1
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Itoh T, Uehara M, Yura S, Wang JC, Fujii Y, Nakanishi A, Shimizu T, Hibi M. Foxp and Skor family proteins control differentiation of Purkinje cells from Ptf1a- and Neurog1-expressing progenitors in zebrafish. Development 2024; 151:dev202546. [PMID: 38456494 PMCID: PMC11057878 DOI: 10.1242/dev.202546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 03/01/2024] [Indexed: 03/09/2024]
Abstract
Cerebellar neurons, such as GABAergic Purkinje cells (PCs), interneurons (INs) and glutamatergic granule cells (GCs) are differentiated from neural progenitors expressing proneural genes, including ptf1a, neurog1 and atoh1a/b/c. Studies in mammals previously suggested that these genes determine cerebellar neuron cell fate. However, our studies on ptf1a;neurog1 zebrafish mutants and lineage tracing of ptf1a-expressing progenitors have revealed that the ptf1a/neurog1-expressing progenitors can generate diverse cerebellar neurons, including PCs, INs and a subset of GCs in zebrafish. The precise mechanisms of how each cerebellar neuron type is specified remains elusive. We found that genes encoding the transcriptional regulators Foxp1b, Foxp4, Skor1b and Skor2, which are reportedly expressed in PCs, were absent in ptf1a;neurog1 mutants. foxp1b;foxp4 mutants showed a strong reduction in PCs, whereas skor1b;skor2 mutants completely lacked PCs, and displayed an increase in immature GCs. Misexpression of skor2 in GC progenitors expressing atoh1c suppressed GC fate. These data indicate that Foxp1b/4 and Skor1b/2 function as key transcriptional regulators in the initial step of PC differentiation from ptf1a/neurog1-expressing neural progenitors, and that Skor1b and Skor2 control PC differentiation by suppressing their differentiation into GCs.
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Affiliation(s)
- Tsubasa Itoh
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Mari Uehara
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Shinnosuke Yura
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Jui Chun Wang
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Yukimi Fujii
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Akiko Nakanishi
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Takashi Shimizu
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Masahiko Hibi
- Department of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
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2
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Kent MR, Calderon D, Silvius KM, Kucinski JP, LaVigne CA, Cannon MV, Kendall GC. Zebrafish her3 knockout impacts developmental and cancer-related gene signatures. Dev Biol 2023; 496:1-14. [PMID: 36696714 PMCID: PMC10054701 DOI: 10.1016/j.ydbio.2023.01.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 01/04/2023] [Accepted: 01/07/2023] [Indexed: 01/24/2023]
Abstract
HES3 is a basic helix-loop-helix transcription factor that regulates neural stem cell renewal during development. HES3 overexpression is predictive of reduced overall survival in patients with fusion-positive rhabdomyosarcoma, a pediatric cancer that resembles immature and undifferentiated skeletal muscle. However, the mechanisms of HES3 cooperation in fusion-positive rhabdomyosarcoma are unclear and are likely related to her3/HES3's role in neurogenesis. To investigate HES3's function during development, we generated a zebrafish CRISPR/Cas9 null mutation of her3, the zebrafish ortholog of HES3. Loss of her3 is not embryonic lethal and adults exhibit expected Mendelian ratios. Embryonic her3 zebrafish mutants exhibit dysregulated neurog1 expression, a her3 target gene, and the mutant her3 fails to bind the neurog1 promoter sequence. Further, her3 mutants are significantly smaller than wildtype and a subset present with lens defects as adults. Transcriptomic analysis of her3 mutant embryos indicates that genes involved in organ development, such as pctp and grinab, are significantly downregulated. Further, differentially expressed genes in her3 null mutant embryos are enriched for Hox and Sox10 motifs. Several cancer-related gene pathways are impacted, including the inhibition of matrix metalloproteinases. Altogether, this new model is a powerful system to study her3/HES3-mediated neural development and its misappropriation in cancer contexts.
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Affiliation(s)
- Matthew R Kent
- Center for Childhood Cancer & Blood Diseases, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, 43205, USA
| | - Delia Calderon
- Center for Childhood Cancer & Blood Diseases, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, 43205, USA; Molecular, Cellular, and Developmental Biology Ph.D. Program, The Ohio State University, Columbus, OH, 43210, USA
| | - Katherine M Silvius
- Center for Childhood Cancer & Blood Diseases, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, 43205, USA
| | - Jack P Kucinski
- Center for Childhood Cancer & Blood Diseases, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, 43205, USA; Molecular, Cellular, and Developmental Biology Ph.D. Program, The Ohio State University, Columbus, OH, 43210, USA
| | - Collette A LaVigne
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Matthew V Cannon
- Center for Childhood Cancer & Blood Diseases, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, 43205, USA
| | - Genevieve C Kendall
- Center for Childhood Cancer & Blood Diseases, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, 43205, USA; Molecular, Cellular, and Developmental Biology Ph.D. Program, The Ohio State University, Columbus, OH, 43210, USA; Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, 43205, USA.
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3
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Stenzel A, Mumme-Monheit A, Sucharov J, Walker M, Mitchell JM, Appel B, Nichols JT. Distinct and redundant roles for zebrafish her genes during mineralization and craniofacial patterning. Front Endocrinol (Lausanne) 2022; 13:1033843. [PMID: 36578958 PMCID: PMC9791542 DOI: 10.3389/fendo.2022.1033843] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022] Open
Abstract
The Notch pathway is a cell-cell communication system which is critical for many developmental processes, including craniofacial development. Notch receptor activation induces expression of several well-known canonical targets including those encoded by the hes and her genes in mammals and zebrafish, respectively. The function of these genes, individually and in combination, during craniofacial development is not well understood. Here, we used zebrafish genetics to investigate her9 and her6 gene function during craniofacial development. We found that her9 is required for osteoblasts to efficiently mineralize bone, while cartilage is largely unaffected. Strikingly, gene expression studies in her9 mutants indicate that although progenitor cells differentiate into osteoblasts at the appropriate time and place, they fail to efficiently lay down mineralized matrix. This mineralization role of her9 is likely independent of Notch activation. In contrast, her9 also functions redundantly with her6 downstream of Jagged1b-induced Notch activation during dorsoventral craniofacial patterning. These studies disentangle distinct and redundant her gene functions during craniofacial development, including an unexpected, Notch independent, requirement during bone mineralization.
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Affiliation(s)
- Amanda Stenzel
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Abigail Mumme-Monheit
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Juliana Sucharov
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Macie Walker
- Department of Pediatrics, Section of Developmental Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Jennyfer M. Mitchell
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - Bruce Appel
- Department of Pediatrics, Section of Developmental Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
| | - James T. Nichols
- Department of Craniofacial Biology, University of Colorado-Anschutz Medical Campus, Aurora, CO, United States
- *Correspondence: James T. Nichols,
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4
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Head B, Traber MG. Expanding role of vitamin E in protection against metabolic dysregulation: Insights gained from model systems, especially the developing nervous system of zebrafish embryos. Free Radic Biol Med 2021; 176:80-91. [PMID: 34555455 DOI: 10.1016/j.freeradbiomed.2021.09.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/27/2021] [Accepted: 09/07/2021] [Indexed: 12/20/2022]
Abstract
This review discusses why the embryo requires vitamin E (VitE) and shows that its lack causes metabolic dysregulation and impacts morphological changes at very early stages in development, which occur prior to when a woman knows she is pregnant. VitE halts the chain reactions of lipid peroxidation (LPO). Metabolomic analyses indicate that thiols become depleted in E- embryos because LPO generates products that require compensation using limited amino acids and methyl donors that are also developmentally relevant. Thus, VitE protects metabolic networks and the integrated gene expression networks that control development. VitE is critical especially for neurodevelopment, which is dependent on trafficking by the α-tocopherol transfer protein (TTPa). VitE-deficient (E-) zebrafish embryos initially appear normal, but by 12 and 24 h post-fertilization (hpf) E- embryos are developmentally abnormal with expression of pax2a and sox10 mis-localized in the midbrain-hindbrain boundary, neural crest cells and throughout the spinal neurons. These patterning defects indicate cells that are especially in need of VitE-protection. They precede obvious morphological abnormalities (cranial-facial malformation, pericardial edema, yolksac edema, skewed body-axis) and impaired behavioral responses to locomotor activity tests. The TTPA gene (ttpa) is expressed at the leading edges of the brain ventricle border. Ttpa knockdown using morpholinos is 100% lethal by 24 hpf, while E- embryo brains are often over- or under-inflated at 24 hpf. Further, E- embryos prior to 24 hpf have increased expression of genes involved in glycolysis and the pentose phosphate pathway, and decreased expression of genes involved in anabolic pathways and transcription. Combined data from both gene expression and the metabolome in E- embryos at 24 hpf suggest that the activity of the mechanistic Target of Rapamycin (mTOR) signaling pathway is decreased, which may impact both metabolism and neurodevelopment. Further evaluation of VitE deficiency in neurogenesis and its subsequent impact on learning and behavior is needed.
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Affiliation(s)
- Brian Head
- Linus Pauling Institute, Corvallis, OR, USA; Molecular and Cell Biology Program, Corvallis, OR, USA
| | - Maret G Traber
- Linus Pauling Institute, Corvallis, OR, USA; School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA.
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5
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Yuikawa T, Ikeda M, Tsuda S, Saito S, Yamasu K. Involvement of Oct4-type transcription factor Pou5f3 in posterior spinal cord formation in zebrafish embryos. Dev Growth Differ 2021; 63:306-322. [PMID: 34331767 DOI: 10.1111/dgd.12742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 07/13/2021] [Accepted: 07/27/2021] [Indexed: 12/21/2022]
Abstract
In vertebrate embryogenesis, elongation of the posterior body is driven by de novo production of the axial and paraxial mesoderm as well as the neural tube at the posterior end. This process is presumed to depend on the stem cell-like population in the tail bud region, but the details of the gene regulatory network involved are unknown. Previous studies suggested the involvement of pou5f3, an Oct4-type POU gene in zebrafish, in axial elongation. In the present study, we first found that pou5f3 is expressed mainly in the dorsal region of the tail bud immediately after gastrulation, and that this expression is restricted to the posterior-most region of the elongating neural tube during somitogenesis. This pou5f3 expression was complementary to the broad expression of sox3 in the neural tube, and formed a sharp boundary with specific expression of tbxta (orthologue of mammalian T/Brachyury) in the tail bud, implicating pou5f3 in the specification of tail bud-derived cells toward neural differentiation in the spinal cord. When pou5f3 was functionally impaired after gastrulation by induction of a dominant-interfering pou5f3 mutant gene (en-pou5f3), trunk and tail elongation were markedly disturbed at distinct positions along the axis depending on the stage. This finding showed involvement of pou5f3 in de novo generation of the body from the tail bud. Conditional functional abrogation also showed that pou5f3 downregulates mesoderm-forming genes but promotes neural development by activating neurogenesis genes around the tail bud. These results suggest that pou5f3 is involved in formation of the posterior spinal cord.
