1
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Bideau L, Velasquillo-Ramirez Z, Baduel L, Basso M, Gilardi-Hebenstreit P, Ribes V, Vervoort M, Gazave E. Variations in cell plasticity and proliferation underlie distinct modes of regeneration along the antero-posterior axis in the annelid Platynereis. Development 2024; 151:dev202452. [PMID: 38950937 DOI: 10.1242/dev.202452] [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] [Received: 10/17/2023] [Accepted: 05/22/2024] [Indexed: 07/03/2024]
Abstract
The capacity to regenerate lost tissues varies significantly among animals. Some phyla, such as the annelids, display substantial regenerating abilities, although little is known about the cellular mechanisms underlying the process. To precisely determine the origin, plasticity and fate of the cells participating in blastema formation and posterior end regeneration after amputation in the annelid Platynereis dumerilii, we developed specific tools to track different cell populations. Using these tools, we find that regeneration is partly promoted by a population of proliferative gut cells whose regenerative potential varies as a function of their position along the antero-posterior axis of the worm. Gut progenitors from anterior differentiated tissues are lineage restricted, whereas gut progenitors from the less differentiated and more proliferative posterior tissues are much more plastic. However, they are unable to regenerate the stem cells responsible for the growth of the worms. Those stem cells are of local origin, deriving from the cells present in the segment abutting the amputation plane, as are most of the blastema cells. Our results favour a hybrid and flexible cellular model for posterior regeneration in Platynereis relying on different degrees of cell plasticity.
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Affiliation(s)
- Loïc Bideau
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | | | - Loeiza Baduel
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Marianne Basso
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | | | - Vanessa Ribes
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Michel Vervoort
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Eve Gazave
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
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2
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Garschall K, Pascual-Carreras E, García-Pascual B, Filimonova D, Guse A, Johnston IG, Steinmetz PRH. The cellular basis of feeding-dependent body size plasticity in sea anemones. Development 2024; 151:dev202926. [PMID: 38980277 PMCID: PMC11267454 DOI: 10.1242/dev.202926] [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] [Received: 04/04/2024] [Accepted: 05/20/2024] [Indexed: 07/10/2024]
Abstract
Many animals share a lifelong capacity to adapt their growth rates and body sizes to changing environmental food supplies. However, the cellular and molecular basis underlying this plasticity remains only poorly understood. We therefore studied how the sea anemones Nematostella vectensis and Aiptasia (Exaiptasia pallida) respond to feeding and starvation. Combining quantifications of body size and cell numbers with mathematical modelling, we observed that growth and shrinkage rates in Nematostella are exponential, stereotypic and accompanied by dramatic changes in cell numbers. Notably, shrinkage rates, but not growth rates, are independent of body size. In the facultatively symbiotic Aiptasia, we show that growth and cell proliferation rates are dependent on the symbiotic state. On a cellular level, we found that >7% of all cells in Nematostella juveniles reversibly shift between S/G2/M and G1/G0 cell cycle phases when fed or starved, respectively. Furthermore, we demonstrate that polyp growth and cell proliferation are dependent on TOR signalling during feeding. Altogether, we provide a benchmark and resource for further investigating the nutritional regulation of body plasticity on multiple scales using the genetic toolkit available for Nematostella.
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Affiliation(s)
- Kathrin Garschall
- Michael Sars Centre, University of Bergen, Thormøhlensgt. 55, N-5008 Bergen, Norway
| | | | - Belén García-Pascual
- Department for Mathematics, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
| | - Daria Filimonova
- Michael Sars Centre, University of Bergen, Thormøhlensgt. 55, N-5008 Bergen, Norway
- Centre for Organismal Studies, Heidelberg University, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany
| | - Annika Guse
- Centre for Organismal Studies, Heidelberg University, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany
| | - Iain G. Johnston
- Department for Mathematics, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
- Computational Biology Unit, Department of Informatics, University of Bergen, Thormøhlensgt. 55, N-5008 Bergen, Norway
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3
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Wang KT, Tapper J, Adler CE. Purification of Planarian Stem Cells Using a Draq5-Based FACS Approach. Methods Mol Biol 2024; 2805:203-212. [PMID: 39008184 DOI: 10.1007/978-1-0716-3854-5_14] [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: 07/16/2024]
Abstract
Planarians are flatworms that have the remarkable ability to regenerate entirely new animals. This regenerative ability requires abundant adult stem cells called neoblasts, which are relatively small in size, sensitive to irradiation and the only proliferative cells in the animal. Despite the lack of cell surface markers, fluorescence-activated cell sorting (FACS) protocols have been developed to discriminate and isolate neoblasts, based on DNA content. Here, we describe a protocol that combines staining of far-red DNA dye Draq5, Calcein-AM and DAPI, along with a shortened processing time. This profiling strategy can be used to functionally characterize the neoblast population in pharmacologically-treated or gene knockdown animals. Highly purified neoblasts can be analyzed with downstream assays, such as in situ hybridization and RNA sequencing.
