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Wiggans M, Zhu SJ, Molinaro AM, Pearson BJ. The BAF chromatin remodeling complex licenses planarian stem cells access to ectodermal and mesodermal cell fates. BMC Biol 2023; 21:227. [PMID: 37864247 PMCID: PMC10589948 DOI: 10.1186/s12915-023-01730-y] [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: 02/09/2023] [Accepted: 10/10/2023] [Indexed: 10/22/2023] Open
Abstract
BACKGROUND The flatworm planarian, Schmidtea mediterranea, has a large population of adult stem cells (ASCs) that replace any cell type during tissue turnover or regeneration. How planarian ASCs (called neoblasts) manage self-renewal with the ability to produce daughter cells of different cell lineages (multipotency) is not well understood. Chromatin remodeling complexes ultimately control access to DNA regions of chromosomes and together with specific transcription factors determine whether a gene is transcribed in a given cell type. Previous work in planarians determined that RNAi of core components of the BAF chromatin remodeling complex, brg1 and smarcc2, caused increased ASCs and failed regeneration, but how these cellular defects arise at the level of gene regulation in neoblasts is unknown. RESULTS Here, we perform ATAC and RNA sequencing on purified neoblasts, deficient for the BAF complex subunits brg-1 and smarcc2. The data demonstrate that the BAF complex promotes chromatin accessibility and facilitates transcription at target loci, as in other systems. Interestingly, we find that the BAF complex enables access to genes known to be required for the generation of mesoderm- and ectoderm-derived lineages, including muscle, parenchymal cathepsin, neural, and epithelial lineages. BAF complex knockdowns result in disrupted differentiation into these cell lineages and functional consequences on planarian regeneration and tissue turnover. Notably, we did not detect a role for the BAF complex in neoblasts making endodermal lineages. CONCLUSIONS Our study provides functional insights into how the BAF complex contributes to cell fate decisions in planarian ASCs in vivo.
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Affiliation(s)
- Mallory Wiggans
- The Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, M5G0A4, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada
| | - Shu Jun Zhu
- The Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, M5G0A4, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada
| | - Alyssa M Molinaro
- Present address: Oregon Health & Science University, Portland, OR, 97239, USA
| | - Bret J Pearson
- The Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, M5G0A4, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada.
- Present address: Oregon Health & Science University, Portland, OR, 97239, USA.
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2
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Dagan Y, Yesharim Y, Bonneau AR, Frankovits T, Schwartz S, Reddien PW, Wurtzel O. m6A is required for resolving progenitor identity during planarian stem cell differentiation. EMBO J 2022; 41:e109895. [PMID: 35971838 PMCID: PMC9627665 DOI: 10.15252/embj.2021109895] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 07/10/2022] [Accepted: 07/12/2022] [Indexed: 12/13/2022] Open
Abstract
Regeneration and tissue homeostasis require accurate production of missing cell lineages. Cell production is driven by changes to gene expression, which is shaped by multiple layers of regulation. Here, we find that the ubiquitous mRNA base-modification, m6A, is required for proper cell fate choice and cellular maturation in planarian stem cells (neoblasts). We mapped m6A-enriched regions in 7,600 planarian genes and found that perturbation of the m6A pathway resulted in progressive deterioration of tissues and death. Using single-cell RNA sequencing of >20,000 cells following perturbation of the m6A pathway, we identified an increase in expression of noncanonical histone variants, and that inhibition of the pathway resulted in accumulation of undifferentiated cells throughout the animal in an abnormal transcriptional state. Analysis of >1,000 planarian gene expression datasets revealed that the inhibition of the chromatin modifying complex NuRD had almost indistinguishable consequences, unraveling an unappreciated link between m6A and chromatin modifications. Our findings reveal that m6A is critical for planarian stem cell homeostasis and gene regulation in tissue maintenance and regeneration.
