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Miao Y, Pourquié O. Cellular and molecular control of vertebrate somitogenesis. Nat Rev Mol Cell Biol 2024; 25:517-533. [PMID: 38418851 DOI: 10.1038/s41580-024-00709-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 03/02/2024]
Abstract
Segmentation is a fundamental feature of the vertebrate body plan. This metameric organization is first implemented by somitogenesis in the early embryo, when paired epithelial blocks called somites are rhythmically formed to flank the neural tube. Recent advances in in vitro models have offered new opportunities to elucidate the mechanisms that underlie somitogenesis. Notably, models derived from human pluripotent stem cells introduced an efficient proxy for studying this process during human development. In this Review, we summarize the current understanding of somitogenesis gained from both in vivo studies and in vitro studies. We deconstruct the spatiotemporal dynamics of somitogenesis into four distinct modules: dynamic events in the presomitic mesoderm, segmental determination, somite anteroposterior polarity patterning, and epithelial morphogenesis. We first focus on the segmentation clock, as well as signalling and metabolic gradients along the tissue, before discussing the clock and wavefront and other models that account for segmental determination. We then detail the molecular and cellular mechanisms of anteroposterior polarity patterning and somite epithelialization.
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Affiliation(s)
- Yuchuan Miao
- Department of Genetics, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
| | - Olivier Pourquié
- Department of Genetics, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA.
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2
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Draga M, Scaal M. Building a vertebra: Development of the amniote sclerotome. J Morphol 2024; 285:e21665. [PMID: 38100740 DOI: 10.1002/jmor.21665] [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: 07/20/2023] [Revised: 10/13/2023] [Accepted: 12/04/2023] [Indexed: 12/17/2023]
Abstract
In embryonic development, the vertebral column arises from the sclerotomal compartment of the somites. The sclerotome is a mesenchymal cell mass which can be subdivided into several subpopulations specified by different regulatory mechanisms and giving rise to different parts of the vertebrae like vertebral body, vertebral arch, ribs, and vertebral joints. This review gives a short overview on the molecular and cellular basis of the formation of sclerotomal subdomains and the morphogenesis of their vertebral derivatives.
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Affiliation(s)
- Margarethe Draga
- Faculty of Medicine and University Hospital Cologne, Center of Anatomy, University of Cologne, Cologne, Germany
| | - Martin Scaal
- Faculty of Medicine and University Hospital Cologne, Center of Anatomy, University of Cologne, Cologne, Germany
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3
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Clayton SW, Angermeier A, Halbrooks JE, McCardell R, Serra R. TGFβ signaling is required for sclerotome resegmentation during development of the spinal column in Gallus gallus. Dev Biol 2022; 488:120-130. [PMID: 35644252 PMCID: PMC9552462 DOI: 10.1016/j.ydbio.2022.05.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 05/02/2022] [Accepted: 05/19/2022] [Indexed: 12/14/2022]
Abstract
We previously showed the importance of TGFβ signaling in development of the mouse axial skeleton. Here, we provide the first direct evidence that TGFβ signaling is required for resegmentation of the sclerotome using chick embryos. Lipophilic fluorescent tracers, DiO and DiD, were microinjected into adjacent somites of embryos treated with or without TGFβRI inhibitors, SB431542, SB525334 or SD208, at developmental day E2.5 (HH16). Lineage tracing of labeled cells was observed over the course of 4 days until the completion of resegmentation at E6.5 (HH32). Vertebrae were malformed and intervertebral discs were small and misshapen in inhibitor injected embryos. Hypaxial myofibers were also increased in thickness after treatment with the inhibitor. Inhibition of TGFβ signaling resulted in alterations in resegmentation that ranged between full, partial, and slanted shifts in distribution of DiO or DiD labeled cells within vertebrae. Patterning of rostro-caudal markers within sclerotome was disrupted at E3.5 after treatment with TGFβRI inhibitor with rostral domains expressing both rostral and caudal markers. We propose that TGFβ signaling regulates rostro-caudal polarity and subsequent resegmentation in sclerotome during spinal column development.
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Affiliation(s)
- Sade W Clayton
- Department of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, AL, USA; Department of Orthopaedic Surgery, Washington University, St. Louis, MO, USA
| | - Allyson Angermeier
- Department of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, AL, USA
| | - Jacob E Halbrooks
- Department of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, AL, USA
| | - Ronisha McCardell
- Department of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, AL, USA; Dillard University, Greensburg, LA, USA
| | - Rosa Serra
- Department of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, AL, USA.
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Schmidt P, Leman E, Lagadec R, Schubert M, Mazan S, Reshef R. Evolutionary Transition in the Regulation of Vertebrate Pronephros Development: A New Role for Retinoic Acid. Cells 2022; 11:1304. [PMID: 35455988 PMCID: PMC9026449 DOI: 10.3390/cells11081304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/29/2022] [Accepted: 04/01/2022] [Indexed: 11/25/2022] Open
Abstract
The anterior-posterior (AP) axis in chordates is regulated by a conserved set of genes and signaling pathways, including Hox genes and retinoic acid (RA), which play well-characterized roles in the organization of the chordate body plan. The intermediate mesoderm (IM), which gives rise to all vertebrate kidneys, is an example of a tissue that differentiates sequentially along this axis. Yet, the conservation of the spatiotemporal regulation of the IM across vertebrates remains poorly understood. In this study, we used a comparative developmental approach focusing on non-conventional model organisms, a chondrichthyan (catshark), a cyclostome (lamprey), and a cephalochordate (amphioxus), to assess the involvement of RA in the regulation of chordate and vertebrate pronephros formation. We report that the anterior expression boundary of early pronephric markers (Pax2 and Lim1), positioned at the level of somite 6 in amniotes, is conserved in the catshark and the lamprey. Furthermore, RA, driving the expression of Hox4 genes like in amniotes, regulates the anterior pronephros boundary in the catshark. We find no evidence for the involvement of this regulatory hierarchy in the AP positioning of the lamprey pronephros and the amphioxus pronephros homolog, Hatschek's nephridium. This suggests that despite the conservation of Pax2 and Lim1 expressions in chordate pronephros homologs, the responsiveness of the IM, and hence of pronephric genes, to RA- and Hox-dependent regulation is a gnathostome novelty.
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Affiliation(s)
- Pascal Schmidt
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel; (P.S.); (E.L.)
- Laboratoire de Biologie du Développement de Villefranche-sur-Mer, Institut de la Mer de Villefranche, CNRS, Sorbonne Université, 06230 Villefranche-sur-Mer, France;
| | - Eva Leman
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel; (P.S.); (E.L.)
| | - Ronan Lagadec
- CNRS, Sorbonne Université, UMR7232-Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, 66650 Banyuls-sur-Mer, France; (R.L.); (S.M.)
| | - Michael Schubert
- Laboratoire de Biologie du Développement de Villefranche-sur-Mer, Institut de la Mer de Villefranche, CNRS, Sorbonne Université, 06230 Villefranche-sur-Mer, France;
| | - Sylvie Mazan
- CNRS, Sorbonne Université, UMR7232-Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, 66650 Banyuls-sur-Mer, France; (R.L.); (S.M.)
| | - Ram Reshef
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel; (P.S.); (E.L.)
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5
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Double-layered two-directional somatopleural cell migration during chicken body wall development revealed with local fluorescent tissue labeling. Anat Sci Int 2022; 97:380-390. [DOI: 10.1007/s12565-022-00652-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 02/05/2022] [Indexed: 11/01/2022]
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6
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Xue X, Zhao S, Li K, Zhao B. Intrathoracic rib: rare rib anomaly, review of the literature and proposal for classification. Int J Med Sci 2021; 18:3800-3807. [PMID: 34790056 PMCID: PMC8579300 DOI: 10.7150/ijms.63828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/21/2021] [Indexed: 11/25/2022] Open
Abstract
Background: Intrathoracic ribs are very rare congenital anomalies, and often discovered incidentally on chest X-ray. Since its first description by Lutz in 1947, approximately 50 cases have been reported in the literature till date. The aim is to review the all reported intrathoracic ribs, summarize their clinical features, and propose a potential classification. Methods: All relevant literatures were searched and reviewed. The terms include intrathoracic rib, intrathoracic bifid rib, trans-thoracic rib and intrathoracic rib anomaly. We have summarized the first finding events, origination, distribution, related anomalies and imaging features of intrathoracic rib, and propose an updated classification. Results: The patients' age at initial finding was from six weeks to 79 years old. Of all, sixty percent was less than 30 years old. There was no difference in gender. Most of them were reported by authors in western countries (85.3%, 58/68), and incidental findings by radiologist and respiratory physician. The intrathoracic rib occurs more frequently on the right side, and is usually single and unilateral. According to the new classification, type I and II was account for 45.6% and 35.3%, respectively. Conclusion: Intrathoracic rib is rare findings in clinical practice. It is useful that radiologists or clinician are familiarized with the imaging appearances of these malformations. These anomalies reflect some disturbances during the embryo development, leading us to propose a potential classification that could contribute to a better understanding of this rib anomaly.
