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García-García RD, Garay-Pacheco E, Marín-Llera JC, Chimal-Monroy J. Recombinant Limb Assay as in Vivo Organoid Model. Front Cell Dev Biol 2022; 10:863140. [PMID: 35557939 PMCID: PMC9086426 DOI: 10.3389/fcell.2022.863140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Organ formation initiates once cells become committed to one of the three embryonic germ layers. In the early stages of embryogenesis, different gene transcription networks regulate cell fate after each germ layer is established, thereby directing the formation of complex tissues and functional organs. These events can be modeled in vitro by creating organoids from induced pluripotent, embryonic, or adult stem cells to study organ formation. Under these conditions, the induced cells are guided down the developmental pathways as in embryonic development, resulting in an organ of a smaller size that possesses the essential functions of the organ of interest. Although organoids are widely studied, the formation of skeletal elements in an organoid model has not yet been possible. Therefore, we suggest that the formation of skeletal elements using the recombinant limb (RL) assay system can serve as an in vivo organoid model. RLs are formed from undissociated or dissociated-reaggregated undifferentiated mesodermal cells introduced into an ectodermal cover obtained from an early limb bud. Next, this filled ectoderm is grafted into the back of a donor chick embryo. Under these conditions, the cells can receive the nascent embryonic signals and develop complex skeletal elements. We propose that the formation of skeletal elements induced through the RL system may occur from stem cells or other types of progenitors, thus enabling the study of morphogenetic properties in vivo from these cells for the first time.
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Affiliation(s)
- Roberto Damián García-García
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, México
| | - Estefanía Garay-Pacheco
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, México
| | - Jessica Cristina Marín-Llera
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, México
| | - Jesús Chimal-Monroy
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, México
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Hota J, Mahapatra PK. FGF2 and FGF10 expression patterns in the epidermis and mesenchyme during homeotic transformation of tail into hindlimbs in frog tadpoles. Acta Histochem 2022; 124:151836. [PMID: 34968793 DOI: 10.1016/j.acthis.2021.151836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 11/21/2021] [Accepted: 12/17/2021] [Indexed: 11/28/2022]
Abstract
Limbs are trunk quintessential in tetrapods. Their development relies on the Retinoic acid (RA) gradient in association with the Fibroblast Growth Factors (FGFs). The role of various FGFs have been probed extensively and confirmed during the induction of ectopic limbs in vertebrates. On such factual backdrops, we studied the expression patterns of FGF2 and FGF10 in the epidermis and mesenchyme by immunohistochemical localization in the regenerating tails of tadpoles of the Indian tree frog, Polypedates maculatus. These tadpoles are known to exhibit a kind of homeotic transformation of tail to limbs during regeneration, whose exact mechanism is still to be established by scientific investigations. Here in this study, we provide the first evidence of the putative involvement of FGF2 and FGF10 during such ectopic appendage development.
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Affiliation(s)
- Jutshina Hota
- Cell and Developmental Biology Laboratory, P.G. Department of Zoology, Utkal University, Vani Vihar, Bhubaneswar, Odisha 751004, India
| | - Pravati Kumari Mahapatra
- Cell and Developmental Biology Laboratory, P.G. Department of Zoology, Utkal University, Vani Vihar, Bhubaneswar, Odisha 751004, India.
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Fernandez-Guerrero M, Zdral S, Castilla-Ibeas A, Lopez-Delisle L, Duboule D, Ros MA. Time-sequenced transcriptomes of developing distal mouse limb buds: A comparative tissue layer analysis. Dev Dyn 2021; 251:1550-1575. [PMID: 34254395 DOI: 10.1002/dvdy.394] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 07/01/2021] [Accepted: 07/05/2021] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The development of the amniote limb has been an important model system to study patterning mechanisms and morphogenesis. For proper growth and patterning, it requires the interaction between the distal sub-apical mesenchyme and the apical ectodermal ridge (AER) that involve the separate implementation of coordinated and tissue-specific genetic programs. RESULTS Here, we produce and analyze the transcriptomes of both distal limb mesenchymal progenitors and the overlying ectodermal cells, following time-coursed dissections that cover from limb bud initiation to fully patterned limbs. The comparison of transcriptomes within each layer as well as between layers over time, allowed the identification of specific transcriptional signatures for each of the developmental stages. Special attention was given to the identification of genes whose transcription dynamics suggest a previously unnoticed role in the context of limb development and also to signaling pathways enriched between layers. CONCLUSION We interpret the transcriptomic data in light of the known development pattern and we conclude that a major transcriptional transition occurs in distal limb buds between E9.5 and E10.5, coincident with the switch from an early phase continuation of the signature of trunk progenitors, related to the initial proximo distal specification, to a late intrinsic phase of development.
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Affiliation(s)
- Marc Fernandez-Guerrero
- Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-University of Cantabria-SODERCAN), Santander, Spain
| | - Sofia Zdral
- Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-University of Cantabria-SODERCAN), Santander, Spain
| | - Alejandro Castilla-Ibeas
- Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-University of Cantabria-SODERCAN), Santander, Spain
| | | | - Denis Duboule
- School of Life Sciences, Federal Institute of Technology, Lausanne, Switzerland.,Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland.,Collège de France, Paris, France
| | - Marian A Ros
- Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-University of Cantabria-SODERCAN), Santander, Spain.,Facultad de Medicina, Departamento de Anatomía y Biología Celular, Universidad de Cantabria, Santander, Spain
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4
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Becic T, Kero D, Vukojevic K, Mardesic S, Saraga-Babic M. Growth factors FGF8 and FGF2 and their receptor FGFR1, transcriptional factors Msx-1 and MSX-2, and apoptotic factors p19 and RIP5 participate in the early human limb development. Acta Histochem 2018; 120:205-214. [PMID: 29409666 DOI: 10.1016/j.acthis.2018.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/30/2018] [Accepted: 01/30/2018] [Indexed: 10/18/2022]
Abstract
The expression pattern of fibroblast growth factors FGF8 and FGF2 and their receptor FGFR1, transcription factors MSX-1 and MSX-2, as well as cell proliferation (Ki-67) and cell death associated caspase-3, p19 and RIP5 factors were analyzed in histological sections of eight 4th-9th-weeks developing human limbs by immunohistochemistry and semi-thin sectioning. Increasing expression of all analyzed factors (except FGF8) characterized both the multilayered human apical ectodermal ridge (AER), sub-ridge mesenchyme (progress zone) and chondrocytes in developing human limbs. While cytoplasmic co-expression of MSX-1 and MSX-2 was observed in both limb epithelium and mesenchyme, p19 displayed strong cytoplasmic expression in non-proliferating cells. Nuclear expression of Ki-67 proliferating cells, and partly of MSX-1 and MSX-2 was detected in the whole limb primordium. Strong expression of factors p19 and RIP5, both in the AER and mesenchyme of human developing limbs indicates their possible involvement in control of cell senescence and cell death. In contrast to animal studies, expression of FGFR1 in the surface ectoderm and p19 in the whole limb primordium might reflect interspecies differences in limb morphology. Expression of FGF2 and downstream RIP5 gene, and transcription factors Msx-1 and MSX-2 did not show human-specific changes in expression pattern. Based on their spatio-temporal expression during human limb development, our study indicates role of FGFs and Msx genes in stimulation of cell proliferation, limb outgrowth, digit elongation and separation, and additionally MSX-2 in control of vasculogenesis. The cascade of orchestrated gene expressions, including the analyzed developmental factors, jointly contribute to the complex human limb development.