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Affiliation(s)
- Yael Dagan
- The George S. Wise Faculty of Life Sciences, School of Neurobiology, Biochemistry, and Biophysics, Tel Aviv University, Tel Aviv, Israel
| | - Yarden Yesharim
- The George S. Wise Faculty of Life Sciences, School of Neurobiology, Biochemistry, and Biophysics, Tel Aviv University, Tel Aviv, Israel
| | - Ashley R Bonneau
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Tamar Frankovits
- The George S. Wise Faculty of Life Sciences, School of Neurobiology, Biochemistry, and Biophysics, Tel Aviv University, Tel Aviv, Israel
| | - Schraga Schwartz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Peter W Reddien
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Omri Wurtzel
- The George S. Wise Faculty of Life Sciences, School of Neurobiology, Biochemistry, and Biophysics, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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3
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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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4
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Sridhar D, Aboobaker A. Monitoring Chromatin Regulation in Planarians Using Chromatin Immunoprecipitation Followed by Sequencing (ChIP-seq). Methods Mol Biol 2022; 2450:529-547. [PMID: 35359327 PMCID: PMC9761535 DOI: 10.1007/978-1-0716-2172-1_28] [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: 10/18/2022]
Abstract
Planarians are an accessible model system to study animal regeneration and stem cells. Over the last two decades, new molecular techniques have provided us with powerful tools to understand whole-body regeneration and pluripotent adult stem cells specifically. We describe a method for performing Chromatin Immunoprecipitation followed by sequencing (ChIP-seq) on planarian cells that relies on FACS to isolate different cell populations followed by immunoprecipitation and library preparation for next-generation sequencing. Whole-genome profiling of histone modifications enables a greater understanding of epigenetic mechanisms in development, pluripotency, and differentiation. This protocol adds to the growing list of functional genomic approaches to study whole-body regeneration in animals.
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Affiliation(s)
- Divya Sridhar
- Department of Zoology, University of Oxford, Oxford, UK
| | - Aziz Aboobaker
- Department of Zoology, University of Oxford, Oxford, UK.
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5
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Reddien PW. Principles of regeneration revealed by the planarian eye. Curr Opin Cell Biol 2021; 73:19-25. [PMID: 34134046 PMCID: PMC11064094 DOI: 10.1016/j.ceb.2021.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 05/06/2021] [Indexed: 02/07/2023]
Abstract
One approach to elucidating the principles of regeneration is to investigate mechanisms that regenerate a target organ. Planarian eyes are discrete, visible structures that are dispensable for viability, making them powerful for studying the logic of regeneration. Fate specification in eye regeneration occurs in stem cells (neoblasts), generating eye progenitors. Eye progenitor production is not responsive to the presence or absence of the eye, with regeneration explained by constant progenitor production in the appropriate positional environment. Eye progenitors display coarse spatial specification. A combination of eye-extrinsic cues and self-organization with differentiated eye cells dictate where migratory eye progenitors target. Finally, guidepost-like cells influence regenerating axons to facilitate the restoration of eye circuitry. These findings from the eye as a case study present a model that explains how regeneration can occur.
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Affiliation(s)
- Peter W Reddien
- Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA; Department of Biology, MIT, Cambridge, MA, 02139, USA; Howard Hughes Medical Institute, MIT, Cambridge, MA, 02139, USA.
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6
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Fraguas S, Cárcel S, Vivancos C, Molina MD, Ginés J, Mazariegos J, Sekaran T, Bartscherer K, Romero R, Cebrià F. CREB-binding protein (CBP) gene family regulates planarian survival and stem cell differentiation. Dev Biol 2021; 476:53-67. [PMID: 33774010 DOI: 10.1016/j.ydbio.2021.02.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/23/2021] [Accepted: 02/24/2021] [Indexed: 12/21/2022]
Abstract
In developmental biology, the regulation of stem cell plasticity and differentiation remains an open question. CBP(CREB-binding protein)/p300 is a conserved gene family that functions as a transcriptional co-activator and plays important roles in a wide range of cellular processes, including cell death, the DNA damage response, and tumorigenesis. The acetyl transferase activity of CBPs is particularly important, as histone and non-histone acetylation results in changes in chromatin architecture and protein activity that affect gene expression. Many studies have described the conserved functions of CBP/p300 in stem cell proliferation and differentiation. The planarian Schmidtea mediterranea is an excellent model for the in vivo study of the molecular mechanisms underlying stem cell differentiation during regeneration. However, how this process is regulated genetically and epigenetically is not well-understood yet. We identified 5 distinct Smed-cbp genes in S. mediterranea that show different expression patterns. Functional analyses revealed that Smed-cbp-2 appears to be essential for stem cell maintenance. On the other hand, the silencing of Smed-cbp-3 resulted in the growth of blastemas that were apparently normal, but remained largely unpigmented and undifferentiated. Smed-cbp-3 silencing also affected the differentiation of several cell lineages including neural, epidermal, digestive, and excretory cell types. Finally, we analysed the predicted interactomes of CBP-2 and CBP-3 as an initial step to better understand their functions in planarian stem cell biology. Our results indicate that planarian cbp genes play key roles in stem cell maintenance and differentiation.