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Affiliation(s)
- Tatsuya Yuikawa
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama City, Japan
| | - Masaaki Ikeda
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama City, Japan
| | - Sachiko Tsuda
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama City, Japan
| | - Shinji Saito
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama City, Japan
| | - Kyo Yamasu
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama City, Japan
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6
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Vitamin E is necessary for zebrafish nervous system development. Sci Rep 2020; 10:15028. [PMID: 32958954 PMCID: PMC7506018 DOI: 10.1038/s41598-020-71760-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 08/17/2020] [Indexed: 12/12/2022] Open
Abstract
Vitamin E (VitE) deficiency results in embryonic lethality. Knockdown of the gene ttpa encoding for the VitE regulatory protein [α-tocopherol transfer protein (α-TTP)] in zebrafish embryos causes death within 24 h post-fertilization (hpf). To test the hypothesis that VitE, not just α-TTP, is necessary for nervous system development, adult 5D strain zebrafish, fed either VitE sufficient (E+) or deficient (E-) diets, were spawned to obtain E+ and E- embryos, which were subjected to RNA in situ hybridization and RT-qPCR. Ttpa was expressed ubiquitously in embryos up to 12 hpf. Early gastrulation (6 hpf) assessed by goosecoid expression was unaffected by VitE status. By 24 hpf, embryos expressed ttpa in brain ventricle borders, which showed abnormal closure in E- embryos. They also displayed disrupted patterns of paired box 2a (pax2a) and SRY-box transcription factor 10 (sox10) expression in the midbrain-hindbrain boundary, spinal cord and dorsal root ganglia. In E- embryos, the collagen sheath notochord markers (col2a1a and col9a2) appeared bent. Severe developmental errors in E- embryos were characterized by improper nervous system patterning of the usually carefully programmed transcriptional signals. Histological analysis also showed developmental defects in the formation of the fore-, mid- and hindbrain and somites of E- embryos at 24 hpf. Ttpa expression profile was not altered by the VitE status demonstrating that VitE itself, and not ttpa, is required for development of the brain and peripheral nervous system in this vertebrate embryo model.
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7
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Her9/Hes4 is required for retinal photoreceptor development, maintenance, and survival. Sci Rep 2020; 10:11316. [PMID: 32647335 PMCID: PMC7347560 DOI: 10.1038/s41598-020-68172-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 06/11/2020] [Indexed: 11/13/2022] Open
Abstract
The intrinsic and extrinsic factors that regulate vertebrate photoreceptor specification and differentiation are complex, and our understanding of all the players is far from complete. Her9, the zebrafish ortholog of human HES4, is a basic helix-loop-helix-orange transcriptional repressor that regulates neurogenesis in several developmental contexts. We have previously shown that her9 is upregulated during chronic rod photoreceptor degeneration and regeneration in adult zebrafish, but little is known about the role of her9 during retinal development. To better understand the function of Her9 in the retina, we generated zebrafish her9 CRISPR mutants. Her9 homozygous mutants displayed striking retinal phenotypes, including decreased numbers of rods and red/green cones, whereas blue and UV cones were relatively unaffected. The reduction in rods and red/green cones correlated with defects in photoreceptor subtype lineage specification. The remaining rods and double cones displayed abnormal outer segments, and elevated levels of apoptosis. In addition to the photoreceptor defects, her9 mutants also possessed a reduced proliferative ciliary marginal zone, and decreased and disorganized Müller glia. Mutation of her9 was larval lethal, with no mutants surviving past 13 days post fertilization. Our results reveal a previously undescribed role for Her9/Hes4 in photoreceptor differentiation, maintenance, and survival.
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8
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Soto X, Biga V, Kursawe J, Lea R, Doostdar P, Thomas R, Papalopulu N. Dynamic properties of noise and Her6 levels are optimized by miR-9, allowing the decoding of the Her6 oscillator. EMBO J 2020; 39:e103558. [PMID: 32395844 PMCID: PMC7298297 DOI: 10.15252/embj.2019103558] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 03/25/2020] [Accepted: 04/03/2020] [Indexed: 01/08/2023] Open
Abstract
Noise is prevalent in biology and has been widely quantified using snapshot measurements. This static view obscures our understanding of dynamic noise properties and how these affect gene expression and cell state transitions. Using a CRISPR/Cas9 Zebrafish her6::Venus reporter combined with mathematical and in vivo experimentation, we explore how noise affects the protein dynamics of Her6, a basic helix-loop-helix transcriptional repressor. During neurogenesis, Her6 expression transitions from fluctuating to oscillatory at single-cell level. We identify that absence of miR-9 input generates high-frequency noise in Her6 traces, inhibits the transition to oscillatory protein expression and prevents the downregulation of Her6. Together, these impair the upregulation of downstream targets and cells accumulate in a normally transitory state where progenitor and early differentiation markers are co-expressed. Computational modelling and double smFISH of her6 and the early neurogenesis marker, elavl3, suggest that the change in Her6 dynamics precedes the downregulation in Her6 levels. This sheds light onto the order of events at the moment of cell state transition and how this is influenced by the dynamic properties of noise. Our results suggest that Her/Hes oscillations, facilitated by dynamic noise optimization by miR-9, endow progenitor cells with the ability to make a cell state transition.
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Affiliation(s)
- Ximena Soto
- Faculty of Biology Medicine and HealthSchool of Medical SciencesThe University of ManchesterManchesterUK
| | - Veronica Biga
- Faculty of Biology Medicine and HealthSchool of Medical SciencesThe University of ManchesterManchesterUK
| | - Jochen Kursawe
- School of Mathematics and StatisticsUniversity of St AndrewsSt AndrewsUK
| | - Robert Lea
- Faculty of Biology Medicine and HealthSchool of Medical SciencesThe University of ManchesterManchesterUK
| | - Parnian Doostdar
- Faculty of Biology Medicine and HealthSchool of Medical SciencesThe University of ManchesterManchesterUK
| | - Riba Thomas
- Faculty of Biology Medicine and HealthSchool of Medical SciencesThe University of ManchesterManchesterUK
| | - Nancy Papalopulu
- Faculty of Biology Medicine and HealthSchool of Medical SciencesThe University of ManchesterManchesterUK
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9
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Tambalo M, Mitter R, Wilkinson DG. A single cell transcriptome atlas of the developing zebrafish hindbrain. Development 2020; 147:dev184143. [PMID: 32094115 PMCID: PMC7097387 DOI: 10.1242/dev.184143] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 02/11/2020] [Indexed: 12/31/2022]
Abstract
Segmentation of the vertebrate hindbrain leads to the formation of rhombomeres, each with a distinct anteroposterior identity. Specialised boundary cells form at segment borders that act as a source or regulator of neuronal differentiation. In zebrafish, there is spatial patterning of neurogenesis in which non-neurogenic zones form at boundaries and segment centres, in part mediated by Fgf20 signalling. To further understand the control of neurogenesis, we have carried out single cell RNA sequencing of the zebrafish hindbrain at three different stages of patterning. Analyses of the data reveal known and novel markers of distinct hindbrain segments, of cell types along the dorsoventral axis, and of the transition of progenitors to neuronal differentiation. We find major shifts in the transcriptome of progenitors and of differentiating cells between the different stages analysed. Supervised clustering with markers of boundary cells and segment centres, together with RNA-seq analysis of Fgf-regulated genes, has revealed new candidate regulators of cell differentiation in the hindbrain. These data provide a valuable resource for functional investigations of the patterning of neurogenesis and the transition of progenitors to neuronal differentiation.
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Affiliation(s)
- Monica Tambalo
- Neural Development Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Richard Mitter
- Bioinformatics and Biostatistics, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - David G Wilkinson
- Neural Development Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
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10
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A systems biology approach reveals neuronal and muscle developmental defects after chronic exposure to ionising radiation in zebrafish. Sci Rep 2019; 9:20241. [PMID: 31882844 PMCID: PMC6934629 DOI: 10.1038/s41598-019-56590-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 12/13/2019] [Indexed: 11/11/2022] Open
Abstract
Contamination of the environment after the Chernobyl and Fukushima Daiichi nuclear power plant (NPP) disasters led to the exposure of a large number of humans and wild animals to radioactive substances. However, the sub-lethal consequences induced by these absorbed radiological doses remain understudied and the long-term biological impacts largely unknown. We assessed the biological effects of chronic exposure to ionizing radiation (IR) on embryonic development by exposing zebrafish embryo from fertilization and up to 120 hours post-fertilization (hpf) at dose rates of 0.5 mGy/h, 5 mGy/h and 50 mGy/h, thereby encompassing the field of low dose rates defined at 6 mGy/h. Chronic exposure to IR altered larval behaviour in a light-dark locomotor test and affected cardiac activity at a dose rate as low as 0.5 mGy/h. The multi-omics analysis of transcriptome, proteome and transcription factor binding sites in the promoters of the deregulated genes, collectively points towards perturbations of neurogenesis, muscle development, and retinoic acid (RA) signaling after chronic exposure to IR. Whole-mount RNA in situ hybridization confirmed the impaired expression of the transcription factors her4.4 in the central nervous system and myogenin in the developing muscles of exposed embryos. At the organ level, the assessment of muscle histology by transmission electron microscopy (TEM) demonstrated myofibers disruption and altered neuromuscular junctions in exposed larvae at 5 mGy/h and 50 mGy/h. The integration of these multi-level data demonstrates that chronic exposure to low dose rates of IR has an impact on neuronal and muscle progenitor cells, that could lead to motility defects in free swimming larvae at 120 hpf. The mechanistic understanding of these effects allows us to propose a model where deregulation of RA signaling by chronic exposure to IR has pleiotropic effects on neurogenesis and muscle development.
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11
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Jacobs CT, Huang P. Notch signalling maintains Hedgehog responsiveness via a Gli-dependent mechanism during spinal cord patterning in zebrafish. eLife 2019; 8:49252. [PMID: 31453809 PMCID: PMC6733594 DOI: 10.7554/elife.49252] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 08/19/2019] [Indexed: 01/11/2023] Open
Abstract
Spinal cord patterning is orchestrated by multiple cell signalling pathways. Neural progenitors are maintained by Notch signalling, whereas ventral neural fates are specified by Hedgehog (Hh) signalling. However, how dynamic interactions between Notch and Hh signalling drive the precise pattern formation is still unknown. We applied the PHRESH (PHotoconvertible REporter of Signalling History) technique to analyse cell signalling dynamics in vivo during zebrafish spinal cord development. This approach reveals that Notch and Hh signalling display similar spatiotemporal kinetics throughout spinal cord patterning. Notch signalling functions upstream to control Hh response of neural progenitor cells. Using gain- and loss-of-function tools, we demonstrate that this regulation occurs not at the level of upstream regulators or primary cilia, but rather at the level of Gli transcription factors. Our results indicate that Notch signalling maintains Hh responsiveness of neural progenitors via a Gli-dependent mechanism in the spinal cord.
