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Bello-Rojas S, Bagnall MW. Clonally related, Notch-differentiated spinal neurons integrate into distinct circuits. eLife 2022; 11:83680. [PMID: 36580075 PMCID: PMC9799969 DOI: 10.7554/elife.83680] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 11/24/2022] [Indexed: 12/30/2022] Open
Abstract
Shared lineage has diverse effects on patterns of neuronal connectivity. In mammalian cortex, excitatory sister neurons assemble into shared microcircuits. In Drosophila, in contrast, sister neurons with different levels of Notch expression (NotchON/NotchOFF) develop distinct identities and diverge into separate circuits. Notch-differentiated sister neurons have been observed in vertebrate spinal cord and cerebellum, but whether they integrate into shared or distinct circuits remains unknown. Here, we evaluate how sister V2a (NotchOFF)/V2b (NotchON) neurons in the zebrafish integrate into spinal circuits. Using an in vivo labeling approach, we identified pairs of sister V2a/b neurons born from individual Vsx1+ progenitors and observed that they have somata in close proximity to each other and similar axonal trajectories. However, paired whole-cell electrophysiology and optogenetics revealed that sister V2a/b neurons receive input from distinct presynaptic sources, do not communicate with each other, and connect to largely distinct targets. These results resemble the divergent connectivity in Drosophila and represent the first evidence of Notch-differentiated circuit integration in a vertebrate system.
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Affiliation(s)
- Saul Bello-Rojas
- Department of Neuroscience, Washington University in St. LouisSt. LouisUnited States
| | - Martha W Bagnall
- Department of Neuroscience, Washington University in St. LouisSt. LouisUnited States
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2
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Zygotic Vsx1 Plays a Key Role in Defining V2a Interneuron Sub-Lineage by Directly Repressing tal1 Transcription in Zebrafish. Int J Mol Sci 2020; 21:ijms21103600. [PMID: 32443726 PMCID: PMC7279403 DOI: 10.3390/ijms21103600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 05/11/2020] [Accepted: 05/15/2020] [Indexed: 12/27/2022] Open
Abstract
In the spinal cord, excitatory V2a and inhibitory V2b interneurons are produced together by the final division of common P2 progenitors. During V2a and V2b diversification, Tal1 is necessary and sufficient to promote V2b differentiation and Vsx2 suppresses the expression of motor neuron genes to consolidate V2a interneuron identity. The expression program of Tal1 is triggered by a Foxn4-driven regulatory network in the common P2 progenitors. Why the expression of Tal1 is inhibited in V2a interneurons at the onset of V2a and V2b sub-lineage diversification remains unclear. Since transcription repressor Vsx1 is expressed in the P2 progenitors and newborn V2a cells in zebrafish, we investigated the role of Vsx1 in V2a fate specification during V2a and V2b interneuron diversification in this species by loss and gain-of-function experiments. In vsx1 knockdown embryos or knockout Go chimeric embryos, tal1 was ectopically expressed in the presumptive V2a cells, while the generation of V2a interneurons was significantly suppressed. By contrast, in vsx1 overexpression embryos, normal expression of tal1 in the presumptive V2b cells was suppressed, while the generation of V2a interneuron was expanded. Chromatin immunoprecipitation and electrophoretic mobility shift assays in combination with core consensus sequence mutation analysis further revealed that Vsx1 can directly bind to tal1 promoter and repress tal1 transcription. These results indicate that Vsx1 can directly repress tal1 transcription and plays an essential role in defining V2a interneuron sub-lineage during V2a and V2b sub-lineage diversification in zebrafish.
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Francius C, Hidalgo-Figueroa M, Debrulle S, Pelosi B, Rucchin V, Ronellenfitch K, Panayiotou E, Makrides N, Misra K, Harris A, Hassani H, Schakman O, Parras C, Xiang M, Malas S, Chow RL, Clotman F. Vsx1 Transiently Defines an Early Intermediate V2 Interneuron Precursor Compartment in the Mouse Developing Spinal Cord. Front Mol Neurosci 2016; 9:145. [PMID: 28082864 PMCID: PMC5183629 DOI: 10.3389/fnmol.2016.00145] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 11/30/2016] [Indexed: 12/30/2022] Open
Abstract
Spinal ventral interneurons regulate the activity of motor neurons, thereby controlling motor activities. Interneurons arise during embryonic development from distinct progenitor domains distributed orderly along the dorso-ventral axis of the neural tube. A single ventral progenitor population named p2 generates at least five V2 interneuron subsets. Whether the diversification of V2 precursors into multiple subsets occurs within the p2 progenitor domain or involves a later compartment of early-born V2 interneurons remains unsolved. Here, we provide evidence that the p2 domain produces an intermediate V2 precursor compartment characterized by the transient expression of the transcriptional repressor Vsx1. These cells display an original repertoire of cellular markers distinct from that of any V2 interneuron population. They have exited the cell cycle but have not initiated neuronal differentiation. They coexpress Vsx1 and Foxn4, suggesting that they can generate the known V2 interneuron populations as well as possible additional V2 subsets. Unlike V2 interneurons, the generation of Vsx1-positive precursors does not depend on the Notch signaling pathway but expression of Vsx1 in these cells requires Pax6. Hence, the p2 progenitor domain generates an intermediate V2 precursor compartment, characterized by the presence of the transcriptional repressor Vsx1, that contributes to V2 interneuron development.
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Affiliation(s)
- Cédric Francius
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université catholique de LouvainBrussels, Belgium
| | - María Hidalgo-Figueroa
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université catholique de LouvainBrussels, Belgium
| | - Stéphanie Debrulle
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université catholique de LouvainBrussels, Belgium
| | - Barbara Pelosi
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université catholique de LouvainBrussels, Belgium
| | - Vincent Rucchin
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université catholique de LouvainBrussels, Belgium
| | | | | | | | - Kamana Misra
- Center for Advanced Biotechnology and Medicine and Department of Pediatrics, Rutgers University - Robert Wood Johnson Medical SchoolPiscataway, NJ, USA
| | - Audrey Harris
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université catholique de LouvainBrussels, Belgium
| | - Hessameh Hassani
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC University Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM)Paris, France
| | - Olivier Schakman
- Laboratory of Cell Physiology, Institute of Neuroscience, Université catholique de LouvainBrussels, Belgium
| | - Carlos Parras
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC University Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM)Paris, France
| | - Mengqing Xiang
- Center for Advanced Biotechnology and Medicine and Department of Pediatrics, Rutgers University - Robert Wood Johnson Medical SchoolPiscataway, NJ, USA
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen UniversityGuangzhou, China
| | - Stavros Malas
- The Cyprus Institute of Neurology and GeneticsNicosia, Cyprus
| | - Robert L. Chow
- Department of Biology, University of VictoriaVictoria, BC, Canada
| | - Frédéric Clotman
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université catholique de LouvainBrussels, Belgium
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4
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Lien HW, Yuan RY, Chou CM, Chen YC, Hung CC, Hu CH, Hwang SPL, Hwang PP, Shen CN, Chen CL, Cheng CH, Huang CJ. Zebrafish cyclin Dx is required for development of motor neuron progenitors, and its expression is regulated by hypoxia-inducible factor 2α. Sci Rep 2016; 6:28297. [PMID: 27323909 PMCID: PMC4915019 DOI: 10.1038/srep28297] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 06/01/2016] [Indexed: 01/31/2023] Open
Abstract
Cyclins play a central role in cell-cycle regulation; in mammals, the D family of cyclins consists of cyclin D1, D2, and D3. In Xenopus, only homologs of cyclins D1 and D2 have been reported, while a novel cyclin, cyclin Dx (ccndx), was found to be required for the maintenance of motor neuron progenitors during embryogenesis. It remains unknown whether zebrafish possess cyclin D3 or cyclin Dx. In this study, we identified a zebrafish ccndx gene encoding a protein which can form a complex with Cdk4. Through whole-mount in situ hybridization, we observed that zccndx mRNA is expressed in the motor neurons of hindbrain and spinal cord during development. Analysis of a 4-kb promoter sequence of the zccndx gene revealed the presence of HRE sites, which can be regulated by HIF2α. Morpholino knockdown of zebrafish Hif2α and cyclin Dx resulted in the abolishment of isl1 and oligo2 expression in the precursors of motor neurons, and also disrupted axon growth. Overexpression of cyclin Dx mRNA in Hif2α morphants partially rescued zccndx expression. Taken together, our data indicate that zebrafish cyclin Dx plays a role in maintaining the precursors of motor neurons.