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Affiliation(s)
- Kuang-Tse Wang
- Department of Molecular Medicine, Cornell University, College of Veterinary Medicine, Ithaca, NY, USA
| | - Justin Tapper
- Department of Molecular Medicine, Cornell University, College of Veterinary Medicine, Ithaca, NY, USA
| | - Carolyn E Adler
- Department of Molecular Medicine, Cornell University, College of Veterinary Medicine, Ithaca, NY, USA.
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4
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Chen JJ, Lei K. The known, unknown, and unknown unknowns of cell-cell communication in planarian regeneration. Zool Res 2023; 44:981-992. [PMID: 37721107 PMCID: PMC10559094 DOI: 10.24272/j.issn.2095-8137.2023.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 09/11/2023] [Indexed: 09/19/2023] Open
Abstract
Planarians represent the most primitive bilateral triploblastic animals. Most planarian species exhibit mechanisms for whole-body regeneration, exemplified by the regeneration of their cephalic ganglion after complete excision. Given their robust whole-body regeneration capacity, planarians have been model organisms in regenerative research for more than 240 years. Advancements in research tools and techniques have progressively elucidated the mechanisms underlying planarian regeneration. Accurate cell-cell communication is recognized as a fundamental requirement for regeneration. In recent decades, mechanisms associated with such communication have been revealed at the cellular level. Notably, stem cells (neoblasts) have been identified as the source of all new cells during planarian homeostasis and regeneration. The interplay between neoblasts and somatic cells affects the identities and proportions of various tissues during homeostasis and regeneration. Here, this review outlines key discoveries regarding communication between stem cell compartments and other cell types in planarians, as well as the impact of communication on planarian regeneration. Additionally, this review discusses the challenges and potential directions of future planarian research, emphasizing the sustained impact of this field on our understanding of animal regeneration.
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Affiliation(s)
- Jia-Jia Chen
- School of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310030, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Kai Lei
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310030, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China. E-mail:
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5
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Shiroor DA, Wang KT, Sanketi BD, Tapper JK, Adler CE. Inhibition of ATM kinase rescues planarian regeneration after lethal radiation. EMBO Rep 2023; 24:e56112. [PMID: 36943023 PMCID: PMC10157310 DOI: 10.15252/embr.202256112] [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: 09/11/2022] [Revised: 02/20/2023] [Accepted: 02/27/2023] [Indexed: 03/23/2023] Open
Abstract
As stem cells divide, they acquire mutations that can be passed on to daughter cells. To mitigate potentially deleterious outcomes, cells activate the DNA damage response (DDR) network, which governs several cellular outcomes following DNA damage, including repairing DNA or undergoing apoptosis. At the helm of the DDR are three PI3-like kinases including Ataxia-Telangiectasia Mutated (ATM). We report here that knockdown of ATM in planarian flatworms enables stem cells to withstand lethal doses of radiation which would otherwise induce cell death. In this context, stem cells circumvent apoptosis, replicate their DNA, and recover function using homologous recombination-mediated DNA repair. Despite radiation exposure, atm knockdown animals survive long-term and regenerate new tissues. These effects occur independently of ATM's canonical downstream effector p53. Together, our results demonstrate that in planarians, ATM promotes radiation-induced apoptosis. This acute, ATM-dependent apoptosis is a key determinant of long-term animal survival. Our results suggest that inhibition of ATM in these organisms could, therefore, potentially favor cell survival after radiation without obvious effects on stem cell behavior.