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Affiliation(s)
- Craig T Jacobs
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Canada
| | - Peng Huang
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Canada
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12
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Monestime CM, Taibi A, Gates KP, Jiang K, Sirotkin HI. CoRest1 regulates neurogenesis in a stage‐dependent manner. Dev Dyn 2019; 248:918-930. [DOI: 10.1002/dvdy.86] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 07/01/2019] [Accepted: 07/04/2019] [Indexed: 12/31/2022] Open
Affiliation(s)
| | - Andrew Taibi
- Department of Neurobiology and BehaviorStony Brook University Stony Brook New York
| | - Keith P. Gates
- Department of Neurobiology and BehaviorStony Brook University Stony Brook New York
| | - Karen Jiang
- Department of Neurobiology and BehaviorStony Brook University Stony Brook New York
| | - Howard I. Sirotkin
- Department of Neurobiology and BehaviorStony Brook University Stony Brook New York
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13
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Zhong Y, Ye Q, Chen C, Wang M, Wang H. Ezh2 promotes clock function and hematopoiesis independent of histone methyltransferase activity in zebrafish. Nucleic Acids Res 2019; 46:3382-3399. [PMID: 29447387 PMCID: PMC5909462 DOI: 10.1093/nar/gky101] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 02/06/2018] [Indexed: 12/13/2022] Open
Abstract
EZH2 is a subunit of polycomb repressive complex 2 (PRC2) that silences gene transcription via H3K27me3 and was shown to be essential for mammalian liver circadian regulation and hematopoiesis through gene silencing. Much less, however, is known about how Ezh2 acts in live zebrafish. Here, we show that zebrafish ezh2 is regulated directly by the circadian clock via both E-box and RORE motif, while core circadian clock genes per1a, per1b, cry1aa and cry1ab are down-regulated in ezh2 null mutant and ezh2 morphant zebrafish, and either knockdown or overexpression of ezh2 alters locomotor rhythms, indicating that Ezh2 is required for zebrafish circadian regulation. In contrast to its canonical silencing function, zebrafish Ezh2 up-regulates these key circadian clock genes independent of histone methyltransferase activity by directly binding to key circadian clock proteins. Similarly, Ezh2 contributes to hematopoiesis by enhancing expression of hematopoietic genes such as cmyb and lck. Together, our findings demonstrate for the first time that Ezh2 acts in both circadian regulation and hematopoiesis independent of silencing PRC2.
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Affiliation(s)
- Yingbin Zhong
- Center for Circadian Clocks, Soochow University, Suzhou, Jiangsu, PR China.,School of Biology & Basic Medical Sciences, Medical College, Soochow University, Suzhou, Jiangsu, PR China
| | - Qiang Ye
- Center for Circadian Clocks, Soochow University, Suzhou, Jiangsu, PR China.,School of Biology & Basic Medical Sciences, Medical College, Soochow University, Suzhou, Jiangsu, PR China
| | - Chengyan Chen
- Center for Circadian Clocks, Soochow University, Suzhou, Jiangsu, PR China.,School of Biology & Basic Medical Sciences, Medical College, Soochow University, Suzhou, Jiangsu, PR China
| | - Mingyong Wang
- Center for Circadian Clocks, Soochow University, Suzhou, Jiangsu, PR China.,School of Biology & Basic Medical Sciences, Medical College, Soochow University, Suzhou, Jiangsu, PR China
| | - Han Wang
- Center for Circadian Clocks, Soochow University, Suzhou, Jiangsu, PR China.,School of Biology & Basic Medical Sciences, Medical College, Soochow University, Suzhou, Jiangsu, PR China
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14
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Veil M, Schaechtle MA, Gao M, Kirner V, Buryanova L, Grethen R, Onichtchouk D. Maternal Nanog is required for zebrafish embryo architecture and for cell viability during gastrulation. Development 2018; 145:dev.155366. [PMID: 29180568 DOI: 10.1242/dev.155366] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 11/07/2017] [Indexed: 12/22/2022]
Abstract
Nanog has been implicated in establishment of pluripotency in mammals and in zygotic genome activation in zebrafish. In this study, we characterize the development of MZnanog (maternal and zygotic null) mutant zebrafish embryos. Without functional Nanog, epiboly is severely affected, embryo axes do not form and massive cell death starts at the end of gastrulation. We show that three independent defects in MZnanog mutants contribute to epiboly failure: yolk microtubule organization required for epiboly is abnormal, maternal mRNA fails to degrade owing to the absence of miR-430, and actin structure of the yolk syncytial layer does not form properly. We further demonstrate that the cell death in MZnanog embryos is cell-autonomous. Nanog is necessary for correct spatial expression of the ventral-specifying genes bmp2b, vox and vent, and the neural transcription factor her3 It is also required for the correctly timed activation of endoderm genes and for the degradation of maternal eomesa mRNA via miR-430. Our findings suggest that maternal Nanog coordinates several gene regulatory networks that shape the embryo during gastrulation.
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Affiliation(s)
- Marina Veil
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany
| | - Melanie Anna Schaechtle
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany
| | - Meijiang Gao
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany
| | - Viola Kirner
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany
| | - Lenka Buryanova
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany
| | - Rachel Grethen
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany
| | - Daria Onichtchouk
- Developmental Biology, Institute Biology I, Faculty of Biology, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany .,BIOSS Centre for Biological Signalling Studies, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany.,Institute of Developmental Biology RAS, 119991 Moscow, Russia
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15
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Galant S, Furlan G, Coolen M, Dirian L, Foucher I, Bally-Cuif L. Embryonic origin and lineage hierarchies of the neural progenitor subtypes building the zebrafish adult midbrain. Dev Biol 2016; 420:120-135. [PMID: 27693369 PMCID: PMC5156517 DOI: 10.1016/j.ydbio.2016.09.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/31/2016] [Accepted: 09/26/2016] [Indexed: 01/11/2023]
Abstract
Neurogenesis in the post-embryonic vertebrate brain varies in extent and efficiency between species and brain territories. Distinct neurogenesis modes may account for this diversity, and several neural progenitor subtypes, radial glial cells (RG) and neuroepithelial progenitors (NE), have been identified in the adult zebrafish brain. The neurogenic sequences issued from these progenitors, and their contribution to brain construction, remain incompletely understood. Here we use genetic tracing techniques based on conditional Cre recombination and Tet-On neuronal birthdating to unravel the neurogenic sequence operating from NE progenitors in the zebrafish post-embryonic optic tectum. We reveal that a subpopulation of her5-positive NE cells of the posterior midbrain layer stands at the top of a neurogenic hierarchy involving, in order, the amplification pool of the tectal proliferation zone (TPZ), followed by her4-positive RG cells with transient neurogenic activity. We further demonstrate that the adult her5-positive NE pool is issued in lineage from an identically located NE pool expressing the same gene in the embryonic neural tube. Finally, we show that these features are reminiscent of the neurogenic sequence and embryonic origin of the her9-positive progenitor NE pool involved in the construction of the lateral pallium at post-embryonic stages. Together, our results highlight the shared recruitment of an identical neurogenic strategy by two remote brain territories, where long-lasting NE pools serve both as a growth zone and as the life-long source of young neurogenic RG cells. Zebrafish post-embryonic tectal neurogenesis is driven by neuroepithelial progenitors. The neuroepithelial progenitor pool is long-lasting and expresses Her5 life long. Tectal radial glia originate from the her5-positive pool and are transiently neurogenic. The post-embryonic neurogenic sequences of the tectum and lateral pallium are similar.
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Affiliation(s)
- Sonya Galant
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France
| | - Giacomo Furlan
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France
| | - Marion Coolen
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France; Department of Developmental and Stem Cell Biology and CNRS UMR 3738, Institut Pasteur, 25 rue du Dr Roux, 75015 Paris, France
| | - Lara Dirian
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France
| | - Isabelle Foucher
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France; Department of Developmental and Stem Cell Biology and CNRS UMR 3738, Institut Pasteur, 25 rue du Dr Roux, 75015 Paris, France.
| | - Laure Bally-Cuif
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France; Department of Developmental and Stem Cell Biology and CNRS UMR 3738, Institut Pasteur, 25 rue du Dr Roux, 75015 Paris, France.
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16
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Gao H, Bu Y, Wu Q, Wang X, Chang N, Lei L, Chen S, Liu D, Zhu X, Hu K, Xiong JW. Mecp2 regulates neural cell differentiation by suppressing the Id1 to Her2 axis in zebrafish. J Cell Sci 2015; 128:2340-50. [DOI: 10.1242/jcs.167874] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/28/2015] [Indexed: 01/20/2023] Open
Abstract
ABSTRACT
Rett syndrome (RTT) is a progressive neurological disorder caused by mutations in the X-linked protein methyl-CpG-binding protein 2 (MeCP2). The endogenous function of MeCP2 during neural differentiation is still unclear. Here, we report that mecp2 is required for brain development in zebrafish. Mecp2 was broadly expressed initially in embryos and enriched later in the brain. Either morpholino knockdown or genetic depletion of mecp2 inhibited neuronal differentiation, whereas its overexpression promoted neuronal differentiation, suggesting an essential role of mecp2 in directing neural precursors into differentiated neurons. Mechanistically, her2 (the zebrafish ortholog of mammalian Hes5) was upregulated in mecp2 morphants in an Id1-dependent manner. Moreover, knockdown of either her2 or id1 fully rescued neuronal differentiation in mecp2 morphants. These results suggest that Mecp2 plays an important role in neural cell development by suppressing the Id1–Her2 axis, and provide new evidence that embryonic neural defects contribute to the later motor and cognitive dysfunctions in RTT.
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Affiliation(s)
- Hai Gao
- Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, China
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Ye Bu
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Qing Wu
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Xu Wang
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Nannan Chang
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Lei Lei
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Shilin Chen
- Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, China
| | - Dong Liu
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Peking University, Beijing, China
| | - Xiaojun Zhu
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Keping Hu
- Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, China
| | - Jing-Wei Xiong
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China
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17
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Whole-mount single molecule FISH method for zebrafish embryo. Sci Rep 2015; 5:8571. [PMID: 25711926 PMCID: PMC4339797 DOI: 10.1038/srep08571] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 01/26/2015] [Indexed: 01/27/2023] Open
Abstract
Noise in gene expression renders cells more adaptable to changing environment by imposing phenotypic and functional heterogeneity on genetically identical individual cells. Hence, quantitative measurement of noise in gene expression is essential for the study of biological processes in cells. Currently, there are two complementary methods for quantitatively measuring noise in gene expression at the single cell level: single molecule FISH (smFISH) and single cell qRT-PCR (or single cell RNA-seq). While smFISH has been developed for culture cells, tissue sections and whole-mount invertebrate organisms, the method has not been reported for whole-mount vertebrate organisms. Here, we report an smFISH method that is suitable for whole-mount zebrafish embryo, a popular vertebrate model organism for the studies of development, physiology and disease. We show the detection of individual transcripts for several cell-type specific and ubiquitously expressed genes at the single cell level in whole-mount zebrafish embryo. We also demonstrate that the method can be adapted to detect two different genes in individual cells simultaneously. The whole-mount smFISH method described in this report is expected to facilitate the study of noise in gene expression and its role in zebrafish, a vertebrate animal model relevant to human biology.
