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Zhang Y, He K, Wang Y, Guo X, Chen J, Shang N, Chen J, Zhang P, Zhang L, Niu Q, Zhang Q. Nano-alumina induced developmental and neurobehavioral toxicity in the early life stage of zebrafish, associated with mTOR. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2024; 276:107086. [PMID: 39277994 DOI: 10.1016/j.aquatox.2024.107086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Revised: 08/30/2024] [Accepted: 09/06/2024] [Indexed: 09/17/2024]
Abstract
The study aims to investigate the effects of nano-alumina (AlNPs) on the early development and neurobehavior of zebrafish and the role of mTOR in this process. After embryos and grown-up larvae exposed to AlNPs from 0 to 200 μg/mL, we examined the development, neurobehavior, AlNPs content, and mTOR pathway genes. Moreover, embryos were randomly administered with control, negative control, mTOR knockdown, AlNPs, and mTOR knockdown + AlNPs, then examined for development, neurobehavior, oxidative stress, neurotransmitters, and development genes. As AlNPs increased, swimming speed and distance initially increased and then decreased; thigmotaxis and panic-avoidance reflex substantially decreased in the high-dose AlNPs group; aluminum and nanoparticles considerably accumulated in the 100 μg/mL AlNPs group; AlNPs at high dose decreased mTOR gene and protein levels, stimulating autophagy via increasing ULK1 and ULK2. mTOR knockdown exacerbated the harm to normal development rate, eye and body length, and neurobehavior induced by AlNPs through raising ROS, SOD, and ACH levels but decreasing AchE activity and development genes. Therefore, AlNPs suppress neurobehavior through downregulating mTOR, and mTOR knockdown further aggravates their early development and neurobehavior loss, suggesting mTOR could be a potential target for the toxicity of AlNPs.
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Affiliation(s)
- Ying Zhang
- Department of Toxicology, Shanxi Provincial Center for Disease Control and Prevention, Taiyuan, 030012, China
| | - Kaihong He
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Yanhong Wang
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Xinyue Guo
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Jin Chen
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Nan Shang
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Jianping Chen
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Ping Zhang
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Ling Zhang
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Qiao Niu
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Qinli Zhang
- Department of Occupational Medicine, School of public health, Shanxi Medical University, Taiyuan, Shanxi, 030001, China; Department of Pathology, University of Mississippi Medical Center, 2500 N State St., Jackson, MS, 39216, United States.
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2
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Huysseune A, Witten PE. Continuous tooth replacement: what can teleost fish teach us? Biol Rev Camb Philos Soc 2024; 99:797-819. [PMID: 38151229 DOI: 10.1111/brv.13045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 12/29/2023]
Abstract
Most tooth-bearing non-mammalian vertebrates have the capacity to replace their teeth throughout life. This capacity was lost in mammals, which replace their teeth only once at most. Not surprisingly, continuous tooth replacement has attracted much attention. Classical morphological studies (e.g. to analyse patterns of replacement) are now being complemented by molecular studies that investigate the expression of genes involved in tooth formation. This review focuses on ray-finned fish (actinopterygians), which have teeth often distributed throughout the mouth and pharynx, and more specifically on teleost fish, the largest group of extant vertebrates. First we highlight the diversity in tooth distribution and in tooth replacement patterns. Replacement tooth formation can start from a distinct (usually discontinuous and transient) dental lamina, but also in the absence of a successional lamina, e.g. from the surface epithelium of the oropharynx or from the outer dental epithelium of a predecessor tooth. The relationship of a replacement tooth to its predecessor is closely related to whether replacement is the result of a prepattern or occurs on demand. As replacement teeth do not necessarily have the same molecular signature as first-generation teeth, the question of the actual trigger for tooth replacement is discussed. Much emphasis has been laid in the past on the potential role of epithelial stem cells in initiating tooth replacement. The outcome of such studies has been equivocal, possibly related to the taxa investigated, and the permanent or transient nature of the dental lamina. Alternatively, replacement may result from local proliferation of undifferentiated progenitors, stimulated by hitherto unknown, perhaps mesenchymal, factors. So far, the role of the neurovascular link in continuous tooth replacement has been poorly investigated, despite the presence of a rich vascularisation surrounding actinopterygian (as well as chondrichthyan) teeth and despite a complete arrest of tooth replacement after nerve resection. Lastly, tooth replacement is possibly co-opted as a process to expand the number of teeth in a dentition ontogenetically whilst conserving features of the primary dentition. That neither a dental lamina, nor stem cells appear to be required for tooth replacement places teleosts in an advantageous position as models for tooth regeneration in humans, where the dental lamina regresses and epithelial stem cells are considered lost.