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Mariani FV, Fernandez-Teran M, Ros MA. Ectoderm-mesoderm crosstalk in the embryonic limb: The role of fibroblast growth factor signaling. Dev Dyn 2017; 246:208-216. [PMID: 28002626 DOI: 10.1002/dvdy.24480] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 12/07/2016] [Accepted: 12/09/2016] [Indexed: 01/27/2023] Open
Abstract
In this commentary we focus on the function of FGFs during limb development and morphogenesis. Our goal is to understand, interpret and, when possible, reconcile the interesting findings and conflicting results that remain unexplained. For example, the cell death pattern observed after surgical removal of the AER versus genetic removal of the AER-Fgfs is strikingly different and the field is at an impasse with regard to an explanation. We also discuss the idea that AER function may involve signaling components in addition to the AER-FGFs and that signaling from the non-AER ectoderm may also have a significant contribution. We hope that a re-evaluation of current studies and a discussion of outstanding questions will motivate new experiments, especially considering the availability of new technologies, that will fuel further progress toward understanding the intricate ectoderm-to-mesoderm crosstalk during limb development. Developmental Dynamics 246:208-216, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Francesca V Mariani
- Department of Cell and Neurobiology, Broad CIRM Center for Regenerative Medicine & Stem Cell Research, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Marian Fernandez-Teran
- Departamento de Anatomía y Biología Celular, Facultad de Medicina, Universidad de Cantabria, 39011, Santander, Spain
| | - Maria A Ros
- Departamento de Anatomía y Biología Celular, Facultad de Medicina, Universidad de Cantabria, 39011, Santander, Spain.,Instituto de Biomedicina y Biotecnología de Cantabria, CSIC-SODERCAN-Universidad de Cantabria, 39011, Santander, Spain
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Spatiotemporal distribution of proliferation, proapoptotic and antiapoptotic factors in the early human limb development. Acta Histochem 2016; 118:527-36. [PMID: 27282649 DOI: 10.1016/j.acthis.2016.05.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/19/2016] [Accepted: 05/24/2016] [Indexed: 12/28/2022]
Abstract
Involvement of proliferation and apoptosis in the human limb development was analyzed electronmicroscopically and immunohistochemically in histological sections of 8 human embryos, 4(th) -10(th) week old, using apoptotic (caspase-3, AIF, BAX), anti-apoptotic (Bcl-2) and proliferation (Ki-67) markers, and TUNEL method. The data were analyzed by Mann-Whitney test, Kruskal-Wallis and Dunn's post hoc test. Initially, developing human limbs consisted of mesenchymal core and surface ectoderm with apical ectodermal ridge (AER). During progression of development, strong proliferation activity gradually decreased in the mesenchyme (from 78% to 68%) and in the epithelium (from 62% to 42%), while in the differentiating finger cartilages proliferation was constantly low (26-7%). Apoptotic caspase-3 and AIF-positive cells characterized mesenchyme and AER at earliest stages, while during digit separation they appeared in interdigital mesenchyme as well. Strong Bcl-2 expression was observed in AER, subridge mesenchyme and phalanges, while BAX expression charaterized limb areas undergoing apoptosis. Ultrastructurally, proliferating cells showed mitotic figures, while apoptotic cells were characterized by nuclear fragmentation. Macrophages were observed around the apoptotic cells. We suggest that intense proliferation enables growth and elongation of human limb primordia, and differential growth of digits. Both caspase-3 and AIF-dependant pathways of cell death control the extent of AER and numer of cells in the subridge mesenchyme at earliest developmental stages, as well as process of digit separation at later stages of limb development. Spatio-temporal co-expresson of Bcl-2 and BAX indicates their role in suppression of apoptosis and selective stimulation of growth during human limb morphogenesis.
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Conte D, Garaffo G, Lo Iacono N, Mantero S, Piccolo S, Cordenonsi M, Perez-Morga D, Orecchia V, Poli V, Merlo GR. The apical ectodermal ridge of the mouse model of ectrodactyly Dlx5;Dlx6-/- shows altered stratification and cell polarity, which are restored by exogenous Wnt5a ligand. Hum Mol Genet 2015; 25:740-54. [PMID: 26685160 PMCID: PMC4743692 DOI: 10.1093/hmg/ddv514] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 12/10/2015] [Indexed: 02/06/2023] Open
Abstract
The congenital malformation split hand/foot (SHFM) is characterized by missing central fingers and dysmorphology or fusion of the remaining ones. Type-1 SHFM is linked to deletions/rearrangements of the DLX5–DLX6 locus and point mutations in the DLX5 gene. The ectrodactyly phenotype is reproduced in mice by the double knockout (DKO) of Dlx5 and Dlx6. During limb development, the apical ectodermal ridge (AER) is a key-signaling center responsible for early proximal–distal growth and patterning. In Dlx5;6 DKO hindlimbs, the central wedge of the AER loses multilayered organization and shows down-regulation of FGF8 and Dlx2. In search for the mechanism, we examined the non-canonical Wnt signaling, considering that Dwnt-5 is a target of distalless in Drosophila and the knockout of Wnt5, Ryk, Ror2 and Vangl2 in the mouse causes severe limb malformations. We found that in Dlx5;6 DKO limbs, the AER expresses lower levels of Wnt5a, shows scattered β-catenin responsive cells and altered basolateral and planar cell polarity (PCP). The addition of Wnt5a to cultured embryonic limbs restored the expression of AER markers and its stratification. Conversely, the inhibition of the PCP molecule c-jun N-terminal kinase caused a loss of AER marker expression. In vitro, the addition of Wnt5a on mixed primary cultures of embryonic ectoderm and mesenchyme was able to confer re-polarization. We conclude that the Dlx-related ectrodactyly defect is associated with the loss of basoapical and PCP, due to reduced Wnt5a expression and that the restoration of the Wnt5a level is sufficient to partially reverts AER misorganization and dysmorphology.
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Affiliation(s)
- Daniele Conte
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Giulia Garaffo
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Nadia Lo Iacono
- Human Genome Department, Istituto Tecnologie Biomediche, CNR Milano, Italy
| | - Stefano Mantero
- Human Genome Department, Istituto Tecnologie Biomediche, CNR Milano, Italy
| | - Stefano Piccolo
- Department of Molecular Medicine, University of Padova, Padova, Italy and
| | | | - David Perez-Morga
- Laboratoire de Parasitologie Moléculaire, IBMM-DBM, Université Libre de Bruxelles, B-6041 Gosselies, Belgium
| | - Valeria Orecchia
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Valeria Poli
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Giorgio R Merlo
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy,
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Tait S, Tassinari R, Maranghi F, Mantovani A. Bisphenol A affects placental layers morphology and angiogenesis during early pregnancy phase in mice. J Appl Toxicol 2015; 35:1278-91. [PMID: 26063408 DOI: 10.1002/jat.3176] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 04/10/2015] [Accepted: 04/19/2015] [Indexed: 12/29/2022]
Abstract
Bisphenol A (BPA) is a widespread endocrine disrupter mainly used in food contact plastics. Much evidence supports the adverse effects of BPA, particularly on susceptible groups such as pregnant women. The present study considered placental development - relevant for pregnancy outcomes and fetal nutrition/programming - as a potential target of BPA. Pregnant CD-1 mice were administered per os with vehicle, 0.5 (BPA05) or 50 mg kg(-1) (BPA50) body weight day(-1) of BPA, from gestational day (GD) 1 to GD11. At GD12, BPA50 induced significant degeneration and necrosis of giant cells, increased vacuolization in the junctional zone in the absence of glycogen accumulation and reduction of the spongiotrophoblast layer. In addition, BPA05 induced glycogen depletion as well as significant nuclear accumulation of β-catenin in trophoblasts of labyrinthine and spongiotrophoblast layers, supporting the activation of the Wnt/β-catenin pathway. Transcriptomic analysis indicated that BPA05 promoted and BPA50 inhibited blood vessel development and branching; morphologically, maternal vessels were narrower in BPA05 placentas, whereas embryonic and maternal vessels were irregularly dilated in the labyrinth of BPA50 placentas. Quantitative polymerase chain reaction evidenced an estrogen receptor β induction by BPA50, which did not correspond to downstream genes activation; indeed, the transcription factor binding sites analysis supported the AhR/Arnt complex as regulator of BPA50-modulated genes. Conversely, Creb appeared as the main transcription factor regulating BPA05-modulated genes. Embryonic structures (head, forelimb) showed divergent perturbations upon BPA05 or BPA50 exposure, potentially related to unbalanced embryonic nutrition and/or to modulation of genes involved in embryo development. Our findings support placenta as an important target of BPA, even at environmentally relevant dose levels.
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Affiliation(s)
- Sabrina Tait
- Food and Veterinary Toxicology Unit, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
| | - Roberta Tassinari
- Food and Veterinary Toxicology Unit, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
| | - Francesca Maranghi
- Food and Veterinary Toxicology Unit, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
| | - Alberto Mantovani
- Food and Veterinary Toxicology Unit, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
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Cage TA, Louie JD, Liu SR, Alvarez-Buylla A, Gupta N, Hyer J. Distinct patterns of human medulloblastoma dissemination in the developing chick embryo nervous system. Clin Exp Metastasis 2012; 29:371-80. [PMID: 22322278 DOI: 10.1007/s10585-012-9456-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 01/21/2012] [Indexed: 11/29/2022]
Abstract
Medulloblastoma (MB) is the most common malignant primary brain tumor in children. Aggressive tumors that disseminate along the leptomeninges carry extremely poor prognoses. Mechanisms that predict dissemination are poorly understood. Our objective was to develop a reliable and reproducible model to study MB dissemination. We have created a chicken-human xenograft to study features of MB with leptomeningeal dissemination. Human MB cell lines (D283, Daoy), primary human MB cells (SF8113), and primary genetic mouse model (Math1cre:SmoM2 flox/flox) MB cells were either transfected to express green fluorescent protein (GFP) or were labeled with a membrane permeable green fluorescent probe. Cells were then injected as aggregates or implanted as pellets into the developing chicken brain immediately after neural tube closure at embryonic day 2 (E2). Most embryos were harvested three days after implantation (E5) though some were harvested up to E15. The developing brain was analyzed via whole mount fluorescent imaging and tissue section immunohistochemistry. Human and mouse MBs survived in the developing chicken central nervous system (CNS). They exhibited distinct patterns of incorporation and dissemination into the CNS that were consistent with observed phenotypes of the corresponding human patient or mouse host. Specifically, metastatic D283 cells disseminated along the leptomeninges whereas Daoy, primary mouse MB, and primary human MB cells did not. This work supports an avian-human xenograft as a successful model to study patterns of MB dissemination. Our model provides a basis for manipulating cell signaling mechanisms to understand critical targets involved in MB dissemination.
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Affiliation(s)
- Tene A Cage
- Department of Neurological Surgery, University of California, San Francisco, 513 Parnassus Ave, San Francisco, CA 94143-0112, USA
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10
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Niswander L. Methods in avian embryology experimental and molecular manipulation of the embryonic chick limb. Methods Cell Biol 2008; 87:135-52. [PMID: 18485295 DOI: 10.1016/s0091-679x(08)00207-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Lee Niswander
- Department of Pediatrics. University of Colorado at Denver, Mailstop 8322 Aurora, Colorado 80045, USA
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11
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Robert B, Lallemand Y. Anteroposterior patterning in the limb and digit specification: contribution of mouse genetics. Dev Dyn 2006; 235:2337-52. [PMID: 16894622 DOI: 10.1002/dvdy.20890] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The limb has been a privileged object of investigation and reflection for scientists over the past two centuries and continues to provide a heuristic framework to analyze vertebrate development. Recently, accumulation of new data has significantly changed our view on the mechanisms of limb patterning, in particular along the anterior-posterior axis. These data have led us to revisit the mode of action of the zone of polarizing activity. They shed light on the molecular and cellular mechanisms of patterning linked to the Shh-Gli3 signaling pathway and give insights into the mechanism of activation of these cardinal factors, as well as the consequences of their activity. These new data are in good part the result of systematic Application of tools used in contemporary mouse molecular genetics. These have extended the power of mouse genetics by introducing mutational strategies that allow fine-tuned modulation of gene expression, interchromosomal deletions and duplication. They have even made the mouse embryo amenable to cell lineage analysis that used to be the realm of chick embryos. In this review, we focus on the data acquired over the last five years from the analysis of mouse limb development and discuss new perspectives opened by these results.
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Affiliation(s)
- Benoît Robert
- Department of Developmental Biology, CNRS URA 2578, Pasteur Institute, Paris, France.
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12
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Berdón-Zapata V, Granillo-Alvarez M, Valdés-Flores M, García-Ortiz JE, Kofman-Alfaro S, Zenteno JC. p63 gene analysis in Mexican patients with syndromic and non-syndromic ectrodactyly. J Orthop Res 2004; 22:1-5. [PMID: 14656652 DOI: 10.1016/s0736-0266(03)00166-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ectrodactyly is a congenital limb malformation that involves a central reduction defect of the hands and/or feet which is frequently associated with other phenotypic abnormalities. The condition appears to be genetically heterogeneous and recently it has been demonstrated that mutations in the p63 gene, a homologue of the tumor suppressor gene p53, are the cause of at least four autosomal dominant genetic syndromes which feature ectrodactyly: ectrodactyly, ectodermal dysplasia, and facial clefting (EEC), split hand/split foot malformation (SHFM), limb-mammary syndrome (LMS), and acro-dermato-ungual-lacrimal-tooth syndrome (ADULT). In this study, genetic analysis of the p63 gene in a group of 13 patients with ectrodactyly (syndromic and isolated) was performed. Four patients with syndromic ectrodactyly had p63 heterozygous point mutations that affect the DNA binding domain of the protein. One of these subjects exhibited the typical features of EEC syndrome as well as ankyloblepharon being, to our knowledge, the first case combining these traits. This finding supports the view of a clinical overlap in this group of autosomal dominant syndromes caused by p63 mutations and demonstrates that there are exceptions in the previously established p63 genotype-phenotype correlation.
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Affiliation(s)
- V Berdón-Zapata
- Department of Genetics, Facultad de Medicina-UNAM, Hospital General de México, Dr. Balmis 148, Col. Doctores, CP 06726, Mexico City, Mexico
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Khokha MK, Hsu D, Brunet LJ, Dionne MS, Harland RM. Gremlin is the BMP antagonist required for maintenance of Shh and Fgf signals during limb patterning. Nat Genet 2003; 34:303-7. [PMID: 12808456 DOI: 10.1038/ng1178] [Citation(s) in RCA: 278] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2003] [Accepted: 05/15/2003] [Indexed: 11/09/2022]
Abstract
During limb outgrowth, signaling by bone morphogenetic proteins (BMPs) must be moderated to maintain the signaling loop between the zone of polarizing activity (ZPA) and the apical ectodermal ridge (AER). Gremlin, an extracellular Bmp antagonist, has been proposed to fulfill this function and therefore be important in limb patterning. We tested this model directly by mutating the mouse gene encoding gremlin (Cktsf1b1, herein called gremlin). In the mutant limb, the feedback loop between the ZPA and the AER is interrupted, resulting in abnormal skeletal pattern. We also show that the gremlin mutation is allelic to the limb deformity mutation (ld). Although Bmps and their antagonists have multiple roles in limb development, these experiments show that gremlin is the principal BMP antagonist required for early limb outgrowth and patterning.
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Affiliation(s)
- Mustafa K Khokha
- Department of Molecular and Cell Biology, University of California-Berkeley, 401 Barker Hall, Berkeley, California 94720, USA
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14
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Bell SM, Schreiner CM, Hess KA, Anderson KP, Scott WJ. Asymmetric limb malformations in a new transgene insertional mutant, footless. Mech Dev 2003; 120:597-605. [PMID: 12782276 DOI: 10.1016/s0925-4773(03)00021-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Six to eight copies of a transgene integrated into mouse chromosome 15 resulting in a new transgene insertional mutant, Footless, presenting with malformations of the limbs, kidney, and soft palate. Homozygotes possess a unique asymmetric pattern of limb truncations. Posterior structures from the autopod and zeugopod of the hindlimbs are missing with left usually more severely affected than right. In contrast, anterior structures are missing from the right forelimbs. The left forelimb is usually normal except for the absence of the distal telephalanges and nails. These structures are absent on all formed digits. In situ hybridization assays examined the expression of Shh, dHand, Msx2, Fgf8, En1, and Lmx1b in mutant limb buds and indicated normal establishment of the anterior/posterior and dorsal/ventral axes of the developing limbs. However, dysmorphology of the apical ectodermal ridge was observed in the mutant limb buds.
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Affiliation(s)
- Sheila M Bell
- Division of Developmental Biology, Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
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15
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Finnell RH, Waes JGV, Eudy JD, Rosenquist TH. Molecular basis of environmentally induced birth defects. Annu Rev Pharmacol Toxicol 2002; 42:181-208. [PMID: 11807170 DOI: 10.1146/annurev.pharmtox.42.083001.110955] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exposure of the developing conceptus to selected environmental agents can lead to deleterious and often times lethal birth defects. These malformations result in serious emotional and financial consequences to families and societies worldwide. As we continue to progress technologically, we face challenges from the introduction of new pharmacological agents and chemical compounds into the environment. This results in a concomitant need to more fully understand the relationship between in utero exposure to environmental teratogens and the risk of congenital malformations. The goal of this review is to provide a current perspective of the major concepts related to the molecular basis of environmentally induced birth defects. Starting with a discussion of commonly occurring birth defects, we consider important fundamental facets of embryonic development, teratology, and gene-environment interactions. The review then summarizes our current understanding of the molecular mechanisms involved in selected birth defects following exposure to pharmacological compounds, including thalidomide, retinoids, and valproic acid. Understanding these signaling pathways may lead to the development of safer pharmaceutical compounds and a reduction in the number of infants born with preventable birth defects.
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Affiliation(s)
- Richard H Finnell
- Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, Texas 77030, USA.
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16
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Sifakis S, Basel D, Ianakiev P, Kilpatrick M, Tsipouras P. Distal limb malformations: underlying mechanisms and clinical associations. Clin Genet 2001; 60:165-72. [PMID: 11595015 DOI: 10.1034/j.1399-0004.2001.600301.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Congenital malformations of the extremities are conspicuous and have been described through the ages. Over the past decade, a wealth of knowledge has been generated regarding the genetic regulation of limb development and the underlying molecular mechanisms. Recent studies have identified several of the signaling molecules, growth factors, and transcriptional regulators involved in the initiation and maintenance of the apical ectodermal ridge (AER) as well as the molecular markers defining the three axes of the developing limb. Studies of abnormal murine phenotypes have uncovered the role played by genes such as p63 and Dactylin in the maintenance of AER activity. These phenotypes resemble human malformations and in this review we describe the underlying mechanisms and clinical associations of split hand/foot malformation and ectrodactyly-ectodermal dysplasia-cleft lip/palate syndrome, which have both been associated with mutations in the p63 gene.
