which blocks endolysosomal trafficking) significantly reduced luc expression, indicating the possible involvement of the endolysosomal system in the viral entry mechanism. The pharmacological inhibition of two-pore channel (TPC) activity or use of the tpcn2dhkz1a mutant zebrafish line also led to diminished luc expression. The localized expression of ACE2 and TPC2 in the anterior neuromasts and the forming olfactory organs was demonstrated, and the occurrence of endocytosis in both locations was confirmed. Together, our data indicate that zebrafish embryos/larvae are a viable and tractable model to explore the mechanism of SARS-CoV-2 host cell entry, that the peripheral sense organs are a likely site for viral host cell entry, and that TPC2 plays a key role in the translocation of the virus through the endolysosomal system. IMPORTANCE Despite the development of effective vaccines to combat the COVID-19 pandemic, which help prevent the most life-threatening symptoms, full protection cannot be guaranteed, especially with the emergence of new viral variants. Moreover, some resistance to vaccination remains in certain age groups and cultures. As such, there is an urgent need for the development of new strategies and therapies to help combat this deadly disease. Here, we provide compelling evidence that the peripheral sensory organs of zebrafish possess several key components required for SARS-CoV-2 host cell entry. The nearly transparent larvae provide a most amenable complementary platform to investigate the key steps of viral entry into host cells, as well as its spread through the tissues and organs. This will help in the identification of key viral entry steps for therapeutic intervention, provide an inexpensive model for screening novel antiviral compounds, and assist in the development of new and more effective vaccines.
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Carstensen MB, Medvetzky A, Weinberger A, Driever W, Gothilf Y, Rath MF. Genetic ablation of the Bsx homeodomain transcription factor in zebrafish: Impact on mature pineal gland morphology and circadian behavior. J Pineal Res 2022; 72:e12795. [PMID: 35249239 PMCID: PMC9285933 DOI: 10.1111/jpi.12795] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 11/30/2022]
Abstract
The pineal gland is a neuroendocrine structure in the brain, which produces and secretes the hormone melatonin at nighttime and is considered a key element in the circadian clock system. Early morphogenesis of the gland is controlled by a number of transcription factors, some of which remain active in adult life. One of these is the brain-specific homeobox (Bsx), a highly conserved homeodomain transcription factor with a developmental role in the pineal gland of several species, including zebrafish, and regulatory roles in mature pinealocytes of the rat. To determine the role of Bsx in circadian biology, we here examined the effects of a bsx loss-of-function mutation on the pineal gland in adult zebrafish and on behavioral circadian rhythms in larvae. In pineal cell type-specific Gfp/Egfp reporter zebrafish lines, we did not detect fluorescence signals in the pineal area of homozygous (bsx-/- ) mutants. Interestingly, a nonpigmented area on the dorsal surface of the head above the gland, known as the pineal window, was pigmented in the homozygous mutants. Furthermore, a structure corresponding to the pineal gland was not detectable in the midline of the adult brain in histological sections analyzed by Nissl staining and S-antigen immunohistochemistry. Moreover, the levels of pineal transcripts were greatly reduced in bsx-/- mutants, as revealed by quantitative real-time polymerase chain reaction analysis. Notably, analysis of locomotor activity at the larval stage revealed altered circadian rhythmicity in the bsx mutants with periods and phases similar to wildtype, but severely reduced amplitudes in locomotor activity patterns. Thus, Bsx is essential for full development of the pineal gland, with its absence resulting in a phenotype of morphological pineal gland ablation and disrupted circadian behavior.
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Affiliation(s)
- Mikkel Bloss Carstensen
- Department of Neuroscience, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
- School of Neurobiology, Biochemistry and Biophysics, Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
| | - Adar Medvetzky
- School of Neurobiology, Biochemistry and Biophysics, Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
| | - Alon Weinberger
- School of Neurobiology, Biochemistry and Biophysics, Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
| | - Wolfgang Driever
- Developmental Biology, Institute Biology, Faculty of BiologyAlbert Ludwig University of FreiburgFreiburgGermany
| | - Yoav Gothilf
- School of Neurobiology, Biochemistry and Biophysics, Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
- Sagol School of NeuroscienceTel Aviv UniversityTel AvivIsrael
| | - Martin Fredensborg Rath
- Department of Neuroscience, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
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4
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Habicher J, Manuel R, Pedroni A, Ferebee C, Ampatzis K, Boije H. A new transgenic reporter line reveals expression of protocadherin 9 at a cellular level within the zebrafish central nervous system. Gene Expr Patterns 2022; 44:119246. [DOI: 10.1016/j.gep.2022.119246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 03/07/2022] [Accepted: 04/09/2022] [Indexed: 11/16/2022]
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5
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Company V, Moreno-Cerdá A, Andreu-Cervera A, Murcia-Ramón R, Almagro-García F, Echevarría D, Martínez S, Puelles E. Wnt1 Role in the Development of the Habenula and the Fasciculus Retroflexus. Front Cell Dev Biol 2021; 9:755729. [PMID: 34722541 PMCID: PMC8551717 DOI: 10.3389/fcell.2021.755729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 09/21/2021] [Indexed: 11/18/2022] Open
Abstract
Wnt1 is one of the morphogenes that controls the specification and differentiation of neuronal populations in the developing central nervous system. The habenula is a diencephalic neuronal complex located in the most dorsal aspect of the thalamic prosomere. This diencephalic neuronal population is involved in the limbic system and its malfunction is related with several psychiatric disorders. Our aim is to elucidate the Wnt1 role in the habenula and its main efferent tract, the fasciculus retroflexus, development. In order to achieve these objectives, we analyzed these structures development in a Wnt1 lack of function mouse model. The habenula was generated in our model, but it presented an enlarged volume. This alteration was due to an increment in habenular neuroblasts proliferation rate. The fasciculus retroflexus also presented a wider and disorganized distribution and a disturbed final trajectory toward its target. The mid-hindbrain territories that the tract must cross were miss-differentiated in our model. The specification of the habenula is Wnt1 independent. Nevertheless, it controls its precursors proliferation rate. Wnt1 expressed in the isthmic organizer is vital to induce the midbrain and rostral hindbrain territories. The alteration of these areas is responsible for the fasciculus retroflexus axons misroute.
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Affiliation(s)
- Verónica Company
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, Spain
| | - Ana Moreno-Cerdá
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, Spain
| | - Abraham Andreu-Cervera
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, Spain
| | - Raquel Murcia-Ramón
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, Spain
| | - Francisca Almagro-García
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, Spain
| | - Diego Echevarría
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, Spain
| | - Salvador Martínez
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, Spain
| | - Eduardo Puelles
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, Spain
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Madelaine R, Ngo KJ, Skariah G, Mourrain P. Genetic deciphering of the antagonistic activities of the melanin-concentrating hormone and melanocortin pathways in skin pigmentation. PLoS Genet 2020; 16:e1009244. [PMID: 33301440 PMCID: PMC7755275 DOI: 10.1371/journal.pgen.1009244] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 12/22/2020] [Accepted: 10/30/2020] [Indexed: 01/18/2023] Open
Abstract
The genetic origin of human skin pigmentation remains an open question in biology. Several skin disorders and diseases originate from mutations in conserved pigmentation genes, including albinism, vitiligo, and melanoma. Teleosts possess the capacity to modify their pigmentation to adapt to their environmental background to avoid predators. This background adaptation occurs through melanosome aggregation (white background) or dispersion (black background) in melanocytes. These mechanisms are largely regulated by melanin-concentrating hormone (MCH) and α-melanocyte–stimulating hormone (α-MSH), two hypothalamic neuropeptides also involved in mammalian skin pigmentation. Despite evidence that the exogenous application of MCH peptides induces melanosome aggregation, it is not known if the MCH system is physiologically responsible for background adaptation. In zebrafish, we identify that MCH neurons target the pituitary gland-blood vessel portal and that endogenous MCH peptide expression regulates melanin concentration for background adaptation. We demonstrate that this effect is mediated by MCH receptor 2 (Mchr2) but not Mchr1a/b. mchr2 knock-out fish cannot adapt to a white background, providing the first genetic demonstration that MCH signaling is physiologically required to control skin pigmentation. mchr2 phenotype can be rescued in adult fish by knocking-out pomc, the gene coding for the precursor of α-MSH, demonstrating the relevance of the antagonistic activity between MCH and α-MSH in the control of melanosome organization. Interestingly, MCH receptor is also expressed in human melanocytes, thus a similar antagonistic activity regulating skin pigmentation may be conserved during evolution, and the dysregulation of these pathways is significant to our understanding of human skin disorders and cancers. Melanocytes produce melanin, a natural skin pigment, for body coloration which helps to protect and camouflage an organism and to attract mates. Melanocytes are ubiquitous pigment cells in vertebrates and the genes underlying their development are well conserved, making fishes that possess the ability to modify their pigmentation, biologically relevant and successful models for human skin disorders. Many human skin diseases including albinism, vitiligo, and melanoma are derived from mutations in conserved pigmentation genes. However, much of the conserved molecular mechanisms behind these diseases and human pigmentation remain unknown. For instance, melanin concentrating hormone (MCH) was originally identified as a peptide that when injected, could make fish paler by promoting melanin aggregation but no mutants demonstrating an endogenous function for MCH in pigmentation have been reported. Here, we use zebrafish mutants of MCH and the MCH receptor to determine their specific genetic function in pigmentation. Additionally, we demonstrate that MCH has an antagonistic pigmentation function to the melanocortin system, where MCH expression promotes lighter pigmentation and melanocortin activity promotes darkening. Thus, we find that the balance between the MCH and melanocortin system activities are likely required for skin pigmentation and dysregulation of these pathways could underlie adverse human skin conditions.