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Affiliation(s)
- Xuhong Xue
- Department of Orthopedics, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030001, P.R. China
| | - Sheng Zhao
- Department of Orthopedics, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030001, P.R. China
| | - Kai Li
- Department of Orthopedics, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030001, P.R. China
| | - Bin Zhao
- Department of Orthopedics, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030001, P.R. China
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7
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Scaal M. Development of the amniote ventrolateral body wall. Dev Dyn 2020; 250:39-59. [PMID: 32406962 DOI: 10.1002/dvdy.193] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/30/2020] [Accepted: 04/30/2020] [Indexed: 12/16/2022] Open
Abstract
In vertebrates, the trunk consists of the musculoskeletal structures of the back and the ventrolateral body wall, which together enclose the internal organs of the circulatory, digestive, respiratory and urogenital systems. This review gives an overview on the development of the thoracic and abdominal wall during amniote embryogenesis. Specifically, I briefly summarize relevant historical concepts and the present knowledge on the early embryonic development of ribs, sternum, intercostal muscles and abdominal muscles with respect to anatomical bauplan, origin and specification of precursor cells, initial steps of pattern formation, and cellular and molecular regulation of morphogenesis.
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Affiliation(s)
- Martin Scaal
- Faculty of Medicine, Institute of Anatomy II, University of Cologne, Cologne, Germany
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8
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Criswell KE, Gillis JA. Resegmentation is an ancestral feature of the gnathostome vertebral skeleton. eLife 2020; 9:51696. [PMID: 32091389 PMCID: PMC7064331 DOI: 10.7554/elife.51696] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 02/19/2020] [Indexed: 01/03/2023] Open
Abstract
The vertebral skeleton is a defining feature of vertebrate animals. However, the mode of vertebral segmentation varies considerably between major lineages. In tetrapods, adjacent somite halves recombine to form a single vertebra through the process of 'resegmentation'. In teleost fishes, there is considerable mixing between cells of the anterior and posterior somite halves, without clear resegmentation. To determine whether resegmentation is a tetrapod novelty, or an ancestral feature of jawed vertebrates, we tested the relationship between somites and vertebrae in a cartilaginous fish, the skate (Leucoraja erinacea). Using cell lineage tracing, we show that skate trunk vertebrae arise through tetrapod-like resegmentation, with anterior and posterior halves of each vertebra deriving from adjacent somites. We further show that tail vertebrae also arise through resegmentation, though with a duplication of the number of vertebrae per body segment. These findings resolve axial resegmentation as an ancestral feature of the jawed vertebrate body plan.
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Affiliation(s)
- Katharine E Criswell
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom.,Marine Biological Laboratory, Woods Hole, United States
| | - J Andrew Gillis
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom.,Marine Biological Laboratory, Woods Hole, United States
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9
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Akama K, Ebata K, Maeno A, Taminato T, Otosaka S, Gengyo-Ando K, Nakai J, Yamasu K, Kawamura A. Role of somite patterning in the formation of Weberian apparatus and pleural rib in zebrafish. J Anat 2019; 236:622-629. [PMID: 31840255 DOI: 10.1111/joa.13135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2019] [Indexed: 01/12/2023] Open
Abstract
In the vertebrate body, a metameric structure is present along the anterior-posterior axis. Zebrafish tbx6-/- larvae, in which somite boundaries do not form during embryogenesis, were shown to exhibit abnormal skeletal morphology such as rib, neural arch and hemal arch. In this study, we investigated the role of somite patterning in the formation of anterior vertebrae and ribs in more detail. Using three-dimensional computed tomography scans, we found that anterior vertebrae including the Weberian apparatus were severely affected in tbx6-/- larvae. In addition, pleural ribs of tbx6 mutants exhibited severe defects in the initial ossification, extension of ossification, and formation of parapophyses. Two-colour staining revealed that bifurcation of ribs was caused by fusion or branching of ribs in tbx6-/- . The parapophyses in tbx6-/- juvenile fish showed irregular positioning to centra and abnormal attachment to ribs. Furthermore, we found that the ossification of the distal portion of ribs proceeded along myotome boundaries even in irregularly positioned myotome boundaries. These results provide evidence of the contribution of somite patterning to the formation of the Weberian apparatus and rib in zebrafish.
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Affiliation(s)
- Kagari Akama
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Kanami Ebata
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Akiteru Maeno
- Plant Cytogenetics Laboratory, National Institute of Genetics, Mishima, Japan
| | - Tomohito Taminato
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Shiori Otosaka
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Keiko Gengyo-Ando
- Brain and Body System Science Institute, Saitama University, Saitama, Japan
| | - Junichi Nakai
- Brain and Body System Science Institute, Saitama University, Saitama, Japan
| | - Kyo Yamasu
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Akinori Kawamura
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
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10
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Matsutani K, Ikegami K, Aoyama H. An in vitro model of region-specific rib formation in chick axial skeleton: Intercellular interaction between somite and lateral plate cells. Mech Dev 2019; 159:103568. [PMID: 31493459 DOI: 10.1016/j.mod.2019.103568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 07/22/2019] [Accepted: 08/30/2019] [Indexed: 11/30/2022]
Abstract
The axial skeleton is divided into different regions based on its morphological features. In particular, in birds and mammals, ribs are present only in the thoracic region. The axial skeleton is derived from a series of somites. In the thoracic region of the axial skeleton, descendants of somites coherently penetrate into the somatic mesoderm to form ribs. In regions other than the thoracic, descendants of somites do not penetrate the somatic lateral plate mesoderm. We performed live-cell time-lapse imaging to investigate the difference in the migration of a somite cell after contact with the somatic lateral plate mesoderm obtained from different regions of anterior-posterior axis in vitro on cytophilic narrow paths. We found that a thoracic somite cell continues to migrate after contact with the thoracic somatic lateral plate mesoderm, whereas it ceases migration after contact with the lumbar somatic lateral plate mesoderm. This suggests that cell-cell interaction works as an important guidance cue that regulates migration of somite cells. We surmise that the thoracic somatic lateral plate mesoderm exhibits region-specific competence to allow penetration of somite cells, whereas the lumbosacral somatic lateral plate mesoderm repels somite cells by contact inhibition of locomotion. The differences in the behavior of the somatic lateral plate mesoderm toward somite cells may confirm the distinction between different regions of the axial skeleton.
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Affiliation(s)
- Kaoru Matsutani
- Department of Anatomy and Developmental Biology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Koji Ikegami
- Department of Anatomy and Developmental Biology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Hirohiko Aoyama
- Department of Anatomy and Developmental Biology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan; Department of Medical Science and Technology, Faculty of Health Sciences, Hiroshima International University, 555-36 Kurosegakuendai, Higashihiroshima City, Hiroshima 739-2695, Japan.
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11
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Normal development of costal element ossification centers of sacral vertebrae in the fetal spine: a postmortem magnetic resonance imaging study. Neuroradiology 2019; 61:183-193. [PMID: 30607474 DOI: 10.1007/s00234-018-2147-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 12/10/2018] [Indexed: 10/27/2022]
Abstract
PURPOSE This postmortem magnetic resonance imaging (MRI) study of the fetal spine aimed to describe the timing of appearance, shape, volume, and relative positions of the S1-S3 costal element ossification centers (CEOCs). METHODS We obtained sagittal 3D dual-echo steady-state with water excitation T2 images of the entire spine in 71 fetuses (gestational ages (GAs), 17-42 weeks). Computed tomography and histological examinations were performed on two fetal specimens (GAs, 21 and 30 weeks) to validate the MR images. The presence/absence of each sacral CEOC was recorded according to the GA. CEOC volume was measured. We analyzed the CEOC position relative to the vertebral column and ilium. RESULTS The S1, S2, and S3 CEOCs first appeared at 23, 22, and 29 weeks, respectively. The S1 and S2 CEOCs could be detected in all fetuses with GAs of ≥ 30 weeks and ≥ 35 weeks, respectively, while the S3 CEOCs were variably present until term. The percentages of detection of the S1 and S2 CEOCs were significantly greater than that of the S3 CEOCs at each GA. At S1 and S2, the CEOC volume increased exponentially with GA. The relative positions of the S1 and S2 CEOCs, but not the S3 CEOCs, significantly correlated with GA (P < 0.001). CONCLUSION We have described the timeline of appearance as well as the volume and position of the S1-S3 CEOCs in the fetal spine on postmortem MRI according to GA.
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12
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Criswell KE, Coates MI, Gillis JA. Embryonic origin of the gnathostome vertebral skeleton. Proc Biol Sci 2018; 284:rspb.2017.2121. [PMID: 29167367 PMCID: PMC5719183 DOI: 10.1098/rspb.2017.2121] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 10/24/2017] [Indexed: 12/17/2022] Open
Abstract
The vertebral column is a key component of the jawed vertebrate (gnathostome) body plan, but the primitive embryonic origin of this skeleton remains unclear. In tetrapods, all vertebral components (neural arches, haemal arches and centra) derive from paraxial mesoderm (somites). However, in teleost fishes, vertebrae have a dual embryonic origin, with arches derived from somites, but centra formed, in part, by secretion of bone matrix from the notochord. Here, we test the embryonic origin of the vertebral skeleton in a cartilaginous fish (the skate, Leucoraja erinacea) which serves as an outgroup to tetrapods and teleosts. We demonstrate, by cell lineage tracing, that both arches and centra are somite-derived. We find no evidence of cellular or matrix contribution from the notochord to the skate vertebral skeleton. These findings indicate that the earliest gnathostome vertebral skeleton was exclusively of somitic origin, with a notochord contribution arising secondarily in teleosts.