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Affiliation(s)
- Ann Huysseune
- Research Group Evolutionary Developmental Biology, Biology Department, Ghent University, K.L. Ledeganckstraat 35, Ghent, B-9000, Belgium
- Department of Zoology, Faculty of Science, Charles University, Vinicna 7, Prague, 128 44, Czech Republic
| | - P Eckhard Witten
- Research Group Evolutionary Developmental Biology, Biology Department, Ghent University, K.L. Ledeganckstraat 35, Ghent, B-9000, Belgium
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3
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Tonelli F, Leoni L, Daponte V, Gioia R, Cotti S, Fiedler IAK, Larianova D, Willaert A, Coucke PJ, Villani S, Busse B, Besio R, Rossi A, Witten PE, Forlino A. Zebrafish Tric-b is required for skeletal development and bone cells differentiation. Front Endocrinol (Lausanne) 2023; 14:1002914. [PMID: 36755921 PMCID: PMC9899828 DOI: 10.3389/fendo.2023.1002914] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 01/03/2023] [Indexed: 01/24/2023] Open
Abstract
INTRODUCTION Trimeric intracellular potassium channels TRIC-A and -B are endoplasmic reticulum (ER) integral membrane proteins, involved in the regulation of calcium release mediated by ryanodine (RyRs) and inositol 1,4,5-trisphosphate (IP3Rs) receptors, respectively. While TRIC-A is mainly expressed in excitable cells, TRIC-B is ubiquitously distributed at moderate level. TRIC-B deficiency causes a dysregulation of calcium flux from the ER, which impacts on multiple collagen specific chaperones and modifying enzymatic activity, leading to a rare form of osteogenesis imperfecta (OI Type XIV). The relevance of TRIC-B on cell homeostasis and the molecular mechanism behind the disease are still unknown. RESULTS In this study, we exploited zebrafish to elucidate the role of TRIC-B in skeletal tissue. We demonstrated, for the first time, that tmem38a and tmem38b genes encoding Tric-a and -b, respectively are expressed at early developmental stages in zebrafish, but only the latter has a maternal expression. Two zebrafish mutants for tmem38b were generated by CRISPR/Cas9, one carrying an out of frame mutation introducing a premature stop codon (tmem38b-/- ) and one with an in frame deletion that removes the highly conserved KEV domain (tmem38bΔ120-7/Δ120-7 ). In both models collagen type I is under-modified and partially intracellularly retained in the endoplasmic reticulum, as described in individuals affected by OI type XIV. Tmem38b-/- showed a mild skeletal phenotype at the late larval and juvenile stages of development whereas tmem38bΔ120-7/Δ120-7 bone outcome was limited to a reduced vertebral length at 21 dpf. A caudal fin regeneration study pointed towards impaired activity of osteoblasts and osteoclasts associated with mineralization impairment. DISCUSSION Our data support the requirement of Tric-b during early development and for bone cell differentiation.
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Affiliation(s)
- Francesca Tonelli
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Laura Leoni
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Valentina Daponte
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Roberta Gioia
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Silvia Cotti
- Department of Biology, Ghent University, Ghent, Belgium
| | - Imke A. K. Fiedler
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Andy Willaert
- Department of Biomolecular Medicine, Center of Medical Genetics, Ghent University-University Hospital, Ghent, Belgium
| | - Paul J. Coucke
- Department of Biomolecular Medicine, Center of Medical Genetics, Ghent University-University Hospital, Ghent, Belgium
| | - Simona Villani
- Department of Public Health and Experimental and Forensic Medicine, Unit of Biostatistics and Clinical Epidemiology, University of Pavia, Pavia, Italy
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Roberta Besio
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Antonio Rossi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | | | - Antonella Forlino
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
- *Correspondence: Antonella Forlino,
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4
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Gu Q, Yuan H, Zhong H, Wei Z, Shu Y, Wang J, Ren L, Gong D, Liu S. Spatiotemporal characteristics of the pharyngeal teeth in interspecific distant hybrids of cyprinid fish: Phylogeny and expression of the initiation marker genes. Front Genet 2022; 13:983444. [PMID: 36051700 PMCID: PMC9424816 DOI: 10.3389/fgene.2022.983444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 07/19/2022] [Indexed: 11/17/2022] Open
Abstract
As an important feeding organ and taxonomical characteristic, the pharyngeal teeth of cyprinid fish have very high morphological diversity and exhibit species-specific numbers and arrangements. Many genes have been verified to regulate the pharyngeal teeth development and act as the initiation marker for teeth. Six initiation marker genes for pharyngeal teeth were used as RNA probes to investigate the expression pattern, and these genes were further used to construct a phylogenetic tree for cyprinid fish including some distant hybrids. The results from in situ hybridization showed that similarities and differences existed in the expression of dlx2b, dlx4b, dlx5a, pitx2, fth1b, and scpp5 in the pharyngeal region of the hybrids (BT) by the crosses of blunt snout bream (BSB, ♀) × topmouth culter (TC, ♂). Particularly, we found a high specificity marker gene scpp5 for the early development of pharyngeal teeth. The Scpp5 expression pattern established a clear graphic representation on the spatiotemporal characteristics of the early morphogenesis of pharyngeal teeth in BT and BSB. Our results suggested that the scpp5 expression in 4V1, 3V1, and 5V1 in BT occurred earlier than that in BSB, while the replacement rate of pharyngeal teeth (4V2, 3V2, and 5V2) was faster in BSB. Phylogenetic analysis revealed that the six marker genes were highly conserved and could be used as the molecular marker for identifying the parents of the distant hybrids in cyprinid fish. The expression patterns of the scpp5 gene was examined in various tissues, including the brain, gill, heart, liver, muscle, skin, fins, gonad, eye, and kidney, showing that the scpp5 gene was ubiquitously expressed, indicating its important role in cyprinid fish.