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Affiliation(s)
- Romain Madelaine
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
| | - Keri J. Ngo
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
- Department of Developmental Biology, Stanford University, Stanford, California, United States of America
| | - Gemini Skariah
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
| | - Philippe Mourrain
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
- INSERM 1024, Ecole Normale Supérieure, Paris, France
- * E-mail:
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7
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Staudt N, Giger FA, Fielding T, Hutt JA, Foucher I, Snowden V, Hellich A, Kiecker C, Houart C. Pineal progenitors originate from a non-neural territory limited by FGF signalling. Development 2019; 146:dev.171405. [PMID: 31754007 PMCID: PMC7375831 DOI: 10.1242/dev.171405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/30/2019] [Indexed: 01/10/2023]
Abstract
The embryonic development of the pineal organ, a neuroendocrine gland on top of the diencephalon, remains enigmatic. Classic fate-mapping studies suggested that pineal progenitors originate from the lateral border of the anterior neural plate. We show here, using gene expression and fate mapping/lineage tracing in zebrafish, that pineal progenitors originate, at least in part, from the non-neural ectoderm. Gene expression in chick indicates that this non-neural origin of pineal progenitors is conserved in amniotes. Genetic repression of placodal, but not neural crest, cell fate results in pineal hypoplasia in zebrafish, while mis-expression of transcription factors known to specify placodal identity during gastrulation promotes the formation of ectopic pineal progenitors. We also demonstrate that fibroblast growth factors (FGFs) position the pineal progenitor domain within the non-neural border by repressing pineal fate and that the Otx transcription factors promote pinealogenesis by inhibiting this FGF activity. The non-neural origin of the pineal organ reveals an underlying similarity in the formation of the pineal and pituitary glands, and suggests that all CNS neuroendocrine organs may require a non-neural contribution to form neurosecretory cells. Highlighted Article: Gene expression and fate mapping/lineage tracing in zebrafish reveals that the pineal organ develops from the non-neural pre-placodal ectoderm under the control of FGF signalling.
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Affiliation(s)
- Nicole Staudt
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Florence A Giger
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Triona Fielding
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - James A Hutt
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Isabelle Foucher
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Vicky Snowden
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Agathe Hellich
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Clemens Kiecker
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Corinne Houart
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
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8
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Mano H, Asaoka Y, Kojima D, Fukada Y. Brain-specific homeobox Bsx specifies identity of pineal gland between serially homologous photoreceptive organs in zebrafish. Commun Biol 2019; 2:364. [PMID: 31602413 PMCID: PMC6779754 DOI: 10.1038/s42003-019-0613-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 09/16/2019] [Indexed: 01/11/2023] Open
Abstract
The pineal gland functioning as a photoreceptive organ in non-mammalian species is a serial homolog of the retina. Here we found that Brain-specific homeobox (Bsx) is a key regulator conferring individuality on the pineal gland between the two serially homologous photoreceptive organs in zebrafish. Bsx knock-down impaired the pineal development with reduced expression of exorh, the pineal-specific gene responsible for the photoreception, whereas it induced ectopic expression of rho, a retina-specific gene, in the pineal gland. Bsx remarkably transactivated the exorh promoter in combination with Otx5, but not with Crx, through its binding to distinct subtypes of PIRE, a DNA cis-element driving Crx/Otx-dependent pineal-specific gene expression. These results demonstrate that the identity of pineal photoreceptive neurons is determined by the combinatorial code of Bsx and Otx5, the former confers the pineal specificity at the tissue level and the latter determines the photoreceptor specificity at the cellular level.
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Affiliation(s)
- Hiroaki Mano
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 Japan
| | - Yoichi Asaoka
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 Japan
| | - Daisuke Kojima
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 Japan
| | - Yoshitaka Fukada
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 Japan
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9
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Madelaine R, Notwell JH, Skariah G, Halluin C, Chen CC, Bejerano G, Mourrain P. A screen for deeply conserved non-coding GWAS SNPs uncovers a MIR-9-2 functional mutation associated to retinal vasculature defects in human. Nucleic Acids Res 2019. [PMID: 29518216 PMCID: PMC5909433 DOI: 10.1093/nar/gky166] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Thousands of human disease-associated single nucleotide polymorphisms (SNPs) lie in the non-coding genome, but only a handful have been demonstrated to affect gene expression and human biology. We computationally identified risk-associated SNPs in deeply conserved non-exonic elements (CNEs) potentially contributing to 45 human diseases. We further demonstrated that human CNE1/rs17421627 associated with retinal vasculature defects showed transcriptional activity in the zebrafish retina, while introducing the risk-associated allele completely abolished CNE1 enhancer activity. Furthermore, deletion of CNE1 led to retinal vasculature defects and to a specific downregulation of microRNA-9, rather than MEF2C as predicted by the original genome-wide association studies. Consistent with these results, miR-9 depletion affects retinal vasculature formation, demonstrating MIR-9-2 as a critical gene underpinning the associated trait. Importantly, we validated that other CNEs act as transcriptional enhancers that can be disrupted by conserved non-coding SNPs. This study uncovers disease-associated non-coding mutations that are deeply conserved, providing a path for in vivo testing to reveal their cis-regulated genes and biological roles.
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Affiliation(s)
- Romain Madelaine
- Department of Psychiatry and Behavioral Sciences, Stanford Center for Sleep Sciences and Medicine, Stanford, CA 94305, USA
| | | | - Gemini Skariah
- Department of Psychiatry and Behavioral Sciences, Stanford Center for Sleep Sciences and Medicine, Stanford, CA 94305, USA
| | - Caroline Halluin
- Department of Psychiatry and Behavioral Sciences, Stanford Center for Sleep Sciences and Medicine, Stanford, CA 94305, USA
| | | | - Gill Bejerano
- Department of Computer Science, Stanford, CA 94305, USA.,Department of Developmental Biology, Stanford, CA 94305, USA.,Division of Medical Genetics, Department of Pediatrics, Stanford, CA 94305, USA
| | - Philippe Mourrain
- Department of Psychiatry and Behavioral Sciences, Stanford Center for Sleep Sciences and Medicine, Stanford, CA 94305, USA.,INSERM 1024, Ecole Normale Supérieure Paris, 75005, France
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10
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Abstract
The circumventricular organs (CVOs) are specialised neuroepithelial structures found in the midline of the brain, grouped around the third and fourth ventricles. They mediate the communication between the brain and the periphery by performing sensory and secretory roles, facilitated by increased vascularisation and the absence of a blood-brain barrier. Surprisingly little is known about the origins of the CVOs (both developmental and evolutionary), but their functional and organisational similarities raise the question of the extent of their relationship. Here, I review our current knowledge of the embryonic development of the seven major CVOs (area postrema, median eminence, neurohypophysis, organum vasculosum of the lamina terminalis, pineal organ, subcommissural organ, subfornical organ) in embryos of different vertebrate species. Although there are conspicuous similarities between subsets of CVOs, no unifying feature characteristic of their development has been identified. Cross-species comparisons suggest that CVOs also display a high degree of evolutionary flexibility. Thus, the term 'CVO' is merely a functional definition, and features shared by multiple CVOs may be the result of homoplasy rather than ontogenetic or phylogenetic relationships.
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Affiliation(s)
- Clemens Kiecker
- Department of Developmental NeurobiologyKing's College LondonLondonUK
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11
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Korzh V. Development of brain ventricular system. Cell Mol Life Sci 2018; 75:375-383. [PMID: 28780589 PMCID: PMC5765195 DOI: 10.1007/s00018-017-2605-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 07/20/2017] [Accepted: 08/02/2017] [Indexed: 12/15/2022]
Abstract
The brain ventricular system (BVS) consists of brain ventricles and channels connecting ventricles filled with cerebrospinal fluid (CSF). The disturbance of CSF flow has been linked to neurodegenerative disease including hydrocephalus, which manifests itself as an abnormal expansion of BVS. This relatively common developmental disorder has been observed in human and domesticated animals and linked to functional deficiency of various cells lineages facing BVS, including the choroid plexus or ependymal cells that generate CSF or the ciliated cells that cilia beating generates CSF flow. To understand the underlying causes of hydrocephalus, several animal models were developed, including rodents (mice, rat, and hamster) and zebrafish. At another side of a spectrum of BVS anomalies there is the "slit-ventricle" syndrome, which develops due to insufficient inflation of BVS. Recent advances in functional genetics of zebrafish brought to light novel genetic elements involved in development of BVS and circulation of CSF. This review aims to reveal common elements of morphologically different BVS of zebrafish as a typical representative of teleosts and other vertebrates and illustrate useful features of the zebrafish model for studies of BVS. Along this line, recent analyses of the two novel zebrafish mutants affecting different subunits of the potassium voltage-gated channels allowed to emphasize an important functional convergence of the evolutionarily conserved elements of protein transport essential for BVS development, which were revealed by the zebrafish and mouse studies.
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Affiliation(s)
- Vladimir Korzh
- International Institute of Molecular and Cell Biology, Warsaw, Poland.
