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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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Pellettieri J. Regenerative tissue remodeling in planarians - The mysteries of morphallaxis. Semin Cell Dev Biol 2018; 87:13-21. [PMID: 29631028 DOI: 10.1016/j.semcdb.2018.04.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 04/05/2018] [Accepted: 04/06/2018] [Indexed: 12/15/2022]
Abstract
Biologists have long marveled at the ability of planarian flatworms to regenerate any parts of their bodies in just a little over a week. While great progress has been made in deciphering the mechanisms by which new tissue is formed at sites of amputation, we know relatively little about the complementary remodeling response that occurs in uninjured tissues to restore anatomical scale and proportion. This review explores the mysterious biology of this process, first described in hydra by the father of experimental zoology, Abraham Trembley, and later termed 'morphallaxis' by the father of experimental genetics, Thomas Hunt Morgan. The perceptive work of these early pioneers, together with recent studies using modern tools, has revealed some of the key features of regenerative tissue remodeling, including repatterning of the body axes, reproportioning of organs like the brain and gut, and a major increase in the rate of cell death. Yet a mechanistic solution to this longstanding problem in the field will require further study by the next generation of planarian researchers.
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53
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Neoblast-enriched zinc finger protein FIR1 triggers local proliferation during planarian regeneration. Protein Cell 2018; 10:43-59. [PMID: 29557542 PMCID: PMC6321819 DOI: 10.1007/s13238-018-0512-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 01/09/2018] [Indexed: 11/30/2022] Open
Abstract
Regeneration, relying mainly on resident adult stem cells, is widespread. However, the mechanism by which stem cells initiate proliferation during this process in vivo is unclear. Using planarian as a model, we screened 46 transcripts showing potential function in the regulation of local stem cell proliferation following 48 h regeneration. By analyzing the regeneration defects and the mitotic activity of animals under administration of RNA interference (RNAi), we identified factor for initiating regeneration 1 (Fir1) required for local proliferation. Our findings reveal that Fir1, enriched in neoblasts, promotes planarian regeneration in any tissue-missing context. Further, we demonstrate that DIS3 like 3′-5′ exoribonuclease 2 (Dis3l2) is required for Fir1 phenotype. Besides, RNAi knockdown of Fir1 causes a decrease of neoblast wound response genes following amputation. These findings suggest that Fir1 recognizes regenerative signals and promotes DIS3L2 proteins to trigger neoblast proliferation following amputation and provide a mechanism critical for stem cell response to injury.
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54
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He Y, Cai C, Sun S, Wang X, Li W, Li H. Effect of JNK inhibitor SP600125 on hair cell regeneration in zebrafish (Danio rerio) larvae. Oncotarget 2018; 7:51640-51650. [PMID: 27438150 PMCID: PMC5239503 DOI: 10.18632/oncotarget.10540] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 06/29/2016] [Indexed: 11/25/2022] Open
Abstract
The c-Jun amino-terminal kinase (JNK) proteins are a subgroup of the mitogen-activated protein kinase family. They play a complex role in cell proliferation, survival, and apoptosis. Here, we report a novel role of JNK signalling in hair cell regeneration. We eliminated hair cells of 5-day post-fertilization zebrafish larvae using neomycin followed by JNK inhibition with SP600125. JNK inhibition strongly decreased the number of regenerated hair cells in response to neomycin damage. These changes were associated with reduced proliferation. JNK inhibition also increased cleaved caspase-3 activity and induced apoptosis in regenerating neuromasts. Finally, JNK inhibition with SP600125 decreased the expression of genes related to Wnt. Over-activation of the Wnt signalling pathway partly rescued the hair cell regeneration defects induced by JNK inhibition. Together, our findings provide novel insights into the function of JNK and show that JNK inhibition blocks hair cell regeneration by controlling the Wnt signalling pathway.
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Affiliation(s)
- Yingzi He
- Department of Otorhinolaryngology, Key Laboratory of Hearing Science, Ministry of Health, EENT Hospital, Fudan University, Shanghai, China.,Laboratory Center, Affiliated Eye and ENT Hospital of Fudan University, Shanghai, China
| | - Chengfu Cai
- Department of Otolaryngology Head and Neck Surgery, the First Affiliated Hospital, Xiamen University, Xiamen, China
| | - Shaoyang Sun
- Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai, China
| | - Xu Wang
- Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai, China
| | - Wenyan Li
- Department of Otorhinolaryngology, Key Laboratory of Hearing Science, Ministry of Health, EENT Hospital, Fudan University, Shanghai, China
| | - Huawei Li
- Department of Otorhinolaryngology, Key Laboratory of Hearing Science, Ministry of Health, EENT Hospital, Fudan University, Shanghai, China.,Institute of Stem Cell and Regeneration Medicine, Institutions of Biomedical Science, Fudan University, Shanghai, China.,Key Laboratory of Hearing Science, Ministry of Health, EENT Hospital, Fudan University, Shanghai, China
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55
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Lai AG, Kosaka N, Abnave P, Sahu S, Aboobaker AA. The abrogation of condensin function provides independent evidence for defining the self-renewing population of pluripotent stem cells. Dev Biol 2018; 433:218-226. [PMID: 28757112 PMCID: PMC5771471 DOI: 10.1016/j.ydbio.2017.07.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 07/18/2017] [Accepted: 07/27/2017] [Indexed: 12/18/2022]
Abstract
Heterogeneity of planarian stem cells has been categorised on the basis of single cell expression analyses and subsequent experiments to demonstrate lineage relationships. Some data suggest that despite heterogeneity in gene expression amongst cells in the cell cycle, in fact only one sub-population, known as sigma neoblasts, can self-renew. Without the tools to perform live in vivo lineage analysis, we instead took an alternative approach to provide independent evidence for defining the self-renewing stem cell population. We exploited the role of highly conserved condensin family genes to functionally assay neoblast self-renewal properties. Condensins are involved in forming properly condensed chromosomes to allow cell division to proceed during mitosis, and their abrogation inhibits mitosis and can lead to repeated endoreplication of the genome in cells that make repeated attempts to divide. We find that planarians possess only the condensin I complex, and that this is required for normal stem cell function. Abrogation of condensin function led to rapid stem cell depletion accompanied by the appearance of 'giant' cells with increased DNA content. Using previously discovered markers of heterogeneity we show that enlarged cells are always from the sigma-class of the neoblast population and we never observe evidence for endoreplication for the other neoblast subclasses. Overall, our data establish that condensins are essential for stem cell maintenance and provide independent evidence that only sigma-neoblasts are capable of multiple rounds of cell division and hence self-renewal.
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Affiliation(s)
- Alvina G Lai
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - Nobuyoshi Kosaka
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - Prasad Abnave
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - Sounak Sahu
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - A Aziz Aboobaker
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, United Kingdom.
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56
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de Sousa N, Rodríguez-Esteban G, Rojo-Laguna JI, Saló E, Adell T. Hippo signaling controls cell cycle and restricts cell plasticity in planarians. PLoS Biol 2018; 16:e2002399. [PMID: 29357350 PMCID: PMC5794332 DOI: 10.1371/journal.pbio.2002399] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 02/01/2018] [Accepted: 12/21/2017] [Indexed: 12/11/2022] Open
Abstract
The Hippo pathway plays a key role in regulating cell turnover in adult tissues, and abnormalities in this pathway are consistently associated with human cancers. Hippo was initially implicated in the control of cell proliferation and death, and its inhibition is linked to the expansion of stem cells and progenitors, leading to larger organ size and tumor formation. To understand the mechanism by which Hippo directs cell renewal and promotes stemness, we studied its function in planarians. These stem cell-based organisms are ideal models for the analysis of the complex cellular events underlying tissue renewal in the whole organism. hippo RNA interference (RNAi) in planarians decreased apoptotic cell death, induced cell cycle arrest, and could promote the dedifferentiation of postmitotic cells. hippo RNAi resulted in extensive undifferentiated areas and overgrowths, with no effect on body size or cell number. We propose an essential role for hippo in controlling cell cycle, restricting cell plasticity, and thereby preventing tumoral transformation.
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Affiliation(s)
- Nídia de Sousa
- Department of Genetics, Microbiology and Statistics and Institute of Biomedicine, Universitat de Barcelona, Barcelona, Catalunya, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Catalunya, Spain
| | - Gustavo Rodríguez-Esteban
- CNAG-CRG, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Catalunya, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Catalunya, Spain
| | - Jose Ignacio Rojo-Laguna
- Department of Genetics, Microbiology and Statistics and Institute of Biomedicine, Universitat de Barcelona, Barcelona, Catalunya, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Catalunya, Spain
| | - Emili Saló
- Department of Genetics, Microbiology and Statistics and Institute of Biomedicine, Universitat de Barcelona, Barcelona, Catalunya, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Catalunya, Spain
| | - Teresa Adell
- Department of Genetics, Microbiology and Statistics and Institute of Biomedicine, Universitat de Barcelona, Barcelona, Catalunya, Spain
- Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Catalunya, Spain
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57
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Abstract
Planarians have gained a well-deserved reputation as an excellent model organism for research on the biology of adult stem cells and their role in regeneration. Though less widely recognized, these animals also offer many advantages for investigating mechanisms and functions of programmed cell death in self-renewing tissues. Apoptosis complements stem cell division during physiological cell turnover and constitutes a prominent feature of the tissue remodeling process that restores anatomical scale and proportion during regeneration. One technical advantage to studying apoptosis in planarians is the availability of a whole-mount TUNEL assay for visualizing dying cells throughout the animal. Here, we provide a detailed protocol for this assay that is likely to benefit researchers investigating planarian cell death in either physiological or pathological contexts.
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58
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When dying is not the end: Apoptotic caspases as drivers of proliferation. Semin Cell Dev Biol 2017; 82:86-95. [PMID: 29199139 DOI: 10.1016/j.semcdb.2017.11.036] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/29/2017] [Accepted: 11/29/2017] [Indexed: 12/21/2022]
Abstract
Caspases are well known for their role as executioners of apoptosis. However, recent studies have revealed that these lethal enzymes also have important mitogenic functions. Caspases can promote proliferation through autonomous regulation of the cell cycle, as well as by induction of secreted signals, which have a profound impact in neighboring tissues. Here, I review the proliferative role of caspases during development and homeostasis, in addition to their key regenerative function during tissue repair upon injury. Furthermore, the emerging properties of apoptotic caspases as drivers of carcinogenesis are discussed, as well as their involvement in other diseases. Finally, I examine further effects of caspases regulating death and survival in a non-autonomous manner.
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Martín R, Pinal N, Morata G. Distinct regenerative potential of trunk and appendages of Drosophila mediated by JNK signalling. Development 2017; 144:3946-3956. [PMID: 28935711 DOI: 10.1242/dev.155507] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 09/11/2017] [Indexed: 12/31/2022]
Abstract
The Drosophila body comprises a central part, the trunk, and outgrowths of the trunk, the appendages. Much is known about appendage regeneration, but little about the trunk. As the wing imaginal disc contains a trunk component, the notum, and a wing appendage, we have investigated the response to ablation of these two components. We find that, in contrast with the strong regenerative response of the wing, the notum does not regenerate. Nevertheless, the elimination of the wing primordium elicits a proliferative response of notum cells, but they do not regenerate wing; they form a notum duplicate. Conversely, the wing cells cannot regenerate an ablated notum; they overproliferate and generate a hinge overgrowth. These results suggest that trunk and appendages cannot be reprogrammed to generate each other. Our experiments demonstrate that the proliferative response is mediated by JNK signalling from dying cells, but JNK functions differently in the trunk and the appendages, which may explain their distinct regenerative potential.
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Affiliation(s)
- Raquel Martín
- Centro de Biología Molecular CSIC-UAM, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Noelia Pinal
- Centro de Biología Molecular CSIC-UAM, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Ginés Morata
- Centro de Biología Molecular CSIC-UAM, Universidad Autónoma de Madrid, Madrid 28049, Spain
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60
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Kinases Involved in Both Autophagy and Mitosis. Int J Mol Sci 2017; 18:ijms18091884. [PMID: 28858266 PMCID: PMC5618533 DOI: 10.3390/ijms18091884] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 08/25/2017] [Accepted: 08/25/2017] [Indexed: 12/23/2022] Open
Abstract
Both mitosis and autophagy are highly regulated dynamic cellular processes and involve various phosphorylation events catalysed by kinases, which play vital roles in almost all physiological and pathological conditions. Mitosis is a key event during the cell cycle, in which the cell divides into two daughter cells. Autophagy is a process in which the cell digests its own cellular contents. Although autophagy regulation has mainly been studied in asynchronous cells, increasing evidence indicates that autophagy is in fact tightly regulated in mitosis. Here in this review, we will discuss kinases that were originally identified to be involved in only one of either mitosis or autophagy, but were later found to participate in both processes, such as CDKs (cyclin-dependent kinases), Aurora kinases, PLK-1 (polo-like kinase 1), BUB1 (budding uninhibited by benzimidazoles 1), MAPKs (mitogen-activated protein kinases), mTORC1 (mechanistic target of rapamycin complex 1), AMPK (AMP-activated protein kinase), PI3K (phosphoinositide-3 kinase) and protein kinase B (AKT). By focusing on kinases involved in both autophagy and mitosis, we will get a more comprehensive understanding about the reciprocal regulation between the two key cellular events, which will also shed light on their related therapeutic investigations.
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61
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Cassella L, Salvetti A, Iacopetti P, Ippolito C, Ghezzani C, Gimenez G, Ghigo E, Rossi L. Putrescine independent wound response phenotype is produced by ODC-like RNAi in planarians. Sci Rep 2017; 7:9736. [PMID: 28851936 PMCID: PMC5574924 DOI: 10.1038/s41598-017-09567-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 07/26/2017] [Indexed: 01/18/2023] Open
Abstract
Despite increasing evidence indicates polyamines as a convergence point for signaling pathways, including cell growth and differentiation, a unifying concept to interpret their role is still missing. The activity of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis, is tightly regulated by a complex molecular machinery, and the demonstration of the existence of multiple ODC paralogs, lacking decarboxylation activity, suggests additional layers of complexity to the intricate ODC regulatory pathway. Because of their extraordinary regenerative abilities and abundance of stem cells, planarians have potential to contribute to our understanding of polyamine function in an in vivo context. We undertook a study on ODC function in planarians and we found six planarian ODCs (ODC1-6). Five out of six ODC homologs carry substitutions of key aminoacids for enzymatic activity, which makes them theoretically unable to decarboxylate ornithine. Silencing of ODC5 and 6 produced a complex phenotype, by prompting animals to an aberrant response, following chronic injury without tissue removal. Phenotype is neither rescued by putrescine, nor mimicked by difluoromethylornithine treatment. Moreover, the co-silencing of other genes of the ODC regulatory pathway did not modulate phenotype outcome or severity, thus suggesting that the function/s of these ODC-like proteins might be unrelated to decarboxylase activity and putrescine production.
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Affiliation(s)
- Lucia Cassella
- Department of Clinical and Experimental Medicine, University of Pisa, via Volta 4, 56126, Pisa, Italy
| | - Alessandra Salvetti
- 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
| | - Chiara Ippolito
- Department of Clinical and Experimental Medicine, University of Pisa, via Volta 4, 56126, Pisa, Italy
| | - Claudio Ghezzani
- Department of Clinical and Experimental Medicine, University of Pisa, via Volta 4, 56126, Pisa, Italy
| | - Gregory Gimenez
- Otago Genomics & Bioinformatics Facility, Department of Biochemistry, University of Otago, PO Box 56, 710 Cumberland Street, Dunedin, 9054, New Zealand
| | - Eric Ghigo
- CNRS UMR 7278, IRD198, INSERM U1095, APHM, Institut Hospitalier Universitaire Méditerranée-Infection, Aix-Marseille Université, 19-21 Bd Jean Moulin, 13385, Marseille Cedex 05, France
| | - Leonardo Rossi
- Department of Clinical and Experimental Medicine, University of Pisa, via Volta 4, 56126, Pisa, Italy.
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62
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Lin AYT, Pearson BJ. Yorkie is required to restrict the injury responses in planarians. PLoS Genet 2017; 13:e1006874. [PMID: 28686611 PMCID: PMC5515462 DOI: 10.1371/journal.pgen.1006874] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 07/18/2017] [Accepted: 06/15/2017] [Indexed: 12/30/2022] Open
Abstract
Regeneration requires the precise integration of cues that initiate proliferation, direct differentiation, and ultimately re-pattern tissues to the proper size and scale. Yet how these processes are integrated with wounding responses remains relatively unknown. The freshwater planarian, Schmidtea mediterranea, is an ideal model to study the stereotyped proliferative and transcriptional responses to injury due to its high capacity for regeneration. Here, we characterize the effector of the Hippo signalling cascade, yorkie, during planarian regeneration and its role in restricting early injury responses. In yki(RNAi) regenerating animals, wound responses are hyper-activated such that both stem cell proliferation and the transcriptional wound response program are heighted and prolonged. Using this observation, we also uncovered novel wound-induced genes by RNAseq that were de-repressed in yki(RNAi) animals compared with controls. Additionally, we show that yki(RNAi) animals have expanded epidermal and muscle cell populations, which we hypothesize are the increased sources of wound-induced genes. Finally, we show that in yki(RNAi) animals, the sensing of the size of an injury by eyes or the pharynx is not appropriate, and the brain, gut, and midline cannot remodel or scale correctly to the size of the regenerating fragment. Taken together, our results suggest that yki functions as a key molecule that can integrate multiple aspects of the injury response including proliferation, apoptosis, injury-induced transcription, and patterning. The planarian displays a remarkable ability to regenerate any tissue from mere fragments of its original size. This high capacity to regenerate is attributed to the abundant population of pluripotent adult stem cells. In response to an injury, such as an amputation, stem cells proliferate and replace the lost tissues de novo (epimorphosis), whereas existing tissue must rescale to the correct proportions in relation to the new fragment size (morphallaxis). Currently, the molecules that control either the responses to injury or the ones that mediate size and scaling are not well understood. For instance, how are the injury responses precisely activated and shut down to ensure regenerating tissues are not under- or overgrown? Here, we find that Yki, the effector of the Hippo signalling cascade, is a critical molecule that influences several injury processes during regeneration. Loss of Yki function in regenerating animals resulted in increased and temporally dysregulated expression of wound-induced genes, proliferation, and apoptosis. Genes that are injury induced were mis-expressed in yki(RNAi) animals, which also showed increases in the epidermal and muscle cell populations. Taken together, our findings suggest that the injury responses must be restricted to ensure proper regenerative outcomes of correct scale, and that Yki is a key regulator in these processes.
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Affiliation(s)
- Alexander Y. T. Lin
- Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Bret J. Pearson
- Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- Ontario Institute for Cancer Research, Toronto, ON, Canada
- * E-mail:
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63
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Gao L, Han Y, Deng H, Hu W, Zhen H, Li N, Qin N, Yan M, Wu W, Liu B, Zhao B, Pang Q. The role of a novel C-type lectin-like protein from planarian in innate immunity and regeneration. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 67:413-426. [PMID: 27565408 DOI: 10.1016/j.dci.2016.08.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/22/2016] [Accepted: 08/22/2016] [Indexed: 06/06/2023]
Abstract
Planarian, a representative of platyhelminthes, has strong regeneration ability and less complicated innate immune system. However, planarian immune system remains poorly understood. In this paper, a novel C-type lectin-like protein, namely, DjCTL was identified and characterized in Dugesia japonica. DjCTL was mainly expressed in the pharyngeal and epidermis and up-regulated upon the induction of lipopolysaccharide (LPS), peptidoglycan (PGN), Gram-positive and Gram-negative bacteria indicating that DjCTL may be involved in the immune responses. Recombination DjCTL protein agglomerated rabbit red blood cells and interacted with LPS, PGN, mannose and galactose as well as both Gram-positive and Gram-negative bacteria, but it can only cause the agglutination of Gram-negative bacteria. Importantly, in the early periods of regeneration, DjCTL had a significantly high expression and was mainly expressed in early blastemas. RNA interference of DjCTL by dsRNA-DjCTL led to a slow wound healing during regeneration. These findings suggest that DjCTL participates in the innate immune response and plays an important role in early stages of regeneration.
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Affiliation(s)
- Lili Gao
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China; Anti-Aging & Regenerative Medicine Research Institution, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China
| | - Yu Han
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China; Anti-Aging & Regenerative Medicine Research Institution, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China
| | - Hongkuan Deng
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China
| | - Wenjing Hu
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China; Anti-Aging & Regenerative Medicine Research Institution, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China
| | - Hui Zhen
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China
| | - Na Li
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China; Anti-Aging & Regenerative Medicine Research Institution, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China
| | - Nianci Qin
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China
| | - Meihui Yan
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China
| | - Weiwei Wu
- Anti-Aging & Regenerative Medicine Research Institution, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China
| | - Baohua Liu
- Anti-Aging & Regenerative Medicine Research Institution, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China; Shenzhen University of Health Science Center, District Shenzhen, 518060, PR China.
| | - Bosheng Zhao
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China.
| | - Qiuxiang Pang
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China; Anti-Aging & Regenerative Medicine Research Institution, School of Life Sciences, Shandong University of Technology, Zibo, 255049, PR China.
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64
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Seebeck F, März M, Meyer AW, Reuter H, Vogg MC, Stehling M, Mildner K, Zeuschner D, Rabert F, Bartscherer K. Integrins are required for tissue organization and restriction of neurogenesis in regenerating planarians. Development 2017; 144:795-807. [PMID: 28137894 PMCID: PMC5374344 DOI: 10.1242/dev.139774] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 01/11/2017] [Indexed: 12/13/2022]
Abstract
Tissue regeneration depends on proliferative cells and on cues that regulate cell division, differentiation, patterning and the restriction of these processes once regeneration is complete. In planarians, flatworms with high regenerative potential, muscle cells express some of these instructive cues. Here, we show that members of the integrin family of adhesion molecules are required for the integrity of regenerating tissues, including the musculature. Remarkably, in regenerating β1-integrin RNAi planarians, we detected increased numbers of mitotic cells and progenitor cell types, as well as a reduced ability of stem cells and lineage-restricted progenitor cells to accumulate at wound sites. These animals also formed ectopic spheroid structures of neural identity in regenerating heads. Interestingly, those polarized assemblies comprised a variety of neural cells and underwent continuous growth. Our study indicates that integrin-mediated cell adhesion is required for the regenerative formation of organized tissues and for restricting neurogenesis during planarian regeneration. Highlighted article: Integrin signaling acts to recruit and localize progenitor cells following injury, thereby promoting the correct organization of regenerating planarian tissue.
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Affiliation(s)
- Florian Seebeck
- Max Planck Research Group Stem Cells & Regeneration, Max Planck Institute for Molecular Biomedicine, Von-Esmarch-Str. 54, Münster 48149, Germany.,Medical Faculty, University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany
| | - Martin März
- Max Planck Research Group Stem Cells & Regeneration, Max Planck Institute for Molecular Biomedicine, Von-Esmarch-Str. 54, Münster 48149, Germany.,Medical Faculty, University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany
| | - Anna-Wiebke Meyer
- Max Planck Research Group Stem Cells & Regeneration, Max Planck Institute for Molecular Biomedicine, Von-Esmarch-Str. 54, Münster 48149, Germany.,Medical Faculty, University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany
| | - Hanna Reuter
- Max Planck Research Group Stem Cells & Regeneration, Max Planck Institute for Molecular Biomedicine, Von-Esmarch-Str. 54, Münster 48149, Germany.,Medical Faculty, University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany
| | - Matthias C Vogg
- Max Planck Research Group Stem Cells & Regeneration, Max Planck Institute for Molecular Biomedicine, Von-Esmarch-Str. 54, Münster 48149, Germany.,Medical Faculty, University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany
| | - Martin Stehling
- Flow Cytometry Unit, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, Münster 48149, Germany
| | - Karina Mildner
- Electron Microscopy Unit, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, Münster 48149, Germany
| | - Dagmar Zeuschner
- Electron Microscopy Unit, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, Münster 48149, Germany
| | - Franziska Rabert
- Max Planck Research Group Stem Cells & Regeneration, Max Planck Institute for Molecular Biomedicine, Von-Esmarch-Str. 54, Münster 48149, Germany.,Medical Faculty, University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany
| | - Kerstin Bartscherer
- Max Planck Research Group Stem Cells & Regeneration, Max Planck Institute for Molecular Biomedicine, Von-Esmarch-Str. 54, Münster 48149, Germany .,Medical Faculty, University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany
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65
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Sureda-Gómez M, Martín-Durán JM, Adell T. Localization of planarian β-CATENIN-1 reveals multiple roles during anterior-posterior regeneration and organogenesis. Development 2016; 143:4149-4160. [PMID: 27737903 DOI: 10.1242/dev.135152] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 10/05/2016] [Indexed: 01/09/2023]
Abstract
The β-catenin-dependent Wnt pathway exerts multiple context-dependent roles in embryonic and adult tissues. In planarians, β-catenin-1 is thought to specify posterior identities through the generation of an anteroposterior gradient. However, the existence of such a gradient has not been directly demonstrated. Here, we use a specific polyclonal antibody to demonstrate that nuclear β-CATENIN-1 exists as an anteroposterior gradient from the pre-pharyngeal region to the tail of the planarian Schmidtea polychroa High levels in the posterior region steadily decrease towards the pre-pharyngeal region but then increase again in the head region. During regeneration, β-CATENIN-1 is nuclearized in both anterior and posterior blastemas, but the canonical WNT1 ligand only influences posterior nuclearization. Additionally, β-catenin-1 is required for proper anterior morphogenesis, consistent with the high levels of nuclear β-CATENIN-1 observed in this region. We further demonstrate that β-CATENIN-1 is abundant in developing and differentiated organs, and is particularly required for the specification of the germline. Altogether, our findings provide the first direct evidence of an anteroposterior nuclear β-CATENIN-1 gradient in adult planarians and uncover novel, context-dependent roles for β-catenin-1 during anterior regeneration and organogenesis.
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Affiliation(s)
- Miquel Sureda-Gómez
- Department of Genetics and Institute of Biomedicine, University of Barcelona, Barcelona, Catalonia E-08028, Spain
| | - José M Martín-Durán
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thørmohlensgate 55, Bergen 5008, Norway
| | - Teresa Adell
- Department of Genetics and Institute of Biomedicine, University of Barcelona, Barcelona, Catalonia E-08028, Spain
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66
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Arnold CP, Merryman MS, Harris-Arnold A, McKinney SA, Seidel CW, Loethen S, Proctor KN, Guo L, Sánchez Alvarado A. Pathogenic shifts in endogenous microbiota impede tissue regeneration via distinct activation of TAK1/MKK/p38. eLife 2016; 5. [PMID: 27441386 PMCID: PMC4993586 DOI: 10.7554/elife.16793] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 07/19/2016] [Indexed: 02/03/2023] Open
Abstract
The interrelationship between endogenous microbiota, the immune system, and tissue regeneration is an area of intense research due to its potential therapeutic applications. We investigated this relationship in Schmidtea mediterranea, a model organism capable of regenerating any and all of its adult tissues. Microbiome characterization revealed a high Bacteroidetes to Proteobacteria ratio in healthy animals. Perturbations eliciting an expansion of Proteobacteria coincided with ectopic lesions and tissue degeneration. The culture of these bacteria yielded a strain of Pseudomonas capable of inducing progressive tissue degeneration. RNAi screening uncovered a TAK1 innate immune signaling module underlying compromised tissue homeostasis and regeneration during infection. TAK1/MKK/p38 signaling mediated opposing regulation of apoptosis during infection versus normal tissue regeneration. Given the complex role of inflammation in either hindering or supporting reparative wound healing and regeneration, this invertebrate model provides a basis for dissecting the duality of evolutionarily conserved inflammatory signaling in complex, multi-organ adult tissue regeneration. DOI:http://dx.doi.org/10.7554/eLife.16793.001 Regeneration, the ability to replace missing or damaged tissue, has fascinated biologists for years and has inspired a new direction for the medical field. Figuring out how some animals easily accomplish this while others do not may help us to develop new therapies that enhance regeneration in humans. Previous work has indicated that the immune system, which is normally used to defend the body against bacteria, plays an important but complicated role in regeneration. By studying the relationships between bacteria, the immune system and regeneration in simple systems, it may be possible to see how their interactions either support or prevent the replacement of lost tissues. Flatworms called planaria can regenerate all of their tissues. Arnold et al. have now investigated what bacteria exist in planaria, how the planarian immune system responds to these bacteria, and how this response affects regeneration. The results reveal that the two main types of bacteria that are present in planaria are also found in humans. In fact, conditions that encourage the growth and spread of one of these types of bacteria (called Proteobacteria, many of which can make humans ill) damaged the worms and prevented them from regenerating. Arnold et al. then looked to see if the worms had genes that were similar to human genes that control the key immune process of inflammation, and found evidence of several such genes. Reducing the activity levels of these genes enabled worms that had been infected with Proteobacteria to regenerate again. However, these genes only seem to be responsible for regeneration when the planaria are infected with bacteria. Thus, planaria could be used as a simple model to discover how changes in resident bacteria can be detected by the immune system and affect the ability to regenerate tissues. Future studies could use planaria to identify even more genes that control regeneration during infection. Also, since the main types of bacteria in planaria are similar to those in humans, planaria may help us to learn how animals can properly balance the levels of these bacteria in order to remain healthy. DOI:http://dx.doi.org/10.7554/eLife.16793.002
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Affiliation(s)
| | - M Shane Merryman
- Stowers Institute for Medical Research, Kansas City, United States
| | | | - Sean A McKinney
- Stowers Institute for Medical Research, Kansas City, United States
| | - Chris W Seidel
- Stowers Institute for Medical Research, Kansas City, United States
| | | | | | - Longhua Guo
- Stowers Institute for Medical Research, Kansas City, United States
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67
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Morata G, Herrera SC. Cell reprogramming during regeneration in Drosophila: transgression of compartment boundaries. Curr Opin Genet Dev 2016; 40:11-16. [PMID: 27266970 DOI: 10.1016/j.gde.2016.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/11/2016] [Accepted: 05/19/2016] [Indexed: 10/21/2022]
Abstract
We discuss recent work about cellular reprogramming during regeneration of the imaginal discs of Drosophila. These contain various lineage blocks, compartments, which express distinct genetic programmes. It has been found that after massive damage to a compartment cells from a neighbour compartment can transgress the compartment border and contribute to its regeneration. The transgressing cells are genetically reprogrammed and acquire a new identity, a process facilitated by up regulation of the JNK pathway and transient loss of epigenetic control by the Pc-G and trx-G genes. The final acquisition of the new identity appears to be mediated by induction by neighbour cells, a phenomenon akin the Community Effect described for the specification of amphibian muscle cells.
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Affiliation(s)
- Ginés Morata
- Centro de Biología Molecular, CSIC-UAM, Madrid, Spain
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68
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Mi Y, Zhang C, Bu Y, Zhang Y, He L, Li H, Zhu H, Li Y, Lei Y, Zhu J. DEPDC1 is a novel cell cycle related gene that regulates mitotic progression. BMB Rep 2016; 48:413-8. [PMID: 25902835 PMCID: PMC4577292 DOI: 10.5483/bmbrep.2015.48.7.036] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Indexed: 11/20/2022] Open
Abstract
DEPDC1 is a recently identified novel tumor-related gene that is upregulated in several types of cancer and contributes to tumorigenesis. In this study, we have investigated the expression pattern and functional implications of DEPDC1 during cell cycle progression. Expression studies using synchronized cells demonstrated that DEPDC1 is highly expressed in the mitotic phase of the cell cycle. Immunofluorescence assays showed that DEPDC1 is predominantly localized in the nucleus during interphase and is redistributed into the whole cell upon nuclear membrane breakdown in metaphase. Subsequently, siRNA-mediated knockdown of DEPDC1 caused a significant mitotic arrest. Moreover, knockdown of DEPDC1 resulted in remarkable mitotic defects such as abnormal multiple nuclei and multipolar spindle structures accompanied by the upregulation of the A20 gene as well as several cell cycle-related genes such as CCNB1 and CCNB2. Taken together, our current observations strongly suggest that this novel cancerous gene, DEPDC1, plays a pivotal role in the regulation of proper mitotic progression.
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Affiliation(s)
- Yan Mi
- Department of Otolaryngology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Chundong Zhang
- Department of Biochemistry and Molecular Biology, Chongqing Medical University; Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China
| | - Youquan Bu
- Department of Biochemistry and Molecular Biology, Chongqing Medical University; Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China
| | - Ying Zhang
- Department of Biochemistry and Molecular Biology, Chongqing Medical University; Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China
| | - Longxia He
- Department of Otolaryngology, The First Affiliated Hospital of Chongqing Medical University; Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China
| | - Hongxia Li
- Department of Otolaryngology, The First Affiliated Hospital of Chongqing Medical University; Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China
| | - Huifang Zhu
- Department of Biochemistry and Molecular Biology, Chongqing Medical University; Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China
| | - Yi Li
- Department of Biochemistry and Molecular Biology, Chongqing Medical University; Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China
| | - Yunlong Lei
- Department of Biochemistry and Molecular Biology, Chongqing Medical University; Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China
| | - Jiang Zhu
- Department of Otolaryngology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
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69
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Durant F, Lobo D, Hammelman J, Levin M. Physiological controls of large-scale patterning in planarian regeneration: a molecular and computational perspective on growth and form. REGENERATION (OXFORD, ENGLAND) 2016; 3:78-102. [PMID: 27499881 PMCID: PMC4895326 DOI: 10.1002/reg2.54] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 02/18/2016] [Accepted: 02/22/2016] [Indexed: 12/12/2022]
Abstract
Planaria are complex metazoans that repair damage to their bodies and cease remodeling when a correct anatomy has been achieved. This model system offers a unique opportunity to understand how large-scale anatomical homeostasis emerges from the activities of individual cells. Much progress has been made on the molecular genetics of stem cell activity in planaria. However, recent data also indicate that the global pattern is regulated by physiological circuits composed of ionic and neurotransmitter signaling. Here, we overview the multi-scale problem of understanding pattern regulation in planaria, with specific focus on bioelectric signaling via ion channels and gap junctions (electrical synapses), and computational efforts to extract explanatory models from functional and molecular data on regeneration. We present a perspective that interprets results in this fascinating field using concepts from dynamical systems theory and computational neuroscience. Serving as a tractable nexus between genetic, physiological, and computational approaches to pattern regulation, planarian pattern homeostasis harbors many deep insights for regenerative medicine, evolutionary biology, and engineering.
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Affiliation(s)
- Fallon Durant
- Department of Biology, Allen Discovery Center at Tufts University, Tufts Center for Regenerative and Developmental BiologyTufts UniversityMA02155USA
| | - Daniel Lobo
- Department of Biological SciencesUniversity of MarylandBaltimore County, 1000 Hilltop CircleBaltimoreMD21250USA
| | - Jennifer Hammelman
- Department of Biology, Allen Discovery Center at Tufts University, Tufts Center for Regenerative and Developmental BiologyTufts UniversityMA02155USA
| | - Michael Levin
- Department of Biology, Allen Discovery Center at Tufts University, Tufts Center for Regenerative and Developmental BiologyTufts UniversityMA02155USA
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70
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Mangel M, Bonsall MB, Aboobaker A. Feedback control in planarian stem cell systems. BMC SYSTEMS BIOLOGY 2016; 10:17. [PMID: 26873593 PMCID: PMC4752765 DOI: 10.1186/s12918-016-0261-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 01/29/2016] [Indexed: 01/10/2023]
Abstract
Background In planarian flatworms, the mechanisms underlying the activity of collectively pluripotent adult stem cells (neoblasts) and their descendants can now be studied from the level of the individual gene to the entire animal. Flatworms maintain startling developmental plasticity and regenerative capacity in response to variable nutrient conditions or injury. We develop a model for cell dynamics in such animals, assuming that fully differentiated cells exert feedback control on neoblast activity. Results Our model predicts a number of whole organism level and general cell biological and behaviours, some of which have been empirically observed or inferred in planarians and others that have not. As previously observed empirically we find: 1) a curvilinear relationship between external food and planarian steady state size; 2) the fraction of neoblasts in the steady state is constant regardless of planarian size; 3) a burst of controlled apoptosis during regeneration after amputation as the number of differentiated cells are adjusted towards their homeostatic/steady state level. In addition our model describes the following properties that can inform and be tested by future experiments: 4) the strength of feedback control from differentiated cells to neoblasts (i.e. the activity of the signalling system) and from neoblasts on themselves in relation to absolute number depends upon the level of food in the environment; 5) planarians adjust size when food level reduces initially through increased apoptosis and then through a reduction in neoblast self-renewal activity; 6) following wounding or excision of differentiated cells, different time scales characterize both recovery of size and the two feedback functions; 7) the temporal pattern of feedback controls differs noticeably during recovery from a removal or neoblasts or a removal of differentiated cells; 8) the signaling strength for apoptosis of differentiated cells depends upon both the absolute and relative deviations of the number of differentiated cells from their homeostatic level; and 9) planaria prioritize resource use for cell divisions. Conclusions We offer the first analytical framework for organizing experiments on planarian flatworm stem cell dynamics in a form that allows models to be compared with quantitative cell data based on underlying molecular mechanisms and thus facilitate the interplay between empirical studies and modeling. This framework is the foundation for studying cell migration during wound repair, the determination of homeostatic levels of differentiated cells by natural selection, and stochastic effects. Electronic supplementary material The online version of this article (doi:10.1186/s12918-016-0261-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marc Mangel
- Department of Applied Mathematics and Statistics, University of California, Santa Cruz, 95064, CA, USA. .,Department of Biology, University of Bergen, Bergen, 9020, Norway.
| | | | - Aziz Aboobaker
- Department of Zoology, University of Oxford, Oxford, UK.
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71
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Pérez-Garijo A, Steller H. Spreading the word: non-autonomous effects of apoptosis during development, regeneration and disease. Development 2016; 142:3253-62. [PMID: 26443630 DOI: 10.1242/dev.127878] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Apoptosis, in contrast to other forms of cell death such as necrosis, was originally regarded as a 'silent' mechanism of cell elimination designed to degrade the contents of doomed cells. However, during the past decade it has become clear that apoptotic cells can produce diverse signals that have a profound impact on neighboring cells and tissues. For example, apoptotic cells can release factors that influence the proliferation and survival of adjacent tissues. Apoptosis can also affect tissue movement and morphogenesis by modifying tissue tension in surrounding cells. As we review here, these findings reveal unexpected roles for apoptosis in tissue remodeling during development, as well as in regeneration and cancer.
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Affiliation(s)
- Ainhoa Pérez-Garijo
- Strang Laboratory of Apoptosis and Cancer Biology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
| | - Hermann Steller
- Strang Laboratory of Apoptosis and Cancer Biology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
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72
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Abstract
The growth and patterning of anatomical structures from specific cellular fields in developing organisms relies on organizing centers that instruct surrounding cells to modify their behavior, namely migration, proliferation, and differentiation. We discuss here how organizers can form in adