1
|
Shahab M, Rosati R, Meyer DN, Shields JN, Crofts E, Baker TR, Jamesdaniel S. Cisplatin-induced hair cell loss in zebrafish neuromasts is accompanied by protein nitration and Lmo4 degradation. Toxicol Appl Pharmacol 2020; 410:115342. [PMID: 33245977 DOI: 10.1016/j.taap.2020.115342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 11/11/2020] [Accepted: 11/19/2020] [Indexed: 12/13/2022]
Abstract
Generation of reactive oxygen species, a critical factor in cisplatin-induced ototoxicity, leads to the formation of peroxynitrite, which in turn results in the nitration of susceptible proteins. Previous studies indicated that LMO4, a transcriptional regulator, is the most abundantly nitrated cochlear protein after cisplatin treatment and that LMO4 nitration facilitates ototoxicity in rodents. However, the role of this mechanism in regulating cisplatin-induced hair cell loss in non-mammalian models is unknown. As the mechanosensory hair cells in the neuromasts of zebrafish share many features with mammalian inner ear and is a good model for studying ototoxicity, we hypothesized that cisplatin treatment induces protein nitration and Lmo4 degradation in zebrafish hair cells, thereby facilitating hair cell loss. Immunostaining with anti-parvalbumin revealed a significant decrease in the number of hair cells in the neuromast of cisplatin treated larvae. In addition, cisplatin treatment induced a significant decrease in the expression of Lmo4 protein and a significant increase in nitrotyrosine levels, in the hair cells. The cisplatin-induced changes in Lmo4 and nitrotyrosine levels strongly correlated with hair cell loss, implying a potential link. Furthermore, a significant increase in the expression of activated Caspase-3 in zebrafish hair cells, post cisplatin treatment, suggested that cisplatin-induced decrease in Lmo4 levels is accompanied by apoptosis. These findings suggest that nitrative stress and Lmo4 degradation are important factors in cisplatin-induced hair cell loss in zebrafish neuromasts and that zebrafish could be used as a model to screen the otoprotective efficacy of compounds that inhibit protein nitration.
Collapse
Affiliation(s)
- Monazza Shahab
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48202, USA; Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA
| | - Rita Rosati
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Danielle N Meyer
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48202, USA; Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA
| | - Jeremiah N Shields
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Emily Crofts
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Tracie R Baker
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48202, USA; Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA
| | - Samson Jamesdaniel
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48202, USA; Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA.
| |
Collapse
|
2
|
Jin K, Xiao D, Andersen B, Xiang M. Lmo4 and Other LIM domain only factors are necessary and sufficient for multiple retinal cell type development. Dev Neurobiol 2015; 76:900-15. [PMID: 26579872 DOI: 10.1002/dneu.22365] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 10/01/2015] [Accepted: 11/12/2015] [Indexed: 12/13/2022]
Abstract
Understanding the molecular basis by which distinct cell types are specified is a central issue in retinogenesis and retinal disease development. Here we examined the role of LIM domain only 4 (Lmo4) in retinal development using both gain-of-function and loss-of-function approaches. By immunostaining, Lmo4 was found to be expressed in mouse retina from E10.5 to mature stages. Retroviral delivery of Lmo4 into retinal progenitor cells could promote the amacrine, bipolar and Müller cell fates at the expense of photoreceptors. It also inhibited the fate of early-born retinal ganglion cells. Using a dominant-negative form of Lmo4 which suppresses transcriptional activities of all LIM domain only factors, we demonstrated that LIM domain only factors are both necessary and sufficient for promoting amacrine and bipolar cell development, but not for the differentiation of ganglion, horizontal, Müller, or photoreceptor cells. Taken together, our study uncovers multiple roles of Lmo4 during retinal development and demonstrates the importance of LIM domain only factors in ensuring proper retinal cell specification and differentiation. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 900-915, 2016.