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12
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Schredelseker T, Driever W. Bsx controls pineal complex development. Development 2018; 145:dev.163477. [DOI: 10.1242/dev.163477] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 06/08/2018] [Indexed: 12/18/2022]
Abstract
Neuroendocrine cells in the pineal gland release melatonin during the night and in teleosts are directly photoreceptive. During development of the pineal complex, a small number of cells migrate leftward away from the pineal anlage to form the parapineal cell cluster, a process which is crucial for asymmetrical development of the bilateral habenular nuclei. Here we show that, throughout zebrafish embryonic development, the brain-specific homeobox (bsx) gene is expressed in all cell types of the pineal complex. We identified Bmp and Noto/Flh as major regulators of bsx expression in the pineal complex. Upon loss of Bsx through the generation of a targeted mutation, embryos fail to form a parapineal organ and develop right-isomerized habenulae. Crucial enzymes in the melatonin biosynthesis pathway are not expressed, suggesting absence of melatonin from the pineal gland of bsx mutants. Several genes involved in rod-like or cone-like phototransduction are also abnormally expressed, indicating that Bsx plays a pivotal role in differentiation of multiple cell types in the zebrafish pineal complex.
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Affiliation(s)
- Theresa Schredelseker
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert-Ludwigs-University Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany
- BIOSS - Centre for Biological Signalling Studies, Albertstrasse 19, 79104 Freiburg, Germany
| | - Wolfgang Driever
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert-Ludwigs-University Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany
- BIOSS - Centre for Biological Signalling Studies, Albertstrasse 19, 79104 Freiburg, Germany
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13
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García-Lecea M, Gasanov E, Jedrychowska J, Kondrychyn I, Teh C, You MS, Korzh V. Development of Circumventricular Organs in the Mirror of Zebrafish Enhancer-Trap Transgenics. Front Neuroanat 2017; 11:114. [PMID: 29375325 PMCID: PMC5770639 DOI: 10.3389/fnana.2017.00114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 11/22/2017] [Indexed: 11/18/2022] Open
Abstract
The circumventricular organs (CVOs) are small structures lining the cavities of brain ventricular system. They are associated with the semitransparent regions of the blood-brain barrier (BBB). Hence it is thought that CVOs mediate biochemical signaling and cell exchange between the brain and systemic blood. Their classification is still controversial and development not fully understood largely due to an absence of tissue-specific molecular markers. In a search for molecular determinants of CVOs we studied the green fluorescent protein (GFP) expression pattern in several zebrafish enhancer trap transgenics including Gateways (ET33-E20) that has been instrumental in defining the development of choroid plexus. In Gateways the GFP is expressed in regions of the developing brain outside the choroid plexus, which remain to be characterized. The neuroanatomical and histological analysis suggested that some previously unassigned domains of GFP expression may correspond to at least six other CVOs–the organum vasculosum laminae terminalis (OVLT), subfornical organ (SFO), paraventricular organ (PVO), pineal (epiphysis), area postrema (AP) and median eminence (ME). Two other CVOs, parapineal and subcommissural organ (SCO) were detected in other enhancer-trap transgenics. Hence enhancer-trap transgenic lines could be instrumental for developmental studies of CVOs in zebrafish and understanding of the molecular mechanism of disease such a hydrocephalus in human. Their future analysis may shed light on general and specific molecular mechanisms that regulate development of CVOs.
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Affiliation(s)
- Marta García-Lecea
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore.,Department of Basic Biomedical Sciences, Universidad Europea de Madrid, Madrid, Spain
| | - Evgeny Gasanov
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Justyna Jedrychowska
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.,Postgraduate School of Molecular Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Igor Kondrychyn
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore.,RIKEN Center for Developmental Biology, Kobe, Japan
| | - Cathleen Teh
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore
| | - May-Su You
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore.,National Health Research Institutes (NHRI), Zhunan, Taiwan
| | - Vladimir Korzh
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore.,International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
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14
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Brafman D, Willert K. Wnt/β-catenin signaling during early vertebrate neural development. Dev Neurobiol 2017; 77:1239-1259. [PMID: 28799266 DOI: 10.1002/dneu.22517] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 07/24/2017] [Accepted: 08/09/2017] [Indexed: 12/29/2022]
Abstract
The vertebrate central nervous system (CNS) is comprised of vast number of distinct cell types arranged in a highly organized manner. This high degree of complexity is achieved by cellular communication, including direct cell-cell contact, cell-matrix interactions, and cell-growth factor signaling. Among the several developmental signals controlling the development of the CNS, Wnt proteins have emerged as particularly critical and, hence, have captivated the attention of many researchers. With Wnts' evolutionarily conserved function as primordial symmetry breaking signals, these proteins and their downstream effects are responsible for simultaneously establishing cellular diversity and tissue organization. With their expansive repertoire of secreted agonists and antagonists, cell surface receptors, signaling cascades and downstream biological effects, Wnts are ideally suited to control the complex processes underlying vertebrate neural development. In this review, we will describe the mechanisms by which Wnts exert their potent effects on cells and tissues and highlight the many roles of Wnt signaling during neural development, starting from the initial induction of the neural plate, the subsequent patterning along the embryonic axes, to the intricately organized structure of the CNS. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1239-1259, 2017.
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Affiliation(s)
- David Brafman
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona, 85287
| | - Karl Willert
- Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA, 92093-0695
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15
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Shainer I, Buchshtab A, Hawkins TA, Wilson SW, Cone RD, Gothilf Y. Novel hypophysiotropic AgRP2 neurons and pineal cells revealed by BAC transgenesis in zebrafish. Sci Rep 2017; 7:44777. [PMID: 28317906 PMCID: PMC5357965 DOI: 10.1038/srep44777] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 02/13/2017] [Indexed: 11/21/2022] Open
Abstract
The neuropeptide agouti-related protein (AgRP) is expressed in the arcuate nucleus of the mammalian hypothalamus and plays a key role in regulating food consumption and energy homeostasis. Fish express two agrp genes in the brain: agrp1, considered functionally homologous with the mammalian AgRP, and agrp2. The role of agrp2 and its relationship to agrp1 are not fully understood. Utilizing BAC transgenesis, we generated transgenic zebrafish in which agrp1- and agrp2-expressing cells can be visualized and manipulated. By characterizing these transgenic lines, we showed that agrp1-expressing neurons are located in the ventral periventricular hypothalamus (the equivalent of the mammalian arcuate nucleus), projecting throughout the hypothalamus and towards the preoptic area. The agrp2 gene was expressed in the pineal gland in a previously uncharacterized subgroup of cells. Additionally, agrp2 was expressed in a small group of neurons in the preoptic area that project directly towards the pituitary and form an interface with the pituitary vasculature, suggesting that preoptic AgRP2 neurons are hypophysiotropic. We showed that direct synaptic connection can exist between AgRP1 and AgRP2 neurons in the hypothalamus, suggesting communication and coordination between AgRP1 and AgRP2 neurons and, therefore, probably also between the processes they regulate.
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Affiliation(s)
- Inbal Shainer
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Adi Buchshtab
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Thomas A. Hawkins
- The Department of Cell and Developmental Biology, Faculty of Life Sciences, University College London, London, UK
| | - Stephen W. Wilson
- The Department of Cell and Developmental Biology, Faculty of Life Sciences, University College London, London, UK
| | - Roger D. Cone
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Yoav Gothilf
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
- Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
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16
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Madelaine R, Lovett-Barron M, Halluin C, Andalman AS, Liang J, Skariah GM, Leung LC, Burns VM, Mourrain P. The hypothalamic NPVF circuit modulates ventral raphe activity during nociception. Sci Rep 2017; 7:41528. [PMID: 28139691 PMCID: PMC5282529 DOI: 10.1038/srep41528] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 12/21/2016] [Indexed: 01/25/2023] Open
Abstract
RFamide neuropeptide VF (NPVF) is expressed by neurons in the hypothalamus and has been implicated in nociception, but the circuit mechanisms remain unexplored. Here, we studied the structural and functional connections from NPVF neurons to downstream targets in the context of nociception, using novel transgenic lines, optogenetics, and calcium imaging in behaving larval zebrafish. We found a specific projection from NPVF neurons to serotonergic neurons in the ventral raphe nucleus (vRN). We showed NPVF neurons and vRN are suppressed and excited by noxious stimuli, respectively. We combined optogenetics with calcium imaging and pharmacology to demonstrate that stimulation of NPVF cells suppresses neuronal activity in vRN. During noxious stimuli, serotonergic neurons activation was due to a suppression of an inhibitory NPVF-ventral raphe peptidergic projection. This study reveals a novel NPVF-vRN functional circuit modulated by noxious stimuli in vertebrates.
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Affiliation(s)
- Romain Madelaine
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Matthew Lovett-Barron
- Department of Bioengineering and CNC program, Stanford University, Stanford, CA 94305, USA
| | - Caroline Halluin
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Aaron S Andalman
- Department of Bioengineering and CNC program, Stanford University, Stanford, CA 94305, USA
| | - Jin Liang
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Gemini M Skariah
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Louis C Leung
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Vanessa M Burns
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Philippe Mourrain
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA.,INSERM U1024, Ecole Normale Supérieure Paris, 75005, France
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17
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Halluin C, Madelaine R, Naye F, Peers B, Roussigné M, Blader P. Habenular Neurogenesis in Zebrafish Is Regulated by a Hedgehog, Pax6 Proneural Gene Cascade. PLoS One 2016; 11:e0158210. [PMID: 27387288 PMCID: PMC4936704 DOI: 10.1371/journal.pone.0158210] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 06/13/2016] [Indexed: 11/19/2022] Open
Abstract
The habenulae are highly conserved nuclei in the dorsal diencephalon that connect the forebrain to the midbrain and hindbrain. These nuclei have been implicated in a broad variety of behaviours in humans, primates, rodents and zebrafish. Despite this, the molecular mechanisms that control the genesis and differentiation of neural progenitors in the habenulae remain relatively unknown. We have previously shown that, in zebrafish, the timing of habenular neurogenesis is left-right asymmetric and that in the absence of Nodal signalling this asymmetry is lost. Here, we show that habenular neurogenesis requires the homeobox transcription factor Pax6a and the redundant action of two proneural bHLH factors, Neurog1 and Neurod4. We present evidence that Hedgehog signalling is required for the expression of pax6a, which is in turn necessary for the expression of neurog1 and neurod4. Finally, we demonstrate by pharmacological inhibition that Hedgehog signalling is required continuously during habenular neurogenesis and by cell transplantation experiments that pathway activation is required cell autonomously. Our data sheds light on the mechanism underlying habenular development that may provide insights into how Nodal signalling imposes asymmetry on the timing of habenular neurogenesis.