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Affiliation(s)
- Susanna Fraguas
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Spain
| | - Sheila Cárcel
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Spain
| | - Coral Vivancos
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Spain
| | - Ma Dolores Molina
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Spain
| | - Jordi Ginés
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Spain
| | - Judith Mazariegos
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Spain
| | | | | | - Rafael Romero
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Spain
| | - Francesc Cebrià
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Spain.
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7
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Stelman CR, Smith BM, Chandra B, Roberts-Galbraith RH. CBP/p300 homologs CBP2 and CBP3 play distinct roles in planarian stem cell function. Dev Biol 2021; 473:130-143. [PMID: 33607113 DOI: 10.1016/j.ydbio.2021.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 11/19/2022]
Abstract
Chromatin modifications function as critical regulators of gene expression and cellular identity, especially in the regulation and maintenance of the pluripotent state. However, many studies of chromatin modification in stem cells-and pluripotent stem cells in particular-are performed in mammalian stem cell culture, an in vitro condition mimicking a very transient state during mammalian development. Thus, new models for studying pluripotent stem cells in vivo could be helpful for understanding the roles of chromatin modification, for confirming prior in vitro studies, and for exploring evolution of the pluripotent state. The freshwater flatworm, Schmidtea mediterranea, is an excellent model for studying adult pluripotent stem cells, particularly in the context of robust, whole-body regeneration. To identify chromatin modifying and remodeling enzymes critical for planarian regeneration and stem cell maintenance, we took a candidate approach and screened planarian homologs of 25 genes known to regulate chromatin biology in other organisms. Through our study, we identified six genes with novel functions in planarian homeostasis, regeneration, and behavior. Of the list of genes characterized, we identified five planarian homologs of the mammalian CREB-Binding Protein (CBP) and p300 family of histone acetyltransferases, representing an expansion of this family in planarians. We find that two planarian CBP family members are required for planarian survival, with knockdown of Smed-CBP2 and Smed-CBP3 causing distinct defects in stem cell maintenance or function. Loss of CBP2 causes a quick, dramatic loss of stem cells, while knockdown of CBP3 affects stem cells more narrowly, influencing differentiation of several cell types that include neuronal subtypes and cells of the eye. Further, we find that Smed-CBP1 is required for planarian fissioning behavior. We propose that the division of labor among a diversified CBP family in planarians presents an opportunity to dissect specific functions of a broadly important histone acetyltransferase family.
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Affiliation(s)
- Clara R Stelman
- Department of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Britessia M Smith
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Bidushi Chandra
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Rachel H Roberts-Galbraith
- Department of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Cellular Biology, University of Georgia, Athens, GA, USA.