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Affiliation(s)
- Katharine E Criswell
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, USA .,Department of Zoology, University of Cambridge, Cambridge, UK.,Marine Biological Laboratory, Woods Hole, MA, USA
| | - Michael I Coates
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, USA
| | - J Andrew Gillis
- Department of Zoology, University of Cambridge, Cambridge, UK.,Marine Biological Laboratory, Woods Hole, MA, USA
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13
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Ward L, Pang ASW, Evans SE, Stern CD. The role of the notochord in amniote vertebral column segmentation. Dev Biol 2018; 439:3-18. [PMID: 29654746 PMCID: PMC5971204 DOI: 10.1016/j.ydbio.2018.04.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 04/05/2018] [Accepted: 04/09/2018] [Indexed: 11/22/2022]
Abstract
The vertebral column is segmented, comprising an alternating series of vertebrae and intervertebral discs along the head-tail axis. The vertebrae and outer portion (annulus fibrosus) of the disc are derived from the sclerotome part of the somites, whereas the inner nucleus pulposus of the disc is derived from the notochord. Here we investigate the role of the notochord in vertebral patterning through a series of microsurgical experiments in chick embryos. Ablation of the notochord causes loss of segmentation of vertebral bodies and discs. However, the notochord cannot segment in the absence of the surrounding sclerotome. To test whether the notochord dictates sclerotome segmentation, we grafted an ectopic notochord. We find that the intrinsic segmentation of the sclerotome is dominant over any segmental information the notochord may possess, and no evidence that the chick notochord is intrinsically segmented. We propose that the segmental pattern of vertebral bodies and discs in chick is dictated by the sclerotome, which first signals to the notochord to ensure that the nucleus pulposus develops in register with the somite-derived annulus fibrosus. Later, the notochord is required for maintenance of sclerotome segmentation as the mature vertebral bodies and intervertebral discs form. These results highlight differences in vertebral development between amniotes and teleosts including zebrafish, where the notochord dictates the segmental pattern. The relative importance of the sclerotome and notochord in vertebral patterning has changed significantly during evolution. The chick notochord has no intrinsic segmentation. Neither notochord or sclerotome can segment normally without the other. The notochord attracts sclerotome cells to the midline. Vertebral segmentation involves reciprocal signals between notochord and sclerotome.
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Affiliation(s)
- Lizzy Ward
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, U.K
| | - Angel S W Pang
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, U.K
| | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, U.K
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, U.K..
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14
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Lawson LY, Harfe BD. Developmental mechanisms of intervertebral disc and vertebral column formation. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2017; 6. [DOI: 10.1002/wdev.283] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 05/09/2017] [Accepted: 05/23/2017] [Indexed: 01/01/2023]
Affiliation(s)
- Lisa Y. Lawson
- Department of Molecular Genetics and Microbiology; Genetics Institute University of Florida, College of Medicine; Gainesville FL USA
| | - Brian D. Harfe
- Department of Molecular Genetics and Microbiology; Genetics Institute University of Florida, College of Medicine; Gainesville FL USA
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15
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Warrier S, Nuwayhid S, Sabatino JA, Sugrue KF, Zohn IE. Supt20 is required for development of the axial skeleton. Dev Biol 2016; 421:245-257. [PMID: 27894818 DOI: 10.1016/j.ydbio.2016.11.009] [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: 12/18/2015] [Revised: 09/08/2016] [Accepted: 11/11/2016] [Indexed: 10/20/2022]
Abstract
Somitogenesis and subsequent axial skeletal development is regulated by the interaction of pathways that determine the periodicity of somite formation, rostrocaudal somite polarity and segment identity. Here we use a hypomorphic mutant mouse line to demonstrate that Supt20 (Suppressor of Ty20) is required for development of the axial skeleton. Supt20 hypomorphs display fusions of the ribs and vertebrae at lower thoracic levels along with anterior homeotic transformation of L1 to T14. These defects are preceded by reduction of the rostral somite and posterior shifts in Hox gene expression. While cycling of Notch target genes in the posterior presomitic mesoderm (PSM) appeared normal, expression of Lfng was reduced. In the anterior PSM, Mesp2 expression levels and cycling were unaffected; yet, expression of downstream targets such as Lfng, Ripply2, Mesp1 and Dll3 in the prospective rostral somite was reduced accompanied by expansion of caudal somite markers such as EphrinB2 and Hes7. Supt20 interacts with the Gcn5-containing SAGA histone acetylation complex. Gcn5 hypomorphic mutant embryos show similar defects in axial skeletal development preceded by posterior shift of Hoxc8 and Hoxc9 gene expression. We demonstrate that Gcn5 and Supt20 hypomorphs show similar defects in rostral-caudal somite patterning potentially suggesting shared mechanisms.
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Affiliation(s)
- Sunita Warrier
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC 20010, USA
| | - Samer Nuwayhid
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC 20010, USA
| | - Julia A Sabatino
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC 20010, USA
| | - Kelsey F Sugrue
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC 20010, USA; Institute for Biomedical Sciences, The George Washington University, Washington, DC 20052, USA
| | - Irene E Zohn
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC 20010, USA.
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16
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Ward L, Evans SE, Stern CD. A resegmentation-shift model for vertebral patterning. J Anat 2016; 230:290-296. [PMID: 27580767 PMCID: PMC5244455 DOI: 10.1111/joa.12540] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2016] [Indexed: 11/27/2022] Open
Abstract
Segmentation of the vertebrate body axis is established in the embryo by formation of somites, which give rise to the axial muscles (myotome) and vertebrae (sclerotome). To allow a muscle to attach to two successive vertebrae, the myotome and sclerotome must be repositioned by half a segment with respect to each other. Two main models have been put forward: ‘resegmentation’ proposes that each half‐sclerotome joins with the half‐sclerotome from the next adjacent somite to form a vertebra containing cells from two successive somites on each side of the midline. The second model postulates that a single vertebra is made from a single somite and that the sclerotome shifts with respect to the myotome. There is conflicting evidence for these models, and the possibility that the mechanism may vary along the vertebral column has not been considered. Here we use DiI and DiO to trace somite contributions to the vertebrae in different axial regions in the chick embryo. We demonstrate that vertebral bodies and neural arches form by resegmentation but that sclerotome cells shift in a region‐specific manner according to their dorsoventral position within a segment. We propose a ‘resegmentation‐shift’ model as the mechanism for amniote vertebral patterning.
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Affiliation(s)
- Lizzy Ward
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, London, UK
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17
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Anderson G, Secor S. Differential growth of body segments explains ontogenetic shifts in organ position for the Diamondback Water Snake (Nerodia rhombifer). CAN J ZOOL 2016. [DOI: 10.1139/cjz-2015-0191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As snakes grow, their organs move anteriorly relative to body size. We explored a developmental explanation for the ontogenetic shift in the relative position of internal organs for snakes using the Diamondback Water Snake (Nerodia rhombifer (Hallowell, 1852)). With age, this water snake’s heart, liver, small intestine, and right kidney move anteriorly by 2.5–5.0 percentage points of snout–vent length. The number of precaudal vertebrae did not vary due to size or sex. The anterior edge of the heart, liver, small intestine, and right kidney were typically aligned within a span of 4–8 vertebrae that likewise did not differ as a function of size or sex. Snakes exhibited a positive relationship between the number of precaudal vertebrae and the vertebra number aligned with each organ. Total length, centrum length, centrum width, ball width, height, and mass of eight vertebrae sampled at consistent vertebral number revealed that vertebrae in the middle region of the body grow at a greater rate than vertebrae at the anterior or distal ends of the body. For N. rhombifer, the observed forward shift in relative organ positions is the product of regional differences in the growth of body segments. Predictably, these differences arise from a developmental program generated by the differential expression of Hox genes.