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Affiliation(s)
- Divya A Shiroor
- Department of Molecular Medicine, Cornell University College of Veterinary Medicine, Ithaca, NY, USA
| | - Kuang-Tse Wang
- Department of Molecular Medicine, Cornell University College of Veterinary Medicine, Ithaca, NY, USA
| | - Bhargav D Sanketi
- Department of Molecular Medicine, Cornell University College of Veterinary Medicine, Ithaca, NY, USA
| | - Justin K Tapper
- Department of Molecular Medicine, Cornell University College of Veterinary Medicine, Ithaca, NY, USA
| | - Carolyn E Adler
- Department of Molecular Medicine, Cornell University College of Veterinary Medicine, Ithaca, NY, USA
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6
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Lindsay-Mosher N, Molinaro AM, Pearson BJ. An RNA/DNA-Based Flow Cytometry Approach for Isolating Slow-Cycling Stem Cells. Methods Mol Biol 2023; 2680:157-168. [PMID: 37428376 DOI: 10.1007/978-1-0716-3275-8_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Flow cytometry methods for sorting specific populations of cells based on fluorescence or physical properties have been a widely used technique for decades. Flow cytometry has been particularly vital to the study of planarians, which remain refractory to transgenic transformation, as it has provided a work-around solution for studying stem cell biology and lineage relationships in the context of regeneration. Many flow cytometry applications have been published in planarians, beginning with broad Hoechst-based strategies for isolating cycling stem cells and progressing to more function-based approaches involving vital dyes and surface antibodies. In this protocol, we look to build on the classic DNA-labeling Hoechst staining strategy by adding pyronin Y staining to label RNA. While Hoechst labeling alone allows for the isolation of stem cells in the S/G2/M phases of the cell cycle, heterogeneity within the population of stem cells with 2 C DNA content is not resolved. By considering RNA levels, this protocol can further divide this population of stem cells into two groups: G1 stem cells with relatively high RNA content and a slow-cycling population with low RNA content, which we call RNAlow stem cells. In addition, we provide instruction for combining this RNA/DNA flow cytometry protocol with EdU labeling experiments and describe an optional step for incorporating immunostaining prior to cell sorting (in this case with the pluripotency marker TSPAN-1). This protocol adds a new staining strategy and examples of combinatorial flow cytometry approaches to the repertoire of flow cytometry techniques for studying planarian stem cells.
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Affiliation(s)
- Nicole Lindsay-Mosher
- Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, Canada
| | - Alyssa M Molinaro
- Pape Research Institute, Oregon Health & Science University, Portland, OR, USA
| | - Bret J Pearson
- Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, Canada.
- Pape Research Institute, Oregon Health & Science University, Portland, OR, USA.
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7
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HYPOTHESIS: Do LRIG Proteins Regulate Stem Cell Quiescence by Promoting BMP Signaling? Stem Cell Rev Rep 2023; 19:59-66. [PMID: 35969315 PMCID: PMC9823064 DOI: 10.1007/s12015-022-10442-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2022] [Indexed: 01/29/2023]
Abstract
Leucine-rich repeats and immunoglobulin-like domains (LRIG) proteins are evolutionarily conserved integral membrane proteins. Mammalian LRIG1 regulates stem cell quiescence in various tissue compartments, including compartments in the epidermis, oral mucosa, intestines, neural system, and incisors. The planarian LRIG1 homolog regulates the quiescence of multipotent neoblasts. The mechanism through which LRIG proteins regulate stem cell quiescence has not been well documented, although it is generally assumed that LRIG1 regulates the epidermal growth factor receptor (EGFR) or other receptor tyrosine kinases. However, Lrig-null (Lrig1-/-;Lrig2-/-; and Lrig3-/-) mouse embryonic fibroblasts (MEFs) have been recently found to exhibit apparently normal receptor tyrosine kinase functions. Moreover, bone morphogenetic protein (BMP) signaling has been shown to depend on LRIG1 and LRIG3 expression. BMPs are well-known regulators of stem cell quiescence. Here, we hypothesize that LRIG1 might regulate stem cell quiescence by promoting BMP signaling. HYPOTHESIS: Based on recent findings, it is hypothesized that LRIG1 regulates stem cell quiescence in mammalian tissues as well as in planarian neoblasts by promoting BMP signaling.
