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Keramidioti A, Schneid S, Busse C, Cramer von Laue C, Bertulat B, Salvenmoser W, Hess M, Alexandrova O, Glauber KM, Steele RE, Hobmayer B, Holstein TW, David CN. A new look at the architecture and dynamics of the Hydra nerve net. eLife 2024; 12:RP87330. [PMID: 38407174 PMCID: PMC10942621 DOI: 10.7554/elife.87330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2024] Open
Abstract
The Hydra nervous system is the paradigm of a 'simple nerve net'. Nerve cells in Hydra, as in many cnidarian polyps, are organized in a nerve net extending throughout the body column. This nerve net is required for control of spontaneous behavior: elimination of nerve cells leads to polyps that do not move and are incapable of capturing and ingesting prey (Campbell, 1976). We have re-examined the structure of the Hydra nerve net by immunostaining fixed polyps with a novel antibody that stains all nerve cells in Hydra. Confocal imaging shows that there are two distinct nerve nets, one in the ectoderm and one in the endoderm, with the unexpected absence of nerve cells in the endoderm of the tentacles. The nerve nets in the ectoderm and endoderm do not contact each other. High-resolution TEM (transmission electron microscopy) and serial block face SEM (scanning electron microscopy) show that the nerve nets consist of bundles of parallel overlapping neurites. Results from transgenic lines show that neurite bundles include different neural circuits and hence that neurites in bundles require circuit-specific recognition. Nerve cell-specific innexins indicate that gap junctions can provide this specificity. The occurrence of bundles of neurites supports a model for continuous growth and differentiation of the nerve net by lateral addition of new nerve cells to the existing net. This model was confirmed by tracking newly differentiated nerve cells.
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Affiliation(s)
- Athina Keramidioti
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | - Sandra Schneid
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | - Christina Busse
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | | | - Bianca Bertulat
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg UniversityHeidelbergGermany
| | - Willi Salvenmoser
- Department of Zoology and Center for Molecular Biosciences Innsbruck (CMBI), University of InnsbruckInnsbruckAustria
| | - Martin Hess
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | - Olga Alexandrova
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | - Kristine M Glauber
- Department of Biological Chemistry, University of CaliforniaIrvineUnited States
| | - Robert E Steele
- Department of Biological Chemistry, University of CaliforniaIrvineUnited States
| | - Bert Hobmayer
- Department of Zoology and Center for Molecular Biosciences Innsbruck (CMBI), University of InnsbruckInnsbruckAustria
| | - Thomas W Holstein
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg UniversityHeidelbergGermany
| | - Charles N David
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
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2
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Holstein TW. The Hydra stem cell system - Revisited. Cells Dev 2023; 174:203846. [PMID: 37121433 DOI: 10.1016/j.cdev.2023.203846] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 04/12/2023] [Accepted: 04/25/2023] [Indexed: 05/02/2023]
Abstract
Cnidarians are >600 million years old and are considered the sister group of Bilateria based on numerous molecular phylogenetic studies. Apart from Hydra, the genomes of all major clades of Cnidaria have been uncovered (e.g. Aurelia, Clytia, Nematostella and Acropora) and they reveal a remarkable completeness of the metazoan genomic toolbox. Of particular interest is Hydra, a model system of aging research, regenerative biology, and stem cell biology. With the knowledge gained from scRNA research, it is now possible to characterize the expression profiles of all cell types with great precision. In functional studies, our picture of the Hydra stem cell biology has changed, and we are in the process of obtaining a clear picture of the homeostasis and properties of the different stem cell populations. Even though Hydra is often compared to plant systems, the new data on germline and regeneration, but also on the dynamics and plasticity of the nervous system, show that Hydra with its simple body plan represents in a nutshell the prototype of an animal with stem cell lineages, whose properties correspond in many ways to Bilateria. This review provides an overview of the four stem cell lineages, the two epithelial lineages that constitute the ectoderm and the endoderm, as well as the multipotent somatic interstitial lineage (MPSC) and the germline stem cell lineage (GSC), also known as the interstitial cells of Hydra.
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Affiliation(s)
- Thomas W Holstein
- Heidelberg University, Centre for Organismal Studies (COS), Molecular Evolution and Genomics, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany.