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18
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Petrovic J, Gálvez H, Neves J, Abelló G, Giraldez F. Differential regulation of Hes/Hey genes during inner ear development. Dev Neurobiol 2014; 75:703-20. [PMID: 25363712 DOI: 10.1002/dneu.22243] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 10/28/2014] [Indexed: 11/09/2022]
Abstract
Notch signaling plays a crucial role during inner ear development and regeneration. Hes/Hey genes encode for bHLH transcription factors identified as Notch targets. We have studied the expression and regulation of Hes/Hey genes during inner ear development in the chicken embryo. Among several Hes/Hey genes examined, only Hey1 and Hes5 map to the sensory regions, although with salient differences. Hey1 expression follows Jag1 expression except at early prosensory stages while Hes5 expression corresponds well to Dl1 expression throughout otic development. Although Hey1 and Hes5 are direct Notch downstream targets, they differ in the level of Notch required for activation. Moreover, they also differ in mRNA stability, showing different temporal decays after Notch blockade. In addition, Bmp, Wnt and Fgf pathways also modify Hey1 and Hes5 expression in the inner ear. Particularly, the Wnt pathway modulates Hey1 and Jag1 expression. Finally, gain of function experiments show that Hey1 and Hes5 cross-regulate each other in a complex manner. Both Hey1 and Hes5 repress Dl1 and Hes5 expression, suggesting that they prevent the transition to differentiation stages, probably by preventing Atoh1 expression. In spite of its association with Jag1, Hey1 does not seem to be instrumental for lateral induction as it does not promote Jag1 expression. We suggest that, besides being both targets of Notch, Hey1 and Hes5 are subject to a rather complex regulation that includes the stability of their transcripts, cross regulation and other signaling pathways.
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Affiliation(s)
- Jelena Petrovic
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Hector Gálvez
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Joana Neves
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Gina Abelló
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Fernando Giraldez
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
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19
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The transcription factor hairy/E(spl)-related 2 induces proliferation of neural progenitors and regulates neurogenesis and gliogenesis. Dev Biol 2014; 397:116-28. [PMID: 25446033 DOI: 10.1016/j.ydbio.2014.10.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 10/15/2014] [Accepted: 10/21/2014] [Indexed: 02/06/2023]
Abstract
The study of molecular regulation in neural development provides information to understand how diverse neural cells are generated. It also helps to establish therapeutic strategies for the treatment of neural degenerative disorders and brain tumors. The Hairy/E(spl) family members are potential targets of Notch signaling, which is fundamental to neural cell maintenance, cell fate decisions, and compartment boundary formation. In this study, we isolated a zebrafish homolog of Hairy/E(spl), her2, and showed that this gene is expressed in neural progenitor cells and in the developing nervous system. The expression of her2 required Notch activation, as revealed by a Notch-defective mutant and a chemical inhibitor, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT). The endogenous expression of Her2 was altered by both overexpression and morpholino-knockdown approaches, and the results demonstrated that Her2 was both necessary and sufficient to promote the proliferation of neural progenitors by inhibiting the transcription of the cell cycle inhibitors cdkn1a, cdkn1ba, and cdkn1bb. Her2 knockdown caused premature neuronal differentiation, which indicates that Her2 is essential for inhibiting neuronal differentiation. At a later stage of neural development, Her2 could induce glial differentiation. The overexpression of Her2 constructs lacking the bHLH or WRPW domain phenocopied the effect of the morpholino knockdown, demonstrating the essential function of these two domains and further confirming the knockdown specificity. In conclusion, our data reveal that Her2 promotes progenitor proliferation and maintains progenitor characteristics by inhibiting neuronal differentiation. Together, these two mechanisms ensure the proper development of the neural progenitor cell pool.
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20
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Radosevic M, Fargas L, Alsina B. The role of her4 in inner ear development and its relationship with proneural genes and Notch signalling. PLoS One 2014; 9:e109860. [PMID: 25299450 PMCID: PMC4192589 DOI: 10.1371/journal.pone.0109860] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/08/2014] [Indexed: 01/13/2023] Open
Abstract
The generation of sensory neurons and hair cells of the inner ear is under tight control. Different members of the Hairy and Enhancer of Split genes (HES) are expressed in the inner ear, their full array of functions still not being disclosed. We have previously shown that zebrafish her9 acts as a patterning gene to restrict otic neurogenesis to an anterior domain. Here, we disclose the role of another her gene, her4, a zebrafish ortholog of Hes5 that is expressed in the neurogenic and sensory domains of the inner ear. The expression of her4 is highly dynamic and spatiotemporally regulated. We demonstrate by loss of function experiments that in the neurogenic domain her4 expression is under the regulation of neurogenin1 (neurog1) and the Notch pathway. Moreover, her4 participates in lateral inhibition during otic neurogenesis since her4 knockdown results in overproduction of the number of neurog1 and deltaB-positive otic neurons. In contrast, during sensorigenesis her4 is initially Notch-independent and induced by atoh1b in a broad prosensory domain. At later stages her4 expression becomes Notch-dependent in the future sensory domains but loss of her4 does not result in hair cell overproduction, suggesting that there other her genes can compensate its function.
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Affiliation(s)
- Marija Radosevic
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
| | - Laura Fargas
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
| | - Berta Alsina
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
- * E-mail:
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21
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Zannino DA, Sagerström CG, Appel B. olig2-Expressing hindbrain cells are required for migrating facial motor neurons. Dev Dyn 2012; 241:315-26. [PMID: 22275004 DOI: 10.1002/dvdy.23718] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The complicated trajectory of facial motor neuron migration requires coordination of intrinsic signals and cues from the surrounding environment. Migration begins in rhombomere (r) 4 where facial motor neurons are born and proceeds in a caudal direction. Once facial motor neurons reach their target rhombomeres, they migrate laterally and radially from the ventral neural tube. In zebrafish, as facial motor neurons migrate through r5/r6, they pass near cells that express olig2, which encodes a bHLH transcription factor. In this study, we found that olig2 function is required for facial motor neurons to complete their caudal migration into r6 and r7 and form stereotypical clusters. Additionally, embryos that lack mafba function, in which facial motor neurons also fail to complete caudal migration, lack olig2 expression in r5 and r6. Our data raise the possibility that cells expressing olig2 are intermediate targets that help guide facial motor neuron migration.
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Affiliation(s)
- Denise A Zannino
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
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22
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Terriente J, Gerety SS, Watanabe-Asaka T, Gonzalez-Quevedo R, Wilkinson DG. Signalling from hindbrain boundaries regulates neuronal clustering that patterns neurogenesis. Development 2012; 139:2978-87. [PMID: 22764046 DOI: 10.1242/dev.080135] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
During central nervous system development, neural progenitors are patterned to form discrete neurogenic and non-neurogenic zones. In the zebrafish hindbrain, neurogenesis is organised by Fgf20a emanating from neurons located at each segment centre that inhibits neuronal differentiation in adjacent progenitors. Here, we have identified a molecular mechanism that clusters fgf20a-expressing neurons in segment centres and uncovered a requirement for this positioning in the regulation of neurogenesis. Disruption of hindbrain boundary cell formation alters the organisation of fgf20a-expressing neurons, consistent with a role of chemorepulsion from boundaries. The semaphorins Sema3fb and Sema3gb, which are expressed by boundary cells, and their receptor Nrp2a are required for clustering of fgf20a-expressing neurons at segment centres. The dispersal of fgf20a-expressing neurons that occurs following the disruption of boundaries or of Sema3fb/Sema3gb signalling leads to reduced FGF target gene expression in progenitors and an increased number of differentiating neurons. Sema3 signalling from boundaries thus links hindbrain segmentation to the positioning of fgf20a-expressing neurons that regulates neurogenesis.
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Affiliation(s)
- Javier Terriente
- Division of Developmental Neurobiology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
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23
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Attenuation of Notch and Hedgehog signaling is required for fate specification in the spinal cord. PLoS Genet 2012; 8:e1002762. [PMID: 22685423 PMCID: PMC3369957 DOI: 10.1371/journal.pgen.1002762] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Accepted: 04/30/2012] [Indexed: 02/01/2023] Open
Abstract
During the development of the spinal cord, proliferative neural progenitors differentiate into postmitotic neurons with distinct fates. How cells switch from progenitor states to differentiated fates is poorly understood. To address this question, we studied the differentiation of progenitors in the zebrafish spinal cord, focusing on the differentiation of Kolmer-Agduhr″ (KA″) interneurons from lateral floor plate (LFP) progenitors. In vivo cell tracking demonstrates that KA″ cells are generated from LFP progenitors by both symmetric and asymmetric cell divisions. A photoconvertible reporter of signaling history (PHRESH) reveals distinct temporal profiles of Hh response: LFP progenitors continuously respond to Hh, while KA″ cells lose Hh response upon differentiation. Hh signaling is required in LFP progenitors for KA″ fate specification, but prolonged Hh signaling interferes with KA″ differentiation. Notch signaling acts permissively to maintain LFP progenitor cells: activation of Notch signaling prevents differentiation, whereas inhibition of Notch signaling results in differentiation of ectopic KA″ cells. These results indicate that neural progenitors depend on Notch signaling to maintain Hh responsiveness and rely on Hh signaling to induce fate identity, whereas proper differentiation depends on the attenuation of both Notch and Hh signaling. During tissue formation, progenitor cells generate both differentiated cells and progenitor cells. It is poorly understood how this balance between self-renewal and differentiation generates the correct number of different cell types. Here, we use zebrafish spinal cord development as a model system to investigate how neural progenitor cells switch from progenitor states to differentiated fates. Combining genetic manipulation and a novel method to study cell signaling in live embryos, our data show that this process requires the dynamic regulation of two signaling pathways: the Notch signaling pathway and the Hedgehog (Hh) signaling pathway. In neural progenitors, Notch signaling maintains the competence of neural progenitors to respond to Hh signaling. In parallel, Hedgehog signaling functions to induce cell fate identity. As cells switch from progenitor states to differentiated states, both Notch and Hh signaling become attenuated. Thus, the dynamic deployment of Notch and Hh signaling controls the renewal and differentiation of progenitor cells.
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24
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Chapouton P, Webb KJ, Stigloher C, Alunni A, Adolf B, Hesl B, Topp S, Kremmer E, Bally-Cuif L. Expression of hairy/enhancer of split genes in neural progenitors and neurogenesis domains of the adult zebrafish brain. J Comp Neurol 2012; 519:1748-69. [PMID: 21452233 DOI: 10.1002/cne.22599] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
All subdivisions of the adult zebrafish brain maintain niches of constitutive neurogenesis, sustained by quiescent and multipotent progenitor populations. In the telencephalon, the latter potential neural stem cells take the shape of radial glia aligned along the ventricle and are controlled by Notch signalling. With the aim of identifying new markers of this cell type and of comparing the effectors of embryonic and adult neurogenesis, we focused on the family of hairy/enhancer of split [E(spl)] genes. We report the expression of seven hairy/E(spl) (her) genes and the new helt gene in three neurogenic areas of the adult zebrafish brain (telencephalon, hypothalamus, and midbrain) in relation to radial glia, proliferation, and neurogenesis. We show that the expression of most her genes in the adult brain characterizes quiescent radial glia, whereas only few are expressed in progenitor domains engaged in active proliferation or neurogenesis. The low proliferation status of most her-positive progenitors contrasts with the embryonic nervous system, in which her genes are expressed in actively dividing progenitors. Likewise, we demonstrate largely overlapping expression domains of a set of her genes in the adult brain, which is in striking contrast to their distinct embryonic expression profiles. Overall, our data provide a consolidated map of her expression, quiescent glia, proliferation, and neurogenesis in these various subdivisions of the adult brain and suggest distinct regulation and function of Her factors in the embryonic and adult contexts.