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Affiliation(s)
- G.E. Anderson
- Department of Biological Sciences, University of Alabama, Box 870344, Tuscaloosa, AL 35487-0344, USA
- Department of Biological Sciences, University of Alabama, Box 870344, Tuscaloosa, AL 35487-0344, USA
| | - S.M. Secor
- Department of Biological Sciences, University of Alabama, Box 870344, Tuscaloosa, AL 35487-0344, USA
- Department of Biological Sciences, University of Alabama, Box 870344, Tuscaloosa, AL 35487-0344, USA
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18
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Williams DR, Shifley ET, Braunreiter KM, Cole SE. Disruption of somitogenesis by a novel dominant allele of Lfng suggests important roles for protein processing and secretion. Development 2016; 143:822-30. [PMID: 26811377 DOI: 10.1242/dev.128538] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 01/14/2016] [Indexed: 12/29/2022]
Abstract
Vertebrate somitogenesis is regulated by a segmentation clock. Clock-linked genes exhibit cyclic expression, with a periodicity matching the rate of somite production. In mice, lunatic fringe (Lfng) expression oscillates, and LFNG protein contributes to periodic repression of Notch signaling. We hypothesized that rapid LFNG turnover could be regulated by protein processing and secretion. Here, we describe a novel Lfng allele (Lfng(RLFNG)), replacing the N-terminal sequences of LFNG, which allow for protein processing and secretion, with the N-terminus of radical fringe (a Golgi-resident protein). This allele is predicted to prevent protein secretion without altering the activity of LFNG, thus increasing the intracellular half-life of the protein. This allele causes dominant skeletal and somite abnormalities that are distinct from those seen in Lfng loss-of-function embryos. Expression of clock-linked genes is perturbed and mature Hes7 transcripts are stabilized in the presomitic mesoderm of mutant mice, suggesting that both transcriptional and post-transcriptional regulation of clock components are perturbed by RLFNG expression. Contrasting phenotypes in the segmentation clock and somite patterning of mutant mice suggest that LFNG protein may have context-dependent effects on Notch activity.
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Affiliation(s)
- Dustin R Williams
- The Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Emily T Shifley
- The Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA Department of Biological Sciences, Northern Kentucky University, Highland Heights, KY 41099, USA
| | - Kara M Braunreiter
- The Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Susan E Cole
- The Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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19
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Fleming A, Kishida MG, Kimmel CB, Keynes RJ. Building the backbone: the development and evolution of vertebral patterning. Development 2015; 142:1733-44. [PMID: 25968309 DOI: 10.1242/dev.118950] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The segmented vertebral column comprises a repeat series of vertebrae, each consisting of two key components: the vertebral body (or centrum) and the vertebral arches. Despite being a defining feature of the vertebrates, much remains to be understood about vertebral development and evolution. Particular controversy surrounds whether vertebral component structures are homologous across vertebrates, how somite and vertebral patterning are connected, and the developmental origin of vertebral bone-mineralizing cells. Here, we assemble evidence from ichthyologists, palaeontologists and developmental biologists to consider these issues. Vertebral arch elements were present in early stem vertebrates, whereas centra arose later. We argue that centra are homologous among jawed vertebrates, and review evidence in teleosts that the notochord plays an instructive role in segmental patterning, alongside the somites, and contributes to mineralization. By clarifying the evolutionary relationship between centra and arches, and their varying modes of skeletal mineralization, we can better appreciate the detailed mechanisms that regulate and diversify vertebral patterning.
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Affiliation(s)
- Angeleen Fleming
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Marcia G Kishida
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
| | - Charles B Kimmel
- Institute of Neuroscience, 1254 University of Oregon, Eugene OR 97403-1254, USA
| | - Roger J Keynes
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
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20
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Böhmer C, Rauhut OWM, Wörheide G. Correlation between Hox code and vertebral morphology in archosaurs. Proc Biol Sci 2015; 282:20150077. [PMID: 26085583 PMCID: PMC4590465 DOI: 10.1098/rspb.2015.0077] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 05/19/2015] [Indexed: 12/30/2022] Open
Abstract
The relationship between developmental genes and phenotypic variation is of central interest in evolutionary biology. An excellent example is the role of Hox genes in the anteroposterior regionalization of the vertebral column in vertebrates. Archosaurs (crocodiles, dinosaurs including birds) are highly variable both in vertebral morphology and number. Nevertheless, functionally equivalent Hox genes are active in the axial skeleton during embryonic development, indicating that the morphological variation across taxa is likely owing to modifications in the pattern of Hox gene expression. By using geometric morphometrics, we demonstrate a correlation between vertebral Hox code and quantifiable vertebral morphology in modern archosaurs, in which the boundaries between morphological subgroups of vertebrae can be linked to anterior Hox gene expression boundaries. Our findings reveal homologous units of cervical vertebrae in modern archosaurs, each with their specific Hox gene pattern, enabling us to trace these homologies in the extinct sauropodomorph dinosaurs, a group with highly variable vertebral counts. Based on the quantifiable vertebral morphology, this allows us to infer the underlying genetic mechanisms in vertebral evolution in fossils, which represents not only an important case study, but will lead to a better understanding of the origin of morphological disparity in recent archosaur vertebral columns.
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Affiliation(s)
- Christine Böhmer
- Department für Geo- und Umweltwissenschaften und GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Strasse 10, München 80333, Deutschland SNSB - Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Strasse 10, München 80333, Deutschland
| | - Oliver W M Rauhut
- Department für Geo- und Umweltwissenschaften und GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Strasse 10, München 80333, Deutschland SNSB - Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Strasse 10, München 80333, Deutschland
| | - Gert Wörheide
- Department für Geo- und Umweltwissenschaften und GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Strasse 10, München 80333, Deutschland SNSB - Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Strasse 10, München 80333, Deutschland
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21
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Casaca A, Nóvoa A, Mallo M. Hoxb6 can interfere with somitogenesis in the posterior embryo through a mechanism independent of its rib-promoting activity. Development 2015; 143:437-48. [DOI: 10.1242/dev.133074] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 12/18/2015] [Indexed: 01/19/2023]
Abstract
Formation of the vertebrate axial skeleton requires coordinated Hox gene activity. Hox group 6 genes are involved in the formation of the thoracic area due to their unique rib-promoting properties. We show here that the linker region (LR) connecting the homeodomain and the hexapeptide is essential for Hoxb6 rib-promoting activity. The LR-defective Hoxb6 protein was still able to bind a target enhancer together with Pax3 producing a dominant negative effect, indicating that the LR brings additional regulatory factors to target DNA elements. We also found an unexpected association between Hoxb6 and segmentation in the paraxial mesoderm. In particular, Hoxb6 can disturb somitogenesis and anterior-posterior somite patterning by deregulating Lfng expression. Interestingly, this interaction occurred differently in thoracic and more caudal embryonic areas, indicating functional differences in somitogenesis before and after the trunk to tail transition. Our results suggest the requirement of precisely regulated Hoxb6 expression for proper segmentation at tailbud stages.
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Affiliation(s)
- Ana Casaca
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Ana Nóvoa
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Moisés Mallo
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
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22
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Rashid DJ, Chapman SC, Larsson HC, Organ CL, Bebin AG, Merzdorf CS, Bradley R, Horner JR. From dinosaurs to birds: a tail of evolution. EvoDevo 2014; 5:25. [PMID: 25621146 PMCID: PMC4304130 DOI: 10.1186/2041-9139-5-25] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 07/10/2014] [Indexed: 01/09/2023] Open
Abstract
A particularly critical event in avian evolution was the transition from long- to short-tailed birds. Primitive bird tails underwent significant alteration, most notably reduction of the number of caudal vertebrae and fusion of the distal caudal vertebrae into an ossified pygostyle. These changes, among others, occurred over a very short evolutionary interval, which brings into focus the underlying mechanisms behind those changes. Despite the wealth of studies delving into avian evolution, virtually nothing is understood about the genetic and developmental events responsible for the emergence of short, fused tails. In this review, we summarize the current understanding of the signaling pathways and morphological events that contribute to tail extension and termination and examine how mutations affecting the genes that control these pathways might influence the evolution of the avian tail. To generate a list of candidate genes that may have been modulated in the transition to short-tailed birds, we analyzed a comprehensive set of mouse mutants. Interestingly, a prevalent pleiotropic effect of mutations that cause fused caudal vertebral bodies (as in the pygostyles of birds) is tail truncation. We identified 23 mutations in this class, and these were primarily restricted to genes involved in axial extension. At least half of the mutations that cause short, fused tails lie in the Notch/Wnt pathway of somite boundary formation or differentiation, leading to changes in somite number or size. Several of the mutations also cause additional bone fusions in the trunk skeleton, reminiscent of those observed in primitive and modern birds. All of our findings were correlated to the fossil record. An open question is whether the relatively sudden appearance of short-tailed birds in the fossil record could be accounted for, at least in part, by the pleiotropic effects generated by a relatively small number of mutational events.