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3
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Lechable M, Tang X, Siebert S, Feldbacher A, Fernández-Quintero ML, Breuker K, Juliano CE, Liedl KR, Hobmayer B, Hartl M. High Intrinsic Oncogenic Potential in the Myc-Box-Deficient Hydra Myc3 Protein. Cells 2023; 12:cells12091265. [PMID: 37174665 PMCID: PMC10177328 DOI: 10.3390/cells12091265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/17/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
The proto-oncogene myc has been intensively studied primarily in vertebrate cell culture systems. Myc transcription factors control fundamental cellular processes such as cell proliferation, cell cycle control and stem cell maintenance. Myc interacts with the Max protein and Myc/Max heterodimers regulate thousands of target genes. The genome of the freshwater polyp Hydra encodes four myc genes (myc1-4). Previous structural and biochemical characterization showed that the Hydra Myc1 and Myc2 proteins share high similarities with vertebrate c-Myc, and their expression patterns suggested a function in adult stem cell maintenance. In contrast, an additional Hydra Myc protein termed Myc3 is highly divergent, lacking the common N-terminal domain and all conserved Myc-boxes. Single cell transcriptome analysis revealed that the myc3 gene is expressed in a distinct population of interstitial precursor cells committed to nerve- and gland-cell differentiation, where the Myc3 protein may counteract the stemness actions of Myc1 and Myc2 and thereby allow the implementation of a differentiation program. In vitro DNA binding studies showed that Myc3 dimerizes with Hydra Max, and this dimer efficiently binds to DNA containing the canonical Myc consensus motif (E-box). In vivo cell transformation assays in avian fibroblast cultures further revealed an unexpected high potential for oncogenic transformation in the conserved Myc3 C-terminus, as compared to Hydra Myc2 or Myc1. Structure modeling of the Myc3 protein predicted conserved amino acid residues in its bHLH-LZ domain engaged in Myc3/Max dimerization. Mutating these amino acid residues in the human c-Myc (MYC) sequence resulted in a significant decrease in its cell transformation potential. We discuss our findings in the context of oncogenic transformation and cell differentiation, both relevant for human cancer, where Myc represents a major driver.
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Affiliation(s)
- Marion Lechable
- Institute of Zoology, University of Innsbruck, 6020 Innsbruck, Austria
- Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
| | - Xuechen Tang
- Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
- Institute of Inorganic and Theoretical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
| | - Stefan Siebert
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Angelika Feldbacher
- Institute of Zoology, University of Innsbruck, 6020 Innsbruck, Austria
- Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
| | - Monica L Fernández-Quintero
- Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
- Institute of Inorganic and Theoretical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
| | - Kathrin Breuker
- Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
- Institute of Organic Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
| | - Celina E Juliano
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Klaus R Liedl
- Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
- Institute of Inorganic and Theoretical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
| | - Bert Hobmayer
- Institute of Zoology, University of Innsbruck, 6020 Innsbruck, Austria
- Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
| | - Markus Hartl
- Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
- Institute of Biochemistry, University of Innsbruck, 6020 Innsbruck, Austria
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4
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Primack AS, Cazet JF, Little HM, Mühlbauer S, Cox BD, David CN, Farrell JA, Juliano CE. Differentiation trajectories of the Hydra nervous system reveal transcriptional regulators of neuronal fate. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.15.531610. [PMID: 36993575 PMCID: PMC10055148 DOI: 10.1101/2023.03.15.531610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
The small freshwater cnidarian polyp Hydra vulgaris uses adult stem cells (interstitial stem cells) to continually replace neurons throughout its life. This feature, combined with the ability to image the entire nervous system (Badhiwala et al., 2021; Dupre & Yuste, 2017) and availability of gene knockdown techniques (Juliano, Reich, et al., 2014; Lohmann et al., 1999; Vogg et al., 2022), makes Hydra a tractable model for studying nervous system development and regeneration at the whole-organism level. In this study, we use single-cell RNA sequencing and trajectory inference to provide a comprehensive molecular description of the adult nervous system. This includes the most detailed transcriptional characterization of the adult Hydra nervous system to date. We identified eleven unique neuron subtypes together with the transcriptional changes that occur as the interstitial stem cells differentiate into each subtype. Towards the goal of building gene regulatory networks to describe Hydra neuron differentiation, we identified 48 transcription factors expressed specifically in the Hydra nervous system, including many that are conserved regulators of neurogenesis in bilaterians. We also performed ATAC-seq on sorted neurons to uncover previously unidentified putative regulatory regions near neuron-specific genes. Finally, we provide evidence to support the existence of transdifferentiation between mature neuron subtypes and we identify previously unknown transition states in these pathways. All together, we provide a comprehensive transcriptional description of an entire adult nervous system, including differentiation and transdifferentiation pathways, which provides a significant advance towards understanding mechanisms that underlie nervous system regeneration.
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Affiliation(s)
- Abby S Primack
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616
| | - Jack F Cazet
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616
| | - Hannah Morris Little
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616
| | - Susanne Mühlbauer
- Department of Plant Biochemistry, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Ben D Cox
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616
| | - Charles N David
- Department of Biology, Ludwig-Maximilians-University Munich, 82152 Martinsried, Germany
| | - Jeffrey A Farrell
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20814, USA
| | - Celina E Juliano
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616
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5
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Single-cell transcriptomics identifies conserved regulators of neuroglandular lineages. Cell Rep 2022; 40:111370. [PMID: 36130520 DOI: 10.1016/j.celrep.2022.111370] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/01/2022] [Accepted: 08/25/2022] [Indexed: 11/23/2022] Open
Abstract
Communication in bilaterian nervous systems is mediated by electrical and secreted signals; however, the evolutionary origin and relation of neurons to other secretory cell types has not been elucidated. Here, we use developmental single-cell RNA sequencing in the cnidarian Nematostella vectensis, representing an early evolutionary lineage with a simple nervous system. Validated by transgenics, we demonstrate that neurons, stinging cells, and gland cells arise from a common multipotent progenitor population. We identify the conserved transcription factor gene SoxC as a key upstream regulator of all neuroglandular lineages and demonstrate that SoxC knockdown eliminates both neuronal and secretory cell types. While in vertebrates and many other bilaterians neurogenesis is largely restricted to early developmental stages, we show that in the sea anemone, differentiation of neuroglandular cells is maintained throughout all life stages, and follows the same molecular trajectories from embryo to adulthood, ensuring lifelong homeostasis of neuroglandular cell lineages.