Collapse
Affiliation(s)
- Kangxin Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, 510060, China.,Center for Advanced Biotechnology and Medicine and Department of Pediatrics, Rutgers University-Robert Wood Johnson Medical School, Piscataway, New Jersey, 08854
| | - Dongchang Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, 510060, China
| | - Bogi Andersen
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, Irvine, California, 92697-4030.,Department of Biological Chemistry, Division of Endocrinology and Metabolism, University of California, Irvine, California, 92697-4030
| | - Mengqing Xiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, 510060, China.,Center for Advanced Biotechnology and Medicine and Department of Pediatrics, Rutgers University-Robert Wood Johnson Medical School, Piscataway, New Jersey, 08854
| |
Collapse
|
3
|
Beccari L, Marco-Ferreres R, Tabanera N, Manfredi A, Souren M, Wittbrodt B, Conte I, Wittbrodt J, Bovolenta P. A trans-Regulatory Code for the Forebrain Expression of Six3.2 in the Medaka Fish. J Biol Chem 2015; 290:26927-26942. [PMID: 26378230 PMCID: PMC4646366 DOI: 10.1074/jbc.m115.681254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/11/2015] [Indexed: 12/16/2022] Open
Abstract
A well integrated and hierarchically organized gene regulatory network is responsible for the progressive specification of the forebrain. The transcription factor Six3 is one of the central components of this network. As such, Six3 regulates several components of the network, but its upstream regulators are still poorly characterized. Here we have systematically identified such regulators, taking advantage of the detailed functional characterization of the regulatory region of the medaka fish Six3.2 ortholog and of a time/cost-effective trans-regulatory screening, which complemented and overcame the limitations of in silico prediction approaches. The candidates resulting from this search were validated with dose-response luciferase assays and expression pattern criteria. Reconfirmed candidates with a matching expression pattern were also tested with chromatin immunoprecipitation and functional studies. Our results confirm the previously proposed direct regulation of Pax6 and further demonstrate that Msx2 and Pbx1 are bona fide direct regulators of early Six3.2 distribution in distinct domains of the medaka fish forebrain. They also point to other transcription factors, including Tcf3, as additional regulators of different spatial-temporal domains of Six3.2 expression. The activity of these regulators is discussed in the context of the gene regulatory network proposed for the specification of the forebrain.
Collapse
Affiliation(s)
- Leonardo Beccari
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolas Cabrera 1, Madrid 28049, Spain,; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolas Cabrera 1, Madrid 28049, Spain; Instituto Cajal, Consejo Superior de Investigaciones Científicas, Avda. Dr. Arce 37, Madrid, 28002, Spain,.
| | - Raquel Marco-Ferreres
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolas Cabrera 1, Madrid 28049, Spain,; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolas Cabrera 1, Madrid 28049, Spain; Instituto Cajal, Consejo Superior de Investigaciones Científicas, Avda. Dr. Arce 37, Madrid, 28002, Spain
| | - Noemi Tabanera
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolas Cabrera 1, Madrid 28049, Spain,; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolas Cabrera 1, Madrid 28049, Spain; Instituto Cajal, Consejo Superior de Investigaciones Científicas, Avda. Dr. Arce 37, Madrid, 28002, Spain
| | - Anna Manfredi
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Avda. Dr. Arce 37, Madrid, 28002, Spain
| | - Marcel Souren
- the Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Beate Wittbrodt
- the Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Ivan Conte
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Avda. Dr. Arce 37, Madrid, 28002, Spain,; the Telethon Institute of Genetics and Medicine, Via Campi Flegrei 34, Pozzuoli, Naples, 80078, Italy
| | - Jochen Wittbrodt
- the Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Paola Bovolenta
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolas Cabrera 1, Madrid 28049, Spain,; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolas Cabrera 1, Madrid 28049, Spain; Instituto Cajal, Consejo Superior de Investigaciones Científicas, Avda. Dr. Arce 37, Madrid, 28002, Spain,.