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Affiliation(s)
- Caroline Halluin
- Université de Toulouse III, UPS, Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), 118 route de Narbonne, F-31062 Toulouse, France
- CNRS, CBD UMR 5547, F-31062 Toulouse, France
- Stanford University, School of Medicine, 269–279 Campus Drive, Stanford, CA 94305, United States of America
| | - Romain Madelaine
- Université de Toulouse III, UPS, Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), 118 route de Narbonne, F-31062 Toulouse, France
- CNRS, CBD UMR 5547, F-31062 Toulouse, France
- Stanford University, School of Medicine, 269–279 Campus Drive, Stanford, CA 94305, United States of America
| | - François Naye
- Unit of Molecular Biology and Genetic Engineering, University of Liège, GIGA-R, B34, Avenue de l'Hôpital 1, B-4000 Liège, Belgium
| | - Bernard Peers
- Unit of Molecular Biology and Genetic Engineering, University of Liège, GIGA-R, B34, Avenue de l'Hôpital 1, B-4000 Liège, Belgium
| | - Myriam Roussigné
- Université de Toulouse III, UPS, Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), 118 route de Narbonne, F-31062 Toulouse, France
- CNRS, CBD UMR 5547, F-31062 Toulouse, France
- * E-mail: (MR); (PB)
| | - Patrick Blader
- Université de Toulouse III, UPS, Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), 118 route de Narbonne, F-31062 Toulouse, France
- CNRS, CBD UMR 5547, F-31062 Toulouse, France
- * E-mail: (MR); (PB)
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18
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Khuansuwan S, Clanton JA, Dean BJ, Patton JG, Gamse JT. A transcription factor network controls cell migration and fate decisions in the developing zebrafish pineal complex. Development 2016; 143:2641-50. [PMID: 27317804 PMCID: PMC4958332 DOI: 10.1242/dev.131680] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 06/02/2016] [Indexed: 11/20/2022]
Abstract
The zebrafish pineal complex consists of four cell types (rod and cone photoreceptors, projection neurons and parapineal neurons) that are derived from a single pineal complex anlage. After specification, parapineal neurons migrate unilaterally away from the rest of the pineal complex whereas rods, cones and projection neurons are non-migratory. The transcription factor Tbx2b is important for both the correct number and migration of parapineal neurons. We find that two additional transcription factors, Flh and Nr2e3, negatively regulate parapineal formation. Flh induces non-migratory neuron fates and limits the extent of parapineal specification, in part by activation of Nr2e3 expression. Tbx2b is positively regulated by Flh, but opposes Flh action during specification of parapineal neurons. Loss of parapineal neuron specification in Tbx2b-deficient embryos can be partially rescued by loss of Nr2e3 or Flh function; however, parapineal migration absolutely requires Tbx2b activity. We conclude that cell specification and migration in the pineal complex are regulated by a network of at least three transcription factors. Summary: Cell fate specification and migration in the zebrafish pineal complex are regulated by a network of at least three transcription factors: Tbx2b, Flh and Nr2e3.
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Affiliation(s)
- Sataree Khuansuwan
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Joshua A Clanton
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Benjamin J Dean
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - James G Patton
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Joshua T Gamse
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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19
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Khuansuwan S, Gamse JT. Identification of differentially expressed genes during development of the zebrafish pineal complex using RNA sequencing. Dev Biol 2014; 395:144-53. [PMID: 25173875 DOI: 10.1016/j.ydbio.2014.08.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 07/17/2014] [Accepted: 08/17/2014] [Indexed: 02/03/2023]
Abstract
We describe a method for isolating RNA suitable for high-throughput RNA sequencing (RNA-seq) from small numbers of fluorescently labeled cells isolated from live zebrafish (Danio rerio) embryos without using costly, commercially available columns. This method ensures high cell viability after dissociation and suspension of cells and gives a very high yield of intact RNA. We demonstrate the utility of our new protocol by isolating RNA from fluorescence activated cell sorted (FAC sorted) pineal complex neurons in wild-type and tbx2b knockdown embryos at 24 hours post-fertilization. Tbx2b is a transcription factor required for pineal complex formation. We describe a bioinformatics pipeline used to analyze differential expression following high-throughput sequencing and demonstrate the validity of our results using in situ hybridization of differentially expressed transcripts. This protocol brings modern transcriptome analysis to the study of small cell populations in zebrafish.
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Affiliation(s)
- Sataree Khuansuwan
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Joshua T Gamse
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
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20
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Functional development of the circadian clock in the zebrafish pineal gland. BIOMED RESEARCH INTERNATIONAL 2014; 2014:235781. [PMID: 24839600 PMCID: PMC4009245 DOI: 10.1155/2014/235781] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 03/13/2014] [Indexed: 11/17/2022]
Abstract
The zebrafish constitutes a powerful model organism with unique advantages for investigating the vertebrate circadian timing system and its regulation by light. In particular, the remarkably early and rapid development of the zebrafish circadian system has facilitated exploring the factors that control the onset of circadian clock function during embryogenesis. Here, we review our understanding of the molecular basis underlying functional development of the central clock in the zebrafish pineal gland. Furthermore, we examine how the directly light-entrainable clocks in zebrafish cell lines have facilitated unravelling the general mechanisms underlying light-induced clock gene expression. Finally, we summarize how analysis of the light-induced transcriptome and miRNome of the zebrafish pineal gland has provided insight into the regulation of the circadian system by light, including the involvement of microRNAs in shaping the kinetics of light- and clock-regulated mRNA expression. The relative contributions of the pineal gland central clock and the distributed peripheral oscillators to the synchronization of circadian rhythms at the whole animal level are a crucial question that still remains to be elucidated in the zebrafish model.
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21
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Garric L, Ronsin B, Roussigné M, Booton S, Gamse JT, Dufourcq P, Blader P. Pitx2c ensures habenular asymmetry by restricting parapineal cell number. Development 2014; 141:1572-9. [PMID: 24598158 DOI: 10.1242/dev.100305] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Left-right (L/R) asymmetries in the brain are thought to underlie lateralised cognitive functions. Understanding how neuroanatomical asymmetries are established has been achieved through the study of the zebrafish epithalamus. Morphological symmetry in the epithalamus is broken by leftward migration of the parapineal, which is required for the subsequent elaboration of left habenular identity; the habenular nuclei flank the midline and show L/R asymmetries in marker expression and connectivity. The Nodal target pitx2c is expressed in the left epithalamus, but nothing is known about its role during the establishment of asymmetry in the brain. We show that abrogating Pitx2c function leads to the right habenula adopting aspects of left character, and to an increase in parapineal cell numbers. Parapineal ablation in Pitx2c loss of function results in right habenular isomerism, indicating that the parapineal is required for the left character detected in the right habenula in this context. Partial parapineal ablation in the absence of Pitx2c, however, reduces the number of parapineal cells to wild-type levels and restores habenular asymmetry. We provide evidence suggesting that antagonism between Nodal and Pitx2c activities sets an upper limit on parapineal cell numbers. We conclude that restricting parapineal cell number is crucial for the correct elaboration of epithalamic asymmetry.
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Affiliation(s)
- Laurence Garric
- Université de Toulouse, UPS, Centre de Biologie du Développement (CBD), 118 route de Narbonne, F-31062 Toulouse, France
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22
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Neugebauer JM, Yost HJ. FGF signaling is required for brain left-right asymmetry and brain midline formation. Dev Biol 2014; 386:123-34. [PMID: 24333178 PMCID: PMC3970204 DOI: 10.1016/j.ydbio.2013.11.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 02/03/2023]
Abstract
Early disruption of FGF signaling alters left-right (LR) asymmetry throughout the embryo. Here we uncover a role for FGF signaling that specifically disrupts brain asymmetry, independent of normal lateral plate mesoderm (LPM) asymmetry. When FGF signaling is inhibited during mid-somitogenesis, asymmetrically expressed LPM markers southpaw and lefty2 are not affected. However, asymmetrically expressed brain markers lefty1 and cyclops become bilateral. We show that FGF signaling controls expression of six3b and six7, two transcription factors required for repression of asymmetric lefty1 in the brain. We found that Z0-1, atypical PKC (aPKC) and β-catenin protein distribution revealed a midline structure in the forebrain that is dependent on a balance of FGF signaling. Ectopic activation of FGF signaling leads to overexpression of six3b, loss of organized midline adherins junctions and bilateral loss of lefty1 expression. Reducing FGF signaling leads to a reduction in six3b and six7 expression, an increase in cell boundary formation in the brain midline, and bilateral expression of lefty1. Together, these results suggest a novel role for FGF signaling in the brain to control LR asymmetry, six transcription factor expressions, and a midline barrier structure.