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Affiliation(s)
- Huang-Wei Lien
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Rey-Yue Yuan
- Department of Neurology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 115, Taiwan
| | - Chih-Ming Chou
- Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 115, Taiwan
| | - Yi-Chung Chen
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Chin-Chun Hung
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
| | - Chin-Hwa Hu
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung 20224, Taiwan
| | - Sheng-Ping L Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Chia-Ning Shen
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Chih-Lung Chen
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Chia-Hsiung Cheng
- Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 115, Taiwan
| | - Chang-Jen Huang
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
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Sun L, Li H, Xu X, Xiao G, Luo C. MicroRNA-20a is essential for normal embryogenesis by targeting vsx1 mRNA in fish. RNA Biol 2015; 12:615-27. [PMID: 25833418 DOI: 10.1080/15476286.2015.1034919] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
MicroRNAs are major post-transcriptional regulators of gene expression and have essential roles in diverse developmental processes. In vertebrates, some regulatory genes play different roles at different developmental stages. These genes are initially transcribed in a wide embryonic region but restricted within distinct cell types at subsequent stages during development. Therefore, post-transcriptional regulation is required for the transition from one developmental stage to the next and the establishment of different cell identities. However, the regulation of many multiple functional genes at post-transcription level during development remains unknown. Here we show that miR-20a can target the mRNA of vsx1, a multiple functional gene, at the 3'-UTR and inhibit protein expression in both goldfish and zebrafish. The expression of miR-20a is initiated ubiquitously at late gastrula stage and exhibits a tissue-specific pattern in the developing retina. Inhibition of vsx1 3'-UTR mediated protein expression occurs when and where miR-20a is expressed. Decoying miR-20a resulted in severely impaired head, eye and trunk formation in association with excessive generation of vsx1 marked neurons in the spinal cord and defects of somites in the mesoderm region. These results demonstrate that miR-20a is essential for normal embryogenesis by restricting Vsx1 expression in goldfish and zebrafish, and that post-transcriptional regulation is an essential mechanism for Vsx1 playing different roles in diverse developmental processes.
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Affiliation(s)
- Lei Sun
- a College of Life Sciences; Zhejiang University ; Hangzhou , Zhejiang , China
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6
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Xu X, He Y, Sun L, Ma S, Luo C. Maternal Vsx1 plays an essential role in regulating prechordal mesendoderm and forebrain formation in zebrafish. Dev Biol 2014; 394:264-76. [PMID: 25150888 DOI: 10.1016/j.ydbio.2014.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 08/10/2014] [Accepted: 08/12/2014] [Indexed: 12/15/2022]
Abstract
Prechordal mesendoderm (PME) is a derivative of gastrula organizer underlying the anterior neural plate of vertebrate embryos. It has been firmly established that PME is critical for head induction and anterior-posterior patterning. Therefore, the establishment of PME in a desired shape and size at a correct position during early embryogenesis is crucial for normal head patterning. However, it remains largely unclear how the desired form and size of PME is generated at a predestined position during early embryogenesis. Here we show that in zebrafish a maternal transcription repressor Vsx1 is essential for this early developmental regulation. Knocking down maternal vsx1 resulted in impaired PME formation and progression associated with a deficient and posteriorized forebrain. Loss- and gain-of-function experiments showed that maternal Vsx1 is essential for repressing ntl ectopic expression in more animal region at early gastrula stages. Chromatin immunoprecipitation assay in combination with core consensus sequence mutation analysis further revealed that maternal Vsx1 can directly repress ntl transcription by binding to the proximal promoter at a specific site. Simultaneous inhibition of ntl function could successfully suppress the defects of both PME and forebrain formation in maternal Vsx1 knockdown embryos. Our results reveal a pivotal role for maternal Vsx1 as a direct transcriptional repressor of ntl expression at the margin of the zebrafish gastrula to ensure directional cell polarization and migration of PME cells.
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Affiliation(s)
- Xiaofeng Xu
- College of Life Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Ying He
- College of Life Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Lei Sun
- College of Life Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Shanshan Ma
- College of Life Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China; School of Life Sciences, Zhengzhou University, Zhengzhou 450001, Henan, China
| | - Chen Luo
- College of Life Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China.
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7
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He Y, Xu X, Zhao S, Ma S, Sun L, Liu Z, Luo C. Maternal control of axial-paraxial mesoderm patterning via direct transcriptional repression in zebrafish. Dev Biol 2013; 386:96-110. [PMID: 24296303 DOI: 10.1016/j.ydbio.2013.11.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 11/01/2013] [Accepted: 11/18/2013] [Indexed: 11/28/2022]
Abstract
Axial-paraxial mesoderm patterning is a special dorsal-ventral patterning event of establishing the vertebrate body plan. Though dorsal-ventral patterning has been extensively studied, the initiation of axial-paraxial mesoderm pattering remains largely unrevealed. In zebrafish, spt cell-autonomously regulates paraxial mesoderm specification and flh represses spt expression to promote axial mesoderm fate, but the expression domains of spt and flh initially overlap in the entire marginal zone of the embryo. Defining spt and flh territories is therefore a premise of axial-paraxial mesoderm patterning. In this study, we investigated why and how the initial expression of flh becomes repressed in the ventrolateral marginal cells during blastula stage. Loss- and gain-of-function experiments showed that a maternal transcription factor Vsx1 is essential for restricting flh expression within the dorsal margin and preserving spt expression and paraxial mesoderm specification in the ventrolateral margin of embryo. Chromatin immunoprecipitation and electrophoretic mobility shift assays in combination with core consensus sequence mutation analysis further revealed that Vsx1 can directly repress flh by binding to the proximal promoter at a specific site. Inhibiting maternal vsx1 translation resulted in confusion of axial and paraxial mesoderm markers expression and axial-paraxial mesoderm patterning. These results demonstrated that direct transcriptional repression of the decisive axial mesoderm gene by maternal ventralizing factor is a crucial regulatory mechanism of initiating axial-paraxial mesoderm patterning in vertebrates.