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Affiliation(s)
- Dana J Rashid
- Museum of the Rockies, Montana State University, 600 West Kagy Blvd, Bozeman, MT 59717, USA
| | - Susan C Chapman
- Department of Biological Sciences, Clemson University, 340 Long Hall, Clemson, SC 29634, USA
| | - Hans Ce Larsson
- Redpath Museum, McGill University, 859 Sherbrooke Street W., Montreal, Quebec H3A 0C4, Canada
| | - Chris L Organ
- Museum of the Rockies, Montana State University, 600 West Kagy Blvd, Bozeman, MT 59717, USA ; Department of Earth Sciences, Montana State University, 226 Traphagen Hall, Bozeman, MT 59717, USA
| | - Anne-Gaelle Bebin
- Museum of the Rockies, Montana State University, 600 West Kagy Blvd, Bozeman, MT 59717, USA ; Current address: Vaccine and Gene Therapy FL, 9801 Discovery Way, Port Lucie, FL 34987, USA
| | - Christa S Merzdorf
- Department of Cell Biology & Neuroscience, Montana State University, 513 Leon Johnson Hall, Bozeman, MT 59717, USA
| | - Roger Bradley
- Department of Cell Biology & Neuroscience, Montana State University, 513 Leon Johnson Hall, Bozeman, MT 59717, USA
| | - John R Horner
- Museum of the Rockies, Montana State University, 600 West Kagy Blvd, Bozeman, MT 59717, USA
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23
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Graham A, Butts T, Lumsden A, Kiecker C. What can vertebrates tell us about segmentation? EvoDevo 2014; 5:24. [PMID: 25009737 PMCID: PMC4088296 DOI: 10.1186/2041-9139-5-24] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 06/11/2014] [Indexed: 12/28/2022] Open
Abstract
Segmentation is a feature of the body plans of a number of diverse animal groupings, including the annelids, arthropods and chordates. However, it has been unclear whether or not these different manifestations of segmentation are independently derived or have a common origin. Central to this issue is whether or not there are common developmental mechanisms that establish segmentation and the evolutionary origins of these processes. A fruitful way to address this issue is to consider how segmentation in vertebrates is directed. During vertebrate development three different segmental systems are established: the somites, the rhombomeres and the pharyngeal arches. In each an iteration of parts along the long axis is established. However, it is clear that the formation of the somites, rhombomeres or pharyngeal arches have little in common, and as such there is no single segmentation process. These different segmental systems also have distinct evolutionary histories, thus highlighting the fact that segmentation can and does evolve independently at multiple points. We conclude that the term segmentation indicates nothing more than a morphological description and that it implies no mechanistic similarity. Thus it is probable that segmentation has arisen repeatedly during animal evolution.
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Affiliation(s)
- Anthony Graham
- MRC Centre for Developmental Neurobiology, King's College London, London SE1 1UL, UK
| | - Thomas Butts
- MRC Centre for Developmental Neurobiology, King's College London, London SE1 1UL, UK
| | - Andrew Lumsden
- MRC Centre for Developmental Neurobiology, King's College London, London SE1 1UL, UK
| | - Clemens Kiecker
- MRC Centre for Developmental Neurobiology, King's College London, London SE1 1UL, UK
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24
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Resegmentation in the mexican axolotl,Ambystoma mexicanum. J Morphol 2013; 275:141-52. [DOI: 10.1002/jmor.20204] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 08/15/2013] [Accepted: 08/19/2013] [Indexed: 12/26/2022]
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25
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Takahashi Y, Yasuhiko Y, Takahashi J, Takada S, Johnson RL, Saga Y, Kanno J. Metameric pattern of intervertebral disc/vertebral body is generated independently of Mesp2/Ripply-mediated rostro-caudal patterning of somites in the mouse embryo. Dev Biol 2013; 380:172-84. [PMID: 23727513 DOI: 10.1016/j.ydbio.2013.05.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 05/17/2013] [Accepted: 05/17/2013] [Indexed: 02/03/2023]
Abstract
The vertebrae are derived from the sclerotome of somites. Formation of the vertebral body involves a process called resegmentation, by which the caudal half of a sclerotome is combined with the rostral half of the next sclerotome. To elucidate the relationship between resegmentation and rostro-caudal patterning of somite, we used the Uncx4.1-LacZ transgene to characterize the resegmentation process. Our observations suggested that in the thoracic and lumbar vertebrae, the Uncx4.1-expressing caudal sclerotome gave rise to the intervertebral disc (IVD) and rostral portion of the vertebral body (VB). In the cervical vertebrae, the Uncx4.1-expressing caudal sclerotome appeared to contribute to the IVD and both caudal and rostral ends of the VB. This finding suggests that the rostro-caudal gene expression boundary does not necessarily coincide with the resegmentation boundary. This conclusion was supported by analyses of Mesp2 KO and Ripply1/2 double KO embryos lacking rostral and caudal properties, respectively. Resegmentation was not observed in Mesp2 KO embryos, but both the IVD and whole VB were formed from the caudalized sclerotome. Expression analysis of IVD marker genes including Pax1 in the wild-type, Mesp2 KO, and Ripply1/2 DKO embryos also supported the idea that a metameric pattern of IVD/VB is generated independently of Mesp2/Ripply-mediated rostro-caudal patterning of somite. However, in the lumbar region, IVD differentiation appeared to be stimulated by the caudal property and suppressed by the rostral property. Therefore, we propose that rostro-caudal patterning of somites is not a prerequisite for metameric patterning of the IVD and VB, but instead required to stimulate IVD differentiation in the caudal half of the sclerotome.
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Affiliation(s)
- Yu Takahashi
- Cellular & Molecular Toxicology Division, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagayaku, Tokyo 158-8501, Japan.
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26
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Lopez TP, Fan CM. Dynamic CREB family activity drives segmentation and posterior polarity specification in mammalian somitogenesis. Proc Natl Acad Sci U S A 2013; 110:E2019-27. [PMID: 23671110 PMCID: PMC3670316 DOI: 10.1073/pnas.1222115110] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The segmented body plan of vertebrates is prefigured by reiterated embryonic mesodermal structures called somites. In the mouse embryo, timely somite formation from the presomitic mesoderm (PSM) is controlled by the "segmentation clock," a molecular oscillator that triggers progressive waves of Notch activity throughout the PSM. Notch clock activity is suppressed in the posterior PSM by FGF signaling until it crosses a determination front at which its net activity is sufficiently high to effect segmentation. Here, Notch and Wnt signaling directs somite anterior/posterior (A/P) polarity specification and boundary formation via regulation of the segmentation effector gene Mesoderm posterior 2. How Notch and Wnt signaling becomes coordinated at this front is incompletely defined. Here we show that the activity of the cAMP responsive element binding protein (CREB) family of transcription factors exhibits Wnt3a-dependent oscillatory behavior near the determination front and is in unison with Notch activity. Inhibition of CREB family in the mesoderm causes defects in somite segmentation and a loss in somite posterior polarity leading to fusions of vertebrae and ribs. Among the CREB family downstream genes, several are known to be regulated by Wnt3a. Of those, we show that the CREB family occupies a conserved binding site in the promoter region of Delta-like 1, encoding a Notch ligand, in the anterior PSM as a mechanism to specify posterior identity of somites. Together, these data support that the CREB family acts at the determination front to modulate Wnt signaling and strengthen Notch signaling as a means to orchestrate cells for somite segmentation and anterior/posterior patterning.
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Affiliation(s)
- T. Peter Lopez
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218; and
- Department of Embryology, Carnegie Institution of Washington, Baltimore, MD 21218
| | - Chen-Ming Fan
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218; and
- Department of Embryology, Carnegie Institution of Washington, Baltimore, MD 21218
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27
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Tubbs RS, Lingo PR, Mortazavi MM, Cohen-Gadol AA. Hypoplastic occipital condyle and third occipital condyle: review of their dysembryology. Clin Anat 2013; 26:928-32. [PMID: 23338989 DOI: 10.1002/ca.22205] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 10/17/2012] [Accepted: 10/21/2012] [Indexed: 11/11/2022]
Abstract
Disruption or embryologic derailment of the normal bony architecture of the craniovertebral junction (CVJ) may result in symptoms. As studies of the embryology and pathology of hypoplasia of the occipital condyles and third occipital condyles are lacking in the literature, the present review was performed. Standard search engines were accessed and queried for publications regarding hypoplastic occipital condyles and third occipital condyles. The literature supports the notion that occipital condyle hypoplasia and a third occipital condyle are due to malformation or persistence of the proatlas, respectively. The Pax-1 gene is most likely involved in this process. Clinically, condylar hypoplasia may narrow the foramen magnum and lead to lateral medullary compression. Additionally, this maldevelopment can result in transient vertebral artery compression secondary to posterior subluxation of the occiput. Third occipital condyles have been associated with cervical canal stenosis, hypoplasia of the dens, transverse ligament laxity, and atlanto-axial instability causing acute and chronic spinal cord compression. Treatment goals are focused on craniovertebral stability. A better understanding of the embryology and pathology related to CVJ anomalies is useful to the clinician treating patients presenting with these entities.
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Affiliation(s)
- R Shane Tubbs
- Pediatric Neurosurgery, Children's Hospital, Birmingham, Alabama
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28
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Vertebral architecture in the earliest stem tetrapods. Nature 2013; 494:226-9. [DOI: 10.1038/nature11825] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 12/07/2012] [Indexed: 11/08/2022]
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29
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Origin of the Turtle Body Plan: The Folding Theory to Illustrate Turtle-Specific Developmental Repatterning. VERTEBRATE PALEOBIOLOGY AND PALEOANTHROPOLOGY 2013. [DOI: 10.1007/978-94-007-4309-0_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
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30
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Saga Y. The mechanism of somite formation in mice. Curr Opin Genet Dev 2012; 22:331-8. [PMID: 22742849 DOI: 10.1016/j.gde.2012.05.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 03/30/2012] [Accepted: 05/15/2012] [Indexed: 12/11/2022]
Abstract
Somitogenesis is a series of dynamic morphogenetic events that involve cyclical signaling. The periodicity of somitogenesis is controlled by segmentation clock operating in the presomitic mesoderm (PSM), the precursor of somites. Notch signaling plays important roles not only in the segmentation clock mechanism but also as an output signal of the clock to induce Mesp2 transcription that controls somite formation. In the present review, recent advances in the understanding of the molecular mechanisms underlying the translation of clock information into the spatial patterning of segmental somites in mice are discussed. Particular attention is paid to the interplay between two the distinct signaling pathways of Notch and FGF and the Mesp2 transcription factor acting as an effector molecule during mouse somitogenesis.