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6
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Traffic light Hydra allows for simultaneous in vivo imaging of all three cell lineages. Dev Biol 2022; 488:74-80. [DOI: 10.1016/j.ydbio.2022.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 05/06/2022] [Accepted: 05/10/2022] [Indexed: 11/19/2022]
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7
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Tomczyk S, Buzgariu W, Perruchoud C, Fisher K, Austad S, Galliot B. Loss of Neurogenesis in Aging Hydra. Dev Neurobiol 2019; 79:479-496. [PMID: 30912256 PMCID: PMC6586502 DOI: 10.1002/dneu.22676] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 02/27/2019] [Accepted: 03/14/2019] [Indexed: 01/07/2023]
Abstract
In Hydra the nervous system is composed of neurons and mechanosensory cells that differentiate from interstitial stem cells (ISCs), which also provide gland cells and germ cells. The adult nervous system is actively maintained through continuous de novo neurogenesis that occurs at two distinct paces, slow in intact animals and fast in regenerating ones. Surprisingly Hydra vulgaris survive the elimination of cycling interstitial cells and the subsequent loss of neurogenesis if force-fed. By contrast, H. oligactis animals exposed to cold temperature undergo gametogenesis and a concomitant progressive loss of neurogenesis. In the cold-sensitive strain Ho_CS, this loss irreversibly leads to aging and animal death. Within four weeks, Ho_CS animals lose their contractility, feeding response, and reaction to light. Meanwhile, two positive regulators of neurogenesis, the homeoprotein prdl-a and the neuropeptide Hym-355, are no longer expressed, while the "old" RFamide-expressing neurons persist. A comparative transcriptomic analysis performed in cold-sensitive and cold-resistant strains confirms the downregulation of classical neuronal markers during aging but also shows the upregulation of putative regulators of neurotransmission and neurogenesis such as AHR, FGFR, FoxJ3, Fral2, Jagged, Meis1, Notch, Otx1, and TCF15. The switch of Fral2 expression from neurons to germ cells suggests that in aging animals, the neurogenic program active in ISCs is re-routed to germ cells, preventing de novo neurogenesis and impacting animal survival.
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Affiliation(s)
- Szymon Tomczyk
- Faculty of Sciences, Department of Genetics and EvolutionUniversity of GenevaGenevaSwitzerland
- iGE3 ‐ Institute for Genomics and Genetics in GenevaGenevaSwitzerland
| | - Wanda Buzgariu
- Faculty of Sciences, Department of Genetics and EvolutionUniversity of GenevaGenevaSwitzerland
- iGE3 ‐ Institute for Genomics and Genetics in GenevaGenevaSwitzerland
| | - Chrystelle Perruchoud
- Faculty of Sciences, Department of Genetics and EvolutionUniversity of GenevaGenevaSwitzerland
- iGE3 ‐ Institute for Genomics and Genetics in GenevaGenevaSwitzerland
| | - Kathleen Fisher
- Department of BiologyUniversity of Alabama at BirminghamBirminghamAlabama
| | - Steven Austad
- Department of BiologyUniversity of Alabama at BirminghamBirminghamAlabama
| | - Brigitte Galliot
- Faculty of Sciences, Department of Genetics and EvolutionUniversity of GenevaGenevaSwitzerland
- iGE3 ‐ Institute for Genomics and Genetics in GenevaGenevaSwitzerland
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8
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Regionalized nervous system in Hydra and the mechanism of its development. Gene Expr Patterns 2019; 31:42-59. [PMID: 30677493 DOI: 10.1016/j.gep.2019.01.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 01/15/2019] [Indexed: 12/15/2022]
Abstract
The last common ancestor of Bilateria and Cnidaria is considered to develop a nervous system over 500 million years ago. Despite the long course of evolution, many of the neuron-related genes, which are active in Bilateria, are also found in the cnidarian Hydra. Thus, Hydra is a good model to study the putative primitive nervous system in the last common ancestor that had the great potential to evolve to a more advanced one. Regionalization of the nervous system is one of the advanced features of bilaterian nervous system. Although a regionalized nervous system is already known to be present in Hydra, its developmental mechanisms are poorly understood. In this study we show how it is formed and maintained, focusing on the neuropeptide Hym-176 gene and its paralogs. First, we demonstrate that four axially localized neuron subsets that express different combination of the neuropeptide Hym-176 gene and its paralogs cover almost an entire body, forming a regionalized nervous system in Hydra. Second, we show that positional information governed by the Wnt signaling pathway plays a key role in determining the regional specificity of the neuron subsets as is the case in bilaterians. Finally, we demonstrated two basic mechanisms, regionally restricted new differentiation and phenotypic conversion, both of which are in part conserved in bilaterians, are involved in maintaining boundaries between the neuron subsets. Therefore, this study is the first comprehensive analysis of the anatomy and developmental regulation of the divergently evolved and axially regionalized peptidergic nervous system in Hydra, implicating an ancestral origin of neural regionalization.