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Affiliation(s)
- Ying He
- College of Life Science, Zhejiang University, Hangzhou 310058, Zhejiang, People's Republic of China
| | - Xiaofeng Xu
- College of Life Science, Zhejiang University, Hangzhou 310058, Zhejiang, People's Republic of China
| | - Shufang Zhao
- College of Life Science, Zhejiang University, Hangzhou 310058, Zhejiang, People's Republic of China
| | - Shanshan Ma
- College of Life Science, Zhejiang University, Hangzhou 310058, Zhejiang, People's Republic of China
| | - Lei Sun
- College of Life Science, Zhejiang University, Hangzhou 310058, Zhejiang, People's Republic of China
| | - Zhenghua Liu
- College of Life Science, Zhejiang University, Hangzhou 310058, Zhejiang, People's Republic of China
| | - Chen Luo
- College of Life Science, Zhejiang University, Hangzhou 310058, Zhejiang, People's Republic of China.
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8
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Meyers JR, Hu L, Moses A, Kaboli K, Papandrea A, Raymond PA. β-catenin/Wnt signaling controls progenitor fate in the developing and regenerating zebrafish retina. Neural Dev 2012; 7:30. [PMID: 22920725 PMCID: PMC3549768 DOI: 10.1186/1749-8104-7-30] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 08/15/2012] [Indexed: 01/01/2023] Open
Abstract
Background The zebrafish retina maintains two populations of stem cells: first, the germinal zone or ciliary marginal zone (CMZ) contains multipotent retinal progenitors that add cells to the retinal periphery as the fish continue to grow; second, radial glia (Müller cells) occasionally divide asymmetrically to generate committed progenitors that differentiate into rod photoreceptors, which are added interstitially throughout the retina with growth. Retinal injury stimulates Müller glia to dedifferentiate, re-enter the cell cycle, and generate multipotent retinal progenitors similar to those in the CMZ to replace missing neurons. The specific signals that maintain these two distinct populations of endogenous retinal stem cells are not understood. Results We used genetic and pharmacological manipulation of the β-catenin/Wnt signaling pathway to show that it is required to maintain proliferation in the CMZ and that hyperstimulation of β-catenin/Wnt signaling inhibits normal retinal differentiation and expands the population of proliferative retinal progenitors. To test whether similar effects occur during regeneration, we developed a method for making rapid, selective photoreceptor ablations in larval zebrafish with intense light. We found that dephosphorylated β-catenin accumulates in Müller glia as they re-enter the cell cycle following injury, but not in Müller glia that remain quiescent. Activation of Wnt signaling is required for regenerative proliferation, and hyperstimulation results in loss of Müller glia from the INL as all proliferative cells move into the ONL. Conclusions β-catenin/Wnt signaling is thus required for the maintenance of retinal progenitors during both initial development and lesion-induced regeneration, and is sufficient to prevent differentiation of those progenitors and maintain them in a proliferative state. This suggests that the β-catenin/Wnt cascade is part of the shared molecular circuitry that maintains retinal stem cells for both homeostatic growth and epimorphic regeneration.
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Affiliation(s)
- Jason R Meyers
- Department of Biology, Colgate University, Hamilton, NY 13346, USA.
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9
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Tong Y, Zheng K, Zhao S, Xiao G, Luo C. Sequence divergence in the 3'-untranslated region has an effect on the subfunctionalization of duplicate genes. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2012; 318:531-44. [PMID: 22674856 DOI: 10.1002/jez.b.22457] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Revised: 02/01/2012] [Accepted: 04/03/2012] [Indexed: 12/20/2022]
Abstract
Recent studies demonstrated that sequence divergence in both transcriptional regulatory region and coding region contributes to the subfunctionalization of duplicate gene. However, whether sequence divergence in the 3'-untranslated region (3'-UTR) has an impact on the subfunctionalization of duplicate genes remains unclear. Here, we identified two diverging duplicate vsx1 (visual system homeobox-1) loci in goldfish, named vsx1A1 and vsx1A2. Phylogenetic analysis suggests that vsx1A1 and vsx1A2 may arise from a duplication of vsx1 after the separation of goldfish and zebrafish. Sequence comparison revealed that divergence in both transcriptional and translational regulatory regions is higher than divergence in the introns. vsx1A2 expresses during blastula and gastrula stages and in adult retina but silences from segmentation stage to hatching stage, vsx1A1 starts expression from segmentation onward. Comparing to that zebrafish vsx1 expresses in all the developmental stages and in the adult retina, it appears that goldfish vsx1A1 and vsx1A2 are under going to share the functions of ancestral vsx1. The different but overlapping temporal expression patterns of vsx1A1 and vsx1A2 suggest that sequence divergence in the promoter region of duplicate vsx1 is not sufficient for partitioning the functions of ancestral vsx1. By comparing vsx1A1 and vsx1A2 3'-UTR-linked green fluorescent protein gene expression patterns, we demonstrated that the 3'-UTR of vsx1A1 remains but the 3'-UTR of vsx1A2 has lost the capability of mediating bipolar cell specific expression during retina development. These results indicate that sequence divergence in the 3'-UTRs has a clear effect on subfunctionalization of the duplicate genes.
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Affiliation(s)
- Ying Tong
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
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10
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Sánchez-Sánchez AV, Camp E, Leal-Tassias A, Mullor JL. Wnt signaling has different temporal roles during retinal development. Dev Dyn 2010; 239:297-310. [PMID: 20014102 DOI: 10.1002/dvdy.22168] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Differentiation of neural retinal precursor (NRP) cells in vertebrates follows an established order of cell-fate determination associated with exit from the cell cycle. Wnt signaling regulates cell cycle in colon carcinoma cells and has been implicated in different aspects of retinal development in various species. To better understand the biological roles of Wnt in the developing retina, we have used a transgenic and pharmacological approach to manipulate the Wnt signaling pathway during retinal development in medaka embryos. With the use of both approaches, we observed that during the early phase of retinal development Wnt signaling regulated cell cycle progression, proliferation, apoptosis, and differentiation of NRP cells. However, during later phases of retinal development, proliferation and apoptosis were not affected by manipulation of Wnt signaling. Instead, Wnt regulated Vsx1 expression, but not the expression of other retinal cell markers tested. Thus, the response of NRP cells to Wnt signaling is stage-dependent.