| |
Collapse
|
4
|
Deml B, Reis LM, Muheisen S, Bick D, Semina EV. EFTUD2 deficiency in vertebrates: Identification of a novel human mutation and generation of a zebrafish model. ACTA ACUST UNITED AC 2015; 103:630-40. [PMID: 26118977 DOI: 10.1002/bdra.23397] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/30/2015] [Accepted: 05/26/2015] [Indexed: 12/17/2022]
Abstract
BACKGROUND Congenital microphthalmia and coloboma are severe developmental defects that are frequently associated with additional systemic anomalies and display a high level of genetic heterogeneity. METHODS To identify the pathogenic variant in a patient with microphthalmia, coloboma, retinal dystrophy, microcephaly, and other features, whole exome sequencing analysis of the patient and parental samples was undertaken. To further explore the identified variant/gene, expression and functional studies in zebrafish were performed. RESULTS Whole exome sequencing revealed a de novo variant, c.473_474delGA, p.(Arg158Lysfs*4), in EFTUD2 which encodes a component of the spliceosome complex. Dominant mutations in EFTUD2 cause Mandibulofacial Dysostosis, Guion-Almeida type, which does not involve microphthalmia, coloboma, or retinal dystrophy; analysis of genes known to cause these ocular phenotypes identified several variants of unknown significance but no causal alleles in the affected patient. Zebrafish eftud2 demonstrated high sequence conservation with the human gene and broad embryonic expression. TALEN-mediated disruption was employed to generate a c.378_385 del, p.(Ser127Aspfs*23) truncation mutation in eftud2. Homozygous mutants displayed a reduced head size, small eye, curved body, and early embryonic lethality. Apoptosis assays demonstrated a striking increase in terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL)-positive cells in the developing brain, eye, spinal cord, and other tissues starting at 30 hours postfertilization. CONCLUSION This study reports a novel mutation in EFTUD2 in a Mandibulofacial Dysostosis, Guion-Almeida type patient with unusual ocular features and the generation of a first animal model of eftud2 deficiency. The severe embryonic phenotype observed in eftud2 mutants indicates an important conserved role during development of diverse tissues in vertebrates.
Collapse
Affiliation(s)
- Brett Deml
- Department of Pediatrics and Children's Research Institute at the Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, Wisconsin.,Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Linda M Reis
- Department of Pediatrics and Children's Research Institute at the Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, Wisconsin
| | - Sanaa Muheisen
- Department of Pediatrics and Children's Research Institute at the Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, Wisconsin
| | - David Bick
- Department of Pediatrics and Children's Research Institute at the Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, Wisconsin
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute at the Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, Wisconsin.,Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin
| |
Collapse
|
5
|
|
6
|
LIM-domain-only proteins: multifunctional nuclear transcription coregulators that interacts with diverse proteins. Mol Biol Rep 2013; 41:1067-73. [DOI: 10.1007/s11033-013-2952-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 12/20/2013] [Indexed: 02/07/2023]
|
7
|
Hao R, Bondesson M, Singh AV, Riu A, McCollum CW, Knudsen TB, Gorelick DA, Gustafsson JÅ. Identification of estrogen target genes during zebrafish embryonic development through transcriptomic analysis. PLoS One 2013; 8:e79020. [PMID: 24223173 PMCID: PMC3819264 DOI: 10.1371/journal.pone.0079020] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 09/17/2013] [Indexed: 12/26/2022] Open
Abstract
Estrogen signaling is important for vertebrate embryonic development. Here we have used zebrafish (Danio rerio) as a vertebrate model to analyze estrogen signaling during development. Zebrafish embryos were exposed to 1 µM 17β-estradiol (E2) or vehicle from 3 hours to 4 days post fertilization (dpf), harvested at 1, 2, 3 and 4 dpf, and subjected to RNA extraction for transcriptome analysis using microarrays. Differentially expressed genes by E2-treatment were analyzed with hierarchical clustering followed by biological process and tissue enrichment analysis. Markedly distinct sets of genes were up and down-regulated by E2 at the four different time points. Among these genes, only the well-known estrogenic marker vtg1 was co-regulated at all time points. Despite this, the biological functional categories targeted by E2 were relatively similar throughout zebrafish development. According to knowledge-based tissue enrichment, estrogen responsive genes were clustered mainly in the liver, pancreas and brain. This was in line with the developmental dynamics of estrogen-target tissues that were visualized using transgenic zebrafish containing estrogen responsive elements driving the expression of GFP (Tg(5xERE:GFP)). Finally, the identified embryonic estrogen-responsive genes were compared to already published estrogen-responsive genes identified in male adult zebrafish (Gene Expression Omnibus database). The expressions of a few genes were co-regulated by E2 in both embryonic and adult zebrafish. These could potentially be used as estrogenic biomarkers for exposure to estrogens or estrogenic endocrine disruptors in zebrafish. In conclusion, our data suggests that estrogen effects on early embryonic zebrafish development are stage- and tissue- specific.
