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Iglesias Ollé L, Perruchoud C, Sanchez PGL, Vogg MC, Galliot B. The Wnt/β-catenin/TCF/Sp5/Zic4 Gene Network That Regulates Head Organizer Activity in Hydra Is Differentially Regulated in Epidermis and Gastrodermis. Biomedicines 2024; 12:1274. [PMID: 38927481 PMCID: PMC11201823 DOI: 10.3390/biomedicines12061274] [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: 04/22/2024] [Revised: 06/02/2024] [Accepted: 06/03/2024] [Indexed: 06/28/2024] Open
Abstract
Hydra head formation depends on an organizing center in which Wnt/β-catenin signaling, that plays an inductive role, positively regulates Sp5 and Zic4, with Sp5 limiting Wnt3/β-catenin expression and Zic4 triggering tentacle formation. Using transgenic lines in which the HySp5 promoter drives eGFP expression in either the epidermis or gastrodermis, we show that Sp5 promoter activity is differentially regulated in each epithelial layer. In intact animals, epidermal HySp5:GFP activity is strong apically and weak along the body column, while in the gastrodermis, it is maximal in the tentacle ring region and maintained at a high level along the upper body column. During apical regeneration, HySp5:GFP is activated early in the gastrodermis and later in the epidermis. Alsterpaullone treatment induces a shift in apical HySp5:GFP expression towards the body column where it forms transient circular figures in the epidermis. Upon β-catenin(RNAi), HySp5:GFP activity is down-regulated in the epidermis while bud-like structures expressing HySp5:GFP in the gastrodermis develop. Sp5(RNAi) reveals a negative Sp5 autoregulation in the epidermis, but not in the gastrodermis. These differential regulations in the epidermis and gastrodermis highlight the distinct architectures of the Wnt/β-catenin/TCF/Sp5/Zic4 network in the hypostome, tentacle base and body column of intact animals, as well as in the buds and apical and basal regenerating tips.
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Affiliation(s)
| | | | | | | | - Brigitte Galliot
- Department of Genetics and Evolution, Institute of Genetics and Genomics (iGE3), Faculty of Sciences, University of Geneva, 30 Quai Ernest Ansermet, 1205 Geneva, Switzerland (C.P.); (P.G.L.S.)
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Gahan JM, Cartwright P, Nicotra ML, Schnitzler CE, Steinmetz PRH, Juliano CE. Cnidofest 2022: hot topics in cnidarian research. EvoDevo 2023; 14:13. [PMID: 37620964 PMCID: PMC10463417 DOI: 10.1186/s13227-023-00217-9] [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: 05/25/2023] [Accepted: 08/08/2023] [Indexed: 08/26/2023] Open
Abstract
The second annual Cnidarian Model Systems Meeting, aka "Cnidofest", took place in Davis, California from 7 to 10th of September, 2022. The meeting brought together scientists using cnidarians to study molecular and cellular biology, development and regeneration, evo-devo, neurobiology, symbiosis, physiology, and comparative genomics. The diversity of topics and species represented in presentations highlighted the importance and versatility of cnidarians in addressing a wide variety of biological questions. In keeping with the spirit of the first meeting (and its predecessor, Hydroidfest), almost 75% of oral presentations were given by early career researchers (i.e., graduate students and postdocs). In this review, we present research highlights from the meeting.
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Affiliation(s)
- James M Gahan
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- Michael Sars Centre, University of Bergen, Thormøhlensgt. 55, 5008, Bergen, Norway
| | - Paulyn Cartwright
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045, USA
| | - Matthew L Nicotra
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, 15261, USA
- Center for Evolutionary Biology and Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Christine E Schnitzler
- Whitney Laboratory for Marine Bioscience and Department of Biology, University of Florida, St. Augustine, FL, 32080, USA
| | | | - Celina E Juliano
- Department of Molecular and Cellular Biology, University of California, Davis, CA, 95616, USA.
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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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Amiel AR, Tsai SL, Wehner D. Embracing the diversity of model systems to deconstruct the basis of regeneration and tissue repair. Development 2023; 150:286821. [PMID: 36718794 DOI: 10.1242/dev.201579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The eighth EMBO conference in the series 'The Molecular and Cellular Basis of Regeneration and Tissue Repair' took place in Barcelona (Spain) in September 2022. A total of 173 researchers from across the globe shared their latest advances in deciphering the molecular and cellular basis of wound healing, tissue repair and regeneration, as well as their implications for future clinical applications. The conference showcased an ever-expanding diversity of model organisms used to identify mechanisms that promote regeneration. Over 25 species were discussed, ranging from invertebrates to humans. Here, we provide an overview of the exciting topics presented at the conference, highlighting novel discoveries in regeneration and perspectives for regenerative medicine.
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Affiliation(s)
- Aldine R Amiel
- Université Côte d'Azur, CNRS, INSERM, Institute for Research on Cancer and Aging (IRCAN), 06107 Nice, France
| | - Stephanie L Tsai
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Daniel Wehner
- Max Planck Institute for the Science of Light, Erlangen 91058, Germany
- Max-Planck-Zentrum für Physik und Medizin, Erlangen 91058, Germany
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A chromosome-scale epigenetic map of the Hydra genome reveals conserved regulators of cell state. Genome Res 2023; 33:283-298. [PMID: 36639202 PMCID: PMC10069465 DOI: 10.1101/gr.277040.122] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 01/10/2023] [Indexed: 01/15/2023]
Abstract
The epithelial and interstitial stem cells of the freshwater polyp Hydra are the best-characterized stem cell systems in any cnidarian, providing valuable insight into cell type evolution and the origin of stemness in animals. However, little is known about the transcriptional regulatory mechanisms that determine how these stem cells are maintained and how they give rise to their diverse differentiated progeny. To address such questions, a thorough understanding of transcriptional regulation in Hydra is needed. To this end, we generated extensive new resources for characterizing transcriptional regulation in Hydra, including new genome assemblies for Hydra oligactis and the AEP strain of Hydra vulgaris, an updated whole-animal single-cell RNA-seq atlas, and genome-wide maps of chromatin interactions, chromatin accessibility, sequence conservation, and histone modifications. These data revealed the existence of large kilobase-scale chromatin interaction domains in the Hydra genome that contain transcriptionally coregulated genes. We also uncovered the transcriptomic profiles of two previously molecularly uncharacterized cell types: isorhiza-type nematocytes and somatic gonad ectoderm. Finally, we identified novel candidate regulators of cell type-specific transcription, several of which have likely been conserved at least since the divergence of Hydra and the jellyfish Clytia hemisphaerica more than 400 million years ago.
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