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Affiliation(s)
- Ana V Sánchez-Sánchez
- Department of Regenerative Medicine, Centro de Investigación Príncipe Felipe, Valencia 46012, Spain
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11
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Zhang Q, Zheng K, Ma S, Tong Y, Luo C. Goldfish β-catenin cell-autonomously inhibits the expression of early neural development regulating gene vsx1. CHINESE SCIENCE BULLETIN-CHINESE 2010. [DOI: 10.1007/s11434-009-0714-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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12
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Yuan H, Zhou J, Deng M, Liu X, Bras ML, The HD, Chen SJ, Chen Z, Liu TX, Zhu J. Small ubiquitin-related modifier paralogs are indispensable but functionally redundant during early development of zebrafish. Cell Res 2009; 20:185-96. [DOI: 10.1038/cr.2009.101] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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13
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vsx1 3′ untranlated region-mediated translation difference at differentdevelopmental stages of goldfish embryos. J Genet Genomics 2009; 36:483-90. [DOI: 10.1016/s1673-8527(08)60138-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 03/19/2009] [Accepted: 03/23/2009] [Indexed: 11/18/2022]
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14
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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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15
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16
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Vitorino M, Jusuf PR, Maurus D, Kimura Y, Higashijima SI, Harris WA. Vsx2 in the zebrafish retina: restricted lineages through derepression. Neural Dev 2009; 4:14. [PMID: 19344499 PMCID: PMC2683830 DOI: 10.1186/1749-8104-4-14] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2008] [Accepted: 04/03/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The neurons in the vertebrate retina arise from multipotent retinal progenitor cells (RPCs). It is not clear, however, which progenitors are multipotent or why they are multipotent. RESULTS In this study we show that the homeodomain transcription factor Vsx2 is initially expressed throughout the retinal epithelium, but later it is downregulated in all but a minor population of bipolar cells and all Müller glia. The Vsx2-negative daughters of Vsx2-positive RPCs divide and give rise to all other cell types in the retina. Vsx2 is a repressor whose targets include transcription factors such as Vsx1, which is expressed in the progenitors of distinct non-Vsx2 bipolars, and the basic helix-loop-helix transcription factor Ath5, which restricts the fate of progenitors to retinal ganglion cells, horizontal cells, amacrine cells and photoreceptors fates. Foxn4, expressed in the progenitors of amacrine and horizontal cells, is also negatively regulated by Vsx2. CONCLUSION Our data thus suggest Vsx2-positive RPCs are fully multipotent retinal progenitors and that when Vsx2 is downregulated, Vsx2-negative progenitors escape Vsx2 repression and so are able to express factors that restrict lineage potential.
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Affiliation(s)
- Marta Vitorino
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK.
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Yokoi H, Yan YL, Miller MR, BreMiller RA, Catchen JM, Johnson EA, Postlethwait JH. Expression profiling of zebrafish sox9 mutants reveals that Sox9 is required for retinal differentiation. Dev Biol 2009; 329:1-15. [PMID: 19210963 DOI: 10.1016/j.ydbio.2009.01.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 12/27/2008] [Accepted: 01/06/2009] [Indexed: 01/01/2023]
Abstract
The transcription factor gene Sox9 plays various roles in development, including differentiation of the skeleton, gonads, glia, and heart. Other functions of Sox9 remain enigmatic. Because Sox9 protein regulates expression of target genes, the identification of Sox9 targets should facilitate an understanding of the mechanisms of Sox9 action. To help identify Sox9 targets, we used microarray expression profiling to compare wild-type embryos to mutant embryos lacking activity for both sox9a and sox9b, the zebrafish co-orthologs of Sox9. Candidate genes were further evaluated by whole-mount in situ hybridization in wild-type and sox9 single and double mutant embryos. Results identified genes expressed in cartilage (col2a1a and col11a2), retina (calb2a, calb2b, crx, neurod, rs1, sox4a and vsx1) and pectoral fin bud (klf2b and EST AI722369) as candidate targets for Sox9. Cartilage is a well-characterized Sox9 target, which validates this strategy, whereas retina represents a novel Sox9 function. Analysis of mutant phenotypes confirmed that Sox9 helps regulate the number of Müller glia and photoreceptor cells and helps organize the neural retina. These roles in eye development were previously unrecognized and reinforce the multiple functions that Sox9 plays in vertebrate development.
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Affiliation(s)
- Hayato Yokoi
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
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18
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Kimura Y, Satou C, Higashijima SI. V2a and V2b neurons are generated by the final divisions of pair-producing progenitors in the zebrafish spinal cord. Development 2008; 135:3001-5. [PMID: 18684740 DOI: 10.1242/dev.024802] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The p2 progenitor domain in the ventral spinal cord gives rise to two interneuron subtypes: V2a and V2b. Delta-Notch-mediated cell-cell interactions between postmitotic immature neurons have been implicated in the segregation of neuron subtypes. However, lineage relationships between V2a and V2b neurons have not been reported. We address this issue using Tg[vsx1:GFP] zebrafish, a model system in which high GFP expression is initiated near the final stage of p2 progenitors. Cell fates were followed in progeny using time-lapse microscopy. Results indicate that the vast majority, if not all, of GFP-labeled p2 progenitors divide once to produce V2a/V2b neuron pairs, indicating that V2a and V2b neurons are generated by the asymmetric division of pair-producing progenitor cells. Together with evidence that Notch signaling is involved in the cell fate specification process, our results strongly suggest that Delta-Notch interactions between sister cells play a crucial role in the final outcome of these asymmetric divisions. This mechanism for determining cell fate is similar to asymmetric divisions that occur during Drosophila neurogenesis, where ganglion mother cells divide once to produce distinct neurons. However, unlike in Drosophila, the divisional axes of p2 progenitors in zebrafish were not fixed. We report that the terminal division of pair-producing progenitor cells in vertebrate neurogenesis can reproducibly produce two distinct neurons through a mechanism that may not depend on the orientation of the division axis.
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Affiliation(s)
- Yukiko Kimura
- National Institutes of Natural Sciences, Okazaki Institute for Integrative Bioscience, National Institute for Physiological Sciences, Higashiyama 5-1, Myodaiji, Okazaki, Aichi 444-8787, Japan
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19
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Batista MF, Jacobstein J, Lewis KE. Zebrafish V2 cells develop into excitatory CiD and Notch signalling dependent inhibitory VeLD interneurons. Dev Biol 2008; 322:263-75. [PMID: 18680739 DOI: 10.1016/j.ydbio.2008.07.015] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2008] [Revised: 06/25/2008] [Accepted: 07/11/2008] [Indexed: 11/26/2022]
Abstract
The vertebrate spinal cord contains distinct classes of cells that form at precise dorsal-ventral locations and express specific combinations of transcription factors. In amniotes, V2 cells develop in the ventral spinal cord, just dorsal to motoneurons. All V2 cells develop from the same progenitor domain and hence are initially molecularly identical. However, as they start to become post-mitotic and differentiate they subdivide into two intermingled molecularly-distinct subpopulations of cells, V2a and V2b cells. Here we show that the molecular identities of V2a and V2b cells are conserved between zebrafish and amniotes. In zebrafish, these two cell types both develop into interneurons with very similar morphologies, but while V2a cells become excitatory Circumferential Descending (CiD) interneurons, V2b cells become inhibitory Ventral Lateral Descending (VeLD) interneurons. In addition, we demonstrate that Notch signalling is required for V2 cells to develop into V2b cells. In the absence of Notch signalling, all V2b cells develop as V2a cells.