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Affiliation(s)
- S Sifakis
- Department of Pediatrics, University of Connecticut Health Center, Farmington, CT 06030, USA
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17
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Abstract
Several advances have been made in our understanding of the control of the growth and patterning of embryonic limbs. Development of the vertebrate limb is dependent on reciprocal interactions between the ectoderm and mesoderm that regulate the structure and function of the apical ectodermal ridge. One key component of this regulatory program appears to be the precise control of signaling by members of the bone morphogenetic protein family via multiple antagonistic interactions.
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Affiliation(s)
- A T Dudley
- Department of Genetics, Harvard Medical School, Boston 02143, USA
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18
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Leader B, Leder P. Formin-2, a novel formin homology protein of the cappuccino subfamily, is highly expressed in the developing and adult central nervous system. Mech Dev 2000; 93:221-31. [PMID: 10781961 DOI: 10.1016/s0925-4773(00)00276-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Formin-1 is the founding member of a family of genes of emerging biological and medical importance that share specific domains of homology, allowing them to be classified together as the formin homology proteins. Although deficiency mutations in formin-1 lead to profound developmental defects in limb and kidney formation, similar deficiency mutations in more distantly related members of this family (diaphanous and cappuccino in Drosophila and BNI1 in yeast) have ostensibly unrelated phenotypes. Here we describe murine and human formin-2 (Fmn2), a gene which bears a high degree of similarity to formin-1 and cappuccino. The mouse gene, which encodes a putative 1567-amino-acid open reading frame and maps to mouse Chromosome 1, is expressed almost exclusively in the developing and mature central nervous system. Expression begins at embryonic day 9. 5 in the developing spinal cord and brain structures and continues in neonatal and adult brain structures including the olfactory bulb, cortex, thalamus, hypothalamus, hippocampus and cerebellum. Human formin-2 has a similar expression pattern.
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Affiliation(s)
- B Leader
- Department of Genetics, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115, USA.
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19
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Post LC, Margulies EH, Kuo A, Innis JW. Severe limb defects in Hypodactyly mice result from the expression of a novel, mutant HOXA13 protein. Dev Biol 2000; 217:290-300. [PMID: 10625554 DOI: 10.1006/dbio.1999.9550] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypodactyly (Hoxa13(Hd)) mice have a 50-bp deletion in the coding region of exon 1 of the Hoxa13 gene and have more severe limb defects than mice with an engineered deletion of the entire gene (Hoxa13(-/-)). Increased cell death is observed in the autopod of Hoxa13(Hd/Hd) but not Hoxa13(-/-) limb buds. In addition, compound heterozygotes for one Hd allele and a Hoxa13(-) allele have a more severe limb phenotype than mice homozygous for the engineered null allele, suggesting a dominant-negative effect of the Hd mutation. The Hoxa13(Hd) deletion does not interfere with steady-state mRNA levels; however, its consequences on translation are unknown. In this paper, we characterize the Hoxa13 transcription initiation site in limbs and determine the initiator methionine of HOXA13. We show that the Hoxa13(Hd) deletion results in a translational frame shift that leads to the loss of wild-type HOXA13 protein and the simultaneous production of a novel, stable protein in the limb buds of mutant mice. The mutant Hd protein (HOXA13(Hd)) consists of the first 25 amino acids of wild-type HOXA13 sequence, followed by 275 amino acids of arginine- and lysine-rich, novel sequence, and lacks the homeodomain. Like wild-type HOXA13, HOXA13(Hd) is localized to the nucleus in transfected COS-7 cells, perhaps mediated by the arginine- and lysine-rich peptide sequences created by the translational frame shift. To determine whether HOXA13(Hd) could alter limb morphogenesis, we misexpressed the mutant mRNA throughout the developing limb bud using a Prx-1 promoter-Hd gene construct in transgenic mice. Three of 15 transgenic founder animals displayed reduction or absence of proximal and distal limb structures. We propose that the expression of HOXA13(Hd) plays a role in the profound failure of digit formation in Hoxa13(Hd/Hd) mice and explains the morphologic differences between these two Hoxa13 alleles.
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Affiliation(s)
- L C Post
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, 48109, USA
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20
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Lettice L, Hecksher-Sørensen J, Hill RE. The dominant hemimelia mutation uncouples epithelial-mesenchymal interactions and disrupts anterior mesenchyme formation in mouse hindlimbs. Development 1999; 126:4729-36. [PMID: 10518490 DOI: 10.1242/dev.126.21.4729] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Epithelial-mesenchymal interactions are essential for both limb outgrowth and pattern formation in the limb. Molecules capable of communication between these two tissues are known and include the signaling molecules SHH and FGF4, FGF8 and FGF10. Evidence suggests that the pattern and maintenance of expression of these genes are dependent on a number of factors including regulatory loops between genes expressed in the AER and those in the underlying mesenchyme. We show here that the mouse mutation dominant hemimelia (Dh) alters the pattern of gene expression in the AER such that Fgf4, which is normally expressed in a posterior domain, and Fgf8, which is expressed throughout are expressed in anterior patterns. We show that maintenance of Shh expression in the posterior mesenchyme is not dependent on either expression of Fgf4 or normal levels of Fgf8 in the overlying AER. Conversely, AER expression of Fgf4 is not directly dependent on Shh expression. Also the reciprocal regulatory loop proposed for Fgf8 in the AER and Fgf10 in the underlying mesenchyme is also uncoupled by this mutation. Early during the process of limb initiation, Dh is involved in regulating the width of the limb bud, the mutation resulting in selective loss of anterior mesenchyme. The Dh gene functions in the initial stages of limb development and we suggest that these initial roles are linked to mechanisms that pattern gene expression in the AER.
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Affiliation(s)
- L Lettice
- MRC Human Genetics Unit, Western General Hospital, Crewe Rd, Edinburgh, EH4 2XU, UK.