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9
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Lai AG, Aboobaker AA. EvoRegen in animals: Time to uncover deep conservation or convergence of adult stem cell evolution and regenerative processes. Dev Biol 2018; 433:118-131. [PMID: 29198565 DOI: 10.1016/j.ydbio.2017.10.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 01/08/2023]
Abstract
How do animals regenerate specialised tissues or their entire body after a traumatic injury, how has this ability evolved and what are the genetic and cellular components underpinning this remarkable feat? While some progress has been made in understanding mechanisms, relatively little is known about the evolution of regenerative ability. Which elements of regeneration are due to lineage specific evolutionary novelties or have deeply conserved roots within the Metazoa remains an open question. The renaissance in regeneration research, fuelled by the development of modern functional and comparative genomics, now enable us to gain a detailed understanding of both the mechanisms and evolutionary forces underpinning regeneration in diverse animal phyla. Here we review existing and emerging model systems, with the focus on invertebrates, for studying regeneration. We summarize findings across these taxa that tell us something about the evolution of adult stem cell types that fuel regeneration and the growing evidence that many highly regenerative animals harbor adult stem cells with a gene expression profile that overlaps with germline stem cells. We propose a framework in which regenerative ability broadly evolves through changes in the extent to which stem cells generated through embryogenesis are maintained into the adult life history.
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Affiliation(s)
- Alvina G Lai
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - A Aziz Aboobaker
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.
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10
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Roles of Germline Stem Cells and Somatic Multipotent Stem Cells in Hydra Sexual Reproduction. DIVERSITY AND COMMONALITY IN ANIMALS 2018. [DOI: 10.1007/978-4-431-56609-0_7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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11
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Impact of cycling cells and cell cycle regulation on Hydra regeneration. Dev Biol 2018; 433:240-253. [DOI: 10.1016/j.ydbio.2017.11.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 10/31/2017] [Accepted: 11/08/2017] [Indexed: 01/12/2023]
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12
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Gahan JM, Schnitzler CE, DuBuc TQ, Doonan LB, Kanska J, Gornik SG, Barreira S, Thompson K, Schiffer P, Baxevanis AD, Frank U. Functional studies on the role of Notch signaling in Hydractinia development. Dev Biol 2017; 428:224-231. [PMID: 28601529 DOI: 10.1016/j.ydbio.2017.06.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/06/2017] [Accepted: 06/06/2017] [Indexed: 11/19/2022]
Abstract
The function of Notch signaling was previously studied in two cnidarians, Hydra and Nematostella, representing the lineages Hydrozoa and Anthozoa, respectively. Using pharmacological inhibition in Hydra and a combination of pharmacological and genetic approaches in Nematostella, it was shown in both animals that Notch is required for tentacle morphogenesis and for late stages of stinging cell maturation. Surprisingly, a role for Notch in neural development, which is well documented in bilaterians, was evident in embryonic Nematostella but not in adult Hydra. Adult neurogenesis in the latter seemed to be unaffected by DAPT, a drug that inhibits Notch signaling. To address this apparent discrepancy, we studied the role of Notch in Hydractinia echinata, an additional hydrozoan, in all life stages. Using CRISPR-Cas9 mediated mutagenesis, transgenesis, and pharmacological interference we show that Notch is dispensable for Hydractinia normal neurogenesis in all life stages but is required for the maturation of stinging cells and for tentacle morphogenesis. Our results are consistent with a conserved role for Notch in morphogenesis and nematogenesis across Cnidaria, and a lineage-specific loss of Notch dependence in neurogenesis in hydrozoans.
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Affiliation(s)
- James M Gahan
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Christine E Schnitzler
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL 320803, USA; Department of Biology, University of Florida, Gainesville, FL 32611, USA; Division of Intramural Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Timothy Q DuBuc
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Liam B Doonan
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Justyna Kanska
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Sebastian G Gornik
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Sofia Barreira
- Division of Intramural Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Kerry Thompson
- Centre for Microscopy and Imaging, Discipline of Anatomy, School of Medicine, National University of Ireland, Galway, Galway, Ireland
| | - Philipp Schiffer
- Department for Genetics Environment and Evolution, University College London, London, UK
| | - Andreas D Baxevanis
- Division of Intramural Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Uri Frank
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland.
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13
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Bosch TCG, Klimovich A, Domazet-Lošo T, Gründer S, Holstein TW, Jékely G, Miller DJ, Murillo-Rincon AP, Rentzsch F, Richards GS, Schröder K, Technau U, Yuste R. Back to the Basics: Cnidarians Start to Fire. Trends Neurosci 2016; 40:92-105. [PMID: 28041633 DOI: 10.1016/j.tins.2016.11.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 11/22/2016] [Accepted: 11/23/2016] [Indexed: 12/15/2022]
Abstract
The nervous systems of cnidarians, pre-bilaterian animals that diverged close to the base of the metazoan radiation, are structurally simple and thus have great potential to reveal fundamental principles of neural circuits. Unfortunately, cnidarians have thus far been relatively intractable to electrophysiological and genetic techniques and consequently have been largely passed over by neurobiologists. However, recent advances in molecular and imaging methods are fueling a renaissance of interest in and research into cnidarians nervous systems. Here, we review current knowledge on the nervous systems of cnidarian species and propose that researchers should seize this opportunity and undertake the study of members of this phylum as strategic experimental systems with great basic and translational relevance for neuroscience.
