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Schwarzer S, Spieß S, Brand M, Hans S. Dlx3b/4b is required for early-born but not later-forming sensory hair cells during zebrafish inner ear development. Biol Open 2017; 6:1270-1278. [PMID: 28751305 PMCID: PMC5612237 DOI: 10.1242/bio.026211] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Morpholino-mediated knockdown has shown that the homeodomain transcription factors Dlx3b and Dlx4b are essential for proper induction of the otic-epibranchial progenitor domain (OEPD), as well as subsequent formation of sensory hair cells in the developing zebrafish inner ear. However, increasing use of reverse genetic approaches has revealed poor correlation between morpholino-induced and mutant phenotypes. Using CRISPR/Cas9-mediated mutagenesis, we generated a defined deletion eliminating the entire open reading frames of dlx3b and dlx4b (dlx3b/4b) and investigated a potential phenotypic difference between mutants and morpholino-mediated knockdown. Consistent with previous findings obtained by morpholino-mediated knockdown of Dlx3b and Dlx4b, dlx3b/4b mutants display compromised otic induction, the development of smaller otic vesicles and an elimination of all indications of otic specification when combined with loss of foxi1, a second known OEPD competence factor in zebrafish. Furthermore, sensorigenesis is also affected in dlx3b/4b mutants. However, we find that only early-born sensory hair cells (tether cells), that seed and anchor the formation of otoliths, are affected. Later-forming sensory hair cells are present, indicating that two genetically distinct pathways control the development of early-born and later-forming sensory hair cells. Finally, impairment of early-born sensory hair cell formation in dlx3b/4b mutant embryos reverses the common temporal sequence of neuronal and sensory hair cell specification in zebrafish, resembling the order of cell specification in amniotes; Neurog1 expression before Atoh1 expression. We conclude that the Dlx3b/4b-dependent pathway has been either acquired newly in the fish lineage or lost in other vertebrate species during evolution, and that the events during early inner ear development are remarkably similar in fish and amniotes in the absence of this pathway. Summary: The transcription factors Dlx3b and Dlx4b control the formation of early-born sensory hair cells or tether cells in the developing zebrafish inner ear.
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Affiliation(s)
- Simone Schwarzer
- Technische Universität Dresden, Biotechnology Center and DFG-Center for Regenerative Therapies Dresden Cluster of Excellence, Tatzberg 47-49, 01307 Dresden, Germany
| | - Sandra Spieß
- Technische Universität Dresden, Biotechnology Center and DFG-Center for Regenerative Therapies Dresden Cluster of Excellence, Tatzberg 47-49, 01307 Dresden, Germany
| | - Michael Brand
- Technische Universität Dresden, Biotechnology Center and DFG-Center for Regenerative Therapies Dresden Cluster of Excellence, Tatzberg 47-49, 01307 Dresden, Germany
| | - Stefan Hans
- Technische Universität Dresden, Biotechnology Center and DFG-Center for Regenerative Therapies Dresden Cluster of Excellence, Tatzberg 47-49, 01307 Dresden, Germany
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Schulz-Mirbach T, Ladich F. Diversity of Inner Ears in Fishes: Possible Contribution Towards Hearing Improvements and Evolutionary Considerations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 877:341-91. [DOI: 10.1007/978-3-319-21059-9_16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Renn J, Winkler C. Osterix/Sp7 regulates biomineralization of otoliths and bone in medaka (Oryzias latipes). Matrix Biol 2014; 34:193-204. [PMID: 24407212 DOI: 10.1016/j.matbio.2013.12.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 12/19/2013] [Accepted: 12/20/2013] [Indexed: 12/17/2022]
Abstract
Osterix/Sp7 is a zinc finger transcription factor and critical regulator of osteoblast differentiation, maturation and activity. Osterix expression has also been described in non-skeletal tissues but functional analyses are lacking. In the present study, we show that in the teleost model medaka, osterix is present as two alternatively spliced transcripts, osx_tv1 and osx_tv2. Knock-down of osx_tv1 and/or osx_tv2 results in mineralization loss in early intramembranous bones while cartilage formation is mostly unaffected. Formation of the parasphenoid, the earliest mineralized bone in the medaka skeleton, is impaired and fails to recover at later stages. Ossification of later bones, such as the operculum and cleithrum, is delayed but recovers during further development. In the axial skeleton, formation of the neural arches and centra is strongly delayed. In vivo analyses using osterix:nlGFP and osteocalcin:GFP transgenic medaka and whole mount in situ hybridization suggest that bone defects observed after knock-down of osterix are caused by a delay of osteoblast maturation and activity. Furthermore, we analyzed expression profile and function of osterix during ear and otolith formation. We show that osterix is expressed in otic placodes at the otic vesicle stage and that its knock-down results in a loss of otoliths. Taken together, we show that osterix is required for bone formation in a teleost fish and that its important regulatory functions are conserved between teleosts and mammals. Furthermore, we provide the first functional evidence for a role of Osterix in a non-skeletal tissue, i.e. the otoliths.