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Affiliation(s)
- Prisca Chapouton
- Zebrafish Neurogenetics Department, Helmholtz Zentrum München, German Research Center for Environmental Health, D-85764 Neuherberg, Germany.
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25
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Hortopan GA, Baraban SC. Aberrant expression of genes necessary for neuronal development and Notch signaling in an epileptic mind bomb zebrafish. Dev Dyn 2011; 240:1964-76. [PMID: 21688347 PMCID: PMC3137702 DOI: 10.1002/dvdy.22680] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2011] [Indexed: 11/11/2022] Open
Abstract
Mutation within an ubiquitin E3 ligase gene can lead to a failure in Notch signaling, excessive neurons, and depletion of neural progenitor cells in mind bomb mutants. Using mib(hi904) zebrafish, we reported seizures and a down-regulation of γ-aminobutyric acid (GABA) signaling pathway genes. A transcriptome analysis also identified differential expression pattern of genes related to Notch signaling and neurodevelopment. Here, we selected nine of these genes (her4.2, hes5, bhlhb5, hoxa5a, hoxb5b, dmbx1a, dbx1a, nxph1, and plxnd1) and performed a more thorough analysis of expression using conventional polymerase chain reaction, real-time polymerase chain reaction and in situ hybridization. Transgenic reporter fish (Gfap:GFP and Dlx5a-6a:GFP) were used to assess early brain morphology in vivo. Down-regulation of many of these genes was prominent throughout key structures of the developing mib(hi904) zebrafish brain including, but not limited to, the pallium, ventral thalamus, and optic tectum. Brain expression of Dlx5a-6a and Gfap was also reduced. In conclusion, these expression studies indicate a general down-regulation of Notch signaling genes necessary for proper brain development and suggest that these mutant fish could provide valuable insights into neurological conditions, such as Angelman syndrome, associated with ubiquitin E3 ligase mutation.
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Affiliation(s)
- Gabriela A. Hortopan
- Epilepsy Research Laboratory, Department of Neurological Surgery, University of California, San Francisco, San Francisco, California 94143
| | - Scott C. Baraban
- Epilepsy Research Laboratory, Department of Neurological Surgery, University of California, San Francisco, San Francisco, California 94143
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26
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Webb KJ, Coolen M, Gloeckner CJ, Stigloher C, Bahn B, Topp S, Ueffing M, Bally-Cuif L. The Enhancer of split transcription factor Her8a is a novel dimerisation partner for Her3 that controls anterior hindbrain neurogenesis in zebrafish. BMC DEVELOPMENTAL BIOLOGY 2011; 11:27. [PMID: 21586122 PMCID: PMC3125270 DOI: 10.1186/1471-213x-11-27] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 05/17/2011] [Indexed: 12/31/2022]
Abstract
Background Neurogenesis control and the prevention of premature differentiation in the vertebrate embryo are crucial processes, allowing the formation of late-born cell types and ensuring the correct shape and cytoarchitecture of the brain. Members of the Hairy/Enhancer of Split (Hairy/E(spl)) family of bHLH-Orange transcription factors, such as zebrafish Her3, 5, 9 and 11, are implicated in the local inhibition of neurogenesis to maintain progenitor pools within the early neural plate. To better understand how these factors exert their inhibitory function, we aimed to isolate some of their functional interactors. Results We used a yeast two-hybrid screen with Her5 as bait and recovered a novel zebrafish Hairy/E(spl) factor - Her8a. Using phylogenetic and synteny analyses, we demonstrate that her8a evolved from an ancient duplicate of Hes6 that was recently lost in the mammalian lineage. We show that her8a is expressed across the mid- and anterior hindbrain from the start of segmentation. Through knockdown and misexpression experiments, we demonstrate that Her8a is a negative regulator of neurogenesis and plays an essential role in generating progenitor pools within rhombomeres 2 and 4 - a role resembling that of Her3. Her8a co-purifies with Her3, suggesting that Her8a-Her3 heterodimers may be relevant in this domain of the neural plate, where both proteins are co-expressed. Finally, we demonstrate that her8a expression is independent of Notch signaling at the early neural plate stage but that SoxB factors play a role in its expression, linking patterning information to neurogenesis control. Overall, the regulation and function of Her8a differ strikingly from those of its closest relative in other vertebrates - the Hes6-like proteins. Conclusions Our results characterize the phylogeny, expression and functional interactions involving a new Her factor, Her8a, and highlight the complex interplay of E(spl) proteins that generates the neurogenesis pattern of the zebrafish early neural plate.
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Affiliation(s)
- Katharine J Webb
- Zebrafish Neurogenetics Department, Helmholtz Zentrum München, German Research Center for Environmental Health, Ingolstädter Landstr, 1, D-85764 Neuherberg, Germany.
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Zebrafish Her8a is activated by Su(H)-dependent Notch signaling and is essential for the inhibition of neurogenesis. PLoS One 2011; 6:e19394. [PMID: 21541299 PMCID: PMC3082574 DOI: 10.1371/journal.pone.0019394] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 04/04/2011] [Indexed: 12/22/2022] Open
Abstract
Understanding how diversity of neural cells is generated is one of the main tasks of developmental biology. The Hairy/E(spl) family members are potential targets of Notch signaling, which has been shown to be fundamental to neural cell maintenance, cell fate decisions, and compartment boundary formation. However, their response to Notch signaling and their roles in neurogenesis are still not fully understood. In the present study, we isolated a zebrafish homologue of hairy/E(spl), her8a, and showed this gene is specifically expressed in the developing nervous system. her8a is positively regulated by Su(H)-dependent Notch signaling as revealed by a Notch-defective mutant and injection of variants of the Notch intracellular regulator, Su(H). Morpholino knockdown of Her8a resulted in upregulation of proneural and post-mitotic neuronal markers, indicating that Her8a is essential for the inhibition of neurogenesis. In addition, markers for glial precursors and mature glial cells were down-regulated in Her8a morphants, suggesting Her8a is required for gliogenesis. The role of Her8a and its response to Notch signaling is thus similar to mammalian HES1, however this is the converse of what is seen for the more closely related mammalian family member, HES6. This study not only provides further understanding of how the fundamental signaling pathway, Notch signaling, and its downstream genes mediate neural development and differentiation, but also reveals evolutionary diversity in the role of H/E(spl) genes.
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Radosevic M, Robert-Moreno À, Coolen M, Bally-Cuif L, Alsina B. Her9 represses neurogenic fate downstream of Tbx1 and retinoic acid signaling in the inner ear. Development 2011; 138:397-408. [DOI: 10.1242/dev.056093] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Proper spatial control of neurogenesis in the inner ear ensures the precise innervation of mechanotransducing cells and the propagation of auditory and equilibrium stimuli to the brain. Members of the Hairy and enhancer of split (Hes) gene family regulate neurogenesis by inhibiting neuronal differentiation and maintaining neural stem cell pools in non-neurogenic zones. Remarkably, their role in the spatial control of neurogenesis in the ear is unknown. In this study, we identify her9, a zebrafish ortholog of Hes1, as a key gene in regulating otic neurogenesis through the definition of the posterolateral non-neurogenic field. First, her9 emerges as a novel otic patterning gene that represses proneural function and regulates the extent of the neurogenic domain. Second, we place Her9 downstream of Tbx1, linking these two families of transcription factors for the first time in the inner ear and suggesting that the reported role of Tbx1 in repressing neurogenesis is in part mediated by the bHLH transcriptional repressor Her9. Third, we have identified retinoic acid (RA) signaling as the upstream patterning signal of otic posterolateral genes such as tbx1 and her9. Finally, we show that at the level of the cranial otic field, opposing RA and Hedgehog signaling position the boundary between the neurogenic and non-neurogenic compartments. These findings permit modeling of the complex genetic cascade that underlies neural patterning of the otic vesicle.
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Affiliation(s)
- Marija Radosevic
- Developmental Biology Laboratory, Dept. Ciències Experimentals i de la Salut, Universitat Pompeu Fabra-Parc de Recerca Biomèdica de Barcelona, Dr Aiguader 88, 08003 Barcelona, Spain
| | - Àlex Robert-Moreno
- Developmental Biology Laboratory, Dept. Ciències Experimentals i de la Salut, Universitat Pompeu Fabra-Parc de Recerca Biomèdica de Barcelona, Dr Aiguader 88, 08003 Barcelona, Spain
| | - Marion Coolen
- Laboratory of Neurobiology and Development, Institute of Neurobiology Alfred Fessard, CNRS, Avenue de Terrasse, 91198 cedex, Gif-sur-Yvette, France
| | - Laure Bally-Cuif
- Laboratory of Neurobiology and Development, Institute of Neurobiology Alfred Fessard, CNRS, Avenue de Terrasse, 91198 cedex, Gif-sur-Yvette, France
| | - Berta Alsina
- Developmental Biology Laboratory, Dept. Ciències Experimentals i de la Salut, Universitat Pompeu Fabra-Parc de Recerca Biomèdica de Barcelona, Dr Aiguader 88, 08003 Barcelona, Spain
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DeltaA/DeltaD regulate multiple and temporally distinct phases of notch signaling during dopaminergic neurogenesis in zebrafish. J Neurosci 2011; 30:16621-35. [PMID: 21148001 DOI: 10.1523/jneurosci.4769-10.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dopaminergic neurons develop at distinct anatomical sites to form some of the major neuromodulatory systems in the vertebrate brain. Despite their relevance in neurodegenerative diseases and the interests in reconstitutive therapies from stem cells, mechanisms of the neurogenic switch from precursor populations to dopaminergic neurons are not well understood. Here, we investigated neurogenesis of different dopaminergic and noradrenergic neuron populations in the zebrafish embryo. Birth-dating analysis by EdU (5-ethynyl-2'-deoxyuridine) incorporation revealed temporal dynamics of catecholaminergic neurogenesis. Analysis of Notch signaling mutants and stage-specific pharmacological inhibition of Notch processing revealed that dopaminergic neurons form by temporally distinct mechanisms: dopaminergic neurons of the posterior tuberculum derive directly from neural plate cells during primary neurogenesis, whereas other dopaminergic groups form in continuous or wavelike neurogenesis phases from proliferating precursor pools. Systematic analysis of Notch ligands revealed that the two zebrafish co-orthologs of mammalian Delta1, DeltaA and DeltaD, control the neurogenic switch of all early developing dopaminergic neurons in a partially redundant manner. DeltaA/D may also be involved in maintenance of dopaminergic precursor pools, as olig2 expression in ventral diencephalic dopaminergic precursors is affected in dla/dld mutants. DeltaA/D act upstream of sim1a and otpa during dopaminergic specification. However, despite the fact that both dopaminergic and corticotropin-releasing hormone neurons derive from sim1a- and otpa-expressing precursors, DeltaA/D does not act as a lineage switch between these two neuronal types. Rather, DeltaA/D limits the size of the sim1a- and otpa-expressing precursor pool from which dopaminergic neurons differentiate.