Collapse
Affiliation(s)
- Ruixin Hao
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Maria Bondesson
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- * E-mail:
| | - Amar V. Singh
- National Center for Computational Toxicology, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, United States of America
| | - Anne Riu
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Catherine W. McCollum
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Thomas B. Knudsen
- National Center for Computational Toxicology, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, United States of America
| | - Daniel A. Gorelick
- Department of Embryology, Carnegie Institute for Science, Baltimore, Maryland, United States of America
| | - Jan-Åke Gustafsson
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| |
Collapse
|
8
|
Beccari L, Marco-Ferreres R, Bovolenta P. The logic of gene regulatory networks in early vertebrate forebrain patterning. Mech Dev 2012; 130:95-111. [PMID: 23111324 DOI: 10.1016/j.mod.2012.10.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 10/09/2012] [Indexed: 01/19/2023]
Abstract
The vertebrate forebrain or prosencephalon is patterned at the beginning of neurulation into four major domains: the telencephalic, hypothalamic, retinal and diencephalic anlagen. These domains will then give rise to the majority of the brain structures involved in sensory integration and the control of higher intellectual and homeostatic functions. Understanding how forebrain pattering arises has thus attracted the interest of developmental neurobiologists for decades. As a result, most of its regulators have been identified and their hierarchical relationship is now the object of active investigation. Here, we summarize the main morphogenetic pathways and transcription factors involved in forebrain specification and propose the backbone of a possible gene regulatory network (GRN) governing its specification, taking advantage of the GRN principles elaborated by pioneer studies in simpler organisms. We will also discuss this GRN and its operational logic in the context of the remarkable morphological and functional diversification that the forebrain has undergone during evolution.
Collapse
Affiliation(s)
- Leonardo Beccari
- Centro de Biología Molecular "Severo Ochoa", CSIC-UAM, c/Nicolas Cabrera, 1, Madrid 28049, Spain
| | | | | |
Collapse
|
9
|
Ochoa SD, Salvador S, LaBonne C. The LIM adaptor protein LMO4 is an essential regulator of neural crest development. Dev Biol 2011; 361:313-25. [PMID: 22119055 DOI: 10.1016/j.ydbio.2011.10.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 10/18/2011] [Accepted: 10/21/2011] [Indexed: 12/20/2022]
Abstract
The neural crest (NC) is a population of multipotent stem cell-like progenitors that arise at the neural plate border in vertebrates and migrate extensively before giving rise to diverse derivatives. A number of components of the neural crest gene regulatory network (NC-GRN) are used reiteratively to control multiple steps in the development of these cells. It is therefore important to understand the mechanisms that control the distinct function of reiteratively used factors in different cellular contexts, and an important strategy for doing so is to identify and characterize the regulatory factors they interact with. Here we report that the LIM adaptor protein, LMO4, is a Slug/Snail interacting protein that is essential for NC development. LMO4 is expressed in NC forming regions of the embryo, as well as in the central nervous system and the cranial placodes. LMO4 is necessary for normal NC development as morpholino-mediated knockdown of this factor leads to loss of NC precursor formation at the neural plate border. Misexpression of LMO4 leads to ectopic expression of some neural crest markers, but a reduction in the expression of others. LMO4 binds directly to Slug and Snail, but not to other components of the NC-GRN and can modulate Slug-mediated neural crest induction, suggesting a mechanistic link between these factors. Together these findings implicate LMO4 as a critical component of the NC-GRN and shed new light on the control of Snail family repressors.
Collapse
Affiliation(s)
- Stacy D Ochoa
- Dept. of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | | | | |
Collapse
|
10
|
Uribe RA, Gross JM. Id2a influences neuron and glia formation in the zebrafish retina by modulating retinoblast cell cycle kinetics. Development 2010; 137:3763-74. [PMID: 20943708 DOI: 10.1242/dev.050484] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Inhibitor of differentiation (Id) family helix-loop-helix proteins regulate the proliferation, survival and differentiation of numerous cell types during development; however, their functions during retinal development have not been analyzed. Using loss-of-function and overexpression assays in zebrafish, we demonstrate that Id2a levels modulate retinoblast cell cycle kinetics and thereby influence neuron and glia formation in the retina. Id2a-deficient retinas possess increased numbers of cells occupying S phase, at the expense of mitotic cells, and kinetic analyses demonstrate that Id2a is required for S-phase progression and/or the transition from S to M phase. Id2a-dependent defects in retinoblast proliferation lead to microphthalmia and to an absence of nearly all differentiated inner and outer nuclear layer cell types. Overexpression of id2a has the opposite effect on retinoblast cell cycle kinetics: id2a-overexpressing retinoblasts progress from S to M phase more rapidly and they undergo mitosis more frequently, which results in macrophthalmia. Mosaic analyses reveal that Id2a function in facilitating both cell cycle progression and neuronal differentiation in the retina is non-cell-autonomous, suggesting that Id2a functions upstream of the extrinsic pathways that regulate retinogenesis.