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Affiliation(s)
- Manuel F Batista
- Department of Physiology, Development and Neuroscience, University of Cambridge, Anatomy Building, Downing Street, Cambridge, UK
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20
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Mok JW, Baek SJ, Joo CK. VSX1 gene variants are associated with keratoconus in unrelated Korean patients. J Hum Genet 2008; 53:842-849. [PMID: 18626569 DOI: 10.1007/s10038-008-0319-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Accepted: 06/23/2008] [Indexed: 10/21/2022]
Abstract
Keratoconus is a bilateral ectatic disorder characterized by the central thinning of corneal tissue leading to visual impairment. To investigate the possibility of visual system homeobox 1 (VSXI) as a candidate susceptibility gene for Korean patients with keratoconus, we performed a mutation screening of the VSXI gene in 249 unrelated patients with keratoconus and 208 control subjects without the ocular disorder. We found two heterozygous novel missense mutations in exon 2: N151S and G160V. The G160V mutation was identified in 13 keratoconus patients (5.3%), and the N151S mutation was found in only one keratoconus patient (0.4%). We also detected three synonymous polymorphisms and four intragenic polymorphisms. The IVS1-11*a allele was associated with a significantly increased risk of keratoconus in Korean patients [3.6 vs. 0.5%, p = 0.001, odds ratio (OR) = 7.76, 95% confidence interval (CI) 1.989-30.241). Other polymorphisms did not show an association with keratoconus risk. Our data is the first reported VSX1 mutation screening in Korean keratoconus patients. We detected two novel missense mutations and one intragenic polymorphism in the VSX1 gene, which show a strong statistical association with unrelated keratoconus patients. Consequently, our study suggests that VSX1 gene variants seem to be significant genetic variants for keratoconus predisposition in unrelated Korean patients.
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Affiliation(s)
- Jee-Won Mok
- Laboratory of Ophthalmology and Visual Science, Department of Ophthalmology and Visual Science, Catholic Research Institutes of Medical Science, Catholic University Medical College, The Catholic University of Korea, 505 Banpo-dong, Seocho-ku, Seoul, 137-701, South Korea.,Korea Eye Tissue and Gene Bank, St. Mary's Hospital, Seoul, South Korea
| | - Sun-Jin Baek
- Laboratory of Ophthalmology and Visual Science, Department of Ophthalmology and Visual Science, Catholic Research Institutes of Medical Science, Catholic University Medical College, The Catholic University of Korea, 505 Banpo-dong, Seocho-ku, Seoul, 137-701, South Korea.,Korea Eye Tissue and Gene Bank, St. Mary's Hospital, Seoul, South Korea
| | - Choun-Ki Joo
- Laboratory of Ophthalmology and Visual Science, Department of Ophthalmology and Visual Science, Catholic Research Institutes of Medical Science, Catholic University Medical College, The Catholic University of Korea, 505 Banpo-dong, Seocho-ku, Seoul, 137-701, South Korea. .,Korea Eye Tissue and Gene Bank, St. Mary's Hospital, Seoul, South Korea. .,Department of Ophthalmology, St. Mary's Hospital, Seoul, South Korea.
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21
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Clark AM, Yun S, Veien ES, Wu YY, Chow RL, Dorsky RI, Levine EM. Negative regulation of Vsx1 by its paralog Chx10/Vsx2 is conserved in the vertebrate retina. Brain Res 2007; 1192:99-113. [PMID: 17919464 DOI: 10.1016/j.brainres.2007.06.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Revised: 06/08/2007] [Accepted: 06/13/2007] [Indexed: 01/03/2023]
Abstract
Chx10/Vsx2 and Vsx1 are the only Paired-like CVC (Prd-L:CVC) homeobox genes in the mouse genome. Both are expressed in the retina and have important but distinct roles in retinal development. Mutations in Chx10/Vsx2 cause reduced retinal progenitor cell (RPC) proliferation and an absence of bipolar cells, while mutations in Vsx1 impair differentiation of cone bipolar cells. Given their structural similarities and importance in retinal development, we sought to determine if a regulatory interaction exists between these genes and whether inactivation of both genes blocks initiation of retinal development. We found that Chx10/Vsx2 binds to a specific sequence in the Vsx1 5'-intergenic region and represses the activity of a luciferase reporter under the control of the Vsx1 promoter. This is consistent with our observation that there is an inverse relationship between the levels of Chx10/Vsx2 and Vsx1 immunostaining within the bipolar cell class. Furthermore, Vsx1 mRNA is upregulated in the RPCs of Chx10/Vsx2 deficient mice and zebrafish embryos injected with a chx10/vsx2 morpholino. In mice deficient for both Chx10/Vsx2 and Vsx1 and zebrafish embryos co-injected with chx10/Vsx2 and vsx1 morpholinos, the changes in embryonic retinal development and marker expression are similar in magnitude to embryos with Chx10/Vsx2 loss of function only. From these studies, we propose that Vsx1 is a direct target of Chx10/Vsx2-mediated transcriptional repression. Although Vsx1 mRNA is upregulated in Chx10/Vsx2 deficient RPCs, Vsx1 does not genetically compensate for loss of Chx10/Vsx2, demonstrating that Prd-L:CVC genes, although important, are not absolutely required to initiate retinal development.
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Affiliation(s)
- Anna M Clark
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
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22
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Dorval KM, Bobechko BP, Ahmad KF, Bremner R. Transcriptional activity of the paired-like homeodomain proteins CHX10 and VSX1. J Biol Chem 2005; 280:10100-8. [PMID: 15647262 DOI: 10.1074/jbc.m412676200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
CHX10 and VSX1 are homeodomain (HD) proteins essential for normal retinal development. CHX10 is required first for retinal progenitor cell proliferation and later for bipolar cell differentiation, whereas VSX1 is important in the terminal differentiation of a subset of bipolar cells. Elucidating the transcriptional activity of CHX10 and VSX1 is required to understand how these factors control retinal development. We show that CHX10 and Vsx1 can function as transcriptional repressors. When tethered to a promoter by a heterologous LexA DNA-binding domain or its HD, CHX10 repressed multiple classes of activators in different immortalized cell lines. CHX10 blocked TATA-containing and TATA-less promoters, repressed at a distance, and inhibited a complex enhancer positioned upstream or downstream of the reporter gene, whereas retinoblastoma protein (RB) inhibited the downstream enhancer only. Interestingly, CHX10 mildly potentiated a subset of activators in chick neuronal cultures. Thus, CHX10 is both a versatile repressor and a context-specific weak activator. The CHX10 HD and CVC domains were sufficient for DNA binding and repression. VSX1 contains closely related homeo and CVC domains and, like CHX10, also repressed transcription. A VSX1 HD mutation, R166W, that impairs DNA binding and causes keratoconus in humans, hindered repressor function. Therefore, CHX10 and VSX1 may control retinal bipolar cell specification or differentiation by repressing genes required for the development of other cell types.