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Affiliation(s)
| | | | - Tomislav Domazet-Lošo
- Ruđer Bošković Institute, Zagreb, Croatia; Catholic University of Croatia, Zagreb, Croatia
| | - Stefan Gründer
- Institute of Physiology, RWTH Aachen University, Germany
| | | | - Gáspár Jékely
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - David J Miller
- ARC Centre of Excellence for Coral Reef Studies, Townsville, Australia
| | | | - Fabian Rentzsch
- Sars International Centre for Marine Molecular Biology, University of Bergen, Norway
| | - Gemma S Richards
- Sars International Centre for Marine Molecular Biology, University of Bergen, Norway; University of Queensland, Brisbane, Australia
| | | | | | - Rafael Yuste
- Neurotechnology Center, Columbia University, New York, NY, USA.
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14
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Gahan JM, Bradshaw B, Flici H, Frank U. The interstitial stem cells in Hydractinia and their role in regeneration. Curr Opin Genet Dev 2016; 40:65-73. [DOI: 10.1016/j.gde.2016.06.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/26/2016] [Accepted: 06/16/2016] [Indexed: 10/21/2022]
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15
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Kelava I, Rentzsch F, Technau U. Evolution of eumetazoan nervous systems: insights from cnidarians. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2015.0065. [PMID: 26554048 PMCID: PMC4650132 DOI: 10.1098/rstb.2015.0065] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cnidarians, the sister group to bilaterians, have a simple diffuse nervous system. This morphological simplicity and their phylogenetic position make them a crucial group in the study of the evolution of the nervous system. The development of their nervous systems is of particular interest, as by uncovering the genetic programme that underlies it, and comparing it with the bilaterian developmental programme, it is possible to make assumptions about the genes and processes involved in the development of ancestral nervous systems. Recent advances in sequencing methods, genetic interference techniques and transgenic technology have enabled us to get a first glimpse into the molecular network underlying the development of a cnidarian nervous system—in particular the nervous system of the anthozoan Nematostella vectensis. It appears that much of the genetic network of the nervous system development is partly conserved between cnidarians and bilaterians, with Wnt and bone morphogenetic protein (BMP) signalling, and Sox genes playing a crucial part in the differentiation of neurons. However, cnidarians possess some specific characteristics, and further studies are necessary to elucidate the full regulatory network. The work on cnidarian neurogenesis further accentuates the need to study non-model organisms in order to gain insights into processes that shaped present-day lineages during the course of evolution.
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Affiliation(s)
- Iva Kelava
- Department of Molecular Evolution and Development, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Fabian Rentzsch
- Sars Centre, Sars International Centre for Marine Molecular Biology, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Ulrich Technau
- Department of Molecular Evolution and Development, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
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Siebert S, Goetz FE, Church SH, Bhattacharyya P, Zapata F, Haddock SHD, Dunn CW. Stem cells in Nanomia bijuga (Siphonophora), a colonial animal with localized growth zones. EvoDevo 2015; 6:22. [PMID: 26090088 PMCID: PMC4471933 DOI: 10.1186/s13227-015-0018-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/11/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Siphonophores (Hydrozoa) have unparalleled colony-level complexity, precision of colony organization, and functional specialization between zooids (i.e., the units that make up colonies). Previous work has shown that, unlike other colonial animals, most growth in siphonophores is restricted to one or two well-defined growth zones that are the sites of both elongation and zooid budding. It remained unknown, however, how this unique colony growth and development is realized at the cellular level. RESULTS To understand the colony-level growth and development of siphonophores at the cellular level, we characterize the distribution of proliferating cells and interstitial stem cells (i-cells) in the siphonophore Nanomia bijuga. Within the colony, we find evidence that i-cells are present at the tip of the horn, the structure within the growth zone that gives rise to new zooids. Co-localized gene expression of vasa-1, pl10, piwi, nanos-1, and nanos-2 suggests that i-cells persist in the youngest zooid buds and that i-cells become progressively restricted to specific regions within the zooids until they are mostly absent from the oldest zooids. The examined genes remain expressed in gametogenic regions. No evidence for i-cells is found in the stem between maturing zooids. Domains of high cell proliferation include regions where the examined genes are expressed, but also include some areas in which the examined genes were not expressed such as the stem within the growth zones. Cell proliferation in regions devoid of vasa-1, pl10, piwi, nanos-1, and nanos-2 expression indicates the presence of mitotically active epithelial cell lineages and, potentially, progenitor cell populations. CONCLUSIONS We provide the first evidence for i-cells in a siphonophore. Our findings suggest maintenance of i-cell populations at the sites of growth zones and that these sites are the main source of i-cells. This restriction of stem cells to particular regions in the colony, in combination with localized budding and spatial patterning during pro-bud subdivision, may play a major role in facilitating the precision of siphonophore growth. Spatially restricted maintenance of i-cells in mature zooids and absence of i-cells along the stem may explain the reduced developmental plasticity in older parts of the colony.
