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Ventriglia S, Kalcheim C. From neural tube to spinal cord: The dynamic journey of the dorsal neuroepithelium. Dev Biol 2024; 511:26-38. [PMID: 38580174 DOI: 10.1016/j.ydbio.2024.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/21/2024] [Accepted: 04/02/2024] [Indexed: 04/07/2024]
Abstract
In a developing embryo, formation of tissues and organs is remarkably precise in both time and space. Through cell-cell interactions, neighboring progenitors coordinate their activities, sequentially generating distinct types of cells. At present, we only have limited knowledge, rather than a systematic understanding, of the underlying logic and mechanisms responsible for cell fate transitions. The formation of the dorsal aspect of the spinal cord is an outstanding model to tackle these dynamics, as it first generates the peripheral nervous system and is later responsible for transmitting sensory information from the periphery to the brain and for coordinating local reflexes. This is reflected first by the ontogeny of neural crest cells, progenitors of the peripheral nervous system, followed by formation of the definitive roof plate of the central nervous system and specification of adjacent interneurons, then a transformation of roof plate into dorsal radial glia and ependyma lining the forming central canal. How do these peripheral and central neural branches segregate from common progenitors? How are dorsal radial glia established concomitant with transformation of the neural tube lumen into a central canal? How do the dorsal radial glia influence neighboring cells? This is only a partial list of questions whose clarification requires the implementation of experimental paradigms in which precise control of timing is crucial. Here, we outline some available answers and still open issues, while highlighting the contributions of avian models and their potential to address mechanisms of neural patterning and function.
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Affiliation(s)
- Susanna Ventriglia
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, 9112102, P.O.Box 12272, Israel.
| | - Chaya Kalcheim
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, 9112102, P.O.Box 12272, Israel.
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Kalcheim C, Rekler D. Recent advances in understanding cell type transitions during dorsal neural tube development. Fac Rev 2022; 11:27. [PMID: 36225209 PMCID: PMC9523542 DOI: 10.12703/r/11-27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The vertebrate neural tube is a representative example of a morphogen-patterned tissue that generates different cell types with spatial and temporal precision. More specifically, the development of the dorsal region of the neural tube is of particular interest because of its highly dynamic behavior. First, early premigratory neural crest progenitors undergo an epithelial-to-mesenchymal transition, exit the neural primordium, and generate, among many derivatives, most of the peripheral nervous system. Subsequently, the dorsal neural tube becomes populated by definitive roof plate cells that constitute an organizing center for dorsal interneurons and guide axonal patterning. In turn, roof plate cells transform into dorsal radial glia that contributes to and shapes the formation of the dorsal ependyma of the central nervous system. To form a normal functional spinal cord, these extraordinary transitions should be tightly regulated in time and space. Thus far, the underlying cellular changes and molecular mechanisms are only beginning to be uncovered. In this review, we discuss recent results that shed light on the end of neural crest production and delamination, the early formation of the definitive roof plate, and its further maturation into radial glia. The last of these processes culminate in the formation of the dorsal ependyma, a component of the stem cell niche of the central nervous system. We highlight how similar mechanisms operate throughout these transitions, which may serve to reveal common design principles applicable to the ontogeny of epithelial tissues.
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Affiliation(s)
- Chaya Kalcheim
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, Israel
| | - Dina Rekler
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, Israel
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Rekler D, Kalcheim C. Completion of neural crest cell production and emigration is regulated by retinoic-acid-dependent inhibition of BMP signaling. eLife 2022; 11:72723. [PMID: 35394423 PMCID: PMC8993216 DOI: 10.7554/elife.72723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 03/02/2022] [Indexed: 12/21/2022] Open
Abstract
Production and emigration of neural crest cells is a transient process followed by the emergence of the definitive roof plate. The mechanisms regulating the end of neural crest ontogeny are poorly understood. Whereas early crest development is stimulated by mesoderm-derived retinoic acid, we report that the end of the neural crest period is regulated by retinoic acid synthesized in the dorsal neural tube. Inhibition of retinoic acid signaling in the neural tube prevents the normal upregulation of BMP inhibitors in the nascent roof plate and prolongs the period of BMP responsiveness which otherwise ceases close to roof plate establishment. Consequently, neural crest production and emigration are extended well into the roof plate stage. In turn, extending the activity of neural crest-specific genes inhibits the onset of retinoic acid synthesis in roof plate suggesting a mutual repressive interaction between neural crest and roof plate traits. Although several roof plate-specific genes are normally expressed in the absence of retinoic acid signaling, roof plate and crest markers are co-expressed in single cells and this domain also contains dorsal interneurons. Hence, the cellular and molecular architecture of the roof plate is compromised. Collectively, our results demonstrate that neural tube-derived retinoic acid, via inhibition of BMP signaling, is an essential factor responsible for the end of neural crest generation and the proper segregation of dorsal neural lineages. The division between the central nervous system – formed by the brain and spinal cord – and the peripheral nervous system – which consists of the neurons that sense and relay information to and from the body – takes place early during embryonic development. Initially, the nervous system consists of a tube of cells called the neural tube. From the top region of this tube, some cells change their shape, exit the tube and migrate to different places in the developing body. These cells are called the ‘neural crest’, and they form many different structures, including the peripheral nervous system. Neural crest cells keep leaving the neural tube for a period of time, but after that, the neural tube stops producing them. At this point, the region of the neural tube that had been producing neural crest cells becomes the ‘roof plate’ of the central nervous system, a structure that is essential for the development of specific groups of neurons in the brain and spinal cord. In bird embryos, a protein called bone morphogenetic protein (BMP) is essential for neural crest production because it triggers the migration of these cells away from the neural tube. Before the roof plate is formed, the activity of BMP is blocked by proteins known as BMP inhibitors, which stop more cells from leaving the neural tube. Around the time when neural crest formation stops, another molecule called retinoic acid begins to be synthesized in the top region of the neural tube. Rekler and Kalcheim asked whether retinoic acid is involved in the transition from neural crest to roof plate. To test this hypothesis, Rekler and Kalcheim blocked the activity of retinoic acid in the neural tube of quail embryos at the time when they should stop producing neural crest cells. This resulted in embryos in which the neural tube keeps producing neural crest cells after the roof plate has formed. In these embryos, individual cells in the resulting ‘roof plate’ produced both proteins that are normally only found in neural crest cells, and proteins typically exclusive to the roof plate. This suggests that, in the absence of retinoic acid activity, the segregation of neural crest identity from roof plate identity is compromised. Rekler and Kalcheim also found that, in the embryos where retinoic acid activity had been blocked, the cells in the area where the roof plate should be produced virtually no BMP inhibitors, and exhibited extended BMP activity. This allowed neural crest cells to continue forming and migrating away from the neural tube well after the period when they would stop in a normal embryo. These results indicate that retinoic acid stops the production of neural crest cells by repressing BMP activity in the roof plate of the neural tube. Rekler and Kalcheim’s experiments shed light on the mechanisms that allow the central and peripheral nervous systems to become segregated. This could increase our understanding of the origin of several neurodevelopmental disorders, potentially providing insights into their treatment or prevention. Additionally, the process of neural crest production and exit from the neural tube is highly similar to the process of metastasis in many invasive cancers. Thus, by understanding how the production of neural crest cells is terminated, it may be possible to learn how to prevent malignant cancer cells from spreading through the body.
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Affiliation(s)
- Dina Rekler
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, Israel
| | - Chaya Kalcheim
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, Israel
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Ofek S, Wiszniak S, Kagan S, Tondl M, Schwarz Q, Kalcheim C. Notch signaling is a critical initiator of roof plate formation as revealed by the use of RNA profiling of the dorsal neural tube. BMC Biol 2021; 19:84. [PMID: 33892704 PMCID: PMC8063321 DOI: 10.1186/s12915-021-01014-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/25/2021] [Indexed: 12/31/2022] Open
Abstract
Background The dorsal domain of the neural tube is an excellent model to investigate the generation of complexity during embryonic development. It is a highly dynamic and multifaceted region being first transiently populated by prospective neural crest (NC) cells that sequentially emigrate to generate most of the peripheral nervous system. Subsequently, it becomes the definitive roof plate (RP) of the central nervous system. The RP, in turn, constitutes a patterning center for dorsal interneuron development. The factors underlying establishment of the definitive RP and its segregation from NC and dorsal interneurons are currently unknown. Results We performed a transcriptome analysis at trunk levels of quail embryos comparing the dorsal neural tube at premigratory NC and RP stages. This unraveled molecular heterogeneity between NC and RP stages, and within the RP itself. By implementing these genes, we asked whether Notch signaling is involved in RP development. First, we observed that Notch is active at the RP-interneuron interface. Furthermore, gain and loss of Notch function in quail and mouse embryos, respectively, revealed no effect on early NC behavior. Constitutive Notch activation caused a local downregulation of RP markers with a concomitant development of dI1 interneurons, as well as an ectopic upregulation of RP markers in the interneuron domain. Reciprocally, in mice lacking Notch activity, both the RP and dI1 interneurons failed to form and this was associated with expansion of the dI2 population. Conclusions Collectively, our results offer a new resource for defining specific cell types, and provide evidence that Notch is required to establish the definitive RP, and to determine the choice between RP and interneuron fates, but not the segregation of RP from NC.
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Affiliation(s)
- Shai Ofek
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, P.O.Box 12272, 9112102, Jerusalem, Israel
| | - Sophie Wiszniak
- Centre for Cancer Biology, University of South Australia and SA Pathology, North Terrace, Adelaide, SA, 5001, Australia
| | - Sarah Kagan
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, P.O.Box 12272, 9112102, Jerusalem, Israel
| | - Markus Tondl
- Centre for Cancer Biology, University of South Australia and SA Pathology, North Terrace, Adelaide, SA, 5001, Australia
| | - Quenten Schwarz
- Centre for Cancer Biology, University of South Australia and SA Pathology, North Terrace, Adelaide, SA, 5001, Australia.
| | - Chaya Kalcheim
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, P.O.Box 12272, 9112102, Jerusalem, Israel.