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Affiliation(s)
- Kimberley M Dorval
- Toronto Western Research Institute, University Health Network Program, University of Toronto, Toronto, Ontario M5T 2S8, Canada
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23
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Shen YC, Raymond PA. Zebrafish cone-rod (crx) homeobox gene promotes retinogenesis. Dev Biol 2004; 269:237-51. [PMID: 15081370 DOI: 10.1016/j.ydbio.2004.01.037] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2003] [Revised: 01/08/2004] [Accepted: 01/26/2004] [Indexed: 01/12/2023]
Abstract
The mammalian Cone-rod homeobox (Crx) gene is a divergent member of the Otx gene family known to be involved in differentiation and survival of retinal photoreceptors and photoentrainment of circadian rhythms. Zebrafish have two genes in the Otx5/crx orthology class, and we previously showed that crx can transactivate rhodopsin expression in vitro, and that otx5 (orthodenticle-related gene), but not crx, regulates expression of circadian genes in the pineal. Here, we show that zebrafish crx does not regulate expression of opsins and other photoreceptor-specific genes in the pineal. We further show that crx is expressed in proliferating retinal progenitors and may be involved in patterning the early optic primordium and in promoting the differentiation of retinal progenitors, including photoreceptors. These results suggest novel functions for zebrafish crx during retinal specification and differentiation.
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Affiliation(s)
- Yu-chi Shen
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-0616, USA
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24
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Brustein E, Saint-Amant L, Buss RR, Chong M, McDearmid JR, Drapeau P. Steps during the development of the zebrafish locomotor network. ACTA ACUST UNITED AC 2004; 97:77-86. [PMID: 14706693 DOI: 10.1016/j.jphysparis.2003.10.009] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
This review summarizes recent data from our lab concerning the development of motor activities in the developing zebrafish. The zebrafish is a leading model for studies of vertebrate development because one can obtain a large number of transparent, externally and rapidly developing embryos with motor behaviors that are easy to assess (e.g. for mutagenic screens). The emergence of embryonic motility was studied behaviorally and at the cellular level. The embryonic behaviors appear sequentially and include an early, transient period of spontaneous, alternating tail coilings, followed by responses to touch, and swimming. Patch clamp recording in vivo revealed that an electrically coupled network of a subset of spinal neurons generates spontaneous tail coiling, whereas a chemical (glutamatergic and glycinergic) synaptic drive underlies touch responses and swimming and requires input from the hindbrain. Swimming becomes sustained in larvae once serotonergic neuromodulatory effects are integrated. We end with a brief overview of the genetic tools available for the study of the molecular determinants implicated in locomotor network development in the zebrafish. Combining genetic, behavioral and cellular experimental approaches will advance our understanding of the general principles of locomotor network assembly and function.
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Affiliation(s)
- Edna Brustein
- McGill Centre for Research in Neuroscience, McGill University, 1650 Cedar Avenue, Montreal, Quebec, Canada H3G 1A4
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25
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Drapeau P, Saint-Amant L, Buss RR, Chong M, McDearmid JR, Brustein E. Development of the locomotor network in zebrafish. Prog Neurobiol 2002; 68:85-111. [PMID: 12450489 DOI: 10.1016/s0301-0082(02)00075-8] [Citation(s) in RCA: 260] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The zebrafish is a leading model for studies of vertebrate development and genetics. Its embryonic motor behaviors are easy to assess (e.g. for mutagenic screens), the embryos develop rapidly (hatching as larvae at 2 days) and are transparent, permitting calcium imaging and patch clamp recording in vivo. We review primarily the recent advances in understanding the cellular basis for the development of motor activities in the developing zebrafish. The motor activities are generated largely in the spinal cord and hindbrain. In the embryo these segmented structures possess a relatively small number of repeating sets of identifiable neurons. Many types of neurons as well as the two types of muscle cells have been classified based on their morphologies. Some of the molecular signals for cellular differentiation have been identified recently and mutations affecting cell development have been isolated. Embryonic motor behaviors appear in sequence and consist of an early period of transient spontaneous coiling contractions, followed by the emergence of twitching responses to touch, and later by the ability to swim. Coiling contractions are generated by an electrically coupled network of a subset of spinal neurons whereas a chemical (glutamatergic and glycinergic) synaptic drive underlies touch responses and swimming. Swimming becomes sustained in larvae once the neuromodulatory serotonergic system develops. These results indicate many similarities between developing zebrafish and other vertebrates in the properties of the synaptic drive underlying locomotion. Therefore, the zebrafish is a useful preparation for gaining new insights into the development of the neural control of vertebrate locomotion. As the types of neurons, transmitters, receptors and channels used in the locomotor network are being defined, this opens the possibility of combining cellular neurophysiology with forward and reverse molecular genetics to understand the principles of locomotor network assembly and function.
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Affiliation(s)
- Pierre Drapeau
- McGill Centre for Research in Neuroscience and Department of Biology, McGill University, Que., Montreal, Canada.
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26
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Oliveri P, Carrick DM, Davidson EH. A regulatory gene network that directs micromere specification in the sea urchin embryo. Dev Biol 2002; 246:209-28. [PMID: 12027443 DOI: 10.1006/dbio.2002.0627] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Micromeres and their immediate descendants have three known developmental functions in regularly developing sea urchins: immediately after their initial segregation, they are the source of an unidentified signal to the adjacent veg(2) cells that is required for normal endomesodermal specification; a few cleavages later, they express Delta, a Notch ligand which triggers the conditional specification of the central mesodermal domain of the vegetal plate; and they exclusively give rise to the skeletogenic mesenchyme of the postgastrular embryo. We demonstrate the key components of the zygotic regulatory gene network that accounts for micromere specificity. This network is a subelement of the overall endomesoderm specification network of the Strongylocentrotus purpuratus embryo. A central role is played by a newly discovered gene encoding a paired class homeodomain transcription factor which in micromeres acts as a repressor of a repressor: the gene is named pmar1 (paired-class micromere anti-repressor). pmar1 is expressed only during cleavage and early blastula stages, and exclusively in micromeres. It is initially activated as soon as the micromeres are formed, in response to Otx and beta-Catenin/Tcf inputs. The repressive nature of the interactions mediated by the pmar1 gene product was shown by the identical effect of introducing mRNA encoding the Pmar1 factor, and mRNA encoding an Engrailed-Pmar1 (En-Pmar1) repressor domain fusion. In both cases, the effects are derepression: of the delta gene; and of skeletogenic genes, including several transcription factors normally expressed only in micromere descendants, and also a set of downstream skeletogenic differentiation genes. The spatial phenotype of embryos bearing exogenous mRNA encoding Pmar1 factor or En-Pmar1 is expansion of the domains of expression of the downstream genes over most or all of the embryo. This results in transformation of much of the embryo into skeletogenic mesenchyme cells that express skeletogenic markers. The normal role of pmarl is to prevent, exclusively in the micromeres, the expression of a repressor that is otherwise operative throughout the embryo. This function accounts for the localization of delta transcription in micromeres, and thereby for the conditional specification of the vegetal plate mesoderm. It also explains why skeletogenic differentiation gene batteries normally function only in micromere descendants. More generally, the regulatory network subelement emerging from this work shows how the specificity of micromere function depends on continuing global regulatory interactions, as well as on early localized inputs.