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Affiliation(s)
- Yumiko Saga
- Division of Mammalian Development, National institute of Genetics and Department of Genetics, SOKENDAI, 1111 Yata, Mishima, Shizuoka 411-8540, Japan.
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31
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Senthinathan B, Sousa C, Tannahill D, Keynes R. The generation of vertebral segmental patterning in the chick embryo. J Anat 2012; 220:591-602. [PMID: 22458512 PMCID: PMC3390512 DOI: 10.1111/j.1469-7580.2012.01497.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2012] [Indexed: 12/20/2022] Open
Abstract
We have carried out a series of experimental manipulations in the chick embryo to assess whether the notochord, neural tube and spinal nerves influence segmental patterning of the vertebral column. Using Pax1 expression in the somite-derived sclerotomes as a marker for segmentation of the developing intervertebral disc, our results exclude such an influence. In contrast to certain teleost species, where the notochord has been shown to generate segmentation of the vertebral bodies (chordacentra), these experiments indicate that segmental patterning of the avian vertebral column arises autonomously in the somite mesoderm. We suggest that in amniotes, the subdivision of each sclerotome into non-miscible anterior and posterior halves plays a critical role in establishing vertebral segmentation, and in maintaining left/right alignment of the developing vertebral elements at the body midline.
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Affiliation(s)
- Biruntha Senthinathan
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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Oates AC, Morelli LG, Ares S. Patterning embryos with oscillations: structure, function and dynamics of the vertebrate segmentation clock. Development 2012; 139:625-39. [PMID: 22274695 DOI: 10.1242/dev.063735] [Citation(s) in RCA: 264] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The segmentation clock is an oscillating genetic network thought to govern the rhythmic and sequential subdivision of the elongating body axis of the vertebrate embryo into somites: the precursors of the segmented vertebral column. Understanding how the rhythmic signal arises, how it achieves precision and how it patterns the embryo remain challenging issues. Recent work has provided evidence of how the period of the segmentation clock is regulated and how this affects the anatomy of the embryo. The ongoing development of real-time clock reporters and mathematical models promise novel insight into the dynamic behavior of the clock.
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Affiliation(s)
- Andrew C Oates
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, Dresden, Germany.
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Nagashima H, Kuraku S, Uchida K, Kawashima-Ohya Y, Narita Y, Kuratani S. Body plan of turtles: an anatomical, developmental and evolutionary perspective. Anat Sci Int 2011; 87:1-13. [DOI: 10.1007/s12565-011-0121-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 10/24/2011] [Indexed: 10/15/2022]
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Sato T, Koizumi M, Kim JH, Kim JH, Wang BJ, Murakami G, Cho BH. Fetal development of deep back muscles in the human thoracic region with a focus on transversospinalis muscles and the medial branch of the spinal nerve posterior ramus. J Anat 2011; 219:756-65. [PMID: 21954879 DOI: 10.1111/j.1469-7580.2011.01430.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Fetal development of human deep back muscles has not yet been fully described, possibly because of the difficulty in identifying muscle bundle directions in horizontal sections. Here, we prepared near-frontal sections along the thoracic back skin (eight fetuses) as well as horizontal sections (six fetuses) from 14 mid-term fetuses at 9-15 weeks of gestation. In the deep side of the trapezius and rhomboideus muscles, the CD34-positive thoracolumbar fascia was evident even at 9 weeks. Desmin-reactivity was strong and homogeneous in the superficial muscle fibers in contrast to the spotty expression in the deep fibers. Thus, in back muscles, formation of the myotendinous junction may start from the superficial muscles and advance to the deep muscles. The fact that developing intramuscular tendons were desmin-negative suggested little possibility of a secondary change from the muscle fibers to tendons. We found no prospective spinalis muscle or its tendinous connections with other muscles. Instead, abundant CD68-positive macrophages along the spinous process at 15 weeks suggested a change in muscle attachment, an event that may result in a later formation of the spinalis muscle. S100-positive intramuscular nerves exhibited downward courses from the multifidus longus muscle in the original segment to the rotatores brevis muscles in the inferiorly adjacent level. The medial cutaneous nerve had already reached the thoracolumbar fascia at 9 weeks, but by 15 weeks the nerve could not penetrate the trapezius muscle. Finally, we propose a folded myotomal model of the primitive transversospinalis muscle that seems to explain a fact that the roofing tile-like configuration of nerve twigs in the semispinalis muscle is reversed in the multifidus and rotatores muscles.
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Affiliation(s)
- Tatsuo Sato
- Division of Basic Sciences, Tokyo Ariake University of Medical and Health Science, Tokyo, Japan
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35
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Alexander PG, Tuan RS. Role of environmental factors in axial skeletal dysmorphogenesis. ACTA ACUST UNITED AC 2010; 90:118-32. [DOI: 10.1002/bdrc.20179] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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36
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Inohaya K, Takano Y, Kudo A. Production of Wnt4b by floor plate cells is essential for the segmental patterning of the vertebral column in medaka. Development 2010; 137:1807-13. [PMID: 20460365 DOI: 10.1242/dev.051540] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The floor plate is a key organizer that controls the specification of neurons in the central nervous system. Here, we show a new role of the floor plate: segmental pattern formation of the vertebral column. Analysis of a spontaneous medaka mutant, fused centrum (fsc), which exhibits fused centra and the absence of the intervertebral ligaments, revealed that fsc encodes wnt4b, which was expressed exclusively in the floor plate. In fsc mutants, we found that wnt4b expression was completely lost in the floor plate and that abnormal conversion of the intervertebral ligament cells into osteoblasts appeared to cause a defect of the intervertebral ligaments. The establishment of the transgenic rescue lines and mosaic analyses allowed the conclusion to be drawn that production of wnt4b by floor plate cells is essential for the segmental patterning of the vertebral column. Our findings provide a novel perspective on the mechanism of vertebrate development.
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Affiliation(s)
- Keiji Inohaya
- Department of Biological Information, Tokyo Institute of Technology, Midori-ku, Yokohama 226-8501, Japan
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Hughes DST, Keynes RJ, Tannahill D. Extensive molecular differences between anterior- and posterior-half-sclerotomes underlie somite polarity and spinal nerve segmentation. BMC DEVELOPMENTAL BIOLOGY 2009; 9:30. [PMID: 19463158 PMCID: PMC2693541 DOI: 10.1186/1471-213x-9-30] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Accepted: 05/22/2009] [Indexed: 01/10/2023]
Abstract
Background The polarization of somite-derived sclerotomes into anterior and posterior halves underlies vertebral morphogenesis and spinal nerve segmentation. To characterize the full extent of molecular differences that underlie this polarity, we have undertaken a systematic comparison of gene expression between the two sclerotome halves in the mouse embryo. Results Several hundred genes are differentially-expressed between the two sclerotome halves, showing that a marked degree of molecular heterogeneity underpins the development of somite polarity. Conclusion We have identified a set of genes that warrant further investigation as regulators of somite polarity and vertebral morphogenesis, as well as repellents of spinal axon growth. Moreover the results indicate that, unlike the posterior half-sclerotome, the central region of the anterior-half-sclerotome does not contribute bone and cartilage to the vertebral column, being associated instead with the development of the segmented spinal nerves.
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Affiliation(s)
- Daniel S T Hughes
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB3 2DY, UK.
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Formation and Differentiation of Avian Somite Derivatives. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 638:1-41. [DOI: 10.1007/978-0-387-09606-3_1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Farin HF, Mansouri A, Petry M, Kispert A. T-box protein Tbx18 interacts with the paired box protein Pax3 in the development of the paraxial mesoderm. J Biol Chem 2008; 283:25372-25380. [PMID: 18644785 DOI: 10.1074/jbc.m802723200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The compartmentalization of somites along their anterior-posterior axis is crucial to the segmental organization of the vertebral column. Anterior-posterior somite polarity is generated in the anterior presomitic mesoderm by Mesp2 and Delta/Notch signaling and is further maintained by two transcriptional regulators, Uncx4.1 and Tbx18, acting in the posterior and anterior somite compartment, respectively. Here, we report that the paired box transcription factor Pax3 cooperates with the T-box protein Tbx18 in maintaining anterior somite half identity. Our findings that both genes are co-expressed in the anterior presomitic mesoderm and in early somites, that Pax3 and Tbx18 proteins physically interact, and that the loss of Pax3 gene function enhances the vertebral defects (i.e. the gain of vertebral elements derived from posterior somite halves in Tbx18 mutant mice) suggests that the two proteins cooperatively regulate the gene expression program necessary for maintaining anterior-posterior somite polarity. Genetic interaction of Pax3 with Tbx18 and the closely related T-box gene Tbx15 was also observed in the development of the scapula blade, indicating an additional cooperative function for these genes in the paraxial mesoderm.