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Rekler D, Kalcheim C. From Neural Crest to Definitive Roof Plate: The Dynamic Behavior of the Dorsal Neural Tube. Int J Mol Sci 2021; 22:3911. [PMID: 33920095 PMCID: PMC8070085 DOI: 10.3390/ijms22083911] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/07/2021] [Accepted: 04/08/2021] [Indexed: 01/11/2023] Open
Abstract
Research on the development of the dorsal neural tube is particularly challenging. In this highly dynamic domain, a temporal transition occurs between early neural crest progenitors that undergo an epithelial-to-mesenchymal transition and exit the neural primordium, and the subsequent roof plate, a resident epithelial group of cells that constitutes the dorsal midline of the central nervous system. Among other functions, the roof plate behaves as an organizing center for the generation of dorsal interneurons. Despite extensive knowledge of the formation, emigration and migration of neural crest progenitors, little is known about the mechanisms leading to the end of neural crest production and the transition into a roof plate stage. Are these two mutually dependent or autonomously regulated processes? Is the generation of roof plate and dorsal interneurons induced by neural tube-derived factors throughout both crest and roof plate stages, respectively, or are there differences in signaling properties and responsiveness as a function of time? In this review, we discuss distinctive characteristics of each population and possible mechanisms leading to the shift between the above cell types.
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Affiliation(s)
| | - Chaya Kalcheim
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, P.O.Box 12272, Jerusalem 9112102, Israel;
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Kahane N, Kalcheim C. Neural tube development depends on notochord-derived sonic hedgehog released into the sclerotome. Development 2020; 147:dev183996. [PMID: 32345743 PMCID: PMC7272346 DOI: 10.1242/dev.183996] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 04/06/2020] [Indexed: 12/18/2022]
Abstract
Sonic hedgehog (Shh), produced in the notochord and floor plate, is necessary for both neural and mesodermal development. To reach the myotome, Shh has to traverse the sclerotome and a reduction of sclerotomal Shh affects myotome differentiation. By investigating loss and gain of Shh function, and floor-plate deletions, we report that sclerotomal Shh is also necessary for neural tube development. Reducing the amount of Shh in the sclerotome using a membrane-tethered hedgehog-interacting protein or Patched1, but not dominant active Patched, decreased the number of Olig2+ motoneuron progenitors and Hb9+ motoneurons without a significant effect on cell survival or proliferation. These effects were a specific and direct consequence of Shh reduction in the mesoderm. In addition, grafting notochords in a basal but not apical location, vis-à-vis the tube, profoundly affected motoneuron development, suggesting that initial ligand presentation occurs at the basal side of epithelia corresponding to the sclerotome-neural tube interface. Collectively, our results reveal that the sclerotome is a potential site of a Shh gradient that coordinates the development of mesodermal and neural progenitors.
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Affiliation(s)
- Nitza Kahane
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem 9112102, P.O. Box 12272, Israel
| | - Chaya Kalcheim
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem 9112102, P.O. Box 12272, Israel
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Yang J, Antin P, Berx G, Blanpain C, Brabletz T, Bronner M, Campbell K, Cano A, Casanova J, Christofori G, Dedhar S, Derynck R, Ford HL, Fuxe J, García de Herreros A, Goodall GJ, Hadjantonakis AK, Huang RYJ, Kalcheim C, Kalluri R, Kang Y, Khew-Goodall Y, Levine H, Liu J, Longmore GD, Mani SA, Massagué J, Mayor R, McClay D, Mostov KE, Newgreen DF, Nieto MA, Puisieux A, Runyan R, Savagner P, Stanger B, Stemmler MP, Takahashi Y, Takeichi M, Theveneau E, Thiery JP, Thompson EW, Weinberg RA, Williams ED, Xing J, Zhou BP, Sheng G. Guidelines and definitions for research on epithelial-mesenchymal transition. Nat Rev Mol Cell Biol 2020; 21:341-352. [PMID: 32300252 PMCID: PMC7250738 DOI: 10.1038/s41580-020-0237-9] [Citation(s) in RCA: 1015] [Impact Index Per Article: 253.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2020] [Indexed: 02/06/2023]
Abstract
Epithelial–mesenchymal transition (EMT) encompasses dynamic changes in cellular organization from epithelial to mesenchymal phenotypes, which leads to functional changes in cell migration and invasion. EMT occurs in a diverse range of physiological and pathological conditions and is driven by a conserved set of inducing signals, transcriptional regulators and downstream effectors. With over 5,700 publications indexed by Web of Science in 2019 alone, research on EMT is expanding rapidly. This growing interest warrants the need for a consensus among researchers when referring to and undertaking research on EMT. This Consensus Statement, mediated by ‘the EMT International Association’ (TEMTIA), is the outcome of a 2-year-long discussion among EMT researchers and aims to both clarify the nomenclature and provide definitions and guidelines for EMT research in future publications. We trust that these guidelines will help to reduce misunderstanding and misinterpretation of research data generated in various experimental models and to promote cross-disciplinary collaboration to identify and address key open questions in this research field. While recognizing the importance of maintaining diversity in experimental approaches and conceptual frameworks, we emphasize that lasting contributions of EMT research to increasing our understanding of developmental processes and combatting cancer and other diseases depend on the adoption of a unified terminology to describe EMT. In this Consensus Statement, the authors (on behalf of the EMT International Association) propose guidelines to define epithelial–mesenchymal transition, its phenotypic plasticity and the associated multiple intermediate epithelial–mesenchymal cell states. Clarification of nomenclature and definitions will help reduce misinterpretation of research data generated in different experimental model systems and promote cross-disciplinary collaboration.
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Affiliation(s)
- Jing Yang
- Departments of Pharmacology and Pediatrics, Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA.
| | - Parker Antin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Geert Berx
- Molecular and Cellular Oncology Lab, Department of Biomedical Molecular Biology, Ghent University, Cancer Research Institute Ghent (CRIG), VIB Center for Inflammation Research, Ghent, Belgium
| | - Cédric Blanpain
- Laboratory of Stem Cells and Cancer, Université Libre de Bruxelles, Bruxelles, Belgium
| | - Thomas Brabletz
- Department of Experimental Medicine 1, Nikolaus-Fiebiger-Center for Molecular Medicine, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Marianne Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Kyra Campbell
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, UK
| | - Amparo Cano
- Departamento de Bioquímica, Universidad Autónoma de Madrid (UAM), Instituto de Investigaciones Biomédicas 'Alberto Sols' (CSIC-UAM), IdiPAZ & Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Madrid, Spain
| | - Jordi Casanova
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology/Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona, Spain
| | | | - Shoukat Dedhar
- Department of Biochemistry and Molecular Biology, University of British Columbia and British Columbia Cancer Research Centre, Vancouver, BC, Canada
| | - Rik Derynck
- Departments of Cell and Tissue Biology, and Anatomy, University of California at San Francisco, San Francisco, CA, USA
| | - Heide L Ford
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jonas Fuxe
- Department of Laboratory Medicine (LABMED), Division of Pathology, Karolinska University Hospital and Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Antonio García de Herreros
- Programa de Recerca en Càncer, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM) and Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain
| | - Gregory J Goodall
- Centre for Cancer Biology, An alliance of SA Pathology and University of South Australia, Adelaide, SA, Australia
| | - Anna-Katerina Hadjantonakis
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Ruby Y J Huang
- School of Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chaya Kalcheim
- Department of Medical Neurobiology, Institute for medical Research Israel-Canada and the Safra Center for Neurosciences, Hebrew University of Jerusalem, Hadassah Medical School, Jerusalem, Israel
| | - Raghu Kalluri
- Department of Cancer Biology, Metastasis Research Center, MD Anderson Cancer Center, Houston, TX, USA
| | - Yibin Kang
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Yeesim Khew-Goodall
- Centre for Cancer Biology, an Alliance of SA Pathology and the University of South Australia, Adelaide, SA, Australia
| | - Herbert Levine
- Department of Physics, Northeastern University, Boston, MA, USA
| | - Jinsong Liu
- Department of Anatomic Pathology, The Division of Pathology and Laboratory Medicine, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Gregory D Longmore
- Department of Medicine (Oncology) and Department of Cell Biology and Physiology, ICCE Institute, Washington University, St. Louis, MO, USA
| | - Sendurai A Mani
- Department of Translational Molecular Pathology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Joan Massagué
- Cancer Biology and Genetics Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, London, UK
| | - David McClay
- Department of Biology, Duke University, Durham, NC, USA
| | - Keith E Mostov
- Departments of Anatomy and Biochemistry/Biophysics, University of California, San Francisco, School of Medicine, San Francisco, CA, USA
| | - Donald F Newgreen
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
| | - M Angela Nieto
- Instituto de Neurociencias (CSIC-UMH) Avda Ramon y Cajal s/n, Sant Joan d´Alacant, Spain
| | - Alain Puisieux
- Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Cancer Research Center of Lyon, Lyon, France.,Institut Curie, PSL Research University, Paris, France
| | - Raymond Runyan
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Pierre Savagner
- INSERM UMR 1186, Integrative Tumor Immunology and Genetic Oncology, Gustave Roussy, University Paris-Saclay, Villejuif, France
| | - Ben Stanger
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Marc P Stemmler
- Department of Experimental Medicine 1, Nikolaus-Fiebiger-Center for Molecular Medicine, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Yoshiko Takahashi
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | | | - Eric Theveneau
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Jean Paul Thiery
- Guangzhou Regenerative Medicine and Health, Guangdong Laboratory, Guangzhou, China
| | - Erik W Thompson
- School of Biomedical Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Translational Research Institute, Woolloongabba, QLD, Australia
| | - Robert A Weinberg
- Whitehead Institute for Biomedical Research, Department of Biology, MIT Ludwig Center for Molecular Oncology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Elizabeth D Williams
- Australian Prostate Cancer Research Centre-Queensland (APCRC-Q) and Queensland Bladder Cancer Initiative (QBCI), School of Biomedical Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD, Australia
| | - Jianhua Xing
- Department of Computational and Systems Biology and UPMC-Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Binhua P Zhou
- Department of Molecular and Cellular Biochemistry and UK Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Guojun Sheng
- International Research Center for Medical Sciences (IRCMS), Kumamoto University, Kumamoto, Japan.