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Song Y, Willer JR, Scherer PC, Panzer JA, Kugath A, Skordalakes E, Gregg RG, Willer GB, Balice-Gordon RJ. Neural and synaptic defects in slytherin, a zebrafish model for human congenital disorders of glycosylation. PLoS One 2010; 5:e13743. [PMID: 21060795 PMCID: PMC2966427 DOI: 10.1371/journal.pone.0013743] [Citation(s) in RCA: 23] [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: 05/21/2010] [Accepted: 08/22/2010] [Indexed: 12/28/2022] Open
Abstract
Congenital disorder of glycosylation type IIc (CDG IIc) is characterized by mental retardation, slowed growth and severe immunodeficiency, attributed to the lack of fucosylated glycoproteins. While impaired Notch signaling has been implicated in some aspects of CDG IIc pathogenesis, the molecular and cellular mechanisms remain poorly understood. We have identified a zebrafish mutant slytherin (srn), which harbors a missense point mutation in GDP-mannose 4,6 dehydratase (GMDS), the rate-limiting enzyme in protein fucosylation, including that of Notch. Here we report that some of the mechanisms underlying the neural phenotypes in srn and in CGD IIc are Notch-dependent, while others are Notch-independent. We show, for the first time in a vertebrate in vivo, that defects in protein fucosylation leads to defects in neuronal differentiation, maintenance, axon branching, and synapse formation. Srn is thus a useful and important vertebrate model for human CDG IIc that has provided new insights into the neural phenotypes that are hallmarks of the human disorder and has also highlighted the role of protein fucosylation in neural development.
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Affiliation(s)
- Yuanquan Song
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Jason R. Willer
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Paul C. Scherer
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Jessica A. Panzer
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Amy Kugath
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | | | - Ronald G. Gregg
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Gregory B. Willer
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Rita J. Balice-Gordon
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Wahl M, Guenther R, Yang L, Bergman A, Straehle U, Strack S, Weiss C. Polybrominated diphenyl ethers and arylhydrocarbon receptor agonists: Different toxicity and target gene expression. Toxicol Lett 2010; 198:119-26. [PMID: 20566336 DOI: 10.1016/j.toxlet.2010.06.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Revised: 05/29/2010] [Accepted: 06/01/2010] [Indexed: 10/19/2022]
Abstract
Polybrominated diphenyl ethers (PBDEs) accumulate in the environment and in humans. PBDEs are developmental neurotoxicants, disturb the endocrine system and induce tumors in rodents. However, underlying mechanisms of PBDE toxicity are still insufficiently understood. Some reports demonstrated activation but also inhibition of the aryl hydrocarbon receptor (AhR) by PBDEs based on expression of its target gene cyp1A1. In the present study, we used different PBDE congeners (BDE47, 99, 153 and 209) and analyzed their effects on AhR signaling in various cell lines and zebrafish embryos. Furthermore, we performed microarray experiments in rat hepatoma cells to compare changes in gene expression induced by either BDE47 or the AhR agonist 2,3,7,8-tetrabromo-dibenzofuran (TBDF). PBDEs did not activate but rather inhibited AhR signaling and specifically induced malformations in zebrafish embryos, which differ from those provoked by AhR agonists. Furthermore, BDE47 and TBDF differentially regulated global gene expression in hepatoma cells. Hence, PBDEs and AhR agonists trigger different toxicity and target gene expression. Several novel target genes of BDE47 and TBDF were identified and verified by RT-PCR. TBDF induced expression of the transcriptional regulators Sim2 and RevErbbeta whereas BDE47 specifically deregulated expression of two subunits of the cytochrome c oxidase complex, cox6a2 and cox4i2, which might be linked to its toxicity.
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Affiliation(s)
- M Wahl
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Campus North, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Kani S, Bae YK, Shimizu T, Tanabe K, Satou C, Parsons MJ, Scott E, Higashijima SI, Hibi M. Proneural gene-linked neurogenesis in zebrafish cerebellum. Dev Biol 2010; 343:1-17. [PMID: 20388506 DOI: 10.1016/j.ydbio.2010.03.024] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2010] [Revised: 03/30/2010] [Accepted: 03/31/2010] [Indexed: 01/30/2023]
Abstract
In mammals, cerebellar neurons are categorized as glutamatergic or GABAergic, and are derived from progenitors that express the proneural genes atoh1 or ptf1a, respectively. In zebrafish, three atoh1 genes, atoh1a, atoh1b, and atoh1c, are expressed in overlapping but distinct expression domains in the upper rhombic lip (URL): ptf1a is expressed exclusively in the ventricular zone (VZ). Using transgenic lines expressing fluorescent proteins under the control of the regulatory elements of atoh1a and ptf1a, we traced the lineages of the cerebellar neurons. The atoh1(+) progenitors gave rise not only to granule cells but also to neurons of the anteroventral rhombencephalon. The ptf1a(+) progenitors generated Purkinje cells. The olig2(+) eurydendroid cells, which are glutamatergic, were derived mostly from ptf1a(+) progenitors in the VZ but some originated from the atoh1(+) progenitors in the URL. In the adult cerebellum, atoh1a, atoh1b, and atoh1c are expressed in the molecular layer of the valvula cerebelli and of the medial corpus cerebelli, and ptf1a was detected in the VZ. The proneural gene expression patterns coincided with the sites of proliferating neuronal progenitors in the adult cerebellum. Our data indicate that proneural gene-linked neurogenesis is evolutionarily conserved in the cerebellum among vertebrates, and that the continuously generated neurons help remodel neural circuits in the adult zebrafish cerebellum.
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Affiliation(s)
- Shuichi Kani
- Laboratory for Vertebrate Axis Formation, RIKEN Center for Developmental Biology, Kobe, Hyogo, Japan
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Sobieszczuk DF, Poliakov A, Xu Q, Wilkinson DG. A feedback loop mediated by degradation of an inhibitor is required to initiate neuronal differentiation. Genes Dev 2010; 24:206-18. [PMID: 20080956 DOI: 10.1101/gad.554510] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Neuronal differentiation is regulated by proneural genes that promote neurogenesis and inhibitory mechanisms that maintain progenitors. This raises the question of how the up-regulation of proneural genes required to initiate neurogenesis occurs in the presence of such inhibition. We carried out loss and gain of gene function, an interaction screen for binding partners, and biochemical analyses to uncover the regulation, developmental role, and mechanism of action of a ubiquitination adaptor protein, Btbd6a (BTB domain containing 6a). We find that the proneural gene neurog1 up-regulates btbd6a, which in turn is required for up-regulation of neurog1. Btbd6a is an adaptor for the Cul3 ubiquitin ligase complex, and we find that it binds to the transcriptional repressor Plzf (promyelocytic leukemia zinc finger). Btbd6a promotes the relocation of Plzf from nucleus to cytoplasm and targets Plzf for ubiquitination and degradation. plzfa is expressed widely in the neural epithelium; when overexpressed, it inhibits neurogenesis, and this inhibition is reversed by btbd6a. The antagonism of endogenous plzfa by btbd6a is required for neurogenesis, since the block in neuronal differentiation caused by btbd6a knockdown is alleviated by plzfa knockdown. These findings reveal a feedback loop mediated by degradation of an inhibitor that is essential for progenitors to undergo the transition to neuronal differentiation.
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Affiliation(s)
- Dorothy F Sobieszczuk
- Division of Developmental Neurobiology, MRC National Institute for Medical Research, London NW7 1AA, United Kingdom
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Gonzalez-Quevedo R, Lee Y, Poss KD, Wilkinson DG. Neuronal regulation of the spatial patterning of neurogenesis. Dev Cell 2010; 18:136-47. [PMID: 20152184 PMCID: PMC2822724 DOI: 10.1016/j.devcel.2009.11.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 10/05/2009] [Accepted: 11/13/2009] [Indexed: 11/25/2022]
Abstract
Precise regulation of neurogenesis is achieved in specific regions of the vertebrate nervous system by formation of distinct neurogenic and nonneurogenic zones. We have investigated how neurogenesis becomes confined to zones adjacent to rhombomere boundaries in the zebrafish hindbrain. The nonneurogenic zone at segment centers comprises a distinct progenitor population that expresses fibroblast growth factor (fgfr) 2, erm, sox9b, and the retinoic acid degrading enzyme, cyp26b1. FGF receptor activation upregulates expression of these genes and inhibits neurogenesis in segment centers. Cyp26 activity is a key effector inhibiting neuronal differentiation, suggesting antagonistic interactions with retinoid signaling. We identify the critical FGF ligand, fgf20a, which is expressed by specific neurons located in the mantle region at the center of segments, adjacent to the nonneurogenic zone. Fgf20a mutants have ectopic neurogenesis and lack the segment center progenitor population. Our findings reveal how signaling from neurons induces formation of a nonneurogenic zone of neural progenitors.
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Affiliation(s)
- Rosa Gonzalez-Quevedo
- Division of Developmental Neurobiology, Medical Research Council National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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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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36
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Dhrs3a regulates retinoic acid biosynthesis through a feedback inhibition mechanism. Dev Biol 2009; 338:1-14. [PMID: 19874812 DOI: 10.1016/j.ydbio.2009.10.029] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 10/13/2009] [Accepted: 10/21/2009] [Indexed: 11/21/2022]
Abstract
Retinoic acid (RA) is an important developmental signaling molecule responsible for the patterning of multiple vertebrate tissues. RA is also a potent teratogen, causing multi-organ birth defects in humans. Endogenous RA levels must therefore be tightly controlled in the developing embryo. We used a microarray approach to identify genes that function as negative feedback regulators of retinoic acid signaling. We screened for genes expressed in early somite-stage embryos that respond oppositely to treatment with RA versus RA antagonists and validated them by RNA in situ hybridization. Focusing on genes known to be involved in RA metabolism, we determined that dhrs3a, which encodes a member of the short-chain dehydrogenase/reductase protein family, is both RA dependent and strongly RA inducible. Dhrs3a is known to catalyze the reduction of the RA precursor all-trans retinaldehyde to vitamin A; however, a developmental function has not been demonstrated. Using morpholino knockdown and mRNA over-expression, we demonstrate that Dhrs3a is required to limit RA levels in the embryo, primarily within the central nervous system. Dhrs3a is thus an RA-induced feedback inhibitor of RA biosynthesis. We conclude that retinaldehyde availability is an important level at which RA biosynthesis is regulated in vertebrate embryos.