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8
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Gambino G, Iacopetti P, Guidi P, Ippolito C, Linsalata S, Salvetti A, Rossi L. Cell quiescence in planarian stem cells, interplay between p53 and nutritional stimuli. Open Biol 2022; 12:220216. [PMID: 36541101 PMCID: PMC9768645 DOI: 10.1098/rsob.220216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cell quiescence appeared early in evolution as an adaptive response to adverse conditions (i.e. nutrient depletion). In metazoans, quiescence has been involved in additional processes like tissue homeostasis, which is made possible by the presence of adult stem cells (ASCs). Cell cycle control machinery is a common hub for quiescence entrance, and evidence indicates a role for p53 in establishing the quiescent state of undamaged cells. Mechanisms responsible for waking up quiescent cells remain elusive, and nutritional stimulus, as a legacy of its original role, still appears to be a player in quiescence exit. Planarians, rich in ASCs, represent a suitable system in which we characterized a quiescent population of ASCs, the dorsal midline cord (DMC) cells, exhibiting unique transcriptional features and maintained quiescent by p53 and awakened upon feeding. The function of DMC cells is puzzling and we speculate that DMC cells, despite retaining ancient properties, might represent a functional drift in which quiescence has been recruited to provide evolutionary advantages.
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Affiliation(s)
- Gaetana Gambino
- Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy
| | - Paola Iacopetti
- Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy
| | - Patrizia Guidi
- Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy
| | - Chiara Ippolito
- Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 55, 56126 Pisa, Italy
| | - Stefania Linsalata
- Medical Physics Unit, Azienda Ospedaliera Universitaria Pisana, Via Roma 67, 56126 Pisa, Italy
| | - Alessandra Salvetti
- Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy
| | - Leonardo Rossi
- Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy
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9
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Reddien PW. Positional Information and Stem Cells Combine to Result in Planarian Regeneration. Cold Spring Harb Perspect Biol 2022; 14:a040717. [PMID: 34518341 PMCID: PMC9121904 DOI: 10.1101/cshperspect.a040717] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The capacity for regeneration is broad in the animal kingdom. Planarians are flatworms that can regenerate any missing body part and their regenerative powers have combined with ease of experimentation to make them a classic regeneration model for more than a century. Pluripotent stem cells called neoblasts generate missing planarian tissues. Fate specification happens in the neoblasts, and this can occur in response to regeneration instructions in the form of positional information. Fate specification can lead to differentiating cells in single steps rather than requiring a long lineage hierarchy. Planarians display constitutive expression of positional information from muscle cells, which is required for patterned maintenance of tissues in tissue turnover. Amputation leads to the rapid resetting of positional information in a process triggered by wound signaling and the resetting of positional information is required for regeneration. These findings suggest a model for planarian regeneration in which adult positional information resets after injury to regulate stem cells to bring about the replacement of missing parts.
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Affiliation(s)
- Peter W Reddien
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
- Department of Biology, MIT, Cambridge, Massachusetts 02139, USA
- Department of Biology, MIT, Cambridge, Massachusetts 02139, USA
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10
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Davidian D, LeGro M, Barghouth PG, Rojas S, Ziman B, Maciel EI, Ardell D, Escobar AL, Oviedo NJ. Restoration of DNA integrity and cell cycle by electric stimulation in planarian tissues damaged by ionizing radiation. J Cell Sci 2022; 135:274829. [PMID: 35322853 PMCID: PMC9264365 DOI: 10.1242/jcs.259304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 03/05/2022] [Indexed: 10/18/2022] Open
Abstract
Exposure to high levels of ionizing γ-radiation leads to irreversible DNA damage and cell death. Here, we establish that exogenous application of electric stimulation enables cellular plasticity to reestablish stem cell activity in tissues damaged by ionizing radiation. We show that sub-threshold direct current stimulation (DCS) rapidly restores pluripotent stem cell populations previously eliminated by lethally γ-irradiated tissues of the planarian flatworm Schmidtea mediterranea. Our findings reveal that DCS enhances DNA repair, transcriptional activity, and cell cycle entry in post-mitotic cells. These responses involve rapid increases in cytosolic [Ca2+] through the activation of L-type Cav channels and intracellular Ca2+ stores leading to the activation of immediate early genes and ectopic expression of stem cell markers in postmitotic cells. Overall, we show the potential of electric current stimulation to reverse the damaging effects of high dose γ-radiation in adult tissues. Furthermore, our results provide mechanistic insights describing how electric stimulation effectively translates into molecular responses capable of regulating fundamental cellular functions without the need for genetic or pharmacological intervention.