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Kumar D, Nitzan E, Kalcheim C. YAP promotes neural crest emigration through interactions with BMP and Wnt activities. Cell Commun Signal 2019; 17:69. [PMID: 31228951 PMCID: PMC6589182 DOI: 10.1186/s12964-019-0383-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 06/04/2019] [Indexed: 12/12/2022] Open
Abstract
Background Premigratory neural crest progenitors undergo an epithelial-to-mesenchymal transition and leave the neural tube as motile cells. Previously, we showed that BMP generates trunk neural crest emigration through canonical Wnt signaling which in turn stimulates G1/S transition. The molecular network underlying this process is, however, not yet completely deciphered. Yes-associated-protein (YAP), an effector of the Hippo pathway, controls various aspects of development including cell proliferation, migration, survival and differentiation. In this study, we examined the possible involvement of YAP in neural crest emigration and its relationship with BMP and Wnt. Methods We implemented avian embryos in which levels of YAP gene activity were either reduced or upregulated by in ovo plasmid electroporation, and monitored effects on neural crest emigration, survival and proliferation. Neural crest-derived sensory neuron and melanocyte development were assessed upon gain of YAP function. Imunohistochemistry was used to assess YAP expression. In addition, the activity of specific signaling pathways including YAP, BMP and Wnt was monitored with specific reporters. Results We find that the Hippo pathway transcriptional co-activator YAP is expressed and is active in premigratory crest of avian embryos. Gain of YAP function stimulates neural crest emigration in vivo, and attenuating YAP inhibits cell exit. This is associated with an accumulation of FoxD3-expressing cells in the dorsal neural tube, with reduced proliferation, and enhanced apoptosis. Furthermore, gain of YAP function inhibits differentiation of Islet-1-positive sensory neurons and augments the number of EdnrB2-positive melanocytes. Using specific in vivo reporters, we show that loss of YAP function in the dorsal neural tube inhibits BMP and Wnt activities whereas gain of YAP function stimulates these pathways. Reciprocally, inhibition of BMP and Wnt signaling by noggin or Xdd1, respectively, downregulates YAP activity. In addition, YAP-dependent stimulation of neural crest emigration is compromised upon inhibition of either BMP or Wnt activities. Together, our results suggest a positive bidirectional cross talk between these pathways. Conclusions Our data show that YAP is necessary for emigration of neural crest progenitors. In addition, they incorporate YAP signaling into a BMP/Wnt-dependent molecular network responsible for emigration of trunk-level neural crest.
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Affiliation(s)
- Deepak Kumar
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University of Jerusalem-Hadassah Medical School, P.O. Box 12272, 91120, Jerusalem, Israel
| | - Erez Nitzan
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University of Jerusalem-Hadassah Medical School, P.O. Box 12272, 91120, Jerusalem, Israel
| | - Chaya Kalcheim
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University of Jerusalem-Hadassah Medical School, P.O. Box 12272, 91120, Jerusalem, Israel.
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Abstract
Neural crest cells are the embryonic precursors of most neurons and all glia of the peripheral nervous system, pigment cells, some endocrine components, and connective tissue of the head, face, neck, and heart. Following induction, crest cells undergo an epithelial to mesenchymal transition that enables them to migrate along specific pathways culminating in their phenotypic differentiation. Researching this unique embryonic population has revealed important understandings of basic biological and developmental principles. These principles are likely to assist in clarifying the etiology and help in finding strategies for the treatment of neural crest diseases, collectively termed neurocristopathies. The progress achieved in neural crest research is made feasible thanks to the continuous development of species-specific in vivo and in vitro paradigms and more recently the possibility to produce neural crest cells and specific derivatives from embryonic or induced pluripotent stem cells. All of the above assist us in elucidating mechanisms that regulate neural crest development using state-of-the art cellular, molecular, and imaging approaches.
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Affiliation(s)
- Chaya Kalcheim
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC), Hebrew University-Hadassah Medical School, Jerusalem, Israel.
- Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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Abstract
The neural crest (NC) originates in the central nervous system (CNS) primordium. Born as an epithelium, NC progenitors undergo an epithelial-to-mesenchymal transition that generates cellular movement away from the CNS. Mesenchymal NC progenitors then migrate through stereotypic pathways characteristic of various axial levels until homing to distinct primordia where phenotypic differentiation takes place. Being the source of most of the peripheral nervous system, pigment cells and ectomesenchyme, the embryonic NC is considered to be a multipotent population of precursors. In spite of numerous recent studies, an essential and still unsolved question is when during ontogeny do the different lineages segregate from putative homogeneous and multipotent progenitors. Evidence suggests that the premigratory NC still resident in the dorsal neural tube epithelium is composed both of multipotent as well as of fate-restricted precursors, supporting the notion of an early appearance of cellular heterogeneity. Understanding these changing states of commitment is a prerequisite for deciphering molecular mechanisms that regulate fate segregation of the embryonic NC. In this review, we present data illustrating the existence of progenitors harboring different states of specification and their emergence as a function of time and space.
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Affiliation(s)
- Chaya Kalcheim
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and The Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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11
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Affiliation(s)
- Chaya Kalcheim
- Department of Medical Neurobiology, IMRIC and ELSC; Hebrew University of Jerusalem-Hadassah Medical School; Jerusalem 9112102 Israel
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Nitzan E, Avraham O, Kahane N, Ofek S, Kumar D, Kalcheim C. Dynamics of BMP and Hes1/Hairy1 signaling in the dorsal neural tube underlies the transition from neural crest to definitive roof plate. BMC Biol 2016; 14:23. [PMID: 27012662 PMCID: PMC4806459 DOI: 10.1186/s12915-016-0245-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 03/10/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The dorsal midline region of the neural tube that results from closure of the neural folds is generally termed the roof plate (RP). However, this domain is highly dynamic and complex, and is first transiently inhabited by prospective neural crest (NC) cells that sequentially emigrate from the neuroepithelium. It only later becomes the definitive RP, the dorsal midline cells of the spinal cord. We previously showed that at the trunk level of the axis, prospective RP progenitors originate ventral to the premigratory NC and progressively reach the dorsal midline following NC emigration. However, the molecular mechanisms underlying the end of NC production and formation of the definitive RP remain virtually unknown. RESULTS Based on distinctive cellular and molecular traits, we have defined an initial NC and a subsequent RP stage, allowing us to investigate the mechanisms responsible for the transition between the two phases. We demonstrate that in spite of the constant production of BMP4 in the dorsal tube at both stages, RP progenitors only transiently respond to the ligand and lose competence shortly before they arrive at their final location. In addition, exposure of dorsal tube cells at the NC stage to high levels of BMP signaling induces premature RP traits, such as Hes1/Hairy1, while concomitantly inhibiting NC production. Reciprocally, early inhibition of BMP signaling prevents Hairy1 mRNA expression at the RP stage altogether, suggesting that BMP is both necessary and sufficient for the development of this RP-specific trait. Furthermore, when Hes1/Hairy1 is misexpressed at the NC stage, it inhibits BMP signaling and downregulates BMPR1A/Alk3 mRNA expression, transcription of BMP targets such as Foxd3, cell-cycle progression, and NC emigration. Reciprocally, Foxd3 inhibits Hairy1, suggesting that repressive cross-interactions at the level of, and downstream from, BMP ensure the temporal separation between both lineages. CONCLUSIONS Together, our data suggest that BMP signaling is important both for NC and RP formation. Given that these two structures develop sequentially, we speculate that the longer exposure of RP progenitors to BMP compared with that of premigratory NC cells may be translated into a higher signaling level in the former. This induces changes in responsiveness to BMP, most likely by downregulating the expression of Alk3 receptors and, consequently, of BMP-dependent downstream transcription factors, which exhibit spatial complementary expression patterns and mutually repress each other to generate alternative fates. This molecular dynamic is likely to account for the transition between the NC and definitive RP stages and thus be responsible for the segregation between central and peripheral lineages during neural development.
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Affiliation(s)
- Erez Nitzan
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, 9112102,, PO Box 12272,, Israel.,Present Address: Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Oshri Avraham
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, 9112102,, PO Box 12272,, Israel.,Present address: Department of Genetics, Washington University, St. Louis, MO, USA
| | - Nitza Kahane
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, 9112102,, PO Box 12272,, Israel
| | - Shai Ofek
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, 9112102,, PO Box 12272,, Israel
| | - Deepak Kumar
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, 9112102,, PO Box 12272,, Israel
| | - Chaya Kalcheim
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, 9112102,, PO Box 12272,, Israel.
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Kalcheim C. Epithelial-Mesenchymal Transitions during Neural Crest and Somite Development. J Clin Med 2015; 5:jcm5010001. [PMID: 26712793 PMCID: PMC4730126 DOI: 10.3390/jcm5010001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 12/09/2015] [Accepted: 12/14/2015] [Indexed: 01/14/2023] Open
Abstract
Epithelial-to-mesenchymal transition (EMT) is a central process during embryonic development that affects selected progenitor cells of all three germ layers. In addition to driving the onset of cellular migrations and subsequent tissue morphogenesis, the dynamic conversions of epithelium into mesenchyme and vice-versa are intimately associated with the segregation of homogeneous precursors into distinct fates. The neural crest and somites, progenitors of the peripheral nervous system and of skeletal tissues, respectively, beautifully illustrate the significance of EMT to the above processes. Ongoing studies progressively elucidate the gene networks underlying EMT in each system, highlighting the similarities and differences between them. Knowledge of the mechanistic logic of this normal ontogenetic process should provide important insights to the understanding of pathological conditions such as cancer metastasis, which shares some common molecular themes.
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Affiliation(s)
- Chaya Kalcheim
- Edmond and Lili Safra Center for Brain Sciences (ELSC), Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC), Hebrew University of Jerusalem-Hadassah Medical School, P.O. Box 12272, Jerusalem 9112102, Israel.
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Carmel MS, Kahane N, Oberman F, Miloslavski R, Sela-Donenfeld D, Kalcheim C, Yisraeli JK. A Novel Role for VICKZ Proteins in Maintaining Epithelial Integrity during Embryogenesis. PLoS One 2015; 10:e0136408. [PMID: 26317350 PMCID: PMC4552865 DOI: 10.1371/journal.pone.0136408] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Accepted: 08/04/2015] [Indexed: 12/31/2022] Open
Abstract
Background VICKZ (IGF2BP1,2,3/ZBP1/Vg1RBP/IMP1,2,3) proteins bind RNA and help regulate many RNA-mediated processes. In the midbrain region of early chick embryos, VICKZ is expressed in the neural folds and along the basal surface of the neural epithelium, but, upon neural tube closure, is down-regulated in prospective cranial neural crest (CNC) cells, concomitant with their emigration and epithelial-to-mesenchymal transition (EMT). Electroporation of constructs that modulate cVICKZ expression demonstrates that this down-regulation is both necessary and sufficient for CNC EMT. These results suggest that VICKZ down-regulation in CNC cell-autonomously promotes EMT and migration. Reduction of VICKZ throughout the embryo, however, inhibits CNC migration non-cell-autonomously, as judged by transplantation experiments in Xenopus embryos. Results and Conclusions Given the positive role reported for VICKZ proteins in promoting cell migration of chick embryo fibroblasts and many types of cancer cells, we have begun to look for specific mRNAs that could mediate context-specific differences. We report here that the laminin receptor, integrin alpha 6, is down-regulated in the dorsal neural tube when CNC cells emigrate, this process is mediated by cVICKZ, and integrin alpha 6 mRNA is found in VICKZ ribonucleoprotein complexes. Significantly, prolonged inhibition of cVICKZ in either the neural tube or the nascent dermomyotome sheet, which also dynamically expresses cVICKZ, induces disruption of these epithelia. These data point to a previously unreported role for VICKZ in maintaining epithelial integrity.