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Affiliation(s)
- Stefan Siebert
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St. Box GW, Providence, RI 02912 USA
| | - Freya E Goetz
- Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, 20004 Washington USA
| | - Samuel H Church
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St. Box GW, Providence, RI 02912 USA
| | - Pathikrit Bhattacharyya
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St. Box GW, Providence, RI 02912 USA
| | - Felipe Zapata
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St. Box GW, Providence, RI 02912 USA
| | | | - Casey W Dunn
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St. Box GW, Providence, RI 02912 USA
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17
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Buzgariu W, Crescenzi M, Galliot B. Robust G2 pausing of adult stem cells in Hydra. Differentiation 2014; 87:83-99. [PMID: 24703763 DOI: 10.1016/j.diff.2014.03.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 03/10/2014] [Accepted: 03/13/2014] [Indexed: 12/18/2022]
Abstract
Hydra is a freshwater hydrozoan polyp that constantly renews its two tissue layers thanks to three distinct stem cell populations that cannot replace each other, epithelial ectodermal, epithelial endodermal, and multipotent interstitial. These adult stem cells, located in the central body column, exhibit different cycling paces, slow for the epithelial, fast for the interstitial. To monitor the changes in cell cycling in Hydra, we established a fast and efficient flow cytometry procedure, which we validated by confirming previous findings, as the Nocodazole-induced reversible arrest of cell cycling in G2/M, and the mitogenic signal provided by feeding. Then to dissect the cycling and differentiation behaviors of the interstitial stem cells, we used the AEP_cnnos1 and AEP_Icy1 transgenic lines that constitutively express GFP in this lineage. For the epithelial lineages we used the sf-1 strain that rapidly eliminates the fast cycling cells upon heat-shock and progressively becomes epithelial. This study evidences similar cycling patterns for the interstitial and epithelial stem cells, which all alternate between the G2 and S-phases traversing a minimal G1-phase. We also found interstitial progenitors with a shorter G2 that pause in G1/G0. At the animal extremities, most cells no longer cycle, the epithelial cells terminally differentiate in G2 and the interstitial progenitors in G1/G0. At the apical pole ~80% cells are post-mitotic differentiated cells, reflecting the higher density of neurons and nematocytes in this region. We discuss how the robust G2 pausing of stem cells, maintained over weeks of starvation, may contribute to regeneration.
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Affiliation(s)
- Wanda Buzgariu
- Department of Genetics and Evolution, University of Geneva, Sciences III, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | | | - Brigitte Galliot
- Department of Genetics and Evolution, University of Geneva, Sciences III, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland.
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18
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Boehm AM, Bosch TC. Migration of multipotent interstitial stem cells in Hydra. ZOOLOGY 2012; 115:275-82. [DOI: 10.1016/j.zool.2012.03.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 02/27/2012] [Accepted: 03/01/2012] [Indexed: 11/27/2022]
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19
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Okamoto K, Nakatsukasa M, Alié A, Masuda Y, Agata K, Funayama N. The active stem cell specific expression of sponge Musashi homolog EflMsiA suggests its involvement in maintaining the stem cell state. Mech Dev 2012; 129:24-37. [DOI: 10.1016/j.mod.2012.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 03/07/2012] [Accepted: 03/17/2012] [Indexed: 12/29/2022]
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20
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Estephane D, Anctil M. Retinoic acid and nitric oxide promote cell proliferation and differentially induce neuronal differentiation in vitro in the cnidarian Renilla koellikeri. Dev Neurobiol 2010; 70:842-52. [DOI: 10.1002/dneu.20824] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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21
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Bosch TCG, Anton-Erxleben F, Hemmrich G, Khalturin K. The Hydra polyp: nothing but an active stem cell community. Dev Growth Differ 2009; 52:15-25. [PMID: 19891641 DOI: 10.1111/j.1440-169x.2009.01143.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Hydra is a powerful stem cell model because its potential immortality and extensive regeneration capacity is due to the presence of three distinct stem cell lineages. All three lineages conform to a well-defined spatial distribution across the whole body column of the polyp. Stem cell function in Hydra is controlled by extracellular cues and intrinsic genetic programs. This review focuses on the elusive stem cell niche of the epithelial layers. Based on a comparison of the differences between, and commonalities among, stem cells and stem cell niches in Hydra and other invertebrates and vertebrates, we propose that the whole body column of the polyp may be considered a stem cell "niche" in which stem cell populations are established and signals ensuring the proper balance between stem cells and progenitor cells are integrated. We show that, at over 500 million years old, Hydra offers an early glimpse of the regulatory potential of stem cell niches.
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Affiliation(s)
- Thomas C G Bosch
- Zoological Institute, Christian-Albrechts-University Kiel, Olshausenstrasse 40, 24098 Kiel, Germany.