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Affiliation(s)
- Devon Davidian
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Melanie LeGro
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Paul G Barghouth
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Salvador Rojas
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Benjamin Ziman
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Eli Isael Maciel
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - David Ardell
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Health Sciences Research Institute, University of California, Merced, USA
| | - Ariel L Escobar
- Department of Bioengineering, University of California, Merced, USA.,Health Sciences Research Institute, University of California, Merced, USA
| | - Néstor J Oviedo
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Health Sciences Research Institute, University of California, Merced, USA
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11
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Molina MD, Cebrià F. Decoding Stem Cells: An Overview on Planarian Stem Cell Heterogeneity and Lineage Progression. Biomolecules 2021; 11:1532. [PMID: 34680165 PMCID: PMC8533874 DOI: 10.3390/biom11101532] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 01/26/2023] Open
Abstract
Planarians are flatworms capable of whole-body regeneration, able to regrow any missing body part after injury or amputation. The extraordinary regenerative capacity of planarians is based upon the presence in the adult of a large population of somatic pluripotent stem cells. These cells, called neoblasts, offer a unique system to study the process of stem cell specification and differentiation in vivo. In recent years, FACS-based isolation of neoblasts, RNAi functional analyses as well as high-throughput approaches such as single-cell sequencing have allowed a rapid progress in our understanding of many different aspects of neoblast biology. Here, we summarize our current knowledge on the molecular signatures that define planarian neoblasts heterogeneity, which includes a percentage of truly pluripotent stem cells, and guide the commitment of pluripotent neoblasts into lineage-specific progenitor cells, as well as their differentiation into specific planarian cell types.
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Affiliation(s)
- M. Dolores Molina
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
- Institute of Biomedicine of the University of Barcelona (IBUB), 08028 Barcelona, Spain
| | - Francesc Cebrià
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
- Institute of Biomedicine of the University of Barcelona (IBUB), 08028 Barcelona, Spain
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12
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Gambino G, Ippolito C, Evangelista M, Salvetti A, Rossi L. Sub-Lethal 5-Fluorouracil Dose Challenges Planarian Stem Cells Promoting Transcriptional Profile Changes in the Pluripotent Sigma-Class Neoblasts. Biomolecules 2021; 11:biom11070949. [PMID: 34206807 PMCID: PMC8301986 DOI: 10.3390/biom11070949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/14/2021] [Accepted: 06/22/2021] [Indexed: 11/16/2022] Open
Abstract
Under physiological conditions, the complex planarian neoblast system is a composite of hierarchically organized stem cell sub-populations with sigma-class neoblasts, including clonogenic neoblasts, endowed with larger self-renewal and differentiation capabilities, thus generating all the other sub-populations and dominating the regenerative process. This complex system responds to differentiated tissue demands, ensuring a continuous cell turnover in a way to replace aged specialized cells and maintain tissue functionality. Potency of the neoblast system can be appreciated under challenging conditions in which these stem cells are massively depleted and the few remaining repopulate the entire body, ensuring animal resilience. These challenging conditions offer the possibility to deepen the relationships among different neoblast sub-populations, allowing to expose uncanonical properties that are negligible under physiological conditions. In this paper, we employ short, sub-lethal 5-fluorouracil treatment to specifically affect proliferating cells passing through the S phase and demonstrate that S-phase slowdown triggers a shift in the transcriptional profile of sigma neoblasts, which reduces the expression of their hallmark sox-P1. Later, some cells reactivate sox-P1 expression, suggesting that some neoblasts in the earlier steps of commitment could modulate their expression profile, reacquiring a wider differentiative potential.