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Affiliation(s)
- Michal Shoshkes Carmel
- Department of Developmental Biology and Cancer Research, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nitza Kahane
- Department of Medical Neurobiology, IMRIC, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Froma Oberman
- Department of Developmental Biology and Cancer Research, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Rachel Miloslavski
- Department of Developmental Biology and Cancer Research, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Dalit Sela-Donenfeld
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, The Robert H. Smith Faculty of Agriculture, Food and Environment, 76100, Rehovot, Israel
| | - Chaya Kalcheim
- Department of Medical Neurobiology, IMRIC, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Joel K. Yisraeli
- Department of Developmental Biology and Cancer Research, The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- * E-mail:
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Abstract
Mesodermal somites are initially composed of columnar cells arranged as a pseudostratified epithelium that undergoes sequential and spatially restricted changes to generate the sclerotome and dermomyotome, intermediate structures that develop into vertebrae, striated muscles of the body and limbs, dermis, smooth muscle, and endothelial cells. Regional cues were elucidated that impart differential traits upon the originally multipotent progenitors. How do somite cells and their intermediate progenitors interpret these extrinsic cues and translate them into various levels and/or modalities of intracellular signaling that lead to differential gene expression profiles remains a significant challenge. So is the understanding of how differential fate specification relates to complex cellular migrations prefiguring the formation of body muscles and vertebrae. Research in the past years has largely transited from a descriptive phase in which the lineages of distinct somite-derived progenitors and their cellular movements were traced to a more mechanistic understanding of the local function of genes and regulatory networks underlying lineage segregation and tissue organization. In this chapter, we focus on some major advances addressing the segregation of lineages from the dermomyotome, while discussing both cellular as well as molecular mechanisms, where possible.
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Affiliation(s)
- Mordechai Applebaum
- Department of Medical Neurobiology, IMRIC and ELSC-Hebrew University-Hadassah Medical School, Jerusalem, 9101201, 12272, Israel,
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Kalcheim C, Storey KG. Neural-mesodermal progenitor interactions in pattern formation: an introduction to the collection. F1000Res 2014; 3:275. [PMID: 25580236 PMCID: PMC4288398 DOI: 10.12688/f1000research.5657.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/30/2014] [Indexed: 11/20/2022] Open
Abstract
Mesodermal and spinal cord progenitors originate from common founder cells from which they segregate during development. Moreover, neural and mesodermal tissues closely interact during embryogenesis to ensure timely patterning and differentiation of both head and trunk structures. For instance, the fate and morphogenesis of neural progenitors is dependent on signals produced by mesodermal cells and vice-versa. While some of the cellular and molecular signals that mediate these interactions have been described, much more remains to be uncovered. The scope of this collection will cover these interactions between neural (CNS or PNS) and mesodermal progenitors in patterning body plans and specific body systems in vertebrate embryos. This includes, but is not limited to, interactions influencing the formation of body axes, neural tube formation, neural crest migration, gut development, muscle patterning and myogenesis.
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Affiliation(s)
- Chaya Kalcheim
- Department of Medical Neurobiology, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Kate G. Storey
- College of Life Sciences, University of Dundee, Dundee, UK
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Affiliation(s)
- Chaya Kalcheim
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC) and The Safra Center for Brain Research (ELSC), Hebrew University of Jerusalem, Hadassah Medical School, Jerusalem, Israel.
| | - Hermann Rohrer
- Research Group Developmental Neurobiology, Max Planck Institute for Brain Research, Frankfurt/M, Germany.
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Applebaum M, Ben-Yair R, Kalcheim C. Segregation of striated and smooth muscle lineages by a Notch-dependent regulatory network. BMC Biol 2014; 12:53. [PMID: 25015411 PMCID: PMC4260679 DOI: 10.1186/s12915-014-0053-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Indexed: 12/31/2022] Open
Abstract
Background Lineage segregation from multipotent epithelia is a central theme in development and in adult stem cell plasticity. Previously, we demonstrated that striated and smooth muscle cells share a common progenitor within their epithelium of origin, the lateral domain of the somite-derived dermomyotome. However, what controls the segregation of these muscle subtypes remains unknown. We use this in vivo bifurcation of fates as an experimental model to uncover the underlying mechanisms of lineage diversification from bipotent progenitors. Results Using the strength of spatio-temporally controlled gene missexpression in avian embryos, we report that Notch harbors distinct pro-smooth muscle activities depending on the duration of the signal; short periods prevent striated muscle development and extended periods, through Snail1, promote cell emigration from the dermomyotome towards a smooth muscle fate. Furthermore, we define a Muscle Regulatory Network, consisting of Id2, Id3, FoxC2 and Snail1, which acts in concert to promote smooth muscle by antagonizing the pro-myogenic activities of Myf5 and Pax7, which induce striated muscle fate. Notch and BMP closely regulate the network and reciprocally reinforce each other’s signal. In turn, components of the network strengthen Notch signaling, while Pax7 silences this signaling. These feedbacks augment the robustness and flexibility of the network regulating muscle subtype segregation. Conclusions Our results demarcate the details of the Muscle Regulatory Network, underlying the segregation of muscle sublineages from the lateral dermomyotome, and exhibit how factors within the network promote the smooth muscle at the expense of the striated muscle fate. This network acts as an exemplar demonstrating how lineage segregation occurs within epithelial primordia by integrating inputs from competing factors.
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Shtukmaster S, Schier MC, Huber K, Krispin S, Kalcheim C, Unsicker K. Sympathetic neurons and chromaffin cells share a common progenitor in the neural crest in vivo. Neural Dev 2013; 8:12. [PMID: 23777568 PMCID: PMC3693940 DOI: 10.1186/1749-8104-8-12] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 05/17/2013] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The neural crest (NC) is a transient embryonic structure unique to vertebrates, which generates peripheral sensory and autonomic neurons, glia, neuroendocrine chromaffin and thyroid C-cells, melanocytes, and mesenchymal derivatives such as parts of the skull, heart, and meninges. The sympathoadrenal (SA) cell lineage is one major sub-lineage of the NC that gives rise to sympathetic neurons, chromaffin cells, and the intermediate small intensely fluorescent (SIF) cells. A key question is when during NC ontogeny do multipotent progenitors segregate into the different NC-derived lineages. Recent evidence suggested that sympathetic, sensory, and melanocyte progenitors delaminate from the thoracic neural tube (NT) in successive, largely non-overlapping waves and that at least certain NC progenitors are already fate-restricted within the NT. Whether sympathetic neurons and chromaffin cells, suggested by cell culture studies to share a common progenitor, are also fate segregated in ovo prior to emigration, is not known. RESULTS We have conducted single cell electroporations of a GFP-encoding plasmid into the dorsal midline of E2 chick NTs at the adrenomedullary level of the NC. Analysis of their derivatives, performed at E6, revealed that in most cases, labelled progeny was detected in both sympathetic ganglia and adrenal glands, where cells co-expressed characteristic marker combinations. CONCLUSIONS Our results show that sympathetic neurons and adrenal chromaffin cells share a common progenitor in the NT. Together with previous findings we suggest that phenotypic diversification of these sublineages is likely to occur after delamination from the NT and prior to target encounter.
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Affiliation(s)
- Stella Shtukmaster
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology University of Freiburg, Albertstr, 17, Freiburg D-79104, Germany
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Kahane N, Ribes V, Kicheva A, Briscoe J, Kalcheim C. The transition from differentiation to growth during dermomyotome-derived myogenesis depends on temporally restricted hedgehog signaling. Development 2013; 140:1740-50. [PMID: 23533174 DOI: 10.1242/dev.092726] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The development of a functional tissue requires coordination of the amplification of progenitors and their differentiation into specific cell types. The molecular basis for this coordination during myotome ontogeny is not well understood. Dermomytome progenitors that colonize the myotome first acquire myocyte identity and subsequently proliferate as Pax7-expressing progenitors before undergoing terminal differentiation. We show that the dynamics of sonic hedgehog (Shh) signaling is crucial for this transition in both avian and mouse embryos. Initially, Shh ligand emanating from notochord/floor plate reaches the dermomyotome, where it both maintains the proliferation of dermomyotome cells and promotes myogenic differentiation of progenitors that colonized the myotome. Interfering with Shh signaling at this stage produces small myotomes and accumulation of Pax7-expressing progenitors. An in vivo reporter of Shh activity combined with mouse genetics revealed the existence of both activator and repressor Shh activities operating on distinct subsets of cells during the epaxial myotomal maturation. In contrast to observations in mice, in avians Shh promotes the differentiation of both epaxial and hypaxial myotome domains. Subsequently, myogenic progenitors become refractory to Shh; this is likely to occur at the level of, or upstream of, smoothened signaling. The end of responsiveness to Shh coincides with, and is thus likely to enable, the transition into the growth phase of the myotome.
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Affiliation(s)
- Nitza Kahane
- Department of Medical Neurobiology, Hebrew University of Jerusalem-Hadassah Medical School, Jerusalem, Israel
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Nitzan E, Krispin S, Pfaltzgraff ER, Klar A, Labosky PA, Kalcheim C. A dynamic code of dorsal neural tube genes regulates the segregation between neurogenic and melanogenic neural crest cells. Development 2013; 140:2269-79. [PMID: 23615280 DOI: 10.1242/dev.093294] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Understanding when and how multipotent progenitors segregate into diverse fates is a key question during embryonic development. The neural crest (NC) is an exemplary model system with which to investigate the dynamics of progenitor cell specification, as it generates a multitude of derivatives. Based on 'in ovo' lineage analysis, we previously suggested an early fate restriction of premigratory trunk NC to generate neural versus melanogenic fates, yet the timing of fate segregation and the underlying mechanisms remained unknown. Analysis of progenitors expressing a Foxd3 reporter reveals that prospective melanoblasts downregulate Foxd3 and have already segregated from neural lineages before emigration. When this downregulation is prevented, late-emigrating avian precursors fail to upregulate the melanogenic markers Mitf and MC/1 and the guidance receptor Ednrb2, generating instead glial cells that express P0 and Fabp. In this context, Foxd3 lies downstream of Snail2 and Sox9, constituting a minimal network upstream of Mitf and Ednrb2 to link melanogenic specification with migration. Consistent with the gain-of-function data in avians, loss of Foxd3 function in mouse NC results in ectopic melanogenesis in the dorsal tube and sensory ganglia. Altogether, Foxd3 is part of a dynamically expressed gene network that is necessary and sufficient to regulate fate decisions in premigratory NC. Their timely downregulation in the dorsal neural tube is thus necessary for the switch between neural and melanocytic phases of NC development.