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Affiliation(s)
- Paola Oliveri
- Division of Biology 156-29, California Institute of Technology, Pasadena 91125, USA
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27
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Poggi L, Carl M, Vignali R, Barsacchi G, Wittbrodt J. Expression of a medaka (Oryzias latipes) Bar homologue in the differentiating central nervous system and retina. Mech Dev 2002; 114:193-6. [PMID: 12175510 DOI: 10.1016/s0925-4773(02)00054-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The Bar homeobox genes play an essential role during nervous system and eye development in Drosophila. We isolated a medaka Bar gene closely related to the Drosophila and mammalian Bar genes. In the medaka embryo, OlBar is expressed from gastrula stages onwards, in a region demarcating the presumptive prosencephalic-mesencephalic boundary. Later in development, OlBar transcripts are found in populations of differentiating neuronal cells of the brain and the retina.
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Affiliation(s)
- Lucia Poggi
- Dipartimento di Fisiologia e Biochimica, Laboratori di Biologia Cellulare e dello Sviluppo, Universita di Pisa, Via G. Carducci 13, Pisa, Italy
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28
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Ohtoshi A, Justice MJ, Behringer RR. Isolation and characterization of Vsx1, a novel mouse CVC paired-like homeobox gene expressed during embryogenesis and in the retina. Biochem Biophys Res Commun 2001; 286:133-40. [PMID: 11485319 DOI: 10.1006/bbrc.2001.5372] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gastrula stage mouse embryo RNA was screened by degenerate RT-PCR to yield a novel paired-like homeobox gene. The open reading frame encoded by the cDNA was most similar to human VSX1. Mouse Vsx1 encodes a protein of 363 amino acid residues that contains a CVC domain that was originally identified as a conserved motif among mouse CHX10, goldfish VSX-1 and C. elegans CEH-10. Linkage analysis showed that mouse Vsx1 mapped to the distal region of chromosome 2. RT-PCR analysis detected mouse Vsx1 transcripts from gastrulation and post-gastrulation stage mouse embryos, suggesting a role for Vsx1 during mouse embryogenesis. Analysis of the eyes of mouse chimeras generated with embryonic stem cells in which a lacZ reporter was targeted to the Vsx1 locus suggested that Vsx1 is expressed in the inner nuclear layer of the retina.
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Affiliation(s)
- A Ohtoshi
- Department of Molecular Genetics, M. D. Anderson Cancer Center, University of Texas, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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29
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Kurtzman AL, Schechter N. Ubc9 interacts with a nuclear localization signal and mediates nuclear localization of the paired-like homeobox protein Vsx-1 independent of SUMO-1 modification. Proc Natl Acad Sci U S A 2001; 98:5602-7. [PMID: 11331779 PMCID: PMC33259 DOI: 10.1073/pnas.101129698] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2001] [Accepted: 03/15/2001] [Indexed: 11/18/2022] Open
Abstract
Vsx-1 is a paired-like:CVC homeobox gene whose expression is linked to bipolar cell differentiation during zebrafish retinogenesis. We used a yeast two-hybrid screen to identify proteins interacting with Vsx-1 and isolated Ubc9, an enzyme that conjugates the small ubiquitin-like modifier SUMO-1. Despite its interaction with Ubc9, we show that Vsx-1 is not a substrate for SUMO-1 in COS-7 cells or in vitro. When a yeast two-hybrid assay is used, deletion analysis of the interacting domain on Vsx-1 shows that Ubc9 binds to a nuclear localization signal (NLS) at the NH(2) terminus of the homeodomain. In SW13 cells, Vsx-1 localizes to the nucleus and is excluded from nucleoli. Deletion of the NLS disrupts this nuclear localization, resulting in a diffuse cytoplasmic distribution of Vsx-1. In SW13 AK1 cells that express low levels of endogenous Ubc9, Vsx-1 accumulates in a perinuclear ring and colocalizes with an endoplasmic reticulum marker. However, NLS-tagged STAT1 protein exhibits normal nuclear localization in both SW13 and SW13 AK1 cells, suggesting that nuclear import is not globally disrupted. Cotransfection of Vsx-1 with Ubc9 restores Vsx-1 nuclear localization in SW3 AK1 cells and demonstrates that Ubc9 is required for the nuclear localization of Vsx-1. Ubc9 continues to restore nuclear localization even after a C93S active site mutation has eliminated its SUMO-1-conjugating ability. These results suggest that Ubc9 mediates the nuclear localization of Vsx-1, and possibly other proteins, through a nonenzymatic mechanism that is independent of SUMO-1 conjugation.
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Affiliation(s)
- A L Kurtzman
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794, USA
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30
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Biemar F, Argenton F, Schmidtke R, Epperlein S, Peers B, Driever W. Pancreas development in zebrafish: early dispersed appearance of endocrine hormone expressing cells and their convergence to form the definitive islet. Dev Biol 2001; 230:189-203. [PMID: 11161572 DOI: 10.1006/dbio.2000.0103] [Citation(s) in RCA: 187] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To begin to understand pancreas development and the control of endocrine lineage formation in zebrafish, we have examined the expression pattern of several genes shown to act in vertebrate pancreatic development: pdx-1, insulin (W. M. Milewski et al., 1998, Endocrinology 139, 1440-1449), glucagon, somatostatin (F. Argenton et al., 1999, Mech. Dev. 87, 217-221), islet-1 (Korzh et al., 1993, Development 118, 417-425), nkx2.2 (Barth and Wilson, 1995, Development 121, 1755-1768), and pax6.2 (Nornes et al., 1998, Mech. Dev. 77, 185-196). To determine the spatial relationship between the exocrine and the endocrine compartments, we have cloned the zebrafish trypsin gene, a digestive enzyme expressed in differentiated pancreatic exocrine cells. We found expression of all these genes in the developing pancreas throughout organogenesis. Endocrine cells first appear in a scattered fashion in two bilateral rows close to the midline during mid-somitogenesis and converge during late-somitogenesis to form a single islet dorsal to the nascent duodenum. We have examined development of the endocrine lineage in a number of previously described zebrafish mutations. Deletion of chordamesoderm in floating head (Xnot homolog) mutants reduces islet formation to small remnants, but does not delete the pancreas, indicating that notochord is involved in proper pancreas development, but not required for differentiation of pancreatic cell fates. In the absence of knypek gene function, which is involved in convergence movements, the bilateral endocrine primordia do not merge. Presence of trunk paraxial mesoderm also appears to be instrumental for convergence since the bilateral endocrine primordia do not merge in spadetail mutants. We discuss our findings on zebrafish pancreatogenesis in the light of evolution of the pancreas in chordates.