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Neural differentiation of embryonic stem cells in vitro: a road map to neurogenesis in the embryo. PLoS One 2009; 4:e6286. [PMID: 19621087 PMCID: PMC2709448 DOI: 10.1371/journal.pone.0006286] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 06/17/2009] [Indexed: 01/07/2023] Open
Abstract
Background The in vitro generation of neurons from embryonic stem (ES) cells is a promising approach to produce cells suitable for neural tissue repair and cell-based replacement therapies of the nervous system. Available methods to promote ES cell differentiation towards neural lineages attempt to replicate, in different ways, the multistep process of embryonic neural development. However, to achieve this aim in an efficient and reproducible way, a better knowledge of the cellular and molecular events that are involved in the process, from the initial specification of neuroepithelial progenitors to their terminal differentiation into neurons and glial cells, is required. Methodology/Principal Findings In this work, we characterize the main stages and transitions that occur when ES cells are driven into a neural fate, using an adherent monolayer culture system. We established improved conditions to routinely produce highly homogeneous cultures of neuroepithelial progenitors, which organize into neural tube-like rosettes when they acquire competence for neuronal production. Within rosettes, neuroepithelial progenitors display morphological and functional characteristics of their embryonic counterparts, namely, apico-basal polarity, active Notch signalling, and proper timing of production of neurons and glia. In order to characterize the global gene activity correlated with each particular stage of neural development, the full transcriptome of different cell populations that arise during the in vitro differentiation protocol was determined by microarray analysis. By using embryo-oriented criteria to cluster the differentially expressed genes, we define five gene expression signatures that correlate with successive stages in the path from ES cells to neurons. These include a gene signature for a primitive ectoderm-like stage that appears after ES cells enter differentiation, and three gene signatures for subsequent stages of neural progenitor development, from an early stage that follows neural induction to a final stage preceding terminal differentiation. Conclusions/Significance Overall, our work confirms and extends the cellular and molecular parallels between monolayer ES cell neural differentiation and embryonic neural development, revealing in addition novel aspects of the genetic network underlying the multistep process that leads from uncommitted cells to differentiated neurons.
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Nikolaou N, Watanabe-Asaka T, Gerety S, Distel M, Köster RW, Wilkinson DG. Lunatic fringe promotes the lateral inhibition of neurogenesis. Development 2009; 136:2523-33. [PMID: 19553285 DOI: 10.1242/dev.034736] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Previous studies have identified roles of the modulation of Notch activation by Fringe homologues in boundary formation and in regulating the differentiation of vertebrate thymocytes and Drosophila glial cells. We have investigated the role of Lunatic fringe (Lfng) expression during neurogenesis in the vertebrate neural tube. We find that in the zebrafish hindbrain, Lfng is expressed by progenitors in neurogenic regions and downregulated in cells that have initiated neuronal differentiation. Lfng is required cell autonomously in neural epithelial cells to limit the amount of neurogenesis and to maintain progenitors. By contrast, Lfng is not required for the role of Notch in interneuronal fate choice, which we show is mediated by Notch1a. The expression of Lfng does not require Notch activity, but rather is regulated downstream of proneural genes that are widely expressed by neural progenitors. These findings suggest that Lfng acts in a feedback loop downstream of proneural genes, which, by promoting Notch activation, maintains the sensitivity of progenitors to lateral inhibition and thus limits further proneural upregulation.
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Affiliation(s)
- Nikolas Nikolaou
- Division of Developmental Neurobiology, MRC National Institute for Medical Research, The Ridgeway, London, UK
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Kubo F, Nakagawa S. Hairy1 acts as a node downstream of Wnt signaling to maintain retinal stem cell-like progenitor cells in the chick ciliary marginal zone. Development 2009; 136:1823-33. [DOI: 10.1242/dev.029272] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In the vertebrate retina, stem cell-like progenitor cells are maintained in a distinct region called the ciliary marginal zone (CMZ). Canonical Wnt signaling regulates the maintenance of the progenitor cells in the CMZ. However, its downstream molecular mechanisms have remained largely unclear. Here, we show that chick Hairy1, an established Notch signaling effector,mediates the Wnt-dependent maintenance of CMZ progenitor cells in chicken. Interestingly, unlike other developmental contexts in which Hes gene expression is regulated by Notch signaling, Hairy1 expression in the CMZ is regulated by Wnt signaling. Hairy1 is necessary and sufficient for the expression of a set of molecular markers characteristic of the CMZ, and Wnt2b fails to induce CMZ markers when Hairy1 activity is inhibited. Furthermore,microarray analysis identifies multiple Wnt-responsive transcription factors that activate Hairy1 expression. We thus propose that Hairy1 functions as a node downstream of Wnt signaling to maintain progenitor cells in the chick CMZ.
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Affiliation(s)
- Fumi Kubo
- RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198,Japan
| | - Shinichi Nakagawa
- RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198,Japan
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Ninkovic J, Stigloher C, Lillesaar C, Bally-Cuif L. Gsk3beta/PKA and Gli1 regulate the maintenance of neural progenitors at the midbrain-hindbrain boundary in concert with E(Spl) factor activity. Development 2008; 135:3137-48. [PMID: 18725518 DOI: 10.1242/dev.020479] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neuronal production in the midbrain-hindbrain domain (MH) of the vertebrate embryonic neural tube depends on a progenitor pool called the ;intervening zone' (IZ), located at the midbrain-hindbrain boundary. The progressive recruitment of IZ progenitors along the mediolateral (future dorsoventral) axis prefigures the earlier maturation of the MH basal plate. It also correlates with a lower sensitivity of medial versus lateral IZ progenitors to the neurogenesis inhibition process that maintains the IZ pool. This role is performed in zebrafish by the E(Spl) factors Her5 and Her11, but the molecular cascades cooperating with Her5/11, and those accounting for their reduced effect in the medial IZ, remain unknown. We demonstrate here that the kinases Gsk3beta and cAMP-dependent protein kinase A (PKA) are novel determinants of IZ formation and cooperate with E(Spl) activity in a dose-dependent manner. Similar to E(Spl), we show that the activity of Gsk3beta/PKA is sensed differently by medial versus lateral IZ progenitors. Furthermore, we identify the transcription factor Gli1, expressed in medial IZ cells, as an antagonist of E(Spl) and Gsk3beta/PKA, and demonstrate that the neurogenesis-promoting activity of Gli1 accounts for the reduced sensitivity of medial IZ progenitors to neurogenesis inhibitors and their increased propensity to differentiate. We also show that the expression and activity of Gli1 in this process are, surprisingly, independent of Hedgehog signaling. Together, our results suggest a model in which the modulation of E(Spl) and Gsk3beta/PKA activities by Gli1 underlies the dynamic properties of IZ maintenance and recruitment.
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Affiliation(s)
- Jovica Ninkovic
- Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Department of Zebrafish Neurogenetics, Institute of Developmental Genetics, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany
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Nichane M, de Crozé N, Ren X, Souopgui J, Monsoro-Burq AH, Bellefroid EJ. Hairy2-Id3 interactions play an essential role in Xenopus neural crest progenitor specification. Dev Biol 2008; 322:355-67. [PMID: 18721802 DOI: 10.1016/j.ydbio.2008.08.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Revised: 07/24/2008] [Accepted: 08/01/2008] [Indexed: 10/21/2022]
Abstract
Loss of function studies have shown that the Xenopus helix-loop-helix transcription factor Hairy2 is essential for neural crest formation and maintains cells in a mitotic undifferentiated state. However, its position in the genetic cascade regulating neural crest formation and its relationship with other neural crest regulators remain largely unknown. Here we find that Hairy2 is regulated by BMP, FGF and Wnt and that it is only required downstream of BMP and FGF for neural crest formation. We show that Hairy2 overexpression represses neural crest and upregulates neural border genes at early stages while it expands a subset of them in later embryos. We show that Hairy2 downregulates Id3, another essential HLH neural crest regulator, through attenuation of BMP signaling. Knockdown and rescue experiments indicate that Id3 protein, which physically interacts with Hairy2, negatively regulates Hairy2 activity. However, Id3 is required to allow Hairy2 to promote neural crest formation. Together, our results provide evidence that Hairy2 acts downstream of FGF and BMP signals at the neural border to maintain cells in an undifferentiated state, and that Hairy2-Id3 interactions play an essential role in neural crest progenitor specification.
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Affiliation(s)
- Massimo Nichane
- Laboratoire d'Embryologie Moléculaire, Université Libre de Bruxelles, Institut de Biologie et de Médecine Moléculaires (IBMM), Gosselies, Belgium
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42
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Leucht C, Stigloher C, Wizenmann A, Klafke R, Folchert A, Bally-Cuif L. MicroRNA-9 directs late organizer activity of the midbrain-hindbrain boundary. Nat Neurosci 2008; 11:641-8. [PMID: 18454145 DOI: 10.1038/nn.2115] [Citation(s) in RCA: 239] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 03/24/2008] [Indexed: 12/22/2022]
Abstract
The midbrain-hindbrain boundary (MHB) is a long-lasting organizing center in the vertebrate neural tube that is both necessary and sufficient for the ordered development of midbrain and anterior hindbrain (midbrain-hindbrain domain, MH). The MHB also coincides with a pool of progenitor cells that contributes neurons to the entire MH. Here we show that the organizing activity and progenitor state of the MHB are co-regulated by a single microRNA, miR-9, during late embryonic development in zebrafish. Endogenous miR-9 expression, initiated at late stages, selectively spares the MHB. Gain- and loss-of-function studies, in silico predictions and sensor assays in vivo demonstrate that miR-9 targets several components of the Fgf signaling pathway, thereby delimiting the organizing activity of the MHB. In addition, miR-9 promotes progression of neurogenesis in the MH, defining the MHB progenitor pool. Together, these findings highlight a previously unknown mechanism by which a single microRNA fine-tunes late MHB coherence via its co-regulation of patterning activities and neurogenesis.
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Affiliation(s)
- Christoph Leucht
- Department of Zebrafish Neurogenetics, Institute of Developmental Genetics, Helmholtz-Zentrum München, German Research Center for Environmental Health, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany
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43
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Stigloher C, Chapouton P, Adolf B, Bally-Cuif L. Identification of neural progenitor pools by E(Spl) factors in the embryonic and adult brain. Brain Res Bull 2008; 75:266-73. [DOI: 10.1016/j.brainresbull.2007.10.032] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Accepted: 10/17/2007] [Indexed: 11/26/2022]
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44
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Hegde A, Qiu NC, Qiu X, Ho SHK, Tay KQY, George J, Ng FSL, Govindarajan KR, Gong Z, Mathavan S, Jiang YJ. Genomewide expression analysis in zebrafish mind bomb alleles with pancreas defects of different severity identifies putative Notch responsive genes. PLoS One 2008; 3:e1479. [PMID: 18213387 PMCID: PMC2195453 DOI: 10.1371/journal.pone.0001479] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Accepted: 12/11/2007] [Indexed: 11/18/2022] Open
Abstract
Background Notch signaling is an evolutionarily conserved developmental pathway. Zebrafish mind bomb (mib) mutants carry mutations on mib gene, which encodes a RING E3 ligase required for Notch activation via Delta/Jagged ubiquitylation and internalization. Methodology/Principal Findings We examined the mib mutants for defects in pancreas development using in situ hybridization and GFP expression analysis of pancreas-specific GFP lines, carried out the global gene expression profile analysis of three different mib mutant alleles and validated the microarray data using real-time PCR and fluorescent double in situ hybridization. Our study showed that the mib mutants have diminished exocrine pancreas and this defect was most severe in mibta52b followed by mibm132 and then mibtfi91, which is consistent with the compromised Notch activity found in corresponding mib mutant alleles. Global expression profile analysis of mib mutants showed that there is a significant difference in gene expression profile of wt and three mib mutant alleles. There are 91 differentially expressed genes that are common to all three mib alleles. Through detailed analysis of microarray data, we have identified several previously characterized genes and some putative Notch-responsive genes involved in pancreas development. Moreover, results from real-time PCR and fluorescent double in situ hybridization were largely consistent with microarray data. Conclusions/Significance This study provides, for the first time, a global gene expression profile in mib mutants generating useful genomic resources and providing an opportunity to identify the function of novel genes involved in Notch signaling and Notch-regulated developmental processes.