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Affiliation(s)
- Qianhong Gu
- The State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Hui Yuan
- The State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Hui Zhong
- The State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Zehong Wei
- The State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Yuqin Shu
- The State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Jing Wang
- The State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Li Ren
- The State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Dingbin Gong
- The State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Shaojun Liu
- The State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
- *Correspondence: Shaojun Liu,
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5
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Huysseune A, Soenens M, Sire JY, Witten PE. High-Resolution Histology for Craniofacial Studies on Zebrafish and Other Teleost Models. Methods Mol Biol 2022; 2403:249-262. [PMID: 34913128 DOI: 10.1007/978-1-0716-1847-9_17] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In the era of molecular biology, identification of cells and even tissues mostly relies on the presence of fluorescent tags, or of "marker gene" expression. We list a number of caveats and present a protocol for embedding, sectioning, and staining semithin plastic sections. The method is neither new nor innovative, but is meant to revive skills that tend to get lost.This easy-to-use and inexpensive protocol (1) yields high-resolution images in transmitted and polarized light, (2) can be utilized simultaneously for transmission electron microscopy, and (3) is applicable to any type of material (wild type, morphants, mutants, transgenic, or pharmacologically treated animals as well as all of their controls), provided the sample size is kept under a limit. Thus, we hope to encourage researchers to use microanatomy and histology to complement molecular studies investigating, e.g., gene function.
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Affiliation(s)
- A Huysseune
- Biology Department, Research Group Evolutionary Developmental Biology, Ghent University, Ghent, Belgium.
| | - M Soenens
- Biology Department, Research Group Evolutionary Developmental Biology, Ghent University, Ghent, Belgium
| | - J-Y Sire
- Université Pierre et Marie Curie, UMR 7138-Evolution Paris Seine, Paris, France
| | - P E Witten
- Biology Department, Research Group Evolutionary Developmental Biology, Ghent University, Ghent, Belgium
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6
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Rosa JT, Witten PE, Huysseune A. Cells at the Edge: The Dentin-Bone Interface in Zebrafish Teeth. Front Physiol 2021; 12:723210. [PMID: 34690799 PMCID: PMC8526719 DOI: 10.3389/fphys.2021.723210] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 09/08/2021] [Indexed: 11/13/2022] Open
Abstract
Bone-producing osteoblasts and dentin-producing odontoblasts are closely related cell types, a result from their shared evolutionary history in the ancient dermal skeleton. In mammals, the two cell types can be distinguished based on histological characters and the cells’ position in the pulp cavity or in the tripartite periodontal complex. Different from mammals, teleost fish feature a broad diversity in tooth attachment modes, ranging from fibrous attachment to firm ankylosis to the underlying bone. The connection between dentin and jaw bone is often mediated by a collar of mineralized tissue, a part of the dental unit that has been termed “bone of attachment”. Its nature (bone, dentin, or an intermediate tissue type) is still debated. Likewise, there is a debate about the nature of the cells secreting this tissue: osteoblasts, odontoblasts, or yet another (intermediate) type of scleroblast. Here, we use expression of the P/Q rich secretory calcium-binding phosphoprotein 5 (scpp5) to characterize the cells lining the so-called bone of attachment in the zebrafish dentition. scpp5 is expressed in late cytodifferentiation stage odontoblasts but not in the cells depositing the “bone of attachment”. nor in bona fide osteoblasts lining the supporting pharyngeal jaw bone. Together with the presence of the osteoblast marker Zns-5, and the absence of covering epithelium, this links the cells depositing the “bone of attachment” to osteoblasts rather than to odontoblasts. The presence of dentinal tubule-like cell extensions and the near absence of osteocytes, nevertheless distinguishes the “bone of attachment” from true bone. These results suggest that the “bone of attachment” in zebrafish has characters intermediate between bone and dentin, and, as a tissue, is better termed “dentinous bone”. In other teleosts, the tissue may adopt different properties. The data furthermore support the view that these two tissues are part of a continuum of mineralized tissues. Expression of scpp5 can be a valuable tool to investigate how differentiation pathways diverge between osteoblasts and odontoblasts in teleost models and help resolving the evolutionary history of tooth attachment structures in actinopterygians.