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Affiliation(s)
- Erez Nitzan
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University, Hadassah Medical School, Jerusalem 91120, PO Box 12272, Israel
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Unsicker K, Huber K, Schober A, Kalcheim C. Resolved and open issues in chromaffin cell development. Mech Dev 2012; 130:324-9. [PMID: 23220335 DOI: 10.1016/j.mod.2012.11.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 11/14/2012] [Accepted: 11/16/2012] [Indexed: 11/19/2022]
Abstract
Ten years of research within the DFG-funded Collaborative Research Grant SFB 488 at the University of Heidelberg have added many new facets to our understanding of chromaffin cell development. Glucocorticoid signaling is no longer the key for understanding the determination of the chromaffin phenotype, yet a novel role has been attributed to glucocorticoids: they are essential for the postnatal maintenance of adrenal and extra-adrenal chromaffin cells. Transcription factors, as, e.g. MASH1 and Phox2B, have similar, but also distinct functions in chromaffin and sympathetic neuronal development, and BMP-4 not only induces sympathoadrenal (SA) cells at the dorsal aorta and within the adrenal gland, but also promotes chromaffin cell maturation. Chromaffin cells and sympathetic neurons share a common progenitor in the dorsal neural tube (NT) in vivo, as revealed by single cell electroporations into the dorsal NT. Thus, specification of chromaffin cells is likely to occur after cell emigration either during migration or close to colonization of the target regions. Mechanisms underlying the specification of chromaffin cells vs. sympathetic neurons are currently being explored.
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Affiliation(s)
- Klaus Unsicker
- Dept. of Molecular Embryology, University of Freiburg, Albertstr. 17, D-79104 Freiburg, Germany.
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Nitzan E, Kalcheim C. Neural crest and somitic mesoderm as paradigms to investigate cell fate decisions during development. Dev Growth Differ 2012; 55:60-78. [PMID: 23043365 DOI: 10.1111/dgd.12004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 09/02/2012] [Accepted: 09/02/2012] [Indexed: 12/25/2022]
Abstract
The dorsal domains of the neural tube and somites are transient embryonic epithelia; they constitute the source of neural crest progenitors that generate the peripheral nervous system, pigment cells and ectomesenchyme, and of the dermomyotome that develops into myocytes, dermis and vascular cells, respectively. Based on the variety of derivatives produced by each type of epithelium, a classical yet still highly relevant question is whether these embryonic epithelia are composed of homogeneous multipotent progenitors or, alternatively, of subsets of fate-restricted cells. Growing evidence substantiates the notion that both the dorsal tube and the dermomyotome are heterogeneous epithelia composed of multipotent as well as fate-restricted precursors that emerge as such in a spatio-temporally regulated manner. Elucidation of the state of commitment of the precedent progenitors is of utmost significance for deciphering the mechanisms that regulate fate segregation during embryogenesis. In addition, it will contribute to understanding the nature of well documented neural crest-somite interactions shown to modulate the timing of neural crest cell emigration, their segmental migration, and myogenesis.
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Affiliation(s)
- Erez Nitzan
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, and Edmond and Lily Safra Center for Brain Sciences, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Shoval I, Kalcheim C. Antagonistic activities of Rho and Rac GTPases underlie the transition from neural crest delamination to migration. Dev Dyn 2012; 241:1155-68. [PMID: 22553120 DOI: 10.1002/dvdy.23799] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2012] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Neural crest progenitors arise as epithelial cells and then undergo a transition into mesenchyme that generates motility. Previously, we showed that active Rho maintains crest cells in the epithelial conformation by keeping stress fibers and membrane-bound N-cadherin. RESULTS While Rho disappears from cell membranes upon delamination, active Rac1 becomes apparent in lamellipodia of mesenchymal cells. Loss of Rac1 function at trunk levels inhibited NC migration but did not prevent cell emigration that is associated with N-cadherin downregulation and G1/S transition. Furthermore, inhibition of Rho stimulated premature Rac1 activity and consequent formation of lamellipodia, leading to NC migration. To examine whether timely migration influences cell fate, Rac1 activity was transiently inhibited to delay dispersion of early NC cells that generate neural derivatives, and its activity was restored by the time of melanoblast migration. Even if confronted with a melanocytic environment, late-dispersing progenitors colonized sensory ganglia where they generated neurons and glia. CONCLUSIONS In the context of crest delamination and migration, activities of Rho and Rac are differential, sequential, and antagonistic. Furthermore, transient inhibition of Rac1 that delays the onset of crest dispersion raises the possibility that the fate of trunk neural progenitors might be restricted prior to migration.
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Affiliation(s)
- Irit Shoval
- Department of Medical Neurobiology, Hebrew University-Hadassah Medical School, IMRIC and ELSC, Jerusalem, Israel
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Ben-Yair R, Kahane N, Kalcheim C. LGN-dependent orientation of cell divisions in the dermomyotome controls lineage segregation into muscle and dermis. Development 2011; 138:4155-66. [PMID: 21852400 DOI: 10.1242/dev.065169] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The plane of cell divisions is pivotal for differential fate acquisition. Dermomyotome development provides an excellent system with which to investigate the link between these processes. In the central sheet of the early dermomyotome, single epithelial cells divide with a planar orientation. Here, we report that in the avian embryo, in addition to self-renewing, a subset of progenitors translocates into the myotome where they generate differentiated myocytes. By contrast, in the late epithelium, individual progenitors divide perpendicularly to produce both mitotic myoblasts and dermis. To examine whether spindle orientations influence fate segregation, early planar divisions were randomized and/or shifted to a perpendicular orientation by interfering with LGN function or by overexpressing inscuteable. Clones derived from single transfected cells exhibited an enhanced proportion of mixed dermomyotome/myotome progeny at the expense of `like' daughter cells in either domain. Loss of LGN or Gαi1 function in the late epithelium randomized otherwise perpendicular mitoses and favored muscle development at the expense of dermis. Hence, LGN-dependent early planar divisions are required for the proper allocation of progenitors into either dermomyotome or myotome, whereas late perpendicular divisions are necessary for the normal balance between muscle and dermis production.
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Affiliation(s)
- Raz Ben-Yair
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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Halperin-Barlev O, Kalcheim C. Sclerotome-derived Slit1 drives directional migration and differentiation of Robo2-expressing pioneer myoblasts. Development 2011; 138:2935-45. [PMID: 21653616 DOI: 10.1242/dev.065714] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pioneer myoblasts generate the first myotomal fibers and act as a scaffold to pattern further myotome development. From their origin in the medial epithelial somite, they dissociate and migrate towards the rostral edge of each somite, from which differentiation proceeds in both rostral-to-caudal and medial-to-lateral directions. The mechanisms underlying formation of this unique wave of pioneer myofibers remain unknown. We show that rostrocaudal or mediolateral somite inversions in avian embryos do not alter the original directions of pioneer myoblast migration and differentiation into fibers, demonstrating that regulation of pioneer patterning is somite-intrinsic. Furthermore, pioneer myoblasts express Robo2 downstream of MyoD and Myf5, whereas the dermomyotome and caudal sclerotome express Slit1. Loss of Robo2 or of sclerotome-derived Slit1 function perturbed both directional cell migration and fiber formation, and their effects were mediated through RhoA. Although myoblast specification was not affected, expression of the intermediate filament desmin was reduced. Hence, Slit1 and Robo2, via RhoA, act to pattern formation of the pioneer myotome through the regulation of cytoskeletal assembly.
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Affiliation(s)
- Osnat Halperin-Barlev
- Department of Medical Neurobiology, IMRIC and ELSC, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Abstract
The dorsal neural tube first generates neural crest cells that exit the neural primordium following an epithelial-to-mesenchymal conversion to become sympathetic ganglia, Schwann cells, dorsal root sensory ganglia, and melanocytes of the skin. Following the end of crest emigration, the dorsal midline of the neural tube becomes the roof plate, a signaling center for the organization of dorsal neuronal cell types. Recent lineage analysis performed before the onset of crest delamination revealed that the dorsal tube is a highly dynamic region sequentially traversed by fate-restricted crest progenitors. Furthermore, prospective roof plate cells were shown to originate ventral to presumptive crest and to progressively relocate dorsalward to occupy their definitive midline position following crest delamination. These data raise important questions regarding the mechanisms of cell emigration in relation to fate acquisition, and suggest the possibility that spatial and/or temporal information in the dorsal neural tube determines initial segregation of neural crest cells into their derivatives. In addition, they emphasize the need to address what controls the end of neural crest production and consequent roof plate formation, a fundamental issue for understanding the separation between central and peripheral lineages during development of the nervous system.
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Affiliation(s)
- Shlomo Krispin
- Department of Medical Neurobiology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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Ben-Yair R, Kalcheim C. Single cell transfection in chick embryos. J Vis Exp 2010:2133. [PMID: 20972396 DOI: 10.3791/2133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
A central theme in developmental biology is the diversification of lineages and the elucidation of underlying molecular mechanisms. This entails a thorough analysis of the fates of single cells under normal and experimental conditions. To this end, transfection methods that target single progenitors are a prerequisite. We describe here a technically straightforward method for transfecting single cells in chicken tissues in-ovo, allowing reliable lineage tracing as well as genetic manipulation. Specific tissue domains are targeted within the somite or neural tube, and DNA is injected directly into the epithelium of interest, resulting in sporadic transfection of single cells. Using reporters, clonal populations may consequently be traced for up to three days, and behavior of genetically manipulated clonal populations can be compared with that of controls. This method takes advantage of the accessibility of the chick embryo along with emerging tools for genetic manipulation. We compare and discuss its advantages over the widely-used electroporation method, and possible applications and use in additional in-vivo models are also suggested. We advocate the use of this method as a significant addition and complement for existing lineage tracing and genetic interference tools.