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21
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Zúñiga A, Haramis AP, McMahon AP, Zeller R. Signal relay by BMP antagonism controls the SHH/FGF4 feedback loop in vertebrate limb buds. Nature 1999; 401:598-602. [PMID: 10524628 DOI: 10.1038/44157] [Citation(s) in RCA: 379] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Outgrowth and patterning of the vertebrate limb are controlled by reciprocal interactions between the posterior mesenchyme (polarizing region) and a specialized ectodermal structure, the apical ectodermal ridge (AER). Sonic hedgehog (SHH) signalling by the polarizing region modulates fibroblast growth factor (FGF)4 signalling by the posterior AER, which in turn maintains the polarizing region (SHH/FGF4 feedback loop). Here we report that the secreted bone-morphogenetic-protein (BMP) antagonist Gremlin relays the SHH signal from the polarizing region to the AER. Mesenchymal Gremlin expression is lost in limb buds of mouse embryos homozygous for the limb deformity (Id) mutation, which disrupts establishment of the SHH/FGF4 feedback loop. Grafting Gremlin-expressing cells into ld mutant limb buds rescues Fgf4 expression and restores the SHH/FGF4 feedback loop. Analysis of Shh-null mutant embryos reveals that SHH signalling is required for maintenance of Gremlin and Formin (the gene disrupted by the ld mutations). In contrast, Formin, Gremlin and Fgf4 activation are independent of SHH signalling. This study uncovers the cascade by which the SHH signal is relayed from the posterior mesenchyme to the AER and establishes that Formin-dependent activation of the BMP antagonist Gremlin is sufficient to induce Fgf4 and establish the SHH/FGF4 feedback loop.
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Affiliation(s)
- A Zúñiga
- Department of Developmental Biology, Faculty of Biology, Utrecht University, The Netherlands
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22
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De Arcangelis A, Mark M, Kreidberg J, Sorokin L, Georges-Labouesse E. Synergistic activities of alpha3 and alpha6 integrins are required during apical ectodermal ridge formation and organogenesis in the mouse. Development 1999; 126:3957-68. [PMID: 10433923 DOI: 10.1242/dev.126.17.3957] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Integrins alpha6beta1 and alpha6beta4 are cell surface receptors for laminins. Integrin alpha6-null mice die at birth with severe skin blistering and defects in the cerebral cortex and in the retina. Integrin alpha3beta1 can associate with laminins and other ligands. Integrin alpha3-null mice also die at birth, with kidney and lung defects at late stages of development, and moderate skin blistering. To investigate possible overlapping functions between alpha3 and alpha6 integrins, we analyzed the phenotype of compound alpha3−/−/alpha6−/− mutant embryos. Double homozygous mutant embryos were growth-retarded and displayed several developmental defects not observed in the single mutant animals. First, limb abnormalities characterized by an absence of digit separation and the fusion of preskeletal elements were observed. Further analyses indicated a defect in the apical ectodermal ridge, an essential limb organizing center. In the double mutant, the ridge appeared flattened, and ridge cells did not show a columnar morphology. A strong reduction in ridge cell proliferation and alterations of the basal lamina underlying the ectoderm were observed. These results suggest that alpha3 and alpha6 integrins are required for the organization or compaction of presumptive apical ectodermal ridge cells into a distinct differentiated structure. Additional defects were present: an absence of neural tube closure, bilateral lung hypoplasia, and several abnormalities in the urogenital tract. Finally, an aggravation of brain and eye lamination defects was observed. The presence of novel phenotypes in double mutant embryos demonstrates the synergism between alpha3 and alpha6 integrins and their essential roles in multiple processes during embryogenesis.
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Affiliation(s)
- A De Arcangelis
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 163, CU de Strasbourg, France
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23
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Caruccio NC, Martinez-Lopez A, Harris M, Dvorak L, Bitgood J, Simandl BK, Fallon JF. Constitutive activation of sonic hedgehog signaling in the chicken mutant talpid(2): Shh-independent outgrowth and polarizing activity. Dev Biol 1999; 212:137-49. [PMID: 10419691 DOI: 10.1006/dbio.1999.9321] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have examined the developmental properties of the polydactylous chicken mutant, talpid(2). Ptc, Gli1, Bmp2, Hoxd13, and Fgf4 are expressed throughout the anteroposterior axis of the mutant limb bud, despite normal Shh expression. The expression of Gli3, Ihh, and Dhh appears to be normal, suggesting that the Shh signaling pathway is constitutively active in talpid(2) mutants. We show that preaxial talpid(2) limb bud mesoderm has polarizing activity in the absence of detectable Shh mRNA. When the postaxial talpid(2) limb bud (including all Shh-expressing cells) is removed, the preaxial cells reform a normal-shaped talpid(2) limb bud (regulate). However, a Shh-expressing region (zone of polarizing activity) does not reform; nevertheless Fgf4 expression in the apical ectodermal ridge is maintained. Such reformed talpid(2) limb buds develop complete talpid(2) limbs. After similar treatment, normal limb buds downregulate Fgf4, the preaxial cells do not regulate, and a truncated anteroposterior deficient limb forms. In talpid(2) limbs, distal outgrowth is independent of Shh and correlates with Fgf4, but not Fgf8, expression by the apical ectodermal ridge. We propose a model for talpid(2) in which leaky activation of the Shh signaling pathway occurs in the absence of Shh ligand.
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Affiliation(s)
- N C Caruccio
- Department of Anatomy, University of Wisconsin at Madison, Madison, Wisconsin, 53706, USA
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24
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Zúñiga A, Zeller R. Gli3 (Xt) and formin (ld) participate in the positioning of the polarising region and control of posterior limb-bud identity. Development 1999; 126:13-21. [PMID: 9834182 DOI: 10.1242/dev.126.1.13] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During initiation of limb-bud outgrowth in vertebrate embryos, the polarising region (limb-bud organizer) is established upon activation of the Sonic Hedgehog (SHH) signaling molecule at the posterior limb-bud margin. Another hallmark of establishing anteroposterior limb-bud identities is the colinear activation of HoxD genes located at the 5′ end of the cluster (5′HoxD genes). The unique and shared functions of Gli3 and formin in these determinative events were genetically analyzed using single and double homozygous Extra-toes (Xt; disrupting Gli3) and limb deformity (ld; disrupting formin) mouse embryos. Analysis of the limb skeletal phenotypes reveals genetic interaction of the two genes. In addition to loss of digit identity and varying degrees of polydactyly, proximal skeletal elements are severely shortened in Xt;ld double homozygous limbs. The underlying molecular defects affect both establishment of the polarising region and posterior limb-bud identity. In particular, the synergism between Gli3- and formin-mediated mesenchyme-AER interactions positions the SHH signaling center at the posterior limb-bud margin. The present study shows that establishment and positioning of the polarising region is regulated both by restriction of Shh through Gli3 and its positive feedback regulation through formin. Concurrently, Gli3 functions independently of formin during initial posterior nesting of 5′HoxD domains, whereas their subsequent distal restriction and anterior expansion depends on genetic interaction of Gli3 and formin.