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Affiliation(s)
- Joana T Rosa
- Research Group Evolutionary Developmental Biology, Biology Department, Ghent University, Ghent, Belgium.,Comparative, Adaptive and Functional Skeletal Biology (BIOSKEL), Centre of Marine Sciences (CCMAR), University of Algarve, Campus Gambelas, Faro, Portugal
| | - Paul Eckhard Witten
- Research Group Evolutionary Developmental Biology, Biology Department, Ghent University, Ghent, Belgium
| | - Ann Huysseune
- Research Group Evolutionary Developmental Biology, Biology Department, Ghent University, Ghent, Belgium
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7
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Oralová V, Rosa JT, Soenens M, Bek JW, Willaert A, Witten PE, Huysseune A. Beyond the whole-mount phenotype: high-resolution imaging in fluorescence-based applications on zebrafish. Biol Open 2019; 8:8/5/bio042374. [PMID: 31126903 PMCID: PMC6550072 DOI: 10.1242/bio.042374] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Zebrafish is now widely used in biomedical research as a model for human diseases, but the relevance of the model depends on a rigorous analysis of the phenotypes obtained. Many zebrafish disease models, experimental techniques and manipulations take advantage of fluorescent reporter molecules. However, phenotypic analysis often does not go beyond establishing overall distribution patterns of the fluorophore in whole-mount embryos or using vibratome or paraffin sections with poor preservation of tissue architecture and limited resolution. Obtaining high-resolution data of fluorescent signals at the cellular level from internal structures mostly depends on the availability of expensive imaging technology. Here, we propose a new and easily applicable protocol for embedding and sectioning of zebrafish embryos using in-house prepared glycol methacrylate (GMA) plastic that is suited for preservation of fluorescent signals (including photoactivatable fluorophores) without the need for antibodies. Four main approaches are described, all involving imaging fluorescent signals on semithin (3 µm or less) sections. These include sectioning transgenic animals, whole-mount immunostained embryos, cell tracking, as well as on-section enzyme histochemistry.
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Affiliation(s)
- Veronika Oralová
- Evolutionary Developmental Biology, Biology Department, Ghent University, 9000 Ghent, Belgium.,Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 602 00 Brno2, Czech Republic
| | - Joana T Rosa
- Evolutionary Developmental Biology, Biology Department, Ghent University, 9000 Ghent, Belgium.,Center of Marine Sciences (CCMAR), University of Algarve, 8005-139 Faro, Portugal
| | - Mieke Soenens
- Evolutionary Developmental Biology, Biology Department, Ghent University, 9000 Ghent, Belgium
| | - Jan Willem Bek
- Center for Medical Genetics Ghent, Ghent University, 9000 Ghent, Belgium
| | - Andy Willaert
- Center for Medical Genetics Ghent, Ghent University, 9000 Ghent, Belgium
| | - Paul Eckhard Witten
- Evolutionary Developmental Biology, Biology Department, Ghent University, 9000 Ghent, Belgium
| | - Ann Huysseune
- Evolutionary Developmental Biology, Biology Department, Ghent University, 9000 Ghent, Belgium
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8
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Verstraeten B, van Hengel J, Huysseune A. Beta-Catenin and Plakoglobin Expression during Zebrafish Tooth Development and Replacement. PLoS One 2016; 11:e0148114. [PMID: 26938059 PMCID: PMC4777446 DOI: 10.1371/journal.pone.0148114] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 02/17/2016] [Indexed: 11/18/2022] Open
Abstract
We analyzed the protein distribution of two cadherin-associated molecules, plakoglobin and β-catenin, during the different stages of tooth development and tooth replacement in zebrafish. Plakoglobin was detected at the plasma membrane already at the onset of tooth development in the epithelial cells of the tooth. This pattern remained unaltered during further tooth development. The mesenchymal cells only showed plakoglobin from cytodifferentiation onwards. Plakoglobin 1a morpholino-injected embryos showed normal tooth development with proper initiation and differentiation. Although plakoglobin is clearly present during normal odontogenesis, the loss of plakoglobin 1a does not influence tooth development. β-catenin was found at the cell borders of all cells of the successional lamina but also in the nuclei of surrounding mesenchymal cells. Only membranous, not nuclear, β-catenin, was found during morphogenesis stage. However, during cytodifferentiation stage, both nuclear and membrane-bound β-catenin was detected in the layers of the enamel organ as well as in the differentiating odontoblasts. Nuclear β-catenin is an indication of an activated Wnt pathway, therefore suggesting a possible role for Wnt signalling during zebrafish tooth development and replacement.
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Affiliation(s)
| | - Jolanda van Hengel
- Molecular Cell Biology Unit, Department for Molecular Biomedical Research, VIB Ghent, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Ann Huysseune
- Evolutionary Developmental Biology, Ghent University, Ghent, Belgium
- * E-mail:
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9
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Gistelinck C, Gioia R, Gagliardi A, Tonelli F, Marchese L, Bianchi L, Landi C, Bini L, Huysseune A, Witten PE, Staes A, Gevaert K, De Rocker N, Menten B, Malfait F, Leikin S, Carra S, Tenni R, Rossi A, De Paepe A, Coucke P, Willaert A, Forlino A. Zebrafish Collagen Type I: Molecular and Biochemical Characterization of the Major Structural Protein in Bone and Skin. Sci Rep 2016; 6:21540. [PMID: 26876635 PMCID: PMC4753508 DOI: 10.1038/srep21540] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 01/26/2016] [Indexed: 12/27/2022] Open
Abstract
Over the last years the zebrafish imposed itself as a powerful model to study skeletal diseases, but a limit to its use is the poor characterization of collagen type I, the most abundant protein in bone and skin. In tetrapods collagen type I is a trimer mainly composed of two α1 chains and one α2 chain, encoded by COL1A1 and COL1A2 genes, respectively. In contrast, in zebrafish three type I collagen genes exist, col1a1a, col1a1b and col1a2 coding for α1(I), α3(I) and α2(I) chains. During embryonic and larval development the three collagen type I genes showed a similar spatio-temporal expression pattern, indicating their co-regulation and interdependence at these stages. In both embryonic and adult tissues, the presence of the three α(I) chains was demonstrated, although in embryos α1(I) was present in two distinct glycosylated states, suggesting a developmental-specific collagen composition. Even though in adult bone, skin and scales equal amounts of α1(I), α3(I) and α2(I) chains are present, the presented data suggest a tissue-specific stoichiometry and/or post-translational modification status for collagen type I. In conclusion, this data will be useful to properly interpret results and insights gained from zebrafish models of skeletal diseases.