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8
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Karge A, Bonar NA, Wood S, Petersen CP. tec-1 kinase negatively regulates regenerative neurogenesis in planarians. eLife 2020; 9:47293. [PMID: 31958270 PMCID: PMC6970515 DOI: 10.7554/elife.47293] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 12/30/2019] [Indexed: 01/03/2023] Open
Abstract
Negative regulators of adult neurogenesis are of particular interest as targets to enhance neuronal repair, but few have yet been identified. Planarians can regenerate their entire CNS using pluripotent adult stem cells, and this process is robustly regulated to ensure that new neurons are produced in proper abundance. Using a high-throughput pipeline to quantify brain chemosensory neurons, we identify the conserved tyrosine kinase tec-1 as a negative regulator of planarian neuronal regeneration. tec-1RNAi increased the abundance of several CNS and PNS neuron subtypes regenerated or maintained through homeostasis, without affecting body patterning or non-neural cells. Experiments using TUNEL, BrdU, progenitor labeling, and stem cell elimination during regeneration indicate tec-1 limits the survival of newly differentiated neurons. In vertebrates, the Tec kinase family has been studied extensively for roles in immune function, and our results identify a novel role for tec-1 as negative regulator of planarian adult neurogenesis.
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Affiliation(s)
- Alexander Karge
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Nicolle A Bonar
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Scott Wood
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Christian P Petersen
- Department of Molecular Biosciences, Northwestern University, Evanston, United States.,Robert Lurie Comprehensive Cancer Center, Northwestern University, Evanston, United States
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9
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Dattani A, Kao D, Mihaylova Y, Abnave P, Hughes S, Lai A, Sahu S, Aboobaker AA. Epigenetic analyses of planarian stem cells demonstrate conservation of bivalent histone modifications in animal stem cells. Genome Res 2018; 28:1543-1554. [PMID: 30143598 PMCID: PMC6169894 DOI: 10.1101/gr.239848.118] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/16/2018] [Indexed: 12/14/2022]
Abstract
Planarian flatworms have an indefinite capacity to regenerate missing or damaged body parts owing to a population of pluripotent adult stems cells called neoblasts (NBs). Currently, little is known about the importance of the epigenetic status of NBs and how histone modifications regulate homeostasis and cellular differentiation. We have developed an improved and optimized ChIP-seq protocol for NBs in Schmidtea mediterranea and have generated genome-wide profiles for the active marks H3K4me3 and H3K36me3, and suppressive marks H3K4me1 and H3K27me3. The genome-wide profiles of these marks were found to correlate well with NB gene expression profiles. We found that genes with little transcriptional activity in the NB compartment but which switch on in post-mitotic progeny during differentiation are bivalent, being marked by both H3K4me3 and H3K27me3 at promoter regions. In further support of this hypothesis, bivalent genes also have a high level of paused RNA Polymerase II at the promoter-proximal region. Overall, this study confirms that epigenetic control is important for the maintenance of a NB transcriptional program and makes a case for bivalent promoters as a conserved feature of animal stem cells and not a vertebrate-specific innovation. By establishing a robust ChIP-seq protocol and analysis methodology, we further promote planarians as a promising model system to investigate histone modification–mediated regulation of stem cell function and differentiation.
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Affiliation(s)
- Anish Dattani
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
| | - Damian Kao
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
| | - Yuliana Mihaylova
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
| | - Prasad Abnave
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
| | - Samantha Hughes
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
| | - Alvina Lai
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
| | - Sounak Sahu
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
| | - A Aziz Aboobaker
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
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10
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Strand NS, Allen JM, Zayas RM. Post-translational regulation of planarian regeneration. Semin Cell Dev Biol 2018; 87:58-68. [PMID: 29705300 DOI: 10.1016/j.semcdb.2018.04.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/24/2018] [Accepted: 04/25/2018] [Indexed: 02/07/2023]
Abstract
Most mammals cannot easily overcome degenerative disease or traumatic injuries. In contrast, an innate ability to regenerate is observed across animal phyla. Freshwater planarians are amongst the organisms that are capable of stem cell-mediated whole-body regeneration and have served as an exemplary model to study how pluripotency is maintained and regulated in vivo. Here, we review findings on the role of post-translational modifications and the genes regulating phosphorylation, ubiquitylation, and chromatin remodeling in planarian regeneration. Furthermore, we discuss how technological advances for identifying cellular targets of these processes will fill gaps in our knowledge of the signaling mechanisms that underlie regeneration in planarians, which should inform how tissue repair can be stimulated in non-regenerative model organisms and in humans.