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Affiliation(s)
- Ashok Hegde
- Laboratory of Developmental Signalling and Patterning, Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Nick Chuanxin Qiu
- Laboratory of Developmental Signalling and Patterning, Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Xuehui Qiu
- Laboratory of Developmental Signalling and Patterning, Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Steven Hao-Kee Ho
- Laboratory of Developmental Signalling and Patterning, Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Kenny Qi-Ye Tay
- Laboratory of Developmental Signalling and Patterning, Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Joshy George
- Genome Institute of Singapore, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Felicia Soo Lee Ng
- Bioinformatics Institute, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | | | - Zhiyuan Gong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Sinnakaruppan Mathavan
- Genome Institute of Singapore, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Yun-Jin Jiang
- Laboratory of Developmental Signalling and Patterning, Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * To whom correspondence should be addressed. E-mail:
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45
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Elsen GE, Choi LY, Millen KJ, Grinblat Y, Prince VE. Zic1 and Zic4 regulate zebrafish roof plate specification and hindbrain ventricle morphogenesis. Dev Biol 2007; 314:376-92. [PMID: 18191121 DOI: 10.1016/j.ydbio.2007.12.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 12/05/2007] [Accepted: 12/06/2007] [Indexed: 01/29/2023]
Abstract
During development, the lumen of the neural tube develops into a system of brain cavities or ventricles, which play important roles in normal CNS function. We have established that the formation of the hindbrain (4th) ventricle in zebrafish is dependent upon the pleiotropic functions of the genes implicated in human Dandy Walker Malformation, Zic1 and Zic4. Using morpholino knockdown we show that zebrafish Zic1 and Zic4 are required for normal morphogenesis of the 4th ventricle. In Zic1 and/or Zic4 morphants the ventricle does not open properly, but remains completely or partially fused from the level of rhombomere (r) 2 towards the posterior. In the absence of Zic function early hindbrain regionalization and neural crest development remain unaffected, but dorsal hindbrain progenitor cell proliferation is significantly reduced. Importantly, we find that Zic1 and Zic4 are required for development of the dorsal roof plate. In Zic morphants expression of roof plate markers, including lmx1b.1 and lmx1b.2, is disrupted. We further demonstrate that zebrafish Lmx1b function is required for both hindbrain roof plate development and 4th ventricle morphogenesis, confirming that roof plate formation is a critical component of ventricle development. Finally, we show that dorsal rhombomere boundary signaling centers depend on Zic1 and Zic4 function and on roof plate signals, and provide evidence that these boundary signals are also required for ventricle morphogenesis. In summary, we conclude that Zic1 and Zic4 control zebrafish 4th ventricle morphogenesis by regulating multiple mechanisms including cell proliferation and fate specification in the dorsal hindbrain.
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Affiliation(s)
- Gina E Elsen
- The Committee on Neurobiology, University of Chicago, 947 East 58th Street, Chicago, IL 60637, USA
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46
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Thatcher EJ, Flynt AS, Li N, Patton JR, Patton JG. MiRNA expression analysis during normal zebrafish development and following inhibition of the Hedgehog and Notch signaling pathways. Dev Dyn 2007; 236:2172-80. [PMID: 17584857 DOI: 10.1002/dvdy.21211] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
microRNAs (miRNAs) are small (approximately 22 nucleotide) non-coding RNAs that regulate gene expression at the post-transcriptional level, typically by inhibiting translation. The genes encoding these small RNAs are estimated to comprise approximately 2-3% of animal genomes yet potentially regulate a majority of protein-coding genes including those involved in cell specification and development. A key remaining question is to identify target mRNAs regulated by microRNAs. As a means to identify potential targets, we designed a sensitive microarray to analyze global miRNA expression patterns at twelve developmental stages in zebrafish. Further, we conducted arrays on zebrafish embryos treated with small molecule inhibitors of the Hedgehog and Notch signaling pathways to enable identification of differentially expressed miRNAs that target genes controlling key developmental pathways during early embryogenesis.
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Affiliation(s)
- Elizabeth J Thatcher
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
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47
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Combined activity of the two Gli2 genes of zebrafish play a major role in Hedgehog signaling during zebrafish neurodevelopment. Mol Cell Neurosci 2007; 37:388-401. [PMID: 18060804 DOI: 10.1016/j.mcn.2007.10.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 10/18/2007] [Accepted: 10/25/2007] [Indexed: 01/26/2023] Open
Abstract
It has been proposed that the downstream mediator of the evolutionarily conserved Hedgehog pathway Gli2 plays a relatively minor role in neural development of zebrafish. The second gli2 of zebrafish, gli2b, is expressed in the neural plate and the central nervous system. Our comparative analysis of the developmental role of gli2/gli2b demonstrate a major role of the two Gli2s in mediating Hh signaling. The Gli2s play an early Hh-independent repressor role in the maintenance of neural progenitors and an Hh-dependent activating role during cell differentiation in the floor plate, branchial motor neurons, and sensory neurons. Our analysis of Gli2b loss-of-function using antisense morpholino oligonucleotides indicates that the functions of the two Gli2s diverged in evolution. Gli2b acts in cell proliferation and plays an early role in the hindbrain within a regulatory cascade involving Notch and Ngn1, as well as a role as specific activator in rhombomere 4.
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48
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Abstract
Adult neurogenesis is an exciting and rapidly advancing field of research. It addresses basic biological questions, such as the how and why of de novo neuronal production during adulthood, as well as medically relevant issues, including the potential link between adult neural stem cells and psychiatric disorders, or how stem cell manipulation might be used as a strategy for neuronal replacement. Current research mainly focuses on rodents, but we review here recent examination of non-mammalian vertebrates, which demonstrates that bona fide adult neural stem cells exist in these species. Importantly, especially in teleost fish, these cells can be abundant and located in various brain areas. Hence, non-mammalian vertebrate species provide invaluable comparative material for extracting core mechanisms of adult neural stem cell maintenance and fate.
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Affiliation(s)
- Prisca Chapouton
- Department Zebrafish Neurogenetics, GSF-National Research Center for Environment and Health, Institute of Developmental Genetics, Neuherberg, Germany
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49
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Abelló G, Khatri S, Giráldez F, Alsina B. Early regionalization of the otic placode and its regulation by the Notch signaling pathway. Mech Dev 2007; 124:631-45. [PMID: 17532192 DOI: 10.1016/j.mod.2007.04.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 04/11/2007] [Accepted: 04/13/2007] [Indexed: 01/30/2023]
Abstract
Otic neuronal precursors are the first cells to be specified and do so in the anterior domain of the otic placode, the proneural domain. In the present study, we have explored the early events of otic proneural regionalization in relation to the activity of the Notch signaling pathway. The proneural domain was characterized by the expression of Sox3, Fgf10 and members of the Notch pathway such as Delta1, Hes5 and Lunatic Fringe. The complementary non-neural domain expressed two patterning genes, Lmx1b and Iroquois1, and the members of the Notch pathway, Serrate1 and Hairy1. Fate map studies and double injections with DiI/DiO showed that labeled cells remained confined to anterior or posterior territories with limited cell intermingling. To explore whether Notch signaling pathway plays a role in the initial regionalization of the otic placode, Notch activity was blocked by a gamma-secretase inhibitor (DAPT). Notch blockade induced the expansion of non-neural genes, Lmx1 and Iroquois1, into the proneural domain. Combined gene expression and DiI experiments showed that these effects were not due to migration of non-neural cells into the proneural domain, suggesting that Notch activity regulates the expression of non-neural genes. This was further confirmed by the electroporation of a dominant-negative form of the Mastermind-like1 gene that caused the up-regulation of Lmx1 within the proneural domain. In addition, Notch pathway was involved in neuronal precursor selection, probably by a classical mechanism of lateral inhibition. We propose that the regionalization of the otic domain into a proneural and a non-neural territory is a very early event in otic development, and that Notch signaling activity is required to exclude the expression of non-neural genes from the proneural territory.
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Affiliation(s)
- Gina Abelló
- DCEXS-Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003 Barcelona, Spain
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50
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Shankaran SS, Sieger D, Schröter C, Czepe C, Pauly MC, Laplante MA, Becker TS, Oates AC, Gajewski M. Completing the set of h/E(spl) cyclic genes in zebrafish: her12 and her15 reveal novel modes of expression and contribute to the segmentation clock. Dev Biol 2007; 304:615-32. [PMID: 17274976 DOI: 10.1016/j.ydbio.2007.01.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 12/19/2006] [Accepted: 01/04/2007] [Indexed: 11/30/2022]
Abstract
Somitogenesis is the key developmental process that lays down the framework for a metameric body in vertebrates. Somites are generated from the un-segmented presomitic mesoderm (PSM) by a pre-patterning process driven by a molecular oscillator termed the segmentation clock. The Delta-Notch intercellular signaling pathway and genes belonging to the hairy (h) and Enhancer of split (E(spl))-related (h/E(spl)) family of transcriptional repressors are conserved components of this oscillator. A subset of these genes, called cyclic genes, is characterized by oscillating mRNA expression that sweeps anteriorly like a wave through the embryonic PSM. Periodic transcriptional repression by H/E(spl) proteins is thought to provide a critical part of a negative feedback loop in the oscillatory process, but it is an open question how many cyclic h/E(spl) genes are involved in the somitogenesis clock in any species, and what distinct roles they might play. From a genome-wide search for h/E(spl) genes in the zebrafish, we previously estimated a total of five cyclic members. Here we report that one of these, the mHes5 homologue her15 actually exists as a very recently duplicated gene pair. We investigate the expression of this gene pair and analyse its regulation and activity in comparison to the paralogous her12 gene, and the other cyclic h/E(spl) genes in the zebrafish. The her15 gene pair and her12 display novel and distinct expression features, including a caudally restricted oscillatory domain and dynamic stripes of expression in the rostral PSM that occur at the future segmental borders. her15 expression stripes demarcate a unique two-segment interval in the rostral PSM. Mutant, morpholino, and inhibitor studies show that her12 and her15 expression in the PSM is regulated by Delta-Notch signaling in a complex manner, and is dependent on her7, but not her1 function. Morpholino-mediated her12 knockdown disrupts cyclic gene expression, indicating that it is a non-redundant core component of the segmentation clock. Over-expression of her12, her15 or her7 disrupts cyclic gene expression and somite border formation, and structure function analysis of Her7 indicates that DNA binding, but not Groucho-recruitment seems to be important in this process. Thus, the zebrafish has five functional cyclic h/E(spl) genes, which are expressed in a distinct spatial configuration. We propose that this creates a segmentation oscillator that varies in biochemical composition depending on position in the PSM.
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Affiliation(s)
- Sunita S Shankaran
- Institute for Genetics, University of Cologne, Zülpicher Str. 47, 50674 Cologne, Germany
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