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Affiliation(s)
- C Gistelinck
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - R Gioia
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - A Gagliardi
- Functional Proteomics Lab., Department of Life Sciences, University of Siena, Siena, Italy
| | - F Tonelli
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - L Marchese
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - L Bianchi
- Functional Proteomics Lab., Department of Life Sciences, University of Siena, Siena, Italy
| | - C Landi
- Functional Proteomics Lab., Department of Life Sciences, University of Siena, Siena, Italy
| | - L Bini
- Functional Proteomics Lab., Department of Life Sciences, University of Siena, Siena, Italy
| | - A Huysseune
- Biology Department, Ghent University, Ghent, Belgium
| | - P E Witten
- Biology Department, Ghent University, Ghent, Belgium
| | - A Staes
- Department of Medical Protein Research, VIB, Ghent, Belgium.,Department of Biochemistry, Ghent University, Ghent, Belgium
| | - K Gevaert
- Department of Medical Protein Research, VIB, Ghent, Belgium.,Department of Biochemistry, Ghent University, Ghent, Belgium
| | - N De Rocker
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - B Menten
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - F Malfait
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - S Leikin
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - S Carra
- Department of Biosciences, University of Milano, Milan, Italy
| | - R Tenni
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - A Rossi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - A De Paepe
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - P Coucke
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - A Willaert
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - A Forlino
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
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10
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Sharma P, Das De T, Sharma S, Kumar Mishra A, Thomas T, Verma S, Kumari V, Lata S, Singh N, Valecha N, Chand Pandey K, Dixit R. Deep sequencing revealed molecular signature of horizontal gene transfer of plant like transcripts in the mosquito Anopheles culicifacies: an evolutionary puzzle. F1000Res 2015; 4:1523. [PMID: 26998230 PMCID: PMC4786938 DOI: 10.12688/f1000research.7534.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/15/2015] [Indexed: 02/05/2023] Open
Abstract
In prokaryotes, horizontal gene transfer (HGT) has been regarded as an important evolutionary drive to acquire and retain beneficial genes for their survival in diverse ecologies. However, in eukaryotes, the functional role of HGTs remains questionable, although current genomic tools are providing increased evidence of acquisition of novel traits within non-mating metazoan species. Here, we provide another transcriptomic evidence for the acquisition of massive plant genes in the mosquito, Anopheles culicifacies. Our multiple experimental validations including genomic PCR, RT-PCR, real-time PCR, immuno-blotting and immuno-florescence microscopy, confirmed that plant like transcripts (PLTs) are of mosquito origin and may encode functional proteins. A comprehensive molecular analysis of the PLTs and ongoing metagenomic analysis of salivary microbiome provide initial clues that mosquitoes may have survival benefits through the acquisition of nuclear as well as chloroplast encoded plant genes. Our findings of PLTs further support the similar questionable observation of HGTs in other higher organisms, which is still a controversial and debatable issue in the community of evolutionists. We believe future understanding of the underlying mechanism of the feeding associated molecular responses may shed new insights in the functional role of PLTs in the mosquito.
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Affiliation(s)
- Punita Sharma
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India; Nano and Biotechnology Department, Guru Jambheshwar University, Haryana, India
| | - Tanwee Das De
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India
| | - Swati Sharma
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India
| | | | - Tina Thomas
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India
| | - Sonia Verma
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India
| | - Vandana Kumari
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India
| | - Suman Lata
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India
| | - Namita Singh
- Nano and Biotechnology Department, Guru Jambheshwar University, Haryana, India
| | - Neena Valecha
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India
| | - Kailash Chand Pandey
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India
| | - Rajnikant Dixit
- Host-Parasite Interaction Biology Group, National Institute of Malaria Research, Delhi, India
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11
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Genetic Defects in TAPT1 Disrupt Ciliogenesis and Cause a Complex Lethal Osteochondrodysplasia. Am J Hum Genet 2015; 97:521-34. [PMID: 26365339 DOI: 10.1016/j.ajhg.2015.08.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 08/18/2015] [Indexed: 11/22/2022] Open
Abstract
The evolutionarily conserved transmembrane anterior posterior transformation 1 protein, encoded by TAPT1, is involved in murine axial skeletal patterning, but its cellular function remains unknown. Our study demonstrates that TAPT1 mutations underlie a complex congenital syndrome, showing clinical overlap between lethal skeletal dysplasias and ciliopathies. This syndrome is characterized by fetal lethality, severe hypomineralization of the entire skeleton and intra-uterine fractures, and multiple congenital developmental anomalies affecting the brain, lungs, and kidneys. We establish that wild-type TAPT1 localizes to the centrosome and/or ciliary basal body, whereas defective TAPT1 mislocalizes to the cytoplasm and disrupts Golgi morphology and trafficking and normal primary cilium formation. Knockdown of tapt1b in zebrafish induces severe craniofacial cartilage malformations and delayed ossification, which is shown to be associated with aberrant differentiation of cranial neural crest cells.