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Affiliation(s)
- Judith M Neugebauer
- Department of Neurobiology & Anatomy, University of Utah School of Medicine, Eccles Institute of Human Genetics, Building 533, Room 3160, 15 North 2030 East, Salt Lake City, UT 84112-5330, United States
| | - H Joseph Yost
- Department of Neurobiology & Anatomy, University of Utah School of Medicine, Eccles Institute of Human Genetics, Building 533, Room 3160, 15 North 2030 East, Salt Lake City, UT 84112-5330, United States.
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23
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Pavlou S, Astell K, Kasioulis I, Gakovic M, Baldock R, van Heyningen V, Coutinho P. Pleiotropic effects of Sox2 during the development of the zebrafish epithalamus. PLoS One 2014; 9:e87546. [PMID: 24498133 PMCID: PMC3909122 DOI: 10.1371/journal.pone.0087546] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 12/26/2013] [Indexed: 12/01/2022] Open
Abstract
The zebrafish epithalamus is part of the diencephalon and encompasses three major components: the pineal, the parapineal and the habenular nuclei. Using sox2 knockdown, we show here that this key transcriptional regulator has pleiotropic effects during the development of these structures. Sox2 negatively regulates pineal neurogenesis. Also, Sox2 is identified as the unknown factor responsible for pineal photoreceptor prepatterning and performs this function independently of the BMP signaling. The correct levels of sox2 are critical for the functionally important asymmetrical positioning of the parapineal organ and for the migration of parapineal cells as a coherent structure. Deviations from this strict control result in defects associated with abnormal habenular laterality, which we have documented and quantified in sox2 morphants.
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Affiliation(s)
- Sofia Pavlou
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Katy Astell
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Ioannis Kasioulis
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Milica Gakovic
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Richard Baldock
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Veronica van Heyningen
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Pedro Coutinho
- Biomedical Systems Analysis Section, Medical Developmental Genetics Section, Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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24
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Wu SY, de Borsetti NH, Bain EJ, Bulow CR, Gamse JT. Mediator subunit 12 coordinates intrinsic and extrinsic control of epithalamic development. Dev Biol 2014; 385:13-22. [DOI: 10.1016/j.ydbio.2013.10.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 10/01/2013] [Accepted: 10/23/2013] [Indexed: 12/22/2022]
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25
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Toyama R, Kim MH, Rebbert ML, Gonzales J, Burgess H, Dawid IB. Habenular commissure formation in zebrafish is regulated by the pineal gland-specific gene unc119c. Dev Dyn 2013; 242:1033-42. [PMID: 23749482 DOI: 10.1002/dvdy.23994] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Revised: 05/24/2013] [Accepted: 05/26/2013] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND The zebrafish pineal gland (epiphysis) is a site of melatonin production, contains photoreceptor cells, and functions as a circadian clock pacemaker. Since it is located on the surface of the forebrain, it is accessible for manipulation and, therefore, is a useful model system to analyze pineal gland function and development. We previously analyzed the pineal transcriptome during development and showed that many genes exhibit a highly dynamic expression pattern in the pineal gland. RESULTS Among genes preferentially expressed in the zebrafish pineal gland, we identified a tissue-specific form of the unc119 gene family, unc119c, which is highly preferentially expressed in the pineal gland during day and night at all stages examined from embryo to adult. When expression of unc119c was inhibited, the formation of the habenular commissure (HC) was specifically compromised. The Unc119c interacting factors Arl3l1 and Arl3l2 as well as Wnt4a also proved indispensible for HC formation. CONCLUSIONS We suggest that Unc119c, together with Arl3l1/2, plays an important role in modulating Wnt4a production and secretion during HC formation in the forebrain of the zebrafish embryo.
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Affiliation(s)
- Reiko Toyama
- Program in Genomics of Development, NICHD, NIH, Bethesda, Maryland, USA
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26
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Rath MF, Rohde K, Klein DC, Møller M. Homeobox genes in the rodent pineal gland: roles in development and phenotype maintenance. Neurochem Res 2013; 38:1100-12. [PMID: 23076630 PMCID: PMC3570627 DOI: 10.1007/s11064-012-0906-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 09/19/2012] [Accepted: 10/04/2012] [Indexed: 12/12/2022]
Abstract
The pineal gland is a neuroendocrine gland responsible for nocturnal synthesis of melatonin. During early development of the rodent pineal gland from the roof of the diencephalon, homeobox genes of the orthodenticle homeobox (Otx)- and paired box (Pax)-families are expressed and are essential for normal pineal development consistent with the well-established role that homeobox genes play in developmental processes. However, the pineal gland appears to be unusual because strong homeobox gene expression persists in the pineal gland of the adult brain. Accordingly, in addition to developmental functions, homeobox genes appear to be key regulators in postnatal phenotype maintenance in this tissue. In this paper, we review ontogenetic and phylogenetic aspects of pineal development and recent progress in understanding the involvement of homebox genes in rodent pineal development and adult function. A working model is proposed for understanding the sequential action of homeobox genes in controlling development and mature circadian function of the mammalian pinealocyte based on knowledge from detailed developmental and daily gene expression analyses in rats, the pineal phenotypes of homebox gene-deficient mice and studies on development of the retinal photoreceptor; the pinealocyte and retinal photoreceptor share features not seen in other tissues and are likely to have evolved from the same ancestral photodetector cell.
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Affiliation(s)
- Martin F Rath
- Department of Neuroscience and Pharmacology, Panum Institute 24.2, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200, Denmark.
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27
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Clanton JA, Hope KD, Gamse JT. Fgf signaling governs cell fate in the zebrafish pineal complex. Development 2013; 140:323-32. [PMID: 23250206 DOI: 10.1242/dev.083709] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Left-right (L-R) asymmetries in neuroanatomy exist throughout the animal kingdom, with implications for function and behavior. The molecular mechanisms that control formation of such asymmetries are beginning to be understood. Significant progress has been made by studying the zebrafish parapineal organ, a group of neurons on the left side of the epithalamus. Parapineal cells arise from the medially located pineal complex anlage and migrate to the left side of the brain. We have found that Fgf8a regulates a fate decision among anterior pineal complex progenitors that occurs just prior to the initiation of leftward migration. Cell fate analysis shows that in the absence of Fgf8a a subset of cells in the anterior pineal complex anlage differentiate as cone photoreceptors rather than parapineal neurons. Fgf8a acts permissively to promote parapineal fate in conjunction with the transcription factor Tbx2b, but might also block cone photoreceptor fate. We conclude that this subset of anterior pineal complex precursors, which normally become parapineal cells, are bipotential and require Fgf8a to maintain parapineal identity and/or prevent cone identity.
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Affiliation(s)
- Joshua A Clanton
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37205, USA
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28
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29
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Abstract
Differences between the left and right sides of the brain are present in many animal species. For instance, in humans the left cerebral hemisphere is largely responsible for language and tool use and the right for processing spatial information. Zebrafish have prominent left-right asymmetries in their epithalamus that have been associated with differential left and right eye use and navigational behavior. In wild-type (WT) zebrafish embryos, Nodal pathway genes are expressed in the left side of the pineal anlage. Shortly thereafter, a parapineal organ forms to the left of the pineal. The parapineal organ causes differences in gene expression, neuropil density, and connectivity of the left and right habenula nuclei. In embryos that have an open neural tube, such as embryos that are deficient in Nodal signaling or the cell adhesion protein N-cadherin, the left and right sides of the developing epithalamus remain separated from one another. We find that the brains of these embryos often become left isomerized: both sides of the brain develop morphology and gene expression patterns that are characteristic of the left side. However, other aspects of epithalamic development, such as differentiation of specific neuronal cell types, are intact. We propose that there is a mechanism in embryos with closed neural tubes that prevents both sides from developing like the left side. This mechanism fails when the two sides of the epithalamus are widely separated from one another, suggesting that it is dependent upon a signaling protein with limited range.
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Danesin C, Houart C. A Fox stops the Wnt: implications for forebrain development and diseases. Curr Opin Genet Dev 2012; 22:323-30. [DOI: 10.1016/j.gde.2012.05.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/17/2012] [Accepted: 05/15/2012] [Indexed: 10/28/2022]
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Shimizu N, Kawakami K, Ishitani T. Visualization and exploration of Tcf/Lef function using a highly responsive Wnt/β-catenin signaling-reporter transgenic zebrafish. Dev Biol 2012; 370:71-85. [PMID: 22842099 DOI: 10.1016/j.ydbio.2012.07.016] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 07/03/2012] [Accepted: 07/10/2012] [Indexed: 01/09/2023]
Abstract
Evolutionarily conserved Tcf/Lef transcription factors (Lef1, Tcf7, Tcf7l1, and Tcf7l2) mediate gene expression regulated by Wnt/β-catenin signaling, which has multiple roles in early embryogenesis, organogenesis, adult tissue homeostasis, and tissue regeneration. However, the spatiotemporal dynamics of Tcf/Lef activity during these events remain poorly understood. We generated stable transgenic zebrafish lines carrying a new Wnt/β-catenin signaling reporter, Tcf/Lef-miniP:dGFP. The reporter revealed the transcriptional activities of four Tcf/Lef members controlled by Wnt/β-catenin signaling, which were expressed in known Wnt/β-catenin signaling-active sites during embryogenesis, organ development and growth, and tissue regeneration. We used the transgenic lines to demonstrate the contribution of Tcf/Lef-mediated Wnt/β-catenin signaling to the development of the anterior lateral line, dorsal and secondary posterior lateral lines, and gill filaments. Thus, these reporter lines are highly useful tools for studying Tcf/Lef-mediated Wnt/β-catenin signaling-dependent processes.