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22
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Tortiglione C, Quarta A, Malvindi MA, Tino A, Pellegrino T. Fluorescent nanocrystals reveal regulated portals of entry into and between the cells of Hydra. PLoS One 2009; 4:e7698. [PMID: 19888325 PMCID: PMC2765617 DOI: 10.1371/journal.pone.0007698] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 10/12/2009] [Indexed: 12/02/2022] Open
Abstract
Initially viewed as innovative carriers for biomedical applications, with unique photophysical properties and great versatility to be decorated at their surface with suitable molecules, nanoparticles can also play active roles in mediating biological effects, suggesting the need to deeply investigate the mechanisms underlying cell-nanoparticle interaction and to identify the molecular players. Here we show that the cell uptake of fluorescent CdSe/CdS quantum rods (QRs) by Hydra vulgaris, a simple model organism at the base of metazoan evolution, can be tuned by modifying nanoparticle surface charge. At acidic pH, amino-PEG coated QRs, showing positive surface charge, are actively internalized by tentacle and body ectodermal cells, while negatively charged nanoparticles are not uptaken. In order to identify the molecular factors underlying QR uptake at acidic pH, we provide functional evidence of annexins involvement and explain the QR uptake as the combined result of QR positive charge and annexin membrane insertion. Moreover, tracking QR labelled cells during development and regeneration allowed us to uncover novel intercellular trafficking and cell dynamics underlying the remarkable plasticity of this ancient organism.
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Affiliation(s)
- Claudia Tortiglione
- Istituto di Cibernetica E Caianiello, Consiglio Nazionale delle Ricerche (CNR), Pozzuoli, Italy.
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23
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Watanabe H, Hoang VT, Mättner R, Holstein TW. Immortality and the base of multicellular life: Lessons from cnidarian stem cells. Semin Cell Dev Biol 2009; 20:1114-25. [PMID: 19761866 DOI: 10.1016/j.semcdb.2009.09.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 09/08/2009] [Accepted: 09/09/2009] [Indexed: 02/01/2023]
Abstract
Cnidarians are phylogenetically basal members of the animal kingdom (>600 million years old). Together with plants they share some remarkable features that cannot be found in higher animals. Cnidarians and plants exhibit an almost unlimited regeneration capacity and immortality. Immortality can be ascribed to the asexual mode of reproduction that requires cells with an unlimited self-renewal capacity. We propose that the basic properties of animal stem cells are tightly linked to this archaic mode of reproduction. The cnidarian stem cells can give rise to a number of differentiated cell types including neuronal and germ cells. The genomes of Hydra and Nematostella, representatives of two major cnidarian classes indicate a surprising complexity of both genomes, which is in the range of vertebrates. Recent work indicates that highly conserved signalling pathways control Hydra stem cell differentiation. Furthermore, the availability of genomic resources and novel technologies provide approaches to analyse these cells in vivo. Studies of stem cells in cnidarians will therefore open important insights into the basic mechanisms of stem cell biology. Their critical phylogenetic position at the base of the metazoan branch in the tree of life makes them an important link in unravelling the common mechanisms of stem cell biology between animals and plants.
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Affiliation(s)
- Hiroshi Watanabe
- Heidelberg University, Institute of Zoology, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
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24
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Takahashi T, Fujisawa T. Important roles for epithelial cell peptides in hydra development. Bioessays 2009; 31:610-9. [DOI: 10.1002/bies.200800163] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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25
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Takahashi T, Koizumi O, Hayakawa E, Minobe S, Suetsugu R, Kobayakawa Y, Bosch TCG, David CN, Fujisawa T. Further characterization of the PW peptide family that inhibits neuron differentiation in Hydra. Dev Genes Evol 2009; 219:119-29. [DOI: 10.1007/s00427-009-0272-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Accepted: 01/02/2009] [Indexed: 10/21/2022]
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26
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27
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Khalturin K, Anton-Erxleben F, Milde S, Plötz C, Wittlieb J, Hemmrich G, Bosch TCG. Transgenic stem cells in Hydra reveal an early evolutionary origin for key elements controlling self-renewal and differentiation. Dev Biol 2007; 309:32-44. [PMID: 17659272 DOI: 10.1016/j.ydbio.2007.06.013] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 06/15/2007] [Accepted: 06/15/2007] [Indexed: 12/31/2022]
Abstract
Little is known about stem cells in organisms at the beginning of evolution. To characterize the regulatory events that control stem cells in the basal metazoan Hydra, we have generated transgenics which express eGFP selectively in the interstitial stem cell lineage. Using them we visualized stem cell and precursor migration in real-time in the context of the native environment. We demonstrate that interstitial cells respond to signals from the cellular environment, and that Wnt and Notch pathways are key players in this process. Furthermore, by analyzing polyps which overexpress the Polycomb protein HyEED in their interstitial cells, we provide in vivo evidence for a role of chromatin modification in terminal differentiation. These findings for the first time uncover insights into signalling pathways involved in stem cell differentiation in the Bilaterian ancestor; they demonstrate that mechanisms controlling stem cell behaviour are based on components which are conserved throughout the animal kingdom.
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Affiliation(s)
- Konstantin Khalturin
- Zoological Institute, Christian-Albrechts-University, Olshausenstrasse 40, 24098 Kiel, Germany
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28
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Bosch TCG. Symmetry breaking in stem cells of the basal metazoan Hydra. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2007; 45:61-78. [PMID: 17585496 DOI: 10.1007/978-3-540-69161-7_3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Among the earliest diverging animal phyla are the Cnidaria. Cnidaria were not only first in evolution having a tissue layer construction and a nervous system but also have cells of remarkable plasticity in their differentiation capacity. How a cell chooses to proliferate or to differentiate is an important issue in stem cell biology and as critical to human stem cells as it is to any other stem cell. Here I revise the key properties of stem cells in the freshwater polyp Hydra with special emphasis on the nature of signals that control the growth and differentiation of these cells.