Collapse
Affiliation(s)
- Rosa A Uribe
- Section of Molecular Cell and Developmental Biology, Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, TX 78722, USA
| | | |
Collapse
|
11
|
Duquette PM, Zhou X, Yap NL, MacLaren EJ, Lu JJ, Wallace VA, Chen HH. Loss of LMO4 in the retina leads to reduction of GABAergic amacrine cells and functional deficits. PLoS One 2010; 5:e13232. [PMID: 20949055 PMCID: PMC2951357 DOI: 10.1371/journal.pone.0013232] [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: 07/01/2010] [Accepted: 09/14/2010] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND LMO4 is a transcription cofactor expressed during retinal development and in amacrine neurons at birth. A previous study in zebrafish reported that morpholino RNA ablation of one of two related genes, LMO4b, increases the size of eyes in embryos. However, the significance of LMO4 in mammalian eye development and function remained unknown since LMO4 null mice die prior to birth. METHODOLOGY/PRINCIPAL FINDINGS We observed the presence of a smaller eye and/or coloboma in ∼40% LMO4 null mouse embryos. To investigate the postnatal role of LMO4 in retinal development and function, LMO4 was conditionally ablated in retinal progenitor cells using the Pax6 alpha-enhancer Cre/LMO4flox mice. We found that these mice have fewer Bhlhb5-positive GABAergic amacrine and OFF-cone bipolar cells. The deficit appears to affect the postnatal wave of Bhlhb5+ neurons, suggesting a temporal requirement for LMO4 in retinal neuron development. In contrast, cholinergic and dopaminergic amacrine, rod bipolar and photoreceptor cell numbers were not affected. The selective reduction in these interneurons was accompanied by a functional deficit revealed by electroretinography, with reduced amplitude of b-waves, indicating deficits in the inner nuclear layer of the retina. CONCLUSIONS/SIGNIFICANCE Inhibitory GABAergic interneurons play a critical function in controlling retinal image processing, and are important for neural networks in the central nervous system. Our finding of an essential postnatal function of LMO4 in the differentiation of Bhlhb5-expressing inhibitory interneurons in the retina may be a general mechanism whereby LMO4 controls the production of inhibitory interneurons in the nervous system.
Collapse
Affiliation(s)
- Philippe M. Duquette
- Centre for Stroke Recovery, Neuroscience, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Xun Zhou
- Centre for Stroke Recovery, Neuroscience, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Nida Lerma Yap
- Centre for Stroke Recovery, Neuroscience, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Erik J. MacLaren
- Centre for Stroke Recovery, Neuroscience, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Jesse J. Lu
- Centre for Stroke Recovery, Neuroscience, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Valerie A. Wallace
- Molecular Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- University of Ottawa Eye Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Hsiao-Huei Chen
- Centre for Stroke Recovery, Neuroscience, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| |
Collapse
|
12
|
Fukazawa C, Santiago C, Park KM, Deery WJ, Gomez de la Torre Canny S, Holterhoff CK, Wagner DS. poky/chuk/ikk1 is required for differentiation of the zebrafish embryonic epidermis. Dev Biol 2010; 346:272-83. [PMID: 20692251 DOI: 10.1016/j.ydbio.2010.07.037] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Revised: 06/24/2010] [Accepted: 07/30/2010] [Indexed: 12/31/2022]
Abstract
An epidermis surrounds all vertebrates, forming a water barrier between the external environment and the internal space of the organism. In the zebrafish, the embryonic epidermis consists of an outer enveloping layer (EVL) and an inner basal layer that have distinct embryonic origins. Differentiation of the EVL requires the maternal effect gene poky/ikk1 in EVL cells prior to establishment of the basal layer. This requirement is transient and maternal Ikk1 is sufficient to allow establishment of the EVL and formation of normal skin in adults. Similar to the requirement for Ikk1 in mouse epidermis, EVL cells in poky mutants fail to exit the cell cycle or express specific markers of differentiation. In spite of the similarity in phenotype, the molecular requirement for Ikk1 is different between mouse and zebrafish. Unlike the mouse, EVL differentiation requires functioning Poky/Ikk1 kinase activity but does not require the HLH domain. Previous work suggested that the EVL was a transient embryonic structure, and that maturation of the epidermis required replacement of the EVL with cells from the basal layer. We show here that the EVL is not lost during embryogenesis but persists to larval stages. Our results show that while the requirement for poky/ikk1 is conserved, the differences in molecular activity indicate that diversification of an epithelial differentiation program has allowed at least two developmental modes of establishing a multilayered epidermis in vertebrates.