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12
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Bruneel B, Mathä M, Paesen R, Ameloot M, Weninger WJ, Huysseune A. Imaging the zebrafish dentition: from traditional approaches to emerging technologies. Zebrafish 2015; 12:1-10. [PMID: 25560992 PMCID: PMC4298156 DOI: 10.1089/zeb.2014.0980] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The zebrafish, a model organism for which a plethora of molecular and genetic techniques exists, has a lifelong replacing dentition of 22 pharyngeal teeth. This is in contrast to the mouse, which is the key organism in dental research but whose teeth are never replaced. Employing the zebrafish as the main organism to elucidate the mechanisms of continuous tooth replacement, however, poses at least one major problem, related to the fact that all teeth are located deep inside the body. Investigating tooth replacement thus relies on conventional histological methods, which are often laborious, time-consuming and can cause tissue deformations. In this review, we investigate the advantages and limitations of adapting current visualization techniques to dental research in zebrafish. We discuss techniques for fast sectioning, such as vibratome sectioning and high-resolution episcopic microscopy, and methods for in toto visualization, such as Alizarin red staining, micro-computed tomography, and optical projection tomography. Techniques for in vivo imaging, such as two-photon excitation fluorescence and second harmonic generation microscopy, are also covered. Finally, the possibilities of light sheet microscopy are addressed.
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Affiliation(s)
- Bart Bruneel
- Evolutionary Developmental Biology, Ghent University, Ghent, Belgium
| | - Markus Mathä
- IMG Centre for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Rik Paesen
- BIOMED, University Hasselt and Transnational University Limburg, Diepenbeek, Belgium
| | - Marcel Ameloot
- BIOMED, University Hasselt and Transnational University Limburg, Diepenbeek, Belgium
| | - Wolfgang J. Weninger
- IMG Centre for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Ann Huysseune
- Evolutionary Developmental Biology, Ghent University, Ghent, Belgium
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13
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Huysseune A, Soenens M, Elderweirdt F. Wnt signaling during tooth replacement in zebrafish (Danio rerio): pitfalls and perspectives. Front Physiol 2014; 5:386. [PMID: 25339911 PMCID: PMC4186270 DOI: 10.3389/fphys.2014.00386] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 09/18/2014] [Indexed: 12/24/2022] Open
Abstract
The canonical (β-catenin dependent) Wnt signaling pathway has emerged as a likely candidate for regulating tooth replacement in continuously renewing dentitions. So far, the involvement of canonical Wnt signaling has been experimentally demonstrated predominantly in amniotes. These studies tend to show stimulation of tooth formation by activation of the Wnt pathway, and inhibition of tooth formation when blocking the pathway. Here, we report a strong and dynamic expression of the soluble Wnt inhibitor dickkopf1 (dkk1) in developing zebrafish (Danio rerio) tooth germs, suggesting an active repression of Wnt signaling during morphogenesis and cytodifferentiation of a tooth, and derepression of Wnt signaling during start of replacement tooth formation. To further analyse the role of Wnt signaling, we used different gain-of-function approaches. These yielded disjunct results, yet none of them indicating enhanced tooth replacement. Thus, masterblind (mbl) mutants, defective in axin1, mimic overexpression of Wnt, but display a normally patterned dentition in which teeth are replaced at the appropriate times and positions. Activating the pathway with LiCl had variable outcomes, either resulting in the absence, or the delayed formation, of first-generation teeth, or yielding a regular dentition with normal replacement, but no supernumerary teeth or accelerated tooth replacement. The failure so far to influence tooth replacement in the zebrafish by perturbing Wnt signaling is discussed in the light of (i) potential technical pitfalls related to dose- or time-dependency, (ii) the complexity of the canonical Wnt pathway, and (iii) species-specific differences in the nature and activity of pathway components. Finally, we emphasize the importance of in-depth knowledge of the wild-type pattern for reliable interpretations. It is hoped that our analysis can be inspiring to critically assess and elucidate the role of Wnt signaling in tooth development in polyphyodonts.