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Affiliation(s)
- F Biemar
- Institut für Biologie I, Abt. Entwicklungsbiologie, Universität Freiburg, Hauptstrasse 1, Freiburg, D-79104, Germany
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31
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Hayashi T, Huang J, Deeb SS. RINX(VSX1), a novel homeobox gene expressed in the inner nuclear layer of the adult retina. Genomics 2000; 67:128-39. [PMID: 10903837 DOI: 10.1006/geno.2000.6248] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The locus control region (LCR) of the human red and green visual pigment genes is critical for the formation of functional red and green cones in the retina. A 37-bp core of the LCR is perfectly conserved among mammals and binds specific retinal nuclear proteins. Here, we employed a yeast one-hybrid screen of an adult retinal cDNA library to clone and characterize these proteins. We identified clones encoding homeodomain (HD) transcription factors Pax6, Rx, and Chx10 and a novel paired-like HD protein, RINX. In the adult retina, RINX is exclusively expressed in a subset of cells (likely to be bipolar cells) of the retinal inner nuclear layer (INL). RINX is closely related to Chx10, which is also exclusively expressed in the INL of the adult retina and is critical for retinal development. The RINX gene is expressed in two classes of mRNA. One class encodes proteins that lack either part of or all of the HD, but retain the transcriptional activation domain. The RINX gene maps to chromosome 20p11.2 to which no retinal disease has been assigned. In conclusion, the LCR contains two adjacent motifs that are targets for binding of HD proteins that may specify the development and differentiation of cone photoreceptors and a subset of INL bipolar cells. Mutations in the related human CHX10 gene cause microphthalmia in a subset of families, and, therefore, the RINX gene is a candidate for this phenotype in another subset of patients. Since the RINX gene is likely an ortholog of the goldfish Vsx1 gene, it has been named VSX1 by the Human Gene Nomenclature Committee.
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MESH Headings
- Adult
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Base Sequence
- Cattle
- Chromosome Mapping
- Chromosomes, Human, Pair 20/genetics
- Cloning, Molecular
- DNA/chemistry
- DNA/genetics
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Exons
- Eye Proteins/genetics
- Gene Expression
- Genes/genetics
- Homeodomain Proteins/genetics
- Humans
- Introns
- Molecular Sequence Data
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Retina/cytology
- Retina/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Tissue Distribution
- Transcription, Genetic
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Affiliation(s)
- T Hayashi
- Department of Medicine, University of Washington, Seattle, Washington 98195, USA
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Affiliation(s)
- L K Barthel
- Department of Anatomy and Cell Biology, University of Michigan Medical School, Ann Arbor 48109-0616, USA
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Kurtzman AL, Gregori L, Haas AL, Schechter N. Ubiquitination and degradation of the zebrafish paired-like homeobox protein VSX-1. J Neurochem 2000; 75:48-55. [PMID: 10854246 DOI: 10.1046/j.1471-4159.2000.0750048.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Vsx-1 is a paired-like : CVC homeobox protein dynamically expressed during zebrafish development. Previous results indicate that Vsx-1 influences bipolar cell differentiation and maintenance of these cells in the adult retina. To understand the developmental regulation of this transcription factor, we investigated ubiquitination as a possible posttranslational mechanism. In vitro, Vsx-1 was conjugated with multiple ubiquitin moieties. Proteasome inhibitors and added ubiquitin increased the accumulation of Vsx-1-ubiquitin(n) complexes and stabilized unmodified Vsx-1. Also, in transiently transfected COS-7 cells, Vsx-1 is ubiquitinated, and pulse-chase experiments show that Vsx-1 proteolysis occurs. Vsx-1 proteins with C-terminal deletions retained the capacity for initial modification by ubiquitin but lost the capacity for efficient chain elongation. These results show that Vsx-1 is a substrate of the ubiquitin/proteasome pathway and suggest that C-terminal sequences of Vsx-1 are critical for ubiquitin chain elongation. In addition, our findings suggest that ubiquitin-dependent proteolysis regulates Vsx-1 during zebrafish retinal development.
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Affiliation(s)
- A L Kurtzman
- Department of Biochemistry, Health Sciences Center, Institute for Developmental Biology, State University of New York, Stony Brook, New York, USA
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Winkler S, Loosli F, Henrich T, Wakamatsu Y, Wittbrodt J. The conditional medaka mutation eyeless uncouples patterning and morphogenesis of the eye. Development 2000; 127:1911-9. [PMID: 10751179 DOI: 10.1242/dev.127.9.1911] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In early vertebrate eye development, the retinal anlage is specified in the anterior neuroectoderm. During neurulation, the optic vesicles evaginate from the lateral wall of the prosencephalon. Here we describe the temperature-sensitive mutation eyeless in the Japanese medakafish. Marker gene analysis indicates that, whereas, specification of two retinal primordia and proximodistal patterning takes place in the mutant embryo, optic vesicle evagination does not occur and subsequent differentiation of the retinal primordia is not observed. The mutation eyeless thus uncouples patterning and morphogenesis at early steps of retinal development. Temperature-shift experiments indicate a requirement for eyeless activity prior to optic vesicle evagination. Cell transplantation shows that eyeless acts cell autonomously.
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Affiliation(s)
- S Winkler
- Developmental Biology Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, PO Box 10.2209, Germany.
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Abstract
We have isolated full-length cDNAs of chick Chx10 and Chx10-1, two members of the paired type homeobox/CVC gene family. A comparison of sequences suggests that Chx10 is closely related to Alx/Vsx-2 and Vsx-2 of zebrafish and goldfish, respectively; while Chx10-1 is closely related to Vsx-1 of zebrafish and goldfish. Chx10 and Chx10-1 are expressed in the early retinal neuroepithelium, but not in the pigment epithelium and lens. The expression of Chx10 is present in most retinal neuroblasts, while Chx10-1 exhibits a novel pattern along the nasotemporal border. In the differentiating retina, both Chx10 and Chx10-1 are restricted to bipolar cells and are maintained at a low level in bipolar cells of the mature retina.
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Affiliation(s)
- C M Chen
- Department of Genetics, Harvard Medical School, Howard Hughes Medical Institute, 200 Longwood Avenue, Boston, MA 02115, USA
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Semina EV, Mintz-Hittner HA, Murray JC. Isolation and characterization of a novel human paired-like homeodomain-containing transcription factor gene, VSX1, expressed in ocular tissues. Genomics 2000; 63:289-93. [PMID: 10673340 DOI: 10.1006/geno.1999.6093] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Homeodomain transcription factors control cell fates during the development of all animals. The paired-like subfamily of homeodomain proteins has been particularly implicated in ocular development in different species. In this paper we report the cDNA sequence, genomic structure, localization, and expression data of a novel paired-like homeobox-containing gene, VSX1, isolated from a human embryonic craniofacial cDNA library using the degenerate-PCR approach. The composed VSX1 cDNA sequence of 1433 bp was predicted to encode a protein of 365 amino acid residues. Maximal homology at the protein level was identified with the paired-like homeoproteins of the CVC-domain family: 92-97% identity was seen in the homeodomain region with 55% overall identity to zebrafish and goldfish Vsx1 and 35% overall identity to goldfish Vsx2 and murine Chx10. The gene was found to consist of five exons that are distributed over 6.2 kb of genomic sequence. VSX1 was localized to the 20p11-q11 region, which is homologous with the distal part of mouse chromosome 2. Expression of VSX1 was detected in embryonic craniofacial and adult ocular tissues. Several ocular phenotypes have been mapped to the VSX1 region in both human and mouse genomes, and its candidacy for these disorders is discussed.
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Affiliation(s)
- E V Semina
- Department of Pediatrics, University of Iowa, Iowa City, Iowa 52242, USA.
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