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Affiliation(s)
- Raz Ben-Yair
- Department of Medical Neurobiology, Hadassah Medical School-Hebrew University, Israel
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Krispin S, Nitzan E, Kassem Y, Kalcheim C. Evidence for a dynamic spatiotemporal fate map and early fate restrictions of premigratory avian neural crest. Development 2010; 137:585-95. [DOI: 10.1242/dev.041509] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Colonization of trunk neural crest derivatives in avians follows a ventral to dorsal order beginning with sympathetic ganglia, Schwann cells, sensory ganglia and finally melanocytes. Continuous crest emigration underlies this process, which is accounted for by a progressive ventral to dorsal relocation of neural tube progenitors prior to departure. This causes a gradual narrowing of FoxD3, Sox9 and Snail2 expression domains in the dorsal tube that characterize the neural progenitors of the crest and these genes are no longer transcribed by the time melanoblasts begin emigrating. Consistently, the final localization of crest cells can be predicted from their relative ventrodorsal position within the premigratory domain or by their time of delamination. Thus, a dynamic spatiotemporal fate map of crest derivatives exists in the dorsal tube at flank levels of the axis with its midline region acting as a sink for the ordered ingression and departure of progenitors. Furthermore, discrete lineage analysis of the dorsal midline at progressive stages generated progeny in single rather than multiple derivatives, revealing early fate restrictions. Compatible with this notion, when early emigrating `neural' progenitors were diverted into the lateral `melanocytic' pathway, they still adopted neural traits, suggesting that initial fate acquisition is independent of the migratory environment and that the potential of crest cells prior to emigration is limited.
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Affiliation(s)
- Shlomo Krispin
- Department of Medical Neurobiology, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem 91120 – P.O. Box 12272, Israel
| | - Erez Nitzan
- Department of Medical Neurobiology, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem 91120 – P.O. Box 12272, Israel
| | - Yachia Kassem
- Department of Medical Neurobiology, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem 91120 – P.O. Box 12272, Israel
| | - Chaya Kalcheim
- Department of Medical Neurobiology, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem 91120 – P.O. Box 12272, Israel
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Nitzan E, Kalcheim C. 03-P074 The relationship between specification and migration of neural crest progenitors. Mech Dev 2009. [DOI: 10.1016/j.mod.2009.06.127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Huber K, Franke A, Brühl B, Krispin S, Ernsberger U, Schober A, von Bohlen und Halbach O, Rohrer H, Kalcheim C, Unsicker K. Persistent expression of BMP-4 in embryonic chick adrenal cortical cells and its role in chromaffin cell development. Neural Dev 2008; 3:28. [PMID: 18945349 PMCID: PMC2582231 DOI: 10.1186/1749-8104-3-28] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2008] [Accepted: 10/22/2008] [Indexed: 11/29/2022] Open
Abstract
Background Adrenal chromaffin cells and sympathetic neurons both originate from the neural crest, yet signals that trigger chromaffin development remain elusive. Bone morphogenetic proteins (BMPs) emanating from the dorsal aorta are important signals for the induction of a sympathoadrenal catecholaminergic cell fate. Results We report here that BMP-4 is also expressed by adrenal cortical cells throughout chick embryonic development, suggesting a putative role in chromaffin cell development. Moreover, bone morphogenetic protein receptor IA is expressed by both cortical and chromaffin cells. Inhibiting BMP-4 with noggin prevents the increase in the number of tyrosine hydroxylase positive cells in adrenal explants without affecting cell proliferation. Hence, adrenal BMP-4 is likely to induce tyrosine hydroxylase in sympathoadrenal progenitors. To investigate whether persistent BMP-4 exposure is able to induce chromaffin traits in sympathetic ganglia, we locally grafted BMP-4 overexpressing cells next to sympathetic ganglia. Embryonic day 8 chick sympathetic ganglia, in addition to principal neurons, contain about 25% chromaffin-like cells. Ectopic BMP-4 did not increase this proportion, yet numbers and sizes of 'chromaffin' granules were significantly increased. Conclusion BMP-4 may serve to promote specific chromaffin traits, but is not sufficient to convert sympathetic neurons into a chromaffin phenotype.
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Affiliation(s)
- Katrin Huber
- Neuroanatomy, Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany.
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Ben-Yair R, Kalcheim C. Notch and bone morphogenetic protein differentially act on dermomyotome cells to generate endothelium, smooth, and striated muscle. ACTA ACUST UNITED AC 2008; 180:607-18. [PMID: 18268106 PMCID: PMC2234248 DOI: 10.1083/jcb.200707206] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We address the mechanisms underlying generation of skeletal muscle, smooth muscle, and endothelium from epithelial progenitors in the dermomyotome. Lineage analysis shows that of all epithelial domains, the lateral region is the most prolific producer of smooth muscle and endothelium. Importantly, individual labeled lateral somitic cells give rise to only endothelial or mural cells (not both), and endothelial and mural cell differentiation is driven by distinct signaling systems. Notch activity is necessary for smooth muscle production while inhibiting striated muscle differentiation, yet it does not affect initial development of endothelial cells. On the other hand, bone morphogenetic protein signaling is required for endothelial cell differentiation and/or migration but inhibits striated muscle differentiation and fails to impact smooth muscle cell production. Hence, although different mechanisms are responsible for smooth muscle and endothelium generation, the choice to become smooth versus striated muscle depends on a single signaling system. Altogether, these findings underscore the spatial and temporal complexity of lineage diversification in an apparently homogeneous epithelium.
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Affiliation(s)
- Raz Ben-Yair
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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Kahane N, Ben-Yair R, Kalcheim C. Medial pioneer fibers pattern the morphogenesis of early myoblasts derived from the lateral somite. Dev Biol 2007; 305:439-50. [PMID: 17382923 DOI: 10.1016/j.ydbio.2007.02.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 02/11/2007] [Accepted: 02/21/2007] [Indexed: 10/23/2022]
Abstract
The first wave of myoblasts which constitutes the post-mitotic myotome stems from the medial epithelial somite. Whereas medial pioneers extend throughout the entire mediolateral myotome at cervical and limb levels, at flank regions they are complemented laterally by a population of early myoblasts emerging from the lateral epithelial somite. These myoblasts delaminate underneath the nascent dermomyotome and become post-mitotic. They are Myf5-positive but express MyoD and desmin only a day later while differentiating into fibers. Overexpression of Noggin in the lateral somite triggers their premature differentiation suggesting that lateral plate-BMP4 maintains them in an undifferentiated state. Moreover, directly accelerating their differentiation by MyoD overexpression prior to arrival of medial fibers, generates a severely mispatterned lateral myotome. This is in contrast to medial pioneers that have the capacity for self-organization. Furthermore, inhibiting differentiation of medial pioneers with dominant-negative MyoD also disrupts lateral myoblast patterning and differentiation. Thus, we propose that medial pioneers are needed for proper morphogenesis of the lateral population which is kept as undifferentiated mesenchyme by BMP4 until their arrival. In addition, medial pioneers also organize dermomyotome lip-derived fibers suggesting that they have a general role in patterning myotome development.
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Affiliation(s)
- Nitza Kahane
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, PO Box 12272, Israel
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Shoval I, Ludwig A, Kalcheim C. Antagonistic roles of full-length N-cadherin and its soluble BMP cleavage product in neural crest delamination. Development 2006; 134:491-501. [PMID: 17185320 DOI: 10.1242/dev.02742] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
During neural crest ontogeny, an epithelial to mesenchymal transition is necessary for cell emigration from the dorsal neural tube. This process is likely to involve a network of gene activities, which remain largely unexplored. We demonstrate that N-cadherin inhibits the onset of crest delamination both by a cell adhesion-dependent mechanism and by repressing canonical Wnt signaling previously found to be necessary for crest delamination by acting downstream of BMP4. Furthermore, N-cadherin protein, but not mRNA, is normally downregulated along the dorsal tube in association with the onset of crest delamination, and we find that this process is triggered by BMP4. BMP4 stimulates cleavage of N-cadherin into a soluble cytoplasmic fragment via an ADAM10-dependent mechanism. Intriguingly, when overexpressed, the cytoplasmic N-cadherin fragment translocates into the nucleus, stimulates cyclin D1 transcription and crest delamination, while enhancing transcription of beta-catenin. CTF2 also rescues the mesenchymal phenotype of crest cells in ADAM10-inhibited neural primordia. Hence, by promoting its cleavage, BMP4 converts N-cadherin inhibition into an activity that is likely to participate, along with canonical Wnt signaling, in the stimulation of neural crest emigration.
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Affiliation(s)
- Irit Shoval
- Department of Anatomy and Cell Biology, Hebrew University, Hadassah Medical School, Jerusalem, Israel
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Kalcheim C, Kahane N, Cinnamon Y, Ben-Yair R. Mechanisms of lineage segregation in the avian dermomyotome. ACTA ACUST UNITED AC 2006; 211 Suppl 1:31-6. [PMID: 16967293 DOI: 10.1007/s00429-006-0116-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Accepted: 08/18/2006] [Indexed: 01/10/2023]
Abstract
The somite and its intermediate derivatives, sclerotome and dermomyotome (DM), are composed of distinct subdomains based on lineage analysis and gene expression patterns. This sets the grounds for elucidating the mechanisms underlying differential cell specification and morphogenesis. By examining the in vivo roles of N-cadherin on discrete domains of the somitic epithelium at various times, our recent studies highlight the existence of a regional and temporal heterogeneity in cellular responsiveness. As examples of this assortment, we document a coupling between asymmetric cell division and fate segregation in the DM sheet, sequential effects of N-cadherin-mediated adhesion on early myogenic specification compared to later myofiber patterning, and a differential behavior of pioneer myoblasts compared to later myogenic waves.
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Affiliation(s)
- Chaya Kalcheim
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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Abstract
Myotomal fibers form by a first wave of pioneer myoblasts from the medial epithelial somite, and by a second wave from all four lips of the dermomyotome. Then, a third wave of mitotic progenitors colonizes the myotome,initially stemming from the extreme lips and, later, from the central dermomyotome sheet. In vitro studies have suggested that N-cadherin plays a role in myogenesis, but its role in vivo remains poorly understood. We find that during the growth phase of the dermomyotome sheet, when the orientation of mitotic spindles is parallel to the mediolateral extent of the epithelium,N-cadherin protein is inherited by both daughter cells. Prior to dermomyotome dissociation into dermis and muscle progenitors, when mitoses become perpendicularly oriented, N-cadherin remains associated only with the apical cell located in apposition to the myotome, generating molecular asymmetry between basal and apical progeny. Local gene missexpression confirms that N-cadherin-mediated adhesion is sufficient to promote myotome colonization,whereas its absence drives cells towards the subectodermal domain, hence coupling the asymmetric distribution of N-cadherin to a shift in mitotic orientation and to fate segregation. Site-directed electroporation to additional, discrete somite regions, further reveals that N-cadherin-mediated adhesion is necessary for maintaining the epithelial configuration of all dermomyotome domains while promoting the onset of Myod transcription and the translocation into the myotome of myofibers and/or of Pax-positive progenitors. By contrast, N-cadherin has no effect on migration or differentiation of the first wave of myotomal pioneers. Altogether, we show for the first time that the asymmetric localization of N-cadherin during mitosis indirectly influences fate segregation by differentially driving the allocation of progenitors to muscle versus dermal primordia, that the adhesive domain of N-cadherin maintains the integrity of the dermomyotome epithelium,which is necessary for myogenic specification, and that different molecular mechanisms underlie the establishment of pioneer and later myotomal waves.