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Affiliation(s)
- Ann Huysseune
- Evolutionary Developmental Biology Research Group, Biology Department, Ghent University Ghent, Belgium
| | - Mieke Soenens
- Evolutionary Developmental Biology Research Group, Biology Department, Ghent University Ghent, Belgium
| | - Fien Elderweirdt
- Evolutionary Developmental Biology Research Group, Biology Department, Ghent University Ghent, Belgium
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14
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Vijayakumar P, Laizé V, Cardeira J, Trindade M, Cancela ML. Development of an in vitro cell system from zebrafish suitable to study bone cell differentiation and extracellular matrix mineralization. Zebrafish 2013; 10:500-9. [PMID: 23909483 PMCID: PMC3842872 DOI: 10.1089/zeb.2012.0833] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mechanisms of bone formation and skeletal development have been successfully investigated in zebrafish using a variety of in vivo approaches, but in vitro studies have been hindered due to a lack of homologous cell lines capable of producing an extracellular matrix (ECM) suitable for mineral deposition. Here we describe the development and characterization of a new cell line termed ZFB1, derived from zebrafish calcified tissues. ZFB1 cells have an epithelium-like phenotype, grow at 28°C in a regular L-15 medium supplemented with 15% of fetal bovine serum, and are maintained and manipulated using standard methods (e.g., trypsinization, cryopreservation, and transfection). They can therefore be propagated and maintained easily in most cell culture facilities. ZFB1 cells show aneuploidy with 2n=78 chromosomes, indicative of cell transformation. Furthermore, because DNA can be efficiently delivered into their intracellular space by nucleofection, ZFB1 cells are suitable for gene targeting approaches and for assessing gene promoter activity. ZFB1 cells can also differentiate toward osteoblast or chondroblast lineages, as demonstrated by expression of osteoblast- and chondrocyte-specific markers, they exhibit an alkaline phosphatase activity, a marker of bone formation in vivo, and they can mineralize their ECM. Therefore, they represent a valuable zebrafish-derived in vitro system for investigating bone cell differentiation and extracellular matrix mineralization.
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Affiliation(s)
- Parameswaran Vijayakumar
- Centre of Marine Sciences (CCMAR/CIMAR-LA), University of Algarve, Campus de Gambelas, Faro, Portugal
| | - Vincent Laizé
- Centre of Marine Sciences (CCMAR/CIMAR-LA), University of Algarve, Campus de Gambelas, Faro, Portugal
| | - João Cardeira
- Centre of Marine Sciences (CCMAR/CIMAR-LA), University of Algarve, Campus de Gambelas, Faro, Portugal
| | - Marlene Trindade
- Centre of Marine Sciences (CCMAR/CIMAR-LA), University of Algarve, Campus de Gambelas, Faro, Portugal
| | - M. Leonor Cancela
- Centre of Marine Sciences (CCMAR/CIMAR-LA), University of Algarve, Campus de Gambelas, Faro, Portugal
- Department of Biomedical Sciences and Medicine (DCBM), University of Algarve, Faro, Portugal
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15
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"Zebrafishing" for novel genes relevant to the glomerular filtration barrier. BIOMED RESEARCH INTERNATIONAL 2013; 2013:658270. [PMID: 24106712 PMCID: PMC3784067 DOI: 10.1155/2013/658270] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 07/15/2013] [Indexed: 01/09/2023]
Abstract
Data for genes relevant to glomerular filtration barrier function or proteinuria is continually increasing in an era of microarrays, genome-wide association studies, and quantitative trait locus analysis. Researchers are limited by published literature searches to select the most relevant genes to investigate. High-throughput cell cultures and other in vitro systems ultimately need to demonstrate proof in an in vivo model. Generating mammalian models for the genes of interest is costly and time intensive, and yields only a small number of test subjects. These models also have many pitfalls such as possible embryonic mortality and failure to generate phenotypes or generate nonkidney specific phenotypes. Here we describe an in vivo zebrafish model as a simple vertebrate screening system to identify genes relevant to glomerular filtration barrier function. Using our technology, we are able to screen entirely novel genes in 4–6 weeks in hundreds of live test subjects at a fraction of the cost of a mammalian model. Our system produces consistent and reliable evidence for gene relevance in glomerular kidney disease; the results then provide merit for further analysis in mammalian models.
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16
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Hosen MJ, Vanakker OM, Willaert A, Huysseune A, Coucke P, De Paepe A. Zebrafish models for ectopic mineralization disorders: practical issues from morpholino design to post-injection observations. Front Genet 2013; 4:74. [PMID: 23760765 PMCID: PMC3669896 DOI: 10.3389/fgene.2013.00074] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 04/15/2013] [Indexed: 01/06/2023] Open
Abstract
Zebrafish (ZF, Danio rerio) has emerged as an important and popular model species to study different human diseases. Key regulators of skeletal development and calcium metabolism are highly conserved between mammals and ZF. The corresponding orthologs share significant sequence similarities and an overlap in expression patterns when compared to mammals, making ZF a potential model for the study of mineralization-related disorders and soft tissue mineralization. To characterize the function of early mineralization-related genes in ZF, these genes can be knocked down by injecting morpholinos into early stage embryos. Validation of the morpholino needs to be performed and the concern of aspecific effects can be addressed by applying one or more independent techniques to knock down the gene of interest. Post-injection assessment of early mineralization defects can be done using general light microscopy, calcein staining, Alizarin red staining, Alizarin red-Alcian blue double staining, and by the use of transgenic lines. Examination of general molecular defects can be done by performing protein and gene expression analysis, and more specific processes can be explored by investigating ectopic mineralization-related mechanisms such as apoptosis and mitochondrial dysfunction. In this paper, we will discuss all details about the aforementioned techniques; shared knowledge will be very useful for the future investigation of ZF models for ectopic mineralization disorders and to understand the underlying pathways involved in soft tissue calcification.