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Affiliation(s)
- Nobuyuki Shimizu
- Division of Cell Regulation Systems, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Li X, Montgomery J, Cheng W, Noh JH, Hyde DR, Li L. Pineal photoreceptor cells are required for maintaining the circadian rhythms of behavioral visual sensitivity in zebrafish. PLoS One 2012; 7:e40508. [PMID: 22815753 PMCID: PMC3398033 DOI: 10.1371/journal.pone.0040508] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 06/08/2012] [Indexed: 11/28/2022] Open
Abstract
In non-mammalian vertebrates, the pineal gland functions as the central pacemaker that regulates the circadian rhythms of animal behavior and physiology. We generated a transgenic zebrafish line [Tg(Gnat2:gal4-VP16/UAS:nfsB-mCherry)] in which the E. coli nitroreductase is expressed in pineal photoreceptor cells. In developing embryos and young adults, the transgene is expressed in both retinal and pineal photoreceptor cells. During aging, the expression of the transgene in retinal photoreceptor cells gradually diminishes. By 8 months of age, the Gnat2 promoter-driven nitroreductase is no longer expressed in retinal photoreceptor cells, but its expression in pineal photoreceptor cells persists. This provides a tool for selective ablation of pineal photoreceptor cells, i.e., by treatments with metronidazole. In the absence of pineal photoreceptor cells, the behavioral visual sensitivity of the fish remains unchanged; however, the circadian rhythms of rod and cone sensitivity are diminished. Brief light exposures restore the circadian rhythms of behavioral visual sensitivity. Together, the data suggest that retinal photoreceptor cells respond to environmental cues and are capable of entraining the circadian rhythms of visual sensitivity; however, they are insufficient for maintaining the rhythms. Cellular signals from the pineal photoreceptor cells may be required for maintaining the circadian rhythms of visual sensitivity.
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Affiliation(s)
- Xinle Li
- Department of Biological Sciences, Center for Zebrafish Research, University of Notre Dame, Notre Dame, Indiana, United States of America
- Tianjin Key Laboratory of Animal Models and Degenerative Neurological Diseases, Nankai University, Tianjin, China
| | - Jake Montgomery
- Department of Biological Sciences, Center for Zebrafish Research, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Wesley Cheng
- Department of Biological Sciences, Center for Zebrafish Research, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Jung Hyun Noh
- Department of Biological Sciences, Center for Zebrafish Research, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - David R. Hyde
- Department of Biological Sciences, Center for Zebrafish Research, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Lei Li
- Department of Biological Sciences, Center for Zebrafish Research, University of Notre Dame, Notre Dame, Indiana, United States of America
- Tianjin Key Laboratory of Animal Models and Degenerative Neurological Diseases, Nankai University, Tianjin, China
- * E-mail:
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Idda ML, Bertolucci C, Vallone D, Gothilf Y, Sánchez-Vázquez FJ, Foulkes NS. Circadian clocks. PROGRESS IN BRAIN RESEARCH 2012; 199:41-57. [DOI: 10.1016/b978-0-444-59427-3.00003-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Madelaine R, Garric L, Blader P. Partially redundant proneural function reveals the importance of timing during zebrafish olfactory neurogenesis. Development 2011; 138:4753-62. [PMID: 21965609 DOI: 10.1242/dev.066563] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Little is known about proneural gene function during olfactory neurogenesis in zebrafish. Here, we show that the zebrafish Atonal genes neurogenin1 (neurog1) and neurod4 are redundantly required for development of both early-born olfactory neurons (EONs) and later-born olfactory sensory neurons (OSNs). We show that neurod4 expression is initially absent in neurog1 mutant embryos but recovers and is sufficient for the delayed development of OSN. By contrast, EON numbers are significantly reduced in neurog1 mutant embryos despite the recovery of neurod4 expression. Our results suggest that a shortened time window for EON development causes this reduction; the last S-phase of EON is delayed in neurog1 mutant embryos but mutant EONs are all post-mitotic at the same stage as EONs in wild-type embryos. Finally, we show that expression of certain genes, such as robo2, is never detected in neurog1 mutant EONs. Failure of robo2 expression to recover correlates with defects in the fasciculation of neurog1 mutant olfactory axonal projections and in the organisation of proto-glomeruli because projections arrive at the olfactory bulb that are reminiscent of those in robo2 mutant embryos. We conclude that the duration of proneural expression in EON progenitors is crucial for correct development of the zebrafish olfactory system.
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Affiliation(s)
- Romain Madelaine
- Université de Toulouse, UPS, Centre de Biologie du Développement (CBD), 118 route de Narbonne, F-31062 Toulouse, France
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Quillien A, Blanco-Sanchez B, Halluin C, Moore JC, Lawson ND, Blader P, Cau E. BMP signaling orchestrates photoreceptor specification in the zebrafish pineal gland in collaboration with Notch. Development 2011; 138:2293-302. [PMID: 21558377 DOI: 10.1242/dev.060988] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A variety of signaling pathways have been shown to regulate specification of neuronal subtype identity. However, the mechanisms by which future neurons simultaneously process information from multiple pathways to establish their identity remain poorly understood. The zebrafish pineal gland offers a simple system with which to address questions concerning the integration of signaling pathways during neural specification as it contains only two types of neurons - photoreceptors and projection neurons. We have previously shown that Notch signaling inhibits the projection neuron fate. Here, we show that BMP signaling is both necessary and sufficient to promote the photoreceptor fate. We also demonstrate that crosstalk between BMP and Notch signaling is required for the inhibition of a projection neuron fate in future photoreceptors. In this case, BMP signaling is required as a competence factor for the efficient activation of Notch targets. Our results indicate that both the induction of a photoreceptor fate and the interaction with Notch relies on a canonical BMP/Smad5 pathway. However, the activation of Notch-dependent transcription does not require a canonical Smad5-DNA interaction. Our results provide new insights into how multiple signaling influences are integrated during cell fate specification in the vertebrate CNS.
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Affiliation(s)
- Aurélie Quillien
- Université de Toulouse, UPS, Centre de Biologie du Développement (CBD), CNRS, Toulouse, France
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Ben-Moshe Z, Vatine G, Alon S, Tovin A, Mracek P, Foulkes NS, Gothilf Y. Multiple PAR and E4BP4 bZIP transcription factors in zebrafish: diverse spatial and temporal expression patterns. Chronobiol Int 2011; 27:1509-31. [PMID: 20854132 DOI: 10.3109/07420528.2010.510229] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Circadian rhythms of physiology and behavior are generated by an autonomous circadian oscillator that is synchronized daily with the environment, mainly by light input. The PAR subfamily of transcriptional activators and the related E4BP4 repressor belonging to the basic leucine zipper (bZIP) family are clock-controlled genes that are suggested to mediate downstream circadian clock processes and to feedback onto the core oscillator. Here, the authors report the characterization of these genes in the zebrafish, an increasingly important model in the field of chronobiology. Five novel PAR and six novel e4bp4 zebrafish homolog genes were identified using bioinformatic tools and their coding sequences were cloned. Based on their evolutionary relationships, these genes were annotated as ztef2, zhlf1 and zhlf2, zdbp1 and zdbp2, and ze4bp4-1 to -6. The spatial and temporal mRNA expression pattern of each of these factors was characterized in zebrafish embryos in the context of a functional circadian clock and regulation by light. Nine of the factors exhibited augmented and rhythmic expression in the pineal gland, a central clock organ in zebrafish. Moreover, these genes were found to be regulated, to variable extents, by the circadian clock and/or by light. Differential expression patterns of multiple paralogs in zebrafish suggest multiple roles for these factors within the vertebrate circadian clock. This study, in the genetically accessible zebrafish model, lays the foundation for further research regarding the involvement and specific roles of PAR and E4BP4 transcription factors in the vertebrate circadian clock mechanism.
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Affiliation(s)
- Zohar Ben-Moshe
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
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Madelaine R, Blader P. A cluster of non-redundant Ngn1 binding sites is required for regulation of deltaA expression in zebrafish. Dev Biol 2010; 350:198-207. [PMID: 21034732 DOI: 10.1016/j.ydbio.2010.10.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 09/16/2010] [Accepted: 10/19/2010] [Indexed: 12/21/2022]
Abstract
Proneural genes encode bHLH transcription factors that are key regulator of neurogenesis in both vertebrates and invertebrates. How these transcription factors regulate targets required for neural determination and/or specification is beginning to be understood. In this study, we show that zebrafish deltaA is a transcriptional target of proneural factors. Using a combination of transient and stable transgenic reporters, we show that regulation of deltaA by one such proneural factor, Ngn1, requires three clustered E-box binding sites that act in a non-redundant manner. Furthermore, we show that as for other proneural targets, members of the different proneural families regulate deltaA expression via distinct cis-regulatory modules (CRMs). Interestingly, however, while the deltaA CRM regulated by a second proneural factor, Ascl1, has been conserved between delta genes of different species, we show that the Ngn1 CRM has not. These results suggest that evolutionary constraints on the mechanism by which Ngn1 regulates gene expression appear less strict than for Ascl1.