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Affiliation(s)
- Henner F Farin
- Institute for Molecular Biology, Medizinische Hochschule Hannover, OE5250, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany and the
| | - Ahmed Mansouri
- Department of Molecular Cell Biology, Max-Planck-Institute of Biophysical Chemistry, 37077 Göttingen, Germany
| | - Marianne Petry
- Institute for Molecular Biology, Medizinische Hochschule Hannover, OE5250, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany and the
| | - Andreas Kispert
- Institute for Molecular Biology, Medizinische Hochschule Hannover, OE5250, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany and the.
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Compartmentalised expression of Delta-like 1 in epithelial somites is required for the formation of intervertebral joints. BMC DEVELOPMENTAL BIOLOGY 2007; 7:68. [PMID: 17572911 PMCID: PMC1924847 DOI: 10.1186/1471-213x-7-68] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 06/17/2007] [Indexed: 01/23/2023]
Abstract
Background Expression of the mouse Delta-like 1 (Dll1) gene in the presomitic mesoderm and in the caudal halves of somites of the developing embryo is required for the formation of epithelial somites and for the maintenance of caudal somite identity, respectively. The rostro-caudal polarity of somites is initiated early on within the presomitic mesoderm in nascent somites. Here we have investigated the requirement of restricted Dll1 expression in caudal somite compartments for the maintenance of rostro-caudal somite polarity and the morphogenesis of the axial skeleton. We did this by overexpressing a functional copy of the Dll1 gene throughout the paraxial mesoderm, in particular in anterior somite compartments, during somitogenesis in transgenic mice. Results Epithelial somites were generated normally and appeared histologically normal in embryos of two independent Dll1 over-expressing transgenic lines. Gene expression analyses of rostro-caudal marker genes suggested that over-expression of Dll1 without restriction to caudal compartments was not sufficient to confer caudal identity to rostral somite halves in transgenic embryos. Nevertheless, Dll1 over-expression caused dysmorphologies of the axial skeleton, in particular, in morphological structures that derive from the articular joint forming compartment of vertebrae. Accordingly, transgenic animals exhibited missing or reduced intervertebral discs, rostral and caudal articular processes as well as costal heads of ribs. In addition, the midline of the vertebral column did not develop normally. Transgenic mice had open neural arches and split vertebral bodies with ectopic pseudo-growth plates. Endochondral bone formation and ossification in the developing vertebrae were delayed. Conclusion The mice overexpressing Dll1 exhibit skeletal dysmorphologies that are also evident in several mutant mice with defects in somite compartmentalisation. The Dll1 transgenic mice demonstrate that vertebral dysmorphologies such as bony fusions of vertebrae and midline vertebral defects can occur without apparent changes in somitic rostro-caudal marker gene expression. Also, we demonstrate that the over-expression of the Dll1 gene in rostral epithelial somites is not sufficient to confer caudal identity to rostral compartments. Our data suggest that the restricted Dll1 expression in caudal epithelial somites may be particularly required for the proper development of the intervertebral joint forming compartment.
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Sparrow DB, Chapman G, Turnpenny PD, Dunwoodie SL. Disruption of the somitic molecular clock causes abnormal vertebral segmentation. ACTA ACUST UNITED AC 2007; 81:93-110. [PMID: 17600782 DOI: 10.1002/bdrc.20093] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Somites are the precursors of the vertebral column. They segment from the presomitic mesoderm (PSM) that is caudally located and newly generated from the tailbud. Somites form in synchrony on either side of the embryonic midline in a reiterative manner. A molecular clock that operates in the PSM drives this reiterative process. Genetic manipulation in mouse, chick and zebrafish has revealed that the molecular clock controls the activity of the Notch and WNT signaling pathways in the PSM. Disruption of the molecular clock impacts on somite formation causing abnormal vertebral segmentation (AVS). A number of dysmorphic syndromes manifest AVS defects. Interaction between developmental biologists and clinicians has lead to groundbreaking research in this area with the identification that spondylocostal dysostosis (SCD) is caused by mutation in Delta-like 3 (DLL3), Mesoderm posterior 2 (MESP2), and Lunatic fringe (LFNG); three genes that are components of the Notch signaling pathway. This review describes our current understanding of the somitic molecular clock and highlights how key findings in developmental biology can impact on clinical practice.
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Affiliation(s)
- Duncan B Sparrow
- Developmental Biology Program, Victor Chang Cardiac Research Institute, Sydney, Australia
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42
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Barrionuevo F, Taketo MM, Scherer G, Kispert A. Sox9 is required for notochord maintenance in mice. Dev Biol 2006; 295:128-40. [PMID: 16678811 DOI: 10.1016/j.ydbio.2006.03.014] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2005] [Revised: 03/01/2006] [Accepted: 03/13/2006] [Indexed: 02/06/2023]
Abstract
Sox9 encodes a HMG-box transcription factor that has been implicated in numerous developmental processes including chondrogenesis, formation of cardiac valves, and neural crest, testis and spinal cord development. Here we show that Sox9 is expressed in the notochord and the sclerotome during mouse development suggesting that the gene may play additional roles in the development of the axial skeleton. We used ubiquitous mosaic inactivation of a conditional Sox9 allele by Cre/loxP-mediated recombination in the mouse to screen for novel functions of Sox9, and revealed that its absence results in severe malformations of the vertebral column. Besides its established role in chondrogenesis, Sox9 is required for maintaining the structural integrity of the notochord. Mutant embryos establish a normal notochord; however, starting from E9.5, the notochord disintegrates in a cranial to caudal manner. The late requirement in notochord development uncovered a function of notochord-derived signals in inducing segmentation of the ventral sclerotome and chondrogenesis. Thus, Sox9 is required for axial skeletogenesis by regulating notochord survival and chondrogenesis.
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Affiliation(s)
- Francisco Barrionuevo
- Institute of Human Genetics and Anthropology, University of Freiburg, D-79106 Freiburg, Germany.
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43
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Colbjørn Larsen K, Fuchtbauer EM, Brand-Saberi B. The Neural Tube Is Required to Maintain Primary Segmentation in the Sclerotome. Cells Tissues Organs 2006; 182:12-21. [PMID: 16651825 DOI: 10.1159/000091714] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2006] [Indexed: 12/29/2022] Open
Abstract
Primary segmentation in vertebrates is considered to be an intrinsic property of the presomitic paraxial mesoderm controlled by a number of interconnected oscillating signals. Re-segmentation, in contrast, has been shown to depend on signals from the axial structures. Here we report the requirement of the neural tube for maintenance but not formation of primary segmentation in chick embryos. Unilateral removal of the neural tube, next to the anterior presomitic mesoderm, caused disturbed development of the neural arches and the spinous processes. But already 24 h postsurgery, the sclerotome showed loss of primary segmentation in the craniocaudal axis. Cells strongly expressing twist and not showing any segmentation were located dorsomedially between the remaining left half of the neural tube and the right side dermomyotome, which frequently was truncated medially.
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Affiliation(s)
- Karen Colbjørn Larsen
- Institute of Anatomy and Cell Biology, Department of Molecular Embryology, University of Freiburg, Freiburg, Germany
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44
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Huppert SS, Ilagan MXG, De Strooper B, Kopan R. Analysis of Notch Function in Presomitic Mesoderm Suggests a γ-Secretase-Independent Role for Presenilins in Somite Differentiation. Dev Cell 2005; 8:677-88. [PMID: 15866159 DOI: 10.1016/j.devcel.2005.02.019] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2004] [Revised: 12/23/2004] [Accepted: 02/17/2005] [Indexed: 10/25/2022]
Abstract
The role of Notch signaling in general and presenilin in particular was analyzed during mouse somitogenesis. We visualize cyclical production of activated Notch (NICD) and establish that somitogenesis requires less NICD than any other tissue in early mouse embryos. Indeed, formation of cervical somites proceeds in Notch1; Notch2-deficient embryos. This is in contrast to mice lacking all presenilin alleles, which have no somites. Since Nicastrin-, Pen-2-, and APH-1a-deficient embryos have anterior somites without gamma-secretase, presenilin may have a gamma-secretase-independent role in somitogenesis. Embryos triple homozygous for both presenilin null alleles and a Notch allele that is a poor substrate for presenilin (N1(V-->G)) experience fortuitous cleavage of N1(V-->G) by another protease. This restores NICD, anterior segmentation, and bilateral symmetry but does not rescue rostral/caudal identities. These data clarify multiple roles for Notch signaling during segmentation and suggest that the earliest stages of somitogenesis are regulated by both Notch-dependent and Notch-independent functions of presenilin.