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Affiliation(s)
- Nicholas S Strand
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - John M Allen
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Ricardo M Zayas
- Department of Biology, San Diego State University, San Diego, CA 92182, USA.
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11
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Dattani A, Sridhar D, Aziz Aboobaker A. Planarian flatworms as a new model system for understanding the epigenetic regulation of stem cell pluripotency and differentiation. Semin Cell Dev Biol 2018; 87:79-94. [PMID: 29694837 DOI: 10.1016/j.semcdb.2018.04.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/21/2018] [Indexed: 12/11/2022]
Abstract
Planarian flatworms possess pluripotent stem cells (neoblasts) that are able to differentiate into all cell types that constitute the adult body plan. Consequently, planarians possess remarkable regenerative capabilities. Transcriptomic studies have revealed that gene expression is coordinated to maintain neoblast pluripotency, and ensure correct lineage specification during differentiation. But as yet they have not revealed how this regulation of expression is controlled. In this review, we propose that planarians represent a unique and effective system to study the epigenetic regulation of these processes in an in vivo context. We consolidate evidence suggesting that although DNA methylation is likely present in some flatworm lineages, it does not regulate neoblast function in Schmidtea mediterranea. A number of phenotypic studies have documented the role of histone modification and chromatin remodelling complexes in regulating distinct neoblast processes, and we focus on four important examples of planarian epigenetic regulators: Nucleosome Remodeling Deacetylase (NuRD) complex, Polycomb Repressive Complex (PRC), the SET1/MLL methyltransferases, and the nuclear PIWI/piRNA complex. Given the recent advent of ChIP-seq in planarians, we propose future avenues of research that will identify the genomic targets of these complexes allowing for a clearer picture of how neoblast processes are coordinated at the epigenetic level. These insights into neoblast biology may be directly relevant to mammalian stem cells and disease. The unique biology of planarians will also allow us to investigate how extracellular signals feed into epigenetic regulatory networks to govern concerted neoblast responses during regenerative polarity, tissue patterning, and remodelling.
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Affiliation(s)
- Anish Dattani
- Department of Zoology, South Parks Road, University of Oxford, OX1 3PS, UK.
| | - Divya Sridhar
- Department of Zoology, South Parks Road, University of Oxford, OX1 3PS, UK
| | - A Aziz Aboobaker
- Department of Zoology, South Parks Road, University of Oxford, OX1 3PS, UK.
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12
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Morton JM, Saad MA, Beane WS. Surgical Ablation Assay for Studying Eye Regeneration in Planarians. J Vis Exp 2017. [PMID: 28448039 DOI: 10.3791/55594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
In the study of adult stem cells and regenerative mechanisms, planarian flatworms are a staple in vivo model system. This is due in large part to their abundant pluripotent stem cell population and ability to regenerate all cell and tissue types after injuries that would be catastrophic for most animals. Recently, planarians have gained popularity as a model for eye regeneration. Their ability to regenerate the entire eye (comprised of two tissue types: pigment cells and photoreceptors) allows for the dissection of the mechanisms regulating visual system regeneration. Eye ablation has several advantages over other techniques (such as decapitation or hole punch) for examining eye-specific pathways and mechanisms, the most important of which is that regeneration is largely restricted to eye tissues alone. The purpose of this video article is to demonstrate how to reliably remove the planarian optic cup without disturbing the brain or surrounding tissues. The handling of worms and maintenance of an established colony is also described. This technique uses a 31 G, 5/16-inch insulin needle to surgically scoop out the optic cup of planarians immobilized on a cold plate. This method encompasses both single and double eye ablation, with eyes regenerating within 1-2 weeks, allowing for a wide range of applications. In particular, this ablation technique can be easily combined with pharmacological and genetic (RNA interference) screens for a better understanding of regenerative mechanisms and their evolution, eye stem cells and their maintenance, and phototaxic behavioral responses and their neurological basis.
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Affiliation(s)
- Jacob M Morton
- Department of Biological Sciences, Western Michigan University
| | - Marwa A Saad
- Department of Biological Sciences, Western Michigan University
| | - Wendy S Beane
- Department of Biological Sciences, Western Michigan University;
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