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Affiliation(s)
- Romain Madelaine
- Université de Toulouse, UPS, Centre de Biologie du Développement, 118 route de Narbonne, F-31062 Toulouse, France
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Pineal-specific agouti protein regulates teleost background adaptation. Proc Natl Acad Sci U S A 2010; 107:20164-71. [PMID: 20980662 DOI: 10.1073/pnas.1014941107] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Background adaptation is used by teleosts as one of a variety of camouflage mechanisms for avoidance of predation. Background adaptation is known to involve light sensing by the retina and subsequent regulation of melanophore dispersion or contraction in melanocytes, mediated by α-melanocyte-stimulating hormone and melanin-concentrating hormone, respectively. Here, we demonstrate that an agouti gene unique to teleosts, agrp2, is specifically expressed in the pineal and is required for up-regulation of hypothalamic pmch and pmchl mRNA and melanosome contraction in dermal melanocytes in response to a white background. floating head, a mutant with defective pineal development, exhibits defective up-regulation of mch mRNAs by white background, whereas nrc, a blind mutant, exhibits a normal response. These studies identify a role for the pineal in background adaptation in teleosts, a unique physiological function for the agouti family of proteins, and define a neuroendocrine axis by which environmental background regulates pigmentation.
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Zanazzi G, Matthews G. Enrichment and differential targeting of complexins 3 and 4 in ribbon-containing sensory neurons during zebrafish development. Neural Dev 2010; 5:24. [PMID: 20809954 PMCID: PMC2941751 DOI: 10.1186/1749-8104-5-24] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 09/01/2010] [Indexed: 12/01/2022] Open
Abstract
Background In sensory systems with broad bandwidths, polarized receptor cells utilize highly specialized organelles in their apical and basolateral compartments to transduce and ultimately transmit signals to the rest of the nervous system. While progress has been made in elucidating the assembly of the transduction apparatus, the development of synaptic ribbon-containing terminals remains poorly understood. To begin to delineate the targeting of the exocytotic machinery specifically in ribbon-containing neurons, we have examined the expression of complexins 3 and 4 in the zebrafish visual and acousticolateral systems during the first week of development. Results We have identified five members of the complexin 3/4 subfamily in zebrafish that show 50 to 75% amino acid identity with mammalian complexins 3 and 4. Utilizing a polyclonal antibody that recognizes all five orthologs, we demonstrate that these proteins are enriched in ribbon-containing sensory neurons. Complexin 3/4 is rapidly targeted to presynaptic terminals in the pineal organ and retina concomitantly with RIBEYE b, a component of ribbons. In hair cells of the inner ear and lateral line, however, complexin 3/4 immunoreactivity clusters on the apical surfaces of hair cells, among their stereocilia, rather than along the basolateral plasma membrane with RIBEYE b. A complexin 4a-specific antibody selectively labels the presynaptic terminals of visual system ribbon-containing neurons. Conclusions These results provide evidence for the concurrent transport and/or assembly of multiple components of the active zone in developing ribbon terminals. Members of the complexin 3/4 subfamily are enriched in these terminals in the visual system and in hair bundles of the acousticolateral system, suggesting that these proteins are differentially targeted and may have multiple roles in ribbon-containing sensory neurons.
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Affiliation(s)
- George Zanazzi
- Graduate Program in Neuroscience, State University of New York, Stony Brook, NY 11794, USA
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Xenopus Bsx links daily cell cycle rhythms and pineal photoreceptor fate. Proc Natl Acad Sci U S A 2010; 107:6352-7. [PMID: 20308548 DOI: 10.1073/pnas.1000854107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In the developing central nervous system, the cell cycle clock plays a crucial role in determining cell fate specification. A second clock, the circadian oscillator, generates daily rhythms of cell cycle progression. Although these two clocks interact, the mechanisms linking circadian cell cycle progression and cell fate determination are still poorly understood. A convenient system to address this issue is the pineal organ of lower vertebrates, which contains only two neuronal types, photoreceptors and projection neurons. In particular, photoreceptors constitute the core of the pineal circadian system, being able to transduce daily light inputs into the rhythmical production of melatonin. However, the genetic program leading to photoreceptor fate largely remains to be deciphered. Here, we report a previously undescribed function for the homeobox gene Bsx in controlling pineal proliferation and photoreceptor fate in Xenopus. We show that Xenopus Bsx (Xbsx) is expressed rhythmically in postmitotic photoreceptor precursors, reaching a peak during the night, with a cycle that is complementary to the daily rhythms of S-phase entry displayed by pineal cells. Xbsx knockdown results in increased night levels of pineal proliferation, whereas activation of a GR-Xbsx protein flattens the daily rhythms of S-phase entry to the lowest level. Furthermore, evidence is presented that Xbsx is necessary and sufficient to promote a photoreceptor fate. Altogether, these data indicate that Xbsx plays a dual role in contributing to shape the profile of the circadian cell cycle progression and in the specification of pineal photoreceptors, thus acting as a unique link between these two events.
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Abstract
For more than a decade, the zebrafish has proven to be an excellent model organism to investigate the mechanisms of neurogenesis during development. The often cited advantages, namely external development, genetic, and optical accessibility, have permitted direct examination and experimental manipulations of neurogenesis during development. Recent studies have begun to investigate adult neurogenesis, taking advantage of its widespread occurrence in the mature zebrafish brain to investigate the mechanisms underlying neural stem cell maintenance and recruitment. Here we provide a comprehensive overview of the tools and techniques available to study neurogenesis in zebrafish both during development and in adulthood. As useful resources, we provide tables of available molecular markers, transgenic, and mutant lines. We further provide optimized protocols for studying neurogenesis in the adult zebrafish brain, including in situ hybridization, immunohistochemistry, in vivo lipofection and electroporation methods to deliver expression constructs, administration of bromodeoxyuridine (BrdU), and finally slice cultures. These currently available tools have put zebrafish on par with other model organisms used to investigate neurogenesis.
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Affiliation(s)
- Prisca Chapouton
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
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Toyama R, Chen X, Jhawar N, Aamar E, Epstein J, Reany N, Alon S, Gothilf Y, Klein DC, Dawid IB. Transcriptome analysis of the zebrafish pineal gland. Dev Dyn 2009; 238:1813-26. [PMID: 19504458 DOI: 10.1002/dvdy.21988] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The zebrafish pineal gland (epiphysis) is a site of melatonin production, contains photoreceptor cells, and functions as a circadian clock pace maker. Here, we have used microarray technology to study the zebrafish pineal transcriptome. Analysis of gene expression at three larval and two adult stages revealed a highly dynamic transcriptional profile, revealing many genes that are highly expressed in the zebrafish pineal gland. Statistical analysis of the data based on Gene Ontology annotation indicates that many transcription factors are highly expressed during larval stages, whereas genes dedicated to phototransduction are preferentially expressed in the adult. Furthermore, several genes were identified that exhibit day/night differences in expression. Among the multiple candidate genes suggested by these data, we note the identification of a tissue-specific form of the unc119 gene with a possible role in pineal development.
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Affiliation(s)
- Reiko Toyama
- Laboratory of Molecular Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, Maryland, USA.
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Ziv L, Gothilf Y. Period2Expression Pattern and its Role in the Development of the Pineal Circadian Clock in Zebrafish. Chronobiol Int 2009; 23:101-12. [PMID: 16687284 DOI: 10.1080/07420520500464551] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
In zebrafish, pineal arylalkylamine-N-acetyltransferase (zfaanat2) mRNA expression begins at 22 h post-fertilization (hpf), and the clock-controlled rhythm of its transcript begins on the third day of development. Here we describe the role of light and of the clock gene, period2 (zper2) in the development of this rhythm. In 1-day-old zebrafish embryos, zper2 expression is transiently up-regulated by light in the pineal gland and, to a lesser extent, in other areas of the brain. Expression of zper2 that was not affected by light occurred in the olfactory placode and lactotroph cells of the pituitary primordium. Circadian analysis of pineal zfaanat2 mRNA expression indicated that light exposure is required for proper development of the circadian clock-controlled rhythmic expression of this gene. Knockdown of zPER2 using antisense technology abolished the effect of light on development of the zfaanat2 rhythm in the pineal gland, corroborating the role of zper2 in light entrainment of the circadian oscillator in zebrafish. Further analysis of zper2 expression at earlier stages of development revealed that light exposure at the blastula to mid-segmentation stages also caused a transient increase in zper2 expression. At mid-segmentation, before pineal differentiation, light-induced zper2 expression was enhanced in pineal progenitor cells. Thus, a possible role for early photoreception and light-induced zper2 expression in the development of clock-controlled rhythms remains to be investigated.
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Affiliation(s)
- Limor Ziv
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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Origins of neurogenesis, a cnidarian view. Dev Biol 2009; 332:2-24. [PMID: 19465018 DOI: 10.1016/j.ydbio.2009.05.563] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 05/14/2009] [Accepted: 05/16/2009] [Indexed: 11/22/2022]
Abstract
New perspectives on the origin of neurogenesis emerged with the identification of genes encoding post-synaptic proteins as well as many "neurogenic" regulators as the NK, Six, Pax, bHLH proteins in the Demosponge genome, a species that might differentiate sensory cells but no neurons. However, poriferans seem to miss some key regulators of the neurogenic circuitry as the Hox/paraHox and Otx-like gene families. Moreover as a general feature, many gene families encoding evolutionarily-conserved signaling proteins and transcription factors were submitted to a wave of gene duplication in the last common eumetazoan ancestor, after Porifera divergence. In contrast gene duplications in the last common bilaterian ancestor, Urbilateria, are limited, except for the bHLH Atonal-class. Hence Cnidaria share with Bilateria a large number of genetic tools. The expression and functional analyses currently available suggest a neurogenic function for numerous orthologs in developing or adult cnidarians where neurogenesis takes place continuously. As an example, in the Hydra polyp, the Clytia medusa and the Acropora coral, the Gsx/cnox2/Anthox-2 ParaHox gene likely supports neurogenesis. Also neurons and nematocytes (mechanosensory cells) share in hydrozoans a common stem cell and several regulatory genes indicating that they can be considered as sister cells. Performed in anthozoan and medusozoan species, these studies should tell us more about the way(s) evolution hazards achieved the transition from epithelial to neuronal cell fate, and about the robustness of the genetic circuitry that allowed neuromuscular transmission to arise and be maintained across evolution.