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Affiliation(s)
- A Zúñiga
- EMBL, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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25
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Ng JK, Tamura K, Büscher D, Izpisúa-Belmonte JC. Molecular and cellular basis of pattern formation during vertebrate limb development. Curr Top Dev Biol 1998; 41:37-66. [PMID: 9784972 DOI: 10.1016/s0070-2153(08)60269-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The body plan is generated by cells and tissues that become arranged precisely in the embryo. This process, termed pattern formation, involves cell interactions in which a particular group of cells produce signals that specify new cell types or patterns of differentiation in responding cells. These patterning signals emanate from very discrete centers called "organizer centers," such as the Hensen's node or Spemann organizer, the midbrain-hindbrain junction, the notochord, or in the case of the limb, the zone of polarizing activity (ZPA) or the apical ectodermal ridge (AER). The developing vertebrate limb is an ideal model system for the study of pattern formation because, in addition to surgical manipulations, molecular manipulations are now feasible. In this review we summarize early experiments that established, by means of surgical manipulations, the different organizer centers of the vertebrate limb: the ectoderm covering the limb bud, the apical ectodermal ridge, the zone of polarizing activity, and the distal mesoderm (progress zone) underlying the AER. We then describe the domains of expression of various genes present during the development of the limb and discuss some of the functional approaches (overexpression and lack of function studies) undertaken to ascertain their role in limb outgrowth. The knowledge acquired in the last few years has had an enormous impact not only on our view of how limbs develop (perhaps now one of the most approachable vertebrate model systems) but also in a more general sense of how the embryo is organized in space and time.
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Affiliation(s)
- J K Ng
- Gene Expression Laboratory, Salk Institute, La Jolla, California 92037, USA
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26
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Dealy CN, Scranton V, Cheng HC. Roles of transforming growth factor-alpha and epidermal growth factor in chick limb development. Dev Biol 1998; 202:43-55. [PMID: 9758702 DOI: 10.1006/dbio.1998.8988] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have examined the distribution of transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), and the chicken EGF receptor (c-erbB), in embryonic chick limbs. Prior to limb budding, TGF-alpha is present in prospective limb-forming mesoderm and in prospective apical ectodermal ridge (AER)-forming ectoderm, but is not detected in non-limb-forming flank mesoderm or ectoderm, nor in presumptive non-AER-forming limb ectoderm, suggesting possible roles in initial limb formation and AER induction. Consistent with this possibility, TGF-alpha is present in the mesoderm of the wing buds of the amelic chick mutants limbless and wingless, which form and bud normally, but is absent from limbless and wingless ectoderm, which fails to form an AER. TGF-alpha and EGF are present in the AER of the developing limb, and TGF-alpha, EGF, and c-erbB are present in the underlying subridge mesoderm, suggesting possible roles in reciprocal AER/subridge mesoderm interactions required for limb outgrowth. We found that exogenous TGF-alpha and EGF can promote the outgrowth of limb mesoderm in the absence of the AER in vitro and can also promote the outgrowth of limbless and wingless wing bud explants. EGF is present in ventral but not dorsal limb ectoderm, suggesting a role for EGF in specification of ventral ectoderm. TGF-alpha and EGF are not detected in the differentiating cartilaginous elements or muscle primordia of the limb, suggesting that cessation of TGF-alpha and EGF expression may be required for cartilage and muscle formation. We have found that exogenous TGF-alpha and EGF inhibit chondrogenesis and myogenesis of limb mesenchyme in vitro. Together these results indicate that signaling through the EGF receptor via endogenous TGF-alpha and EGF may be important for initial limb formation, AER induction, outgrowth of limb mesoderm, and regulation of limb chondrogenic and myogenic differentiation.
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Affiliation(s)
- C N Dealy
- Department of Anatomy, University of Connecticut Health Center, Farmington, Connecticut, 06030, USA
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27
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Affiliation(s)
- G R Martin
- Department of Anatomy and Program in Developmental Biology, School of Medicine, University of California at San Francisco, San Francisco, California 94143-0452 USA.
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28
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Bell SM, Schreiner CM, Scott WJ. The loss of ventral ectoderm identity correlates with the inability to form an AER in the legless hindlimb bud. Mech Dev 1998; 74:41-50. [PMID: 9651475 DOI: 10.1016/s0925-4773(98)00065-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We have characterized the early stages of murine hindlimb morphogenesis in the legless (lgl)mutant and non-mutant littermates. Initially the entire ventral ectoderm expresses many genetic markers characteristic of the AER (en-1, fgf-8, msx-2, dlx-2, cd44, and cx-43). Subsequently, the expression domain of most of these genes is restricted to the thickened ectoderm of the disto-ventral limb margin prior to forming an AER. In lgl, the expression of these genes is initiated but not maintained and the disto-ventral marginal ectoderm does not thicken. In contrast, Wnt7a expression is initiated and maintained in the dorsal ectoderm. The limb mesenchyme of lgl and non-mutant embryos initially expresses lmx-1b and fgf-10 uniformly. As the ventro-distal marginal ectoderm thickens, lmx-1b is progressively dorsally restricted in non-mutants but continues to be expressed ventrally in lgl hindlimb buds. These data suggest that establishment of a dorso-ventral ectodermal interface is not sufficient for AER formation and that restriction of lmx-1b to the dorsal mesenchyme is coordinately linked to AER formation.
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Affiliation(s)
- S M Bell
- Division of Developmental Biology Children's Hospital Research Foundation, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
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29
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Wang W, Van De Water T, Lufkin T. Inner ear and maternal reproductive defects in mice lacking the Hmx3 homeobox gene. Development 1998; 125:621-34. [PMID: 9435283 DOI: 10.1242/dev.125.4.621] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Hmx homeobox gene family is of ancient origin, being present in species as diverse as Drosophila, sea urchin and mammals. The three members of the murine Hmx family, designated Hmx1, Hmx2 and Hmx3, are expressed in tissues that suggest a common functional role in sensory organ development and pregnancy. Hmx3 is one of the earliest markers for vestibular inner ear development during embryogenesis, and is also upregulated in the myometrium of the uterus during pregnancy. Targeted disruption of the Hmx3 gene results in mice with abnormal circling behavior and severe vestibular defects owing to a depletion of sensory cells in the saccule and utricle, and a complete loss of the horizontal semicircular canal crista, as well as a fusion of the utricle and saccule endolymphatic spaces into a common utriculosaccular cavity. Both the sensory and secretory epithelium of the cochlear duct appear normal in the Hmx3 null animals. The majority of Hmx3 null females have a reproductive defect. Hmx3 null females can be fertilized and their embryos undergo normal preimplantation development, but the embryos fail to implant successfully in the Hmx3 null uterus and subsequently die. Transfer of preimplantation embryos from mutant Hmx3 uterine horns to wild-type pseudopregnant females results in successful pregnancy, indicating a failure of the Hmx3 null uterus to support normal post-implantation pregnancy. Molecular analysis revealed the perturbation of Hmx, Wnt and LIF gene expression in the Hmx3 null uterus. Interestingly, expression of both Hmx1 and Hmx2 is downregulated in the Hmx3 null uterus, suggesting a hierarchical relationship among the three Hmx genes during pregnancy.