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Affiliation(s)
- Mohammad Jakir Hosen
- Center for Medical Genetics, Ghent University Hospital Ghent, Belgium ; Department of Genetic Engineering and Biotechnology, Shahjalal University of Science and Technology Sylhet, Bangladesh
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17
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Verstraeten B, van Hengel J, Sanders E, Van Roy F, Huysseune A. N-cadherin is required for cytodifferentiation during zebrafish odontogenesis. J Dent Res 2013; 92:365-70. [PMID: 23396519 DOI: 10.1177/0022034513477424] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
N-cadherin is a well-studied classic cadherin involved in multiple developmental processes and is also known to have a signaling function. Using the zebrafish (Danio rerio) as a model, we tested the hypothesis that tooth morphogenesis is accompanied by dynamic changes in N-cadherin distribution and that absence of N-cadherin disturbs tooth development. N-cadherin, encoded by the gene cdh2, is absent during the initiation and morphogenesis stages of both primary (first-generation) and replacement teeth, as demonstrated by immunohistochemistry. However, N-cadherin is up-regulated at the onset of differentiation of cells of the inner dental epithelium and the dental papilla, i.e., the ameloblasts and odontoblasts, respectively. In the inner dental epithelium, N-cadherin is co-expressed with E-cadherin, excluding the occurrence of cadherin switching such as observed during human tooth development. While early lethality of N-cadherin knockout mice prevents any functional study of N-cadherin in mouse odontogenesis, zebrafish parachute (pac) mutants, deficient for N-cadherin, survive beyond the age when primary teeth normally start to form. In these mutants, the first tooth forms, but its development stops at the early cytodifferentiation stage. N-cadherin deficiency also completely inhibits the development of the other first-generation teeth, possibly due to the absence of N-cadherin signaling once the first tooth has differentiated.
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Affiliation(s)
- B Verstraeten
- Evolutionary Developmental Biology, Ghent University, Belgium
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18
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Bensimon-Brito A, Cardeira J, Cancela ML, Huysseune A, Witten PE. Distinct patterns of notochord mineralization in zebrafish coincide with the localization of Osteocalcin isoform 1 during early vertebral centra formation. BMC DEVELOPMENTAL BIOLOGY 2012; 12:28. [PMID: 23043290 PMCID: PMC3517302 DOI: 10.1186/1471-213x-12-28] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 10/03/2012] [Indexed: 11/10/2022]
Abstract
BACKGROUND In chondrichthyans, basal osteichthyans and tetrapods, vertebral bodies have cartilaginous anlagen that subsequently mineralize (chondrichthyans) or ossify (osteichthyans). Chondrocytes that form the vertebral centra derive from somites. In teleost fish, vertebral centrum formation starts in the absence of cartilage, through direct mineralization of the notochord sheath. In a second step, the notochord is surrounded by somite-derived intramembranous bone. In several small teleost species, including zebrafish (Danio rerio), even haemal and neural arches form directly as intramembranous bone and only modified caudalmost arches remain cartilaginous. This study compares initial patterns of mineralization in different regions of the vertebral column in zebrafish. We ask if the absence or presence of cartilaginous arches influences the pattern of notochord sheath mineralization. RESULTS To reveal which cells are involved in mineralization of the notochord sheath we identify proliferating cells, we trace mineralization on the histological level and we analyze cell ultrastructure by TEM. Moreover, we localize proteins and genes that are typically expressed by skeletogenic cells such as Collagen type II, Alkaline phosphatase (ALP) and Osteocalcin (Oc). Mineralization of abdominal and caudal vertebrae starts with a complete ring within the notochord sheath and prior to the formation of the bony arches. In contrast, notochord mineralization of caudal fin centra starts with a broad ventral mineral deposition, associated with the bases of the modified cartilaginous arches. Similar, arch-related, patterns of mineralization occur in teleosts that maintain cartilaginous arches throughout the spine.Throughout the entire vertebral column, we were able to co-localize ALP-positive signal with chordacentrum mineralization sites, as well as Collagen II and Oc protein accumulation in the mineralizing notochord sheath. In the caudal fin region, ALP and Oc signals were clearly produced both by the notochord epithelium and cells outside the notochord, the cartilaginous arches. Based on immunostaining, real time PCR and oc2:gfp transgenic fish, we identify Oc in the mineralizing notochord sheath as osteocalcin isoform 1 (Oc1). CONCLUSIONS If notochord mineralization occurs prior to arch formation, mineralization of the notochord sheath is ring-shaped. If notochord mineralization occurs after cartilaginous arch formation, mineralization of the notochord sheath starts at the insertion point of the arches, with a basiventral origin. The presence of ALP and Oc1, not only in cells outside the notochord, but also in the notochord epithelium, suggests an active role of the notochord in the mineralization process. The same may apply to Col II-positive chondrocytes of the caudalmost haemal arches that show ALP activity and Oc1 accumulation, since these chondrocytes do not mineralize their own cartilage matrix. Even without cartilaginous preformed vertebral centra, the cartilaginous arches may have an inductive role in vertebral centrum formation, possibly contributing to the distinct mineralization patterns of zebrafish vertebral column and caudal fin vertebral fusion.
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