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Affiliation(s)
- Yuval Cinnamon
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, PO Box 12272, Jerusalem 91120, Israel
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Gut P, Huber K, Lohr J, Brühl B, Oberle S, Treier M, Ernsberger U, Kalcheim C, Unsicker K. Lack of an adrenal cortex in Sf1 mutant mice is compatible with the generation and differentiation of chromaffin cells. Development 2005; 132:4611-9. [PMID: 16176945 DOI: 10.1242/dev.02052] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The diversification of neural-crest-derived sympathoadrenal (SA) progenitor cells into sympathetic neurons and neuroendocrine adrenal chromaffin cells was thought to be largely understood. In-vitro studies with isolated SA progenitor cells had suggested that chromaffin cell differentiation depends crucially on glucocorticoids provided by adrenal cortical cells. However, analysis of mice lacking the glucocorticoid receptor gene had revealed that adrenal chromaffin cells develop mostly normally in these mice. Alternative cues from the adrenal cortex that may promote chromaffin cell determination and differentiation have not been identified. We therefore investigated whether the chromaffin cell phenotype can develop in the absence of an adrenal cortex, using mice deficient for the nuclear orphan receptor steroidogenic factor-1 (SF1), which lack adrenal cortical cells and gonads. We show that in Sf1–/– mice typical chromaffin cells assemble correctly in the suprarenal region adjacent to the suprarenal sympathetic ganglion. The cells display most features of chromaffin cells, including the typical large chromaffin granules. Sf1–/–chromaffin cells are numerically reduced by about 50% compared with the wild type at embryonic day (E) 13.5 and E17.5. This phenotype is not accounted for by reduced survival or cell proliferation beyond E12.5. However, already at E12.5 the `adrenal' region in Sf1–/– mice is occupied by fewer PHOX2B+ and TH+ SA cells as well as SOX10+ neural crest cells. Our results suggest that cortical cues are not essential for determining chromaffin cell fate, but may be required for proper migration of SA progenitors to and/or colonization of the adrenal anlage.
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Affiliation(s)
- Philipp Gut
- Neuroanatomy and Interdisciplinary Center for Neurosciences (IZN) of Heidelberg, INF 307, D-69120 Heidelberg, Germany
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Kalcheim C, Ben-Yair R. Cell rearrangements during development of the somite and its derivatives. Curr Opin Genet Dev 2005; 15:371-80. [PMID: 15950454 DOI: 10.1016/j.gde.2005.05.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2005] [Accepted: 05/23/2005] [Indexed: 12/21/2022]
Abstract
The generation of somites, and the subsequent formation of their major derivatives, muscle-, cartilage-, dermis- and tendon-cell lineages, is tightly orchestrated and, to different extents, these are also mutually supporting processes. They involve complex and timely reorganizations of the paraxial mesoderm, such as multiple phases of epithelial-mesenchymal rearrangements and vice-versa, cellular movements and migrations, and modifications of both cell shape and cell cycle properties. These morphogenetic changes are triggered by local environmental signals and are tightly associated to a genetic program imparting cell-specific fates. Elucidating these signals and their downstream effectors, in addition to determining the state of specification of responsive cell subsets and that of single progenitors in the various domains, is only beginning.
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Affiliation(s)
- Chaya Kalcheim
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, PO Box 12272, Israel.
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Abstract
This article summarizes some of the recent progress in understanding the development of chromaffin cells. These cells are derivatives of the neural crest and are intimately associated with the sympathetic nervous system. Although a common sympathoadrenal (SA) progenitor cell for chromaffin cells and sympathetic neurons has been postulated, there is evidence to suggest that chromaffin progenitors are already distinct, at least in part, from neuronal SA progenitors prior to invading the adrenal gland. The concept of an essential role of glucocorticoid signalling for chromaffin cell development has been shaken by the observation that chromaffin cells in mice lacking the glucocorticoid receptor develop largely normal. Distinct developmental requirements of chromaffin cells and sympathetic neurons must also be assumed based on the analyses of mice carrying targeted mutations of the genes for two transcription factors, MASH1 and Phox2B. Both genes are expressed by SA progenitors, but are distinctly required for the development of chromaffin cells and sympathetic neurons. There is an ongoing search for molecules selectively operating at the sites, where chromaffin cells develop. Such molecules may be candidates for triggering the distinct developmental pathway of chromaffin cells, as opposed to sympathetic neurons.
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Affiliation(s)
- Klaus Unsicker
- Interdisciplinary Center for Neurosciences (IZN) & Neuroanatomy, University of Heidelberg, INF 307, D-69120, Heidelberg, Germany.
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Ben-Yair R, Kalcheim C. Lineage analysis of the avian dermomyotome sheet reveals the existence of single cells with both dermal and muscle progenitor fates. Development 2005; 132:689-701. [PMID: 15659485 DOI: 10.1242/dev.01617] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The dermomyotome develops into myotome and dermis. We previously showed that overall growth of the dermomyotome and myotome in the mediolateral direction occurs in a uniform pattern. While myofibers arise from all four dermomyotome lips, the dermis derives from both medial and lateral halves of the dermomyotome sheet. Here we mapped the fate of this epithelial sheet by analyzing cell types that arise from its central region. We found that these precursors give rise not only to dermis, as expected, but also to a population of proliferating progenitors in the myotome that maintain expression of PAX7,PAX3 and FREK. Given this dual fate, we asked whether single dermomyotome precursors generate both dermal and mitotic myoblast precursors, or alternatively, whether these cell types derive from distinct epithelial founders. Inovo clonal analysis revealed that single dermomyotome progenitors give rise to both derivatives. This is associated with a sharp change in the plane of cell division from the young epithelium, in which symmetrical divisions occur parallel to the mediolateral plane of the dermomyotome, to the dissociating dermomyotome, in which cell divisions become mostly perpendicular. Taken together with clonal analysis of the dermomyotome sheet,this suggests that a first stage of progenitor self-renewal, accounting for dermomyotomal expansion, is followed by fate segregation, which correlates with the observed shift in mitotic spindle orientation.
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Affiliation(s)
- Raz Ben-Yair
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120-PO Box 12272, Israel
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Abstract
Long standing research of the Neural Crest embodies the most fundamental questions of Developmental Biology. Understanding the mechanisms responsible for specification, delamination, migration and phenotypic differentiation of this highly diversifying group of progenitors has been a challenge for many researchers over the years and continues to attract newcomers into the field. Only a few leaps were more significant than the discovery and successful exploitation of the quail-chick model by Nicole Le Douarin and colleagues from the Institute of Embryology at Nogent-sur-Marne. The accurate fate mapping of the neural crest performed at virtually all axial levels was followed by the determination of its developmental potentialities as initially analysed at a population level and then followed by many other significant findings. Altogether, these results paved the way to innumerable questions which brought us from an organismic view to mechanistic approaches. Among them, elucidation of functions played by identified genes is now rapidly underway. Emerging results lead the way back to an integrated understanding of the nature of interactions between the developing neural crest and neighbouring structures. The Nogent Institute thus performed an authentic "tour de force" in bringing the Neural Crest to the forefront of Developmental Biology. The present review is dedicated to the pivotal contributions of Nicole Le Douarin and her collaborators and to unforgettable memories that one of the authors bears from the time spent in the Nogent Institute. We summarize here recent advances in our understanding of early stages of crest ontogeny that comprise specification of epithelial progenitors to a neural crest fate and the onset of neural crest migration. Particular emphasis is given to signaling by BMP and Wnt molecules, to the role of the cell cycle in generating cell movement and to possible interactions between both mechanisms.
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Affiliation(s)
- Chaya Kalcheim
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem, Israel .
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Ernsberger U, Esposito L, Partimo S, Huber K, Franke A, Bixby JL, Kalcheim C, Unsicker K. Expression of neuronal markers suggests heterogeneity of chick sympathoadrenal cells prior to invasion of the adrenal anlagen. Cell Tissue Res 2004; 319:1-13. [PMID: 15565470 DOI: 10.1007/s00441-004-0996-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Accepted: 09/06/2004] [Indexed: 11/27/2022]
Abstract
We have analyzed the distribution of neural crest-derived precursors and the expression of catecholaminergic and neuronal markers in developing adrenal tissue of chick embryos. Undifferentiated neural crest cells are found in presumptive adrenal regions from embryonic day 3 (E3) onward. An increasing proportion of cells expressing tyrosine hydroxylase (TH) mRNA indicates catecholaminergic differentiation of precursors not only in primary sympathetic ganglia, but also in presumptive adrenal regions. Whereas precursors and differentiating cells show mesenchymal distribution until E5, discrete adrenal anlagen form during E6. Even during E5, catecholaminergic cells with low or undetectable neurofilament M (NF-M) mRNA expression prevail in positions at which adrenal anlagen become distinct during E6. The predominance of TH-positive and NF-M-negative cells is maintained throughout embryogenesis in adrenal tissue. RNA encoding SCG10, a pan-neuronal marker like NF-M, is strongly expressed throughout adrenal anlagen during E6 but is found at reduced levels in chromaffin cells compared with neuronal cells at E15. Two additional neuronal markers, synaptotagmin 1 and neurexin 1, are expressed at low to undetectable levels in developing chromaffin cells throughout embryogenesis. The developmental regulation of neuronal markers shows at least three different patterns among the four mRNAs analyzed. Importantly, there is no generalized downregulation of neuronal markers in developing adrenal anlagen. Thus, our observations question the classical concept of chromaffin differentiation from a common sympathoadrenal progenitor expressing neuronal properties and suggest alternative models with changing instructive signals or separate progenitor populations for sympathetic neuronal and chromaffin endocrine cells.