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Affiliation(s)
- Gaetana Gambino
- Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy; (G.G.); (C.I.); (L.R.)
| | - Chiara Ippolito
- Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy; (G.G.); (C.I.); (L.R.)
| | | | - Alessandra Salvetti
- Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy; (G.G.); (C.I.); (L.R.)
- Correspondence: ; Tel.: +39-0502219108
| | - Leonardo Rossi
- Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy; (G.G.); (C.I.); (L.R.)
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13
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Bohr TE, Shiroor DA, Adler CE. Planarian stem cells sense the identity of the missing pharynx to launch its targeted regeneration. eLife 2021; 10:e68830. [PMID: 34156924 PMCID: PMC8219383 DOI: 10.7554/elife.68830] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/22/2021] [Indexed: 12/25/2022] Open
Abstract
In order to regenerate tissues successfully, stem cells must detect injuries and restore missing cell types through largely unknown mechanisms. Planarian flatworms have an extensive stem cell population responsible for regenerating any organ after amputation. Here, we compare planarian stem cell responses to different injuries by either amputation of a single organ, the pharynx, or removal of tissues from other organs by decapitation. We find that planarian stem cells adopt distinct behaviors depending on what tissue is missing to target progenitor and tissue production towards missing tissues. Loss of non-pharyngeal tissues only increases non-pharyngeal progenitors, while pharynx removal selectively triggers division and expansion of pharynx progenitors. By pharmacologically inhibiting either mitosis or activation of the MAP kinase ERK, we identify a narrow window of time during which stem cell division and ERK signaling produces pharynx progenitors necessary for regeneration. These results indicate that planarian stem cells can tailor their output to match the regenerative needs of the animal.
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Affiliation(s)
- Tisha E Bohr
- Department of Molecular Medicine, Cornell University College of Veterinary MedicineIthacaUnited States
| | - Divya A Shiroor
- Department of Molecular Medicine, Cornell University College of Veterinary MedicineIthacaUnited States
| | - Carolyn E Adler
- Department of Molecular Medicine, Cornell University College of Veterinary MedicineIthacaUnited States
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14
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Molinaro AM, Lindsay‐Mosher N, Pearson BJ. Identification of TOR-responsive slow-cycling neoblasts in planarians. EMBO Rep 2021; 22:e50292. [PMID: 33511776 PMCID: PMC7926258 DOI: 10.15252/embr.202050292] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 11/19/2020] [Accepted: 12/14/2020] [Indexed: 12/11/2022] Open
Abstract
Epimorphic regeneration commonly relies on the activation of reserved stem cells to drive new cell production. The planarian Schmidtea mediterranea is among the best regenerators in nature, thanks to its large population of adult stem cells, called neoblasts. While neoblasts have long been known to drive regeneration, whether a subset of neoblasts is reserved for this purpose is unknown. Here, we revisit the idea of reserved neoblasts by approaching neoblast heterogeneity from a regulatory perspective. By implementing a new fluorescence-activated cell sorting strategy in planarians, we identify a population of neoblasts defined by low transcriptional activity. These RNAlow neoblasts are relatively slow-cycling at homeostasis and undergo a morphological regeneration response characterized by cell growth at 48 h post-amputation. At this time, RNAlow neoblasts proliferate in a TOR-dependent manner. Additionally, knockdown of the tumour suppressor Lrig-1, which is enriched in RNAlow neoblasts, results in RNAlow neoblast growth and hyperproliferation at homeostasis, and ultimately delays regeneration. We propose that slow-cycling RNAlow neoblasts represent a regeneration-reserved neoblast population.
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Affiliation(s)
- Alyssa M Molinaro
- Program in Developmental and Stem Cell BiologyHospital for Sick ChildrenTorontoONCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoONCanada
- Present address:
Department of Systems BiologyHarvard Medical SchoolBostonMAUSA
| | - Nicole Lindsay‐Mosher
- Program in Developmental and Stem Cell BiologyHospital for Sick ChildrenTorontoONCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoONCanada
| | - Bret J Pearson
- Program in Developmental and Stem Cell BiologyHospital for Sick ChildrenTorontoONCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoONCanada
- Ontario Institute for Cancer ResearchTorontoONCanada
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