Collapse
Affiliation(s)
- Cindy Fukazawa
- Department of Biochemistry and Cell Biology, Rice University, MS-140, PO Box 1892, Houston, TX 77251, USA
| | | | | | | | | | | | | |
Collapse
|
13
|
Chao CH, Wang HD, Yuh CH. Complexity of cis-regulatory organization of six3a during forebrain and eye development in zebrafish. BMC DEVELOPMENTAL BIOLOGY 2010; 10:35. [PMID: 20346166 PMCID: PMC2858731 DOI: 10.1186/1471-213x-10-35] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Accepted: 03/26/2010] [Indexed: 11/10/2022]
Abstract
BACKGROUND Six3a belongs to the SIX family of homeodomain proteins and is expressed in the most anterior neural plate at the beginning of neurogenesis in various species. Though the function of Six3a as a crucial regulator of eye and forebrain development has been thoroughly investigated, the transcriptional regulation of six3a is not well understood. RESULTS To elucidate the transcriptional regulation of six3a, we performed an in vivo reporter assay. Alignment of the 21-kb region surrounding the zebrafish six3a gene with the analogous region from different species identified several conserved non-coding modules. Transgenesis in zebrafish identified two enhancer elements and one suppressor. The D module drives the GFP reporter in the forebrain and eyes at an early stage, while the A module is responsible for the later expression. The A module also works as a repressor suppressing ectopic expression from the D module. Mutational analysis further minimized the A module to four highly conserved elements and the D module to three elements. Using electrophoresis mobility shift assays, we also provided evidence for the presence of DNA-binding proteins in embryonic nuclear extracts. The transcription factors that may occupy those highly conserved elements were also predicted. CONCLUSION This study provides a comprehensive view of six3a transcription regulation during brain and eye development and offers an opportunity to establish the gene regulatory networks underlying neurogenesis in zebrafish.
Collapse
Affiliation(s)
- Chung-Hao Chao
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan Town, Miaoli County, Taiwan
- College of Life Science and Institute of Biotechnology, National Tsing-Hua University, HsinChu, Taiwan
| | - Horng-Dar Wang
- College of Life Science and Institute of Biotechnology, National Tsing-Hua University, HsinChu, Taiwan
| | - Chiou-Hwa Yuh
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan Town, Miaoli County, Taiwan
- College of Life Science and Institute of Bioinformatics and Structural Biology, National Tsing-Hua University, HsinChu, Taiwan
- Department of Biological Science & Technology, National Chiao Tung University, HsinChu, Taiwan
| |
Collapse
|
14
|
Sanek NA, Taylor AA, Nyholm MK, Grinblat Y. Zebrafish zic2a patterns the forebrain through modulation of Hedgehog-activated gene expression. Development 2009; 136:3791-800. [PMID: 19855021 PMCID: PMC2766342 DOI: 10.1242/dev.037820] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2009] [Indexed: 11/20/2022]
Abstract
Holoprosencephaly (HPE) is the most common congenital malformation of the forebrain in human. Several genes with essential roles during forebrain development have been identified because they cause HPE when mutated. Among these are genes that encode the secreted growth factor Sonic hedgehog (Shh) and the transcription factors Six3 and Zic2. In the mouse, Six3 and Shh activate each other's transcription, but a role for Zic2 in this interaction has not been tested. We demonstrate that in zebrafish, as in mouse, Hh signaling activates transcription of six3b in the developing forebrain. zic2a is also activated by Hh signaling, and represses six3b non-cell-autonomously, i.e. outside of its own expression domain, probably through limiting Hh signaling. Zic2a repression of six3b is essential for the correct formation of the prethalamus. The diencephalon-derived optic stalk (OS) and neural retina are also patterned in response to Hh signaling. We show that zebrafish Zic2a limits transcription of the Hh targets pax2a and fgf8a in the OS and retina. The effects of Zic2a depletion in the forebrain and in the OS and retina are rescued by blocking Hh signaling or by increasing levels of the Hh antagonist Hhip, suggesting that in both tissues Zic2a acts to attenuate the effects of Hh signaling. These data uncover a novel, essential role for Zic2a as a modulator of Hh-activated gene expression in the developing forebrain and advance our understanding of a key gene regulatory network that, when disrupted, causes HPE.