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Affiliation(s)
- Jörg Renn
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore; Centre for BioImaging Sciences (CBIS), National University of Singapore, Singapore 117543, Singapore.
| | - Christoph Winkler
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore; Centre for BioImaging Sciences (CBIS), National University of Singapore, Singapore 117543, Singapore.
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Bajoghli B, Aghaallaei N, Jung G, Czerny T. Induction of otic structures by canonical Wnt signalling in medaka. Dev Genes Evol 2009; 219:391-8. [PMID: 19760182 PMCID: PMC2773112 DOI: 10.1007/s00427-009-0302-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 08/30/2009] [Indexed: 12/21/2022]
Abstract
The Wnt family of signalling proteins is known to participate in multiple developmental decisions during embryogenesis. We misexpressed Wnt1 in medaka embryos and observed anterior truncations, similar to those described for ectopic activation of canonical Wnt signalling in other species. Interestingly, when we induced a heat-shock Wnt1 transgenic line exactly at 30% epiboly, we observed multiple ectopic otic vesicles in the truncated embryos. The vesicles then fused, forming a single large ear structure. These "cyclopic ears" filled the complete anterior region of the embryos. The ectopic induction of otic development can be explained by the juxtaposition of hindbrain tissue with anterior ectoderm. Fibroblast growth factor (Fgf) ligands are thought to mediate the otic-inducing properties of the hindbrain. However, signals different from Fgf3 and Fgf8 are necessary to explain the formation of the ectopic ear structures, suggesting that Wnt signalling is involved in the otic induction process in medaka.
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Affiliation(s)
- Baubak Bajoghli
- Department for Biomedical Sciences, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria
- Present Address: Max-Planck Institute of Immunobiology, Stuebeweg 51, 79108 Freiburg, Germany
| | - Narges Aghaallaei
- Department for Biomedical Sciences, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria
- Present Address: Max-Planck Institute of Immunobiology, Stuebeweg 51, 79108 Freiburg, Germany
| | - Gerlinde Jung
- Department for Applied Life Sciences, University of Applied Sciences, FH Campus Wien, Viehmarktgasse 2A, 1030 Vienna, Austria
| | - Thomas Czerny
- Department for Biomedical Sciences, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria
- Department for Applied Life Sciences, University of Applied Sciences, FH Campus Wien, Viehmarktgasse 2A, 1030 Vienna, Austria
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Grimes AC, Kirby ML. The outflow tract of the heart in fishes: anatomy, genes and evolution. JOURNAL OF FISH BIOLOGY 2009; 74:983-1036. [PMID: 20735616 DOI: 10.1111/j.1095-8649.2008.02125.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A large number of congenital heart defects associated with mortality in humans are those that affect the cardiac outflow tract, and this provides a strong imperative to understand its development during embryogenesis. While there is wide phylogenetic variation in adult vertebrate heart morphology, recent work has demonstrated evolutionary conservation in the early processes of cardiogenesis, including that of the outflow tract. This, along with the utility and high reproductive potential of fish species such as Danio rerio, Oryzias latipes etc., suggests that fishes may provide ideal comparative biological models to facilitate a better understanding of this poorly understood region of the heart. In this review, the authors present the current understanding of both phylogeny and ontogeny of the cardiac outflow tract in fishes and examine how new molecular studies are informing the phylogenetic relationships and evolutionary trajectories that have been proposed. The authors also attempt to address some of the issues of nomenclature that confuse this area of research.