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O-GlcNAc modifications regulate cell survival and epiboly during zebrafish development. BMC DEVELOPMENTAL BIOLOGY 2009; 9:28. [PMID: 19383152 PMCID: PMC2680843 DOI: 10.1186/1471-213x-9-28] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2008] [Accepted: 04/21/2009] [Indexed: 12/27/2022]
Abstract
Background The post-translational addition of the monosaccharide O-linked β-N-acetylglucosamine (O-GlcNAc) regulates the activity of a wide variety of nuclear and cytoplasmic proteins. The enzymes O-GlcNAc Transferase (Ogt) and O-GlcNAcase (Oga) catalyze, respectively, the attachment and removal of O-GlcNAc to target proteins. In adult mice, Ogt and Oga attenuate the response to insulin by modifying several components of the signal transduction pathway. Complete loss of ogt function, however, is lethal to mouse embryonic stem cells, suggesting that the enzyme has additional, unstudied roles in development. We have utilized zebrafish as a model to determine role of O-GlcNAc modifications in development. Zebrafish has two ogt genes, encoding six different enzymatic isoforms that are expressed maternally and zygotically. Results We manipulated O-GlcNAc levels in zebrafish embryos by overexpressing zebrafish ogt, human oga or by injecting morpholinos against ogt transcripts. Each of these treatments results in embryos with shortened body axes and reduced brains at 24 hpf. The embryos had 23% fewer cells than controls, and displayed increased rates of cell death as early as the mid-gastrula stages. An extensive marker analysis indicates that derivatives of three germ layers are reduced to variable extents, and the embryos are severely disorganized after gastrulation. Overexpression of Ogt and Oga delayed epiboly and caused a severe disorganization of the microtubule and actin based cytoskeleton in the extra-embryonic yolk syncytial layer (YSL). The cytoskeletal defects resemble those previously reported for embryos lacking function of the Pou5f1/Oct4 transcription factor spiel ohne grenzen. Consistent with this, Pou5f1/Oct4 is modified by O-GlcNAc in human embryonic stem cells. Conclusion We conclude that O-GlcNAc modifications control the activity of proteins that regulate apoptosis and epiboly movements, but do not seem to regulate germ layer specification. O-GlcNAc modifies the transcription factor Spiel ohne grenzen/Pou5f1 and may regulate its activity.
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Snelson CD, Burkart JT, Gamse JT. Formation of the asymmetric pineal complex in zebrafish requires two independently acting transcription factors. Dev Dyn 2009; 237:3538-44. [PMID: 18629869 DOI: 10.1002/dvdy.21607] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The pineal complex of zebrafish consists of a pineal organ and a left-sided parapineal organ. Mutation of the floating head (flh) gene, which encodes a homeodomain protein, causes premature termination of pineal cell division without affecting specification or asymmetric placement of the parapineal. The from beyond (fby) mutation, a premature stop codon in the T-domain-containing protein Tbx2b, disrupts formation of the parapineal while leaving the pineal largely intact. However, flh is reported as being required for tbx2b transcription. To resolve the paradox that flhand tbx2b mutants have opposite phenotypes but have been placed in the same genetic pathway, we have examined transcriptional cross-regulation in single flh or fby mutants and genetic epistasis in double mutants. Careful analysis shows that flh is not required for tbx2b transcription and double mutants exhibit an additive phenotype. We conclude that Flh and Tbx2b regulate separate programs of pineal and parapineal development.
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Affiliation(s)
- Corey D Snelson
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
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47
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Snelson CD, Gamse JT. Building an asymmetric brain: development of the zebrafish epithalamus. Semin Cell Dev Biol 2008; 20:491-7. [PMID: 19084075 DOI: 10.1016/j.semcdb.2008.11.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 11/07/2008] [Accepted: 11/14/2008] [Indexed: 10/21/2022]
Abstract
The human brain exhibits notable asymmetries. Little is known about these symmetry deviations; however scientists are beginning to understand them by employing the lateralized zebrafish epithalamus as a model. The zebrafish epithalamus consists of the pineal and parapineal organs and paired habenular nuclei located bilateral to the pineal complex. While zebrafish pineal and parapineal organs arise from a common population of cells, parapineal cells undergo a separate program that allows them to migrate left of the pineal anlage. Studying the processes that lead to brain laterality in zebrafish will allow a better understanding of how human brain laterality is established.
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Affiliation(s)
- Corey D Snelson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA.
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Wang H, Kesinger JW, Zhou Q, Wren JD, Martin G, Turner S, Tang Y, Frank MB, Centola M. Identification and characterization of zebrafish ocular formation genes. Genome 2008; 51:222-35. [PMID: 18356958 DOI: 10.1139/g07-098] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To study genes that are specifically expressed in the eyes, we employed microarray and in situ hybridization analyses to identify and characterize differentially expressed ocular genes in eyeless masterblind (mbl-/-) zebrafish (Danio rerio). Among 70 differentially expressed genes in the mbl-/- mutant identified by microarray analysis, 8 down-regulated genes were characterized, including 4 eye-specific genes, opsin 1 short-wave-sensitive 1 (opn1sw1), crystallinbetaa1b (cryba1b), crystallinbetaa2b (cryba2b), and crystallingamma M2d3 (crygm2d3); 2 eye and brain genes, ATPase, H+ transporting, lysosomal, V0 subunit c (atp6v0c) and basic leucine zipper and W2 domains 1a (bzw1a); and 2 constitutive genes, heat shock protein 8 (hspa8) and ribosomal protein L7a (rpl7a). In situ hybridization experiments confirmed down-regulation of these 8 ocular formation genes in mbl-/- zebrafish and showed their ocular and dynamic temporal expression patterns during zebrafish early development. Further, an automated literature analysis of the 70 differentially expressed genes identified a sub-network of genes with known associations, either with each other or with ocular structures or development, and shows how this study contributes to the current body of knowledge.
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Affiliation(s)
- Han Wang
- Department of Zoology and Stephenson Research and Technology Center, University of Oklahoma, 101 David L. Boren Boulevard, Norman, OK 73019, USA.
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Cau E, Quillien A, Blader P. Notch resolves mixed neural identities in the zebrafish epiphysis. Development 2008; 135:2391-401. [PMID: 18550717 DOI: 10.1242/dev.013482] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Manipulation of Notch activity alters neuronal subtype identity in vertebrate neuronal lineages. Nonetheless, it remains controversial whether Notch activity diversifies cell fate by regulating the timing of neurogenesis or acts directly in neuronal subtype specification. Here, we address the role of Notch in the zebrafish epiphysis, a simple structure containing only two neural subtypes: projection neurons and photoreceptors. Reducing the activity of the Notch pathway results in an excess of projection neurons at the expense of photoreceptors, as well as an increase in cells retaining a mixed identity. However, although forced activation of the pathway inhibits the projection neuron fate, it does not promote photoreceptor identity. As birthdating experiments show that projection neurons and photoreceptors are born simultaneously, Notch acts directly during neuronal specification rather than by controlling the timing of neurogenesis. Finally, our data suggest that two distinct signals are required for photoreceptor fate specification: one for the induction of the photoreceptor fate and the other, involving Notch, for the inhibition of projection neuron traits. We propose a novel model in which Notch resolves mixed neural identities by repressing an undesired genetic program.
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Affiliation(s)
- Elise Cau
- Centre de Biologie du Développement, UMR 5547 CNRS/UPS, Université Paul Sabatier Bât. 4R3, Toulouse Cedex 9, France
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Pierce LX, Noche RR, Ponomareva O, Chang C, Liang JO. Novel functions for Period 3 and Exo-rhodopsin in rhythmic transcription and melatonin biosynthesis within the zebrafish pineal organ. Brain Res 2008; 1223:11-24. [PMID: 18597743 DOI: 10.1016/j.brainres.2008.05.020] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 04/25/2008] [Accepted: 05/01/2008] [Indexed: 11/29/2022]
Abstract
Entrainment of circadian clocks to environmental cues such as photoperiod ensures that daily biological rhythms stay in synchronization with the Earth's rotation. The vertebrate pineal organ has a conserved role in circadian regulation as the primary source of the nocturnal hormone melatonin. In lower vertebrates, the pineal has an endogenous circadian clock as well as photoreceptive cells that regulate this clock. The zebrafish opsin protein Exo-rhodopsin (Exorh) is expressed in pineal photoreceptors and is a candidate to mediate the effects of environmental light on pineal rhythms and melatonin synthesis. We demonstrate that Exorh has an important role in regulating gene transcription within the pineal. In developing embryos that lack Exorh, expression of the exorh gene itself and of the melatonin synthesis gene serotonin N-acetyl transferase 2 (aanat2) are significantly reduced. This suggests that the Exorh protein at the cell membrane is part of a signaling pathway that positively regulates transcription of these genes, and ultimately melatonin production, in the pineal. Like many other opsin genes, exorh is expressed with a daily rhythm: mRNA levels are higher at night than during the day. We found that the transcription factor Orthodenticle homeobox 5 (Otx5) activates exorh transcription, while the putative circadian clock component Period 3 (Per3) represses expression during the day, thereby contributing to the rhythm of transcription. This work identifies novel roles for Exorh and Per3, and gives insight into potential interactions between the sensory and circadian systems within the pineal.
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Affiliation(s)
- Lain X Pierce
- Department of Genetics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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