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Affiliation(s)
- Thomas C G Bosch
- Zoological Institute, Christian-Albrechts-University Kiel, Olshausenstrasse 40, 24098 Kiel, Germany.
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29
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Galliot B, Miljkovic-Licina M, de Rosa R, Chera S. Hydra, a niche for cell and developmental plasticity. Semin Cell Dev Biol 2006; 17:492-502. [PMID: 16807002 DOI: 10.1016/j.semcdb.2006.05.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The silencing of genes whose expression is restricted to specific cell types and/or specific regeneration stages opens avenues to decipher the molecular control of the cellular plasticity underlying head regeneration in hydra. In this review, we highlight recent studies that identified genes involved in the immediate cytoprotective function played by gland cells after amputation; the early dedifferentiation of digestive cells into blastema-like cells during head regeneration, and the early late proliferation of neuronal progenitors required for head patterning. Hence, developmental plasticity in hydra relies on spatially restricted and timely orchestrated cellular modifications, where the functions played by stem cells remain to be characterized.
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Affiliation(s)
- Brigitte Galliot
- Department of Zoology and Animal Biology, University of Geneva, Sciences III, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland.
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30
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Morishita F, Nitagai Y, Furukawa Y, Matsushima O, Takahashi T, Hatta M, Fujisawa T, Tunamoto S, Koizumi O. Identification of a vasopressin-like immunoreactive substance in hydra. Peptides 2003; 24:17-26. [PMID: 12576081 DOI: 10.1016/s0196-9781(02)00272-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vasopressin (VP)-like immunoreactivity has long been known in the hydra nervous system, but has not yet been structurally identified. In this study, using HPLC fractionation and an immunological assay, we have purified two peptides, FPQSFLPRGamide and SFLPRGamide, from Hydra magnipapillata. Both the peptides shared the same C-terminal structure, -PRGamide, with Arg-VP. The nonapeptide proved to be Hym-355, a peptide that stimulates neuronal differentiation in hydra. Detailed evaluation by competitive enzyme-linked immunosorbent assay (ELISA) and double immunostaining using anti-VP and anti-Hym-355 antibodies enabled us to conclude that the two peptides account for a major part of the VP-like immunoreactivity in hydra nerve cells.
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Affiliation(s)
- F Morishita
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
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31
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Davidsen J, Ebel H, Bornholdt S. Emergence of a small world from local interactions: modeling acquaintance networks. PHYSICAL REVIEW LETTERS 2002; 88:128701. [PMID: 11909506 DOI: 10.1103/physrevlett.88.128701] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2001] [Revised: 12/06/2001] [Indexed: 05/23/2023]
Abstract
How do we make acquaintances? A simple observation from everyday experience is that often one of our acquaintances introduces us to one of his or her acquaintances. Such a simple triangle interaction may be viewed as the basis of the evolution of many social networks. Here, it is demonstrated that this assumption is sufficient to reproduce major nontrivial features of social networks: short path length, high clustering, and scale-free or exponential link distributions.
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Affiliation(s)
- Jörn Davidsen
- Institut für Theoretische Physik, Universität Kiel, Leibnizstrasse 15, D-24098 Kiel, Germany
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32
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Takahashi T, Koizumi O, Ariura Y, Romanovitch A, Bosch TC, Kobayakawa Y, Mohri S, Bode HR, Yum S, Hatta M, Fujisawa T. A novel neuropeptide, Hym-355, positively regulates neuron differentiation in Hydra. Development 2000; 127:997-1005. [PMID: 10662639 DOI: 10.1242/dev.127.5.997] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During the course of a systematic screening of peptide signaling molecules in Hydra a novel peptide, Hym-355 (FPQSFLPRG-NH(2)), was identified. A cDNA encoding the peptide was isolated and characterized. Using both in situ hybridization and immunohistochemistry, Hym-355 was shown to be expressed in neurons and hence is a neuropeptide. The peptide was shown to specifically enhance neuron differentiation throughout the animal by inducing interstitial cells to enter the neuron pathway. Further, co-treatment with a PW peptide, which inhibits neuron differentiation, nullified the effects of both peptides, suggesting that they act in an antagonistic manner. This effect is discussed in terms of a feedback mechanism for maintaining the steady state neuron population in Hydra.
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Affiliation(s)
- T Takahashi
- National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
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Abstract
The neural crest and cranial ectodermal placodes are traditionally thought to be unique to vertebrates; however, they must have had evolutionary precursors. Here, we review recent evidence suggesting that such ancestral cell types can be identified in modern non-vertebrate chordates, such as amphioxus (a cephalochordate) and ascidians (urochordates). Hence, migratory neuroectodermal cells may well have been present in the common ancestor of the chordates, such that the possibility of their existence in non-chordate deuterostomes (hemichordates and echinoderms) must also be considered. Finally, we discuss the various non-neuronal cell types produced by the neural crest in order to demonstrate that it is plausible that these different cell types evolved from an ancestral population that was neuronal in nature.
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Affiliation(s)
- C V Baker
- Division of Biology, Beckman Institute 139-74, California Institute of Technology, Pasadena 91125, USA.
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