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Affiliation(s)
- W Wang
- Brookdale Center for Development and Molecular Biology, Mount Sinai School of Medicine, New York, NY 10029-6574, USA
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30
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Yang Y, Drossopoulou G, Chuang PT, Duprez D, Marti E, Bumcrot D, Vargesson N, Clarke J, Niswander L, McMahon A, Tickle C. Relationship between dose, distance and time in Sonic Hedgehog-mediated regulation of anteroposterior polarity in the chick limb. Development 1997; 124:4393-404. [PMID: 9334287 DOI: 10.1242/dev.124.21.4393] [Citation(s) in RCA: 248] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Anteroposterior polarity in the vertebrate limb is thought to be regulated in response to signals derived from a specialized region of distal posterior mesenchyme, the zone of polarizing activity. Sonic Hedgehog (Shh) is expressed in the zone of polarizing activity and appears to mediate the action of the zone of polarizing activity. Here we have manipulated Shh signal in the limb to assess whether it acts as a long-range signal to directly pattern all the digits. Firstly, we demonstrate that alterations in digit development are dependent upon the dose of Shh applied. DiI-labeling experiments indicate that cells giving rise to the extra digits lie within a 300 microm radius of a Shh bead and that the most posterior digits come from cells that lie very close to the bead. A response to Shh involves a 12–16 hour period in which no irreversible changes in digit pattern occur. Increasing the time of exposure to Shh leads to specification of additional digits, firstly digit 2, then 3, then 4. Cell marking experiments demonstrate that cells giving rise to posterior digits are first specified as anterior digits and later adopt a more posterior character. To monitor the direct range of Shh signalling, we developed sensitive assays for localizing Shh by attaching alkaline phosphatase to Shh and introducing cells expressing these forms into the limb bud. These experiments demonstrate that long-range diffusion across the anteroposterior axis of the limb is possible. However, despite a dramatic difference in their diffusibility in the limb mesenchyme, the two forms of alkaline phosphatase-tagged Shh proteins share similar polarizing activity. Moreover, Shh-N (aminoterminal peptide of Shh)-coated beads and Shh-expressing cells also exhibit similar patterning activity despite a significant difference in the diffusibility of Shh from these two sources. Finally, we demonstrate that when Shh-N is attached to an integral membrane protein, cells transfected with this anchored signal also induce mirror-image pattern duplications in a dose-dependent fashion similar to the zone of polarizing activity itself. These data suggest that it is unlikely that Shh itself signals digit formation at a distance. Beads soaked in Shh-N do not induce Shh in anterior limb mesenchyme ruling out direct propagation of a Shh signal. However, Shh induces dose-dependent expression of Bmp genes in anterior mesenchyme at the start of the promotion phase. Taken together, these results argue that the dose-dependent effects of Shh in the regulation of anteroposterior pattern in the limb may be mediated by some other signal(s). BMPs are plausible candidates.
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Affiliation(s)
- Y Yang
- Department of Molecular and Cellular Biology, The Biolabs, Harvard University, Cambridge, Massachusetts 02138, USA
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31
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Hérault Y, Fraudeau N, Zákány J, Duboule D. Ulnaless (Ul), a regulatory mutation inducing both loss-of-function and gain-of-function of posterior Hoxd genes. Development 1997; 124:3493-500. [PMID: 9342042 DOI: 10.1242/dev.124.18.3493] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ulnaless (Ul), an X-ray-induced dominant mutation in mice, severely disrupts development of forearms and forelegs. The mutation maps on chromosome 2, tightly linked to the HoxD complex, a cluster of regulatory genes required for proper morphogenesis. In particular, 5′-located (posterior) Hoxd genes are involved in limb development and combined mutations within these genes result in severe alterations in appendicular skeleton. We have used several engineered alleles of the HoxD complex to genetically assess the potential linkage between these two loci. We present evidence indicating that Ulnaless is allelic to Hoxd genes. Important modifications in the expression patterns of the posterior Hoxd-12 and Hoxd-13 genes at the Ul locus suggest that Ul is a regulatory mutation that interferes with a control mechanism shared by multiple genes to coordinate Hoxd function during limb morphogenesis.
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Affiliation(s)
- Y Hérault
- Department of Zoology and Animal Biology, University of Geneva, Sciences III, Switzerland
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Abstract
Classical mutations and those that derive from gene targeting have provided an important resource to explore the molecular control of vertebrate limb development. Recent studies have combined molecular analysis of limb mutants with embryological approaches to understand the regulation of limb patterning and growth.
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Affiliation(s)
- L Niswander
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
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Zeller R, Duboule D. Dorso-ventral limb polarity and origin of the ridge: on the fringe of independence? Bioessays 1997; 19:541-6. [PMID: 9230686 DOI: 10.1002/bies.950190703] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Molecular and developmental studies of limb pattern formation have recently gained widespread attention. The fact that vertebrate limbs are amenable to both genetic and embryological manipulations has established this model system as a valuable paradigm for studying vertebrate development. Limb buds are polarised along all three major axes and the establishment of the dorso-ventral (DV) polarity is dependent upon cues localised in the trunk, where a DV ectodermal interface is produced by confrontation of dorsal and ventral identities. By analogy to Drosophila imaginal disc development, this interface has been proposed to determine and position an ectodermal organising centre, the Apical Ectodermal Ridge (AER), controlling limb bud outgrowth. Recent fate mapping studies and studies of genes regulating DV limb polarity, AER formation and differentiation suggest, however, that DV patterning and AER induction, though coordinately regulated during limb bud outgrowth, may early on be more dissociated than expected.
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Affiliation(s)
- R Zeller
- European Molecular Biology Laboratory, Heidelberg, Germany.
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34
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The Role of a Single Formin Isoform in the Limb and Renal Phenotypes of Limb Deformity. Mol Med 1997. [DOI: 10.1007/bf03401684] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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