Collapse
Affiliation(s)
- Nicholas A Sanek
- Department of Zoology and Anatomy, University of Wisconsin, Madison, WI 53706, USA
| | | | | | | |
Collapse
|
15
|
Bai Q, Burton EA. Cis-acting elements responsible for dopaminergic neuron-specific expression of zebrafish slc6a3 (dopamine transporter) in vivo are located remote from the transcriptional start site. Neuroscience 2009; 164:1138-51. [PMID: 19755139 DOI: 10.1016/j.neuroscience.2009.09.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/13/2009] [Accepted: 09/05/2009] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to analyze the transcriptional regulation of the zebrafish solute carrier family 6 member 3 gene (slc6a3, dopamine transporter, dat), as a first step towards isolating regulatory sequences useful for driving transgene expression within dopaminergic neurons of the zebrafish CNS in vivo. We found that the 3.0 kb slc6a3 mRNA is expressed in each of the major groups of dopaminergic neurons previously identified in the zebrafish CNS. The slc6a3 gene spans >20 kb of genomic DNA and contains 15 exons. The genomic organization of slc6a3 is highly conserved with respect to its human orthologue, including the presence of an untranslated first exon. The promoter lacks a canonical TATA box and there are multiple transcriptional start sites. Functional analysis of cis-acting elements responsible for the expression pattern of slc6a3 was carried out by generating stable transgenic zebrafish lines expressing fluorescent reporters under transcriptional control of fragments of slc6a3 genomic sequence. The region between -2 kb and +5 kb with respect to the transcriptional start site contains the core slc6a3 promoter, in addition to neuronal enhancers and/or non-neuronal repressors that restrict expression to the CNS, but this region lacks cis-acting elements responsible for slc6a3 expression in dopaminergic neurons. The upstream sequence between -6 kb and -2 kb contains an enhancer element that drives slc6a3 expression in dopaminergic neurons of the pretectal region, and additional sequences that partially repress expression in non-dopaminergic neurons. However, expression of slc6a3 in dopaminergic neurons of the ventral diencephalon and telencephalon is dependent on elements that lie outside the region -6 kb to +5 kb. These data provide a detailed analysis of the slc6a3 gene and show that its expression in different populations of dopamine neurons is driven by discrete enhancers, rather than a single target sequence for a terminal factor involved in specifying neurochemical phenotype.
Collapse
Affiliation(s)
- Q Bai
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15217, USA
| | | |
Collapse
|
16
|
Feijóo CG, Sarrazin AF, Allende ML, Glavic A. Cystein-serine-rich nuclear protein 1, Axud1/Csrnp1, is essential for cephalic neural progenitor proliferation and survival in zebrafish. Dev Dyn 2009; 238:2034-43. [PMID: 19544579 DOI: 10.1002/dvdy.22006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The CSRNP (cystein-serine-rich nuclear protein) family has been conserved from Drosophila to human. Although knockout mice for each of the mammalian proteins have been generated, their function during vertebrate development has remained elusive. As an alternative to obtain insights on CSRNP's role in development, we have analysed the expression pattern and function of one member of this family, axud1, during zebrafish development. Our expression analysis indicates that axud1 is expressed from cleavage to larval stages in a dynamic pattern, becoming restricted after gastrulation to anterior regions of the developing neuraxis and later on concentrated predominantly in proliferating domains of the brain. Knockdown analysis using antisense morpholinos shows that reducing Axud1 levels impairs neural progenitor cell proliferation and survival, revealing an essential function of this gene for the growth of cephalic derivatives. The brain growth phenotypes elicited by decreasing Axud1 expression are specific and independent of anterior-posterior patterning events, initial establishment of neural progenitors, or neural differentiation occurring in this tissue. However, Axud1 is necessary for six3.1 expression and is positively regulated by sonic hedgehog. Phylogenetic examination shows that axud1 is likely to be the ortholog of the only member of this family present in Drosophila, as well as to the previously described mouse CSRNP1 and to human AXUD1 (Axin upregulated-1). Thus, we provide evidence as to the role of axud1 in brain growth in vertebrates.
Collapse
Affiliation(s)
- Carmen G Feijóo
- Center for Genomics of the Cell, Facultad de Ciencias, Universidad Chile, Santiago, Chile
| | | | | | | |
Collapse
|