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Affiliation(s)
- Uwe Ernsberger
- Department of Neuroanatomy, Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, INF 307, 69120 Heidelberg, Germany.
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Burstyn-Cohen T, Stanleigh J, Sela-Donenfeld D, Kalcheim C. Canonical Wnt activity regulates trunk neural crest delamination linking BMP/noggin signaling with G1/S transition. Development 2004; 131:5327-39. [PMID: 15456730 DOI: 10.1242/dev.01424] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Delamination of premigratory neural crest cells depends on a balance between BMP/noggin and on successful G1/S transition. Here, we report that BMP regulates G1/S transition and consequent crest delamination through canonical Wnt signaling. Noggin overexpression inhibits G1/S transition and blocking G1/S abrogates BMP-induced delamination; moreover, transcription of Wnt1 is stimulated by BMP and by the developing somites, which concomitantly inhibit noggin production. Interfering with β-catenin and LEF/TCF inhibits G1/S transition, neural crest delamination and transcription of various BMP-dependent genes, which include Cad6B, Pax3 and Msx1, but not that of Slug,Sox9 or FoxD3. Hence, we propose that developing somites inhibit noggin transcription in the dorsal tube, resulting in activation of BMP and consequent Wnt1 production. Canonical Wnt signaling in turn stimulates G1/S transition and generation of neural crest cell motility independently of its proposed role in earlier neural crest specification.
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Affiliation(s)
- Tal Burstyn-Cohen
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, PO Box 12272, Jerusalem 91120, Israel
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Yaniv K, Fainsod A, Kalcheim C, Yisraeli JK. The RNA-binding protein Vg1 RBP is required for cell migration during early neural development. Development 2003; 130:5649-61. [PMID: 14522877 DOI: 10.1242/dev.00810] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
After mid-blastula transition, populations of cells within the Xenopus embryo become motile. Using antisense morpholino oligonucleotides, we find that Vg1 RBP, an RNA-binding protein implicated in RNA localization in oocytes, is required for the migration of cells forming the roof plate of the neural tube and, subsequently, for neural crest migration. These cells are properly determined but remain at their site of origin. Consistent with a possible role in cell movement, Vg1 RBP asymmetrically localizes to extended processes in migrating neural crest cells. Given that Vg1 RBP is a member of the conserved VICKZ family of proteins, expressed in embryonic and neoplastic cells, these data shed light on the likely role of these RNA-binding proteins in regulating cell movements during both development and metastasis.
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Affiliation(s)
- Karina Yaniv
- Department of Anatomy and Cell Biology, Hebrew University - Hadassah Medical School, POB 12272, 91120 Jerusalem, Israel
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Abstract
We have previously shown that overall growth of the myotome in the mediolateral direction occurs in a coherent and uniform pattern. We asked whether development of the dermomyotome and resultant dermis follow a similar pattern or are, alternatively, controlled by restricted pools of stem cells driving directional growth. To this end, we studied cellular events that govern dermomyotome development and the regional origin of dermis. Measurements of cell proliferation, nuclear density and cellular rearrangements revealed that the developing dermomyotome can be subdivided in the transverse plane into three distinct and dynamic regions: medial, central and lateral, rather than simply into epaxial and hypaxial domains. To understand how these temporally and spatially restricted changes affect overall dermomyotome growth, lineage tracing with CM-DiI was performed. A proportional pattern of growth was measured along the entire epithelium, suggesting that mediolateral growth of the dermomyotome is coherent. Hence, they contrast with a stem cell view suggesting focal and inversely oriented sources of growth restricted to the medial and lateral edges. Consistent with this uniform mediolateral growth, lineage tracing experiments showed that the dermomyotome-derived dermis originates from progenitors that reside along the medial as well as the lateral halves of somites, and whose contribution to dermis is regionally restricted. Taken together, our results support the view that all derivatives of the dorsal somite (dermomyotome, myotome and dermis) keep a direct topographical relationship with their epithelial ascendants.
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Affiliation(s)
- Raz Ben-Yair
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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Huber K, Combs S, Ernsberger U, Kalcheim C, Unsicker K. Generation of neuroendocrine chromaffin cells from sympathoadrenal progenitors: beyond the glucocorticoid hypothesis. Ann N Y Acad Sci 2002; 971:554-9. [PMID: 12438182 DOI: 10.1111/j.1749-6632.2002.tb04526.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The developmental diversification of neural crest-derived sympathoadrenal (SA) progenitor cells into neuroendocrine adrenal chromaffin cells and sympathetic neurons has been thought to be largely understood. Based on two decades of in vitro studies with isolated SA progenitor and chromaffin cells, it was widely assumed that chromaffin cell development crucially depends on glucocorticoid hormones provided by adrenal cortical cells. However, analysis of mice lacking the glucocorticoid receptor has revealed that the chromaffin cell phenotype develops largely normally in these mice, except for the induction of the adrenaline synthesizing enzyme phenylethylamine N-methyl transferase. In a search for novel candidate genes that might be involved in triggering the sympathetic neuron/chromaffin cell decision, we have studied putative contributions of transforming growth factor (TGF)-alpha, BMP-4, and the transcription factor MASH-1, molecules with distinct expressions in SA progenitor cells, in their migratory pathways and final destinations. TGF-beta2 and -beta3 and BMP-4 are highly expressed in the wall of the dorsal aorta and in the adrenal anlagen during and after immigration of SA progenitors but expressed at much lower levels in sympathetic ganglia. We found that neutralizing antibodies against all three TGF-beta isoforms applied to the chorionic-allantoic membrane (CAM) of quail embryos interfere with proliferation of immigrated adrenal chromaffin cells but do not affect their specific neuroendocrine ultrastructural phenotype. Grafting of noggin-producing cells to the CAM, which scavenges BMPs, interferes with visceral arch and limb development but does not overtly affect the chromaffin phenotype. The transcription factor MASH-1 promotes early differentiation of SA progenitors. Mice deficient for MASH-1 lack sympathetic ganglia, whereas the adrenal medulla previously has been reported to be present. We show here that most adrenal medullary cells in MASH-1(-/-) mice identified by Phox2b immunoreactivity lack the catecholaminergic marker tyrosine hydroxylase. More surprisingly, most cells do not contain chromaffin granules and display a neuroblast-like ultrastructure and show strongly enhanced expression of c-RET comparable to that observed in sympathetic ganglia. Together, our data suggest that TGF-betas and BMP-4 do not seem to be essential for chromaffin cell differentiation. In contrast with previous reports, however, MASH-1 apparently plays a crucial role in chromaffin cell development.
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Affiliation(s)
- Katrin Huber
- Department of Neuroanatomy, Interdisciplinary Center for Neurosciences, University of Heidelberg, Heidelberg, Germany
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Abstract
The autonomic nervous system consists of sympathetic, parasympathetic, and enteric ganglia and also of a specialized neuroendocrine derivative, the adrenomedullary chromaffin cells.
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Affiliation(s)
- Chaya Kalcheim
- Department of Anatomy and Cell Biology, Hebrew University, Hadassah Medical School, Jerusalem, 91120 Israel
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Abstract
Delamination of premigratory neural crest cells from the dorsal neural tube depends both upon environmental signals and cell-intrinsic mechanisms and is a prerequisite for cells to engage in migration. Here we show that avian neural crest cells synchronously emigrate from the neural tube in the S phase of the cell cycle. Furthermore, specific inhibition of the transition from G1 to S both in ovo and in explants blocks delamination, whereas arrest at the S or G2 phases has no immediate effect. Thus, the events taking place during G1 that control the transition from G1 to S are necessary for the epithelial to mesenchymal conversion of crest precursors.
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Affiliation(s)
- Tal Burstyn-Cohen
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, P.O. Box 12272, Jerusalem 91120, Israel
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Abstract
Interactions between BMP4 and its inhibitor, noggin, regulate patterning of somites and neural crest. During mesoderm development, noggin mRNA is expressed in the intermediate mesoderm. Upon segmentation, it is detected in the lateral portion of epithelial somites becoming progressively medialized as they mature. In dissociated segments, noggin becomes transiently confined to the dorsomedial lip of the dermomyotome. Here, we investigated the factor(s) that control this lateral-to-medial shift in transcription of somitic noggin. Inhibition of BMP activity in the caudal lateral plate/intermediate mesoderm prevented noggin transcription in the lateral somite. Further rostrally (or later in development), inhibition of tube-derived BMP, but not of Wnt activity, prevented initial noggin expression in the dorsomedial lip of the dermomyotome. Moreover, BMP4 was sufficient to trigger initial expression of noggin even in the absence of ectoderm and/or neural tube, suggesting a direct action on the dorsomedial somite. Thus, the patterns of noggin transcription in somites are directly regulated by BMP4 activities emanating first from the mesoderm and later from the neural tube. Expression patterns of BMP4 and of type IA BMP receptors are spatiotemporally compatible with this lateral-to-medial shift. These results highlight the existence in the neural tube-mesoderm complex of a regulatory loop by which BMP positively regulates transcription of noggin, which in turn represses further ligand activity.
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Affiliation(s)
- Dalit Sela-Donenfeld
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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Abstract
We have previously found that the postmitotic myotome is formed by two successive waves of myoblasts. A first wave of pioneer cells is generated from the dorsomedial region of epithelial somites. A second wave originates from all four edges of the dermomyotome but cells enter the myotome only from the rostral and caudal lips. We provide new evidence for the existence of these distinctive waves. We show for the first time that when the somite dissociates, pioneer myotomal progenitors migrate as mesenchymal cells from the medial side towards the rostral edge of the segment. Subsequently, they generate myofibers that elongate caudally. Pioneer myofiber differentiation then progresses in a medial-to-lateral direction with fibers reaching the lateralmost region of each segment. At later stages, pioneers participate in the formation of multinucleated fibers during secondary myogenesis by fusing with younger cells. We also demonstrate that subsequent to primary myotome formation by pioneers, growth occurs by uniform cell addition along the dorsoventral myotome. At this stage, the contributing cells arise from multiple sources as the myotome keeps growing even in the absence of the dorsomedial lip. Moreover, as opposed to suggestions that myotome growth is driven primarily and directly by the medial and lateral edges, we demonstrate that there is no direct fiber generation from the dorsomedial lip. Instead, we find that added fibers elongate from the extreme edges. Altogether, the integration between both myogenic waves results in an even pattern of dorsoventral growth of the myotome which is accounted for by progressive cell intercalation of second wave cells between preexisting pioneer fibers.
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Affiliation(s)
- Nitza Kahane
- Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, PO Box 12272, Israel
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