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Affiliation(s)
- A C Grimes
- Departamento de Biología del Desarrollo Cardiovascular, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Melchor Fernández Almagro, 3 28029 Madrid, Spain.
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Ramialison M, Bajoghli B, Aghaallaei N, Ettwiller L, Gaudan S, Wittbrodt B, Czerny T, Wittbrodt J. Rapid identification of PAX2/5/8 direct downstream targets in the otic vesicle by combinatorial use of bioinformatics tools. Genome Biol 2008; 9:R145. [PMID: 18828907 PMCID: PMC2760872 DOI: 10.1186/gb-2008-9-10-r145] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 09/29/2008] [Accepted: 10/01/2008] [Indexed: 01/05/2023] Open
Abstract
A novel bioinformatics pipeline is used to discover PAX2/5/8 direct downstream targets involved in inner ear development. Background The pax2/5/8 genes belonging to the PAX family of transcription factors are key developmental regulators that are involved in the patterning of various embryonic tissues. More particularly, their function in inner ear specification has been widely described. However, little is known about the direct downstream targets and, so far, no global approaches have been performed to identify these target genes in this particular tissue. Results Here we present an original bioinformatics pipeline composed of comparative genomics, database querying and text mining tools, which is designed to rapidly and specifically discover PAX2/5/8 direct downstream targets involved in inner ear development. We provide evidence supported by experimental validation in medaka fish that brain 2 (POU domain, class 3, transcription factor 2), claudin-7, secretory pathway component sec31-like and meteorin-like precursor are novel direct downstream targets of PAX2/5/8. Conclusions This study illustrates the power of extensive mining of public data repositories using bioinformatics methods to provide answers for a specific biological question. It furthermore demonstrates how the usage of such a combinatorial approach is advantageous for the biologist in terms of experimentation time and costs.
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Affiliation(s)
- Mirana Ramialison
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg, Germany
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Nemoto Y, Chatani M, Inohaya K, Hiraki Y, Kudo A. Expression of marker genes during otolith development in medaka. Gene Expr Patterns 2007; 8:92-5. [PMID: 17981516 DOI: 10.1016/j.modgep.2007.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 10/02/2007] [Accepted: 10/05/2007] [Indexed: 11/16/2022]
Abstract
Little is known about the genes and processes involved in the development of otoliths. In this study, we isolated the biomineralization-related genes otolin and chondromodulin-1 (chm1) from medaka, and examined their spatiotemporal expression pattern as well as that of two other genes also related to biomineralization, i.e., sparc/osteonectin and type II collagen (col2a), during otic development in medaka. Our results demonstrated that all the tested genes were expressed in the otic vesicle, and that chm1 was exclusively expressed in the semicircular canal of the otic vesicle.
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Affiliation(s)
- Yoshiyuki Nemoto
- Department of Biological Information, Tokyo Institute of Technology, Yokohama 226-8501, Japan
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Aghaallaei N, Bajoghli B, Czerny T. Distinct roles of Fgf8, Foxi1, Dlx3b and Pax8/2 during otic vesicle induction and maintenance in medaka. Dev Biol 2007; 307:408-20. [PMID: 17555740 DOI: 10.1016/j.ydbio.2007.04.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 04/16/2007] [Accepted: 04/17/2007] [Indexed: 10/23/2022]
Abstract
The development of the vertebrate inner ear is a complex process that has been investigated in several model organisms. In this work, we examined genetic interactions regulating early development of otic structures in medaka. We demonstrate that misexpression of Fgf8, Dlx3b and Foxi1 during early gastrulation is sufficient to produce ectopic otic vesicles. Combined misexpression strongly increases the appearance of this phenotype. By using a heat-inducible promoter we were furthermore able to separate the regulatory interactions among Fgf8, Foxi1, Dlx3b, Pax8 and Pax2 genes, which are active during different stages of early otic development. In the preplacodal stage we suggest a central position of Foxi1 within a regulatory network of early patterning genes including Dlx3b and Pax8. Different pathways are active after the placodal stage with Dlx3b playing a central role. There Dlx3b regulates members of the Pax-Six-Eya-Dach network and also strongly affects the early dorsoventral marker genes Otx1 and Gbx2.
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Affiliation(s)
- Narges Aghaallaei
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Veterinärplatz 1, A-1210 Vienna, Austria
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