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MESH Headings
- Amyloid Precursor Protein Secretases
- Animals
- Aspartic Acid Endopeptidases
- Body Patterning/genetics
- Body Patterning/physiology
- Cell Differentiation
- Endopeptidases/metabolism
- In Situ Hybridization
- Membrane Proteins/deficiency
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Mutant Strains
- Microscopy, Electron, Scanning
- Phenotype
- Presenilin-1
- Presenilin-2
- Receptor, Notch1
- Receptor, Notch2
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Somites/cytology
- Somites/metabolism
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transcription Factors/physiology
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Affiliation(s)
- Stacey S Huppert
- Department of Molecular Biology and Pharmacology, Division of Dermatology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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45
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Hirao A, Aoyama H. Somite development without influence of the surface ectoderm in the chick embryo: the compartments of a somite responsible for distal rib development. Dev Growth Differ 2005; 46:351-62. [PMID: 15367203 DOI: 10.1111/j.1440-169x.2004.00752.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the development of the somite, signals from neighboring tissues have been suggested to play critical roles. We have found that when interaction between the ectoderm and the somite is blocked by inserting a piece of polyethylene terephatalate film between them in 2-day-chicken embryo, one of the derivatives of somite, the distal rib, did not form. We examined somite development after the operation, to know the correlation between somite development and distal rib formation. In the operated embryo, the dermomyotome was medio-laterally shorter than in the normal embryo, and Pax3 and Sim1 expressions that are seen in the lateral part of normal dermomyotomes were not found, suggesting that the lateral part of the dermomyotome was missing. Although the sclerotome appeared to be normal in its histology and Pax1 expression pattern in the operated embryo, we could not detect the expression of either Scleraxis nor gamma-FBP that are expressed in the cells around the boundaries between the adjacent dermomyotomes in normal embryos. Thus, under the influence of surface ectoderm, the lateral part of dermomyotome and/or the mesenchyme around rostral and caudal edges of dermomyotomes are suggested to play an important role in the distal rib development.
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Affiliation(s)
- Akiko Hirao
- Department of Biology, Graduate School of Science, Osaka University, 1-16, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
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46
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Smith TG, Sweetman D, Patterson M, Keyse SM, Münsterberg A. Feedback interactions between MKP3 and ERK MAP kinase control scleraxis expression and the specification of rib progenitors in the developing chick somite. Development 2005; 132:1305-14. [PMID: 15716340 DOI: 10.1242/dev.01699] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cells in the early vertebrate somite receive cues from surrounding tissues,which are important for their specification. A number of signalling pathways involved in somite patterning have been described extensively. By contrast,the interactions between cells from different regions within the somite are less well characterised. Here, we demonstrate that myotomally derived FGFs act through the MAPK signal transduction cascade and in particular, ERK1/2 to activate scleraxis expression in a population of mesenchymal progenitor cells in the dorsal sclerotome. We show that the levels of active,phosphorylated ERK protein in the developing somite are crucial for the expression of scleraxis and Mkp3. MKP3 is a dual specificity phosphatase and a specific antagonist of ERK MAP kinases and we demonstrate that in somites Mkp3 transcription depends on the presence of active ERK. Therefore, MKP3 and ERK MAP kinase constitute a negative feedback loop activated by FGF in sclerotomal progenitor cells. We propose that tight control of ERK signalling strength by MKP3 is important for the appropriate regulation of downstream cellular responses including the activation of scleraxis. We show that increased or decreased levels of phosphorylated ERK result in the loss of scleraxis transcripts and the loss of distal rib development, highlighting the importance of the MKP3-ERK-MAP kinase mediated feedback loop for cell specification and differentiation.
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47
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Oostra RJ, Hennekam RCM, de Rooij L, Moorman AFM. Malformations of the axial skeleton inMuseum Vrolik I: Homeotic transformations and numerical anomalies. Am J Med Genet A 2005; 134:268-81. [PMID: 15732082 DOI: 10.1002/ajmg.a.30639] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The Museum Vrolik collection of anatomical specimens in Amsterdam, The Netherlands, comprises over 5,000 specimens of human and animal anatomy, embryology, pathology, and congenital anomalies. Recently, we rediagnosed a subset of the collection comprising dried human trunk skeletons and cranial base preparations presenting with homeotic transformations (vertebral phenotypic shifts) and numerical vertebral anomalies. We identified 11 trunk skeletons with either anterior or posterior homeotic transformations (AHT or PHT), 5 trunk skeletons with either less or more than the normal number of vertebrae, and well over a hundred cranial base preparations with either AHT (atlas-assimilation) or PHT (occipital vertebra). We found that, although homeotic transformations and numerical anomalies are distinct conditions, both can be described in terms of mismatch between homeotic patterning and morphological segmentation of the paraxial mesoderm. Therefore these two processes are perhaps not as tightly linked as they may seem on the basis of recent molecular studies. In homeotic transformations there is a constant mismatch between homeotic patterning and morphological segmentation throughout the affected region of the vertebral column. In numerical anomalies there is a variable mismatch between homeotic patterning and morphological segmentation, either because of stretching or squeezing of the homeotic pattern or because of oligo- or polysegmentation of the presomitic mesoderm (PSM). Homeotic transformations of the axial skeleton have an incidence of about 1%-5%, apart from their occurrence in malformation syndromes. Of the various etiological possibilities, explaining their frequent but mostly sporadic occurrence, maternal hyperthermia seems an attractive candidate.
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Affiliation(s)
- Roelof-Jan Oostra
- Department of Anatomy and Embryology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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48
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Brent AE, Tabin CJ. FGF acts directly on the somitic tendon progenitors through the Ets transcription factors Pea3 and Erm to regulate scleraxis expression. Development 2004; 131:3885-96. [PMID: 15253939 DOI: 10.1242/dev.01275] [Citation(s) in RCA: 162] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
During somite development, a fibroblast growth factor (FGF) signal secreted from the myotome induces formation of a scleraxis (Scx)-expressing tendon progenitor population in the sclerotome, at the juncture between the future lineages of muscle and cartilage. While overexpression studies show that the entire sclerotome is competent to express Scx in response to FGF signaling, the normal Scx expression domain includes only the anterior and posterior dorsal sclerotome. To understand the molecular basis for this restriction, we examined the expression of a set of genes involved in FGF signaling and found that several members of the Fgf8 synexpression group are co-expressed with Scx in the dorsal sclerotome. Of particular interest were the Ets transcription factors Pea3 and Erm, which function as transcriptional effectors of FGF signaling. We show here that transcriptional activation by Pea3 and Erm in response to FGF signaling is both necessary and sufficient for Scx expression in the somite, and propose that the domain of the somitic tendon progenitors is regulated both by the restricted expression of Pea3 and Erm, and by the precise spatial relationship between these Ets transcription factors and the FGF signal originating in the myotome.
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Affiliation(s)
- Ava E Brent
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
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49
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Bussen M, Petry M, Schuster-Gossler K, Leitges M, Gossler A, Kispert A. The T-box transcription factor Tbx18 maintains the separation of anterior and posterior somite compartments. Genes Dev 2004; 18:1209-21. [PMID: 15155583 PMCID: PMC415645 DOI: 10.1101/gad.300104] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The compartmentalization of somites along their anterior-posterior (AP) axis is pivotal to the segmental organization of the vertebrate axial skeleton and the peripheral nervous system. Anterior and posterior somite halves contribute to different vertebral elements. They are also characterized by different proliferation rates and properties with respect to neural crest cell migration and spinal nerve passage. AP-somite polarity is generated in the anterior presomitic mesoderm by Mesp2 and Delta/Notch signaling. Here, we demonstrate that maintenance of AP-somite polarity is mediated by the T-box transcription factor Tbx18. Mice deficient for Tbx18 show expansion of pedicles with transverse processes and proximal ribs, elements derived from the posterior lateral sclerotome. AP-somite polarity is established in Tbx18 mutant embryos but is not maintained. During somite maturation, posterior somite compartments expand most likely because of posterior cells invading the anterior somite half. In the anterior lateral sclerotome, Tbx18 acts as an antiapoptotic factor. Ectopic expression experiments suggest that Tbx18 can promote anterior at the expense of posterior somite compartments. In summary, Tbx18 appears to act downstream of Mesp2 and Delta/Notch signaling to maintain the separation of anterior and posterior somite compartments.
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Affiliation(s)
- Markus Bussen
- Institut für Molekularbiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
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50
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Fleming A, Keynes R, Tannahill D. A central role for the notochord in vertebral patterning. Development 2004; 131:873-80. [PMID: 14736741 DOI: 10.1242/dev.00952] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The vertebrates are defined by their segmented vertebral column, and vertebral periodicity is thought to originate from embryonic segments, the somites. According to the widely accepted 'resegmentation' model, a single vertebra forms from the recombination of the anterior and posterior halves of two adjacent sclerotomes on both sides of the embryo. Although there is supporting evidence for this model in amniotes, it remains uncertain whether it applies to all vertebrates. To explore this, we have investigated vertebral patterning in the zebrafish. Surprisingly, we find that vertebral bodies (centra) arise by secretion of bone matrix from the notochord rather than somites; centra do not form via a cartilage intermediate stage, nor do they contain osteoblasts. Moreover, isolated, cultured notochords secrete bone matrix in vitro, and ablation of notochord cells at segmentally reiterated positions in vivo prevents the formation of centra. Analysis of fss mutant embryos, in which sclerotome segmentation is disrupted, shows that whereas neural arch segmentation is also disrupted, centrum development proceeds normally. These findings suggest that the notochord plays a key, perhaps ancient, role in the segmental patterning of vertebrae.
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Affiliation(s)
- Angeleen Fleming
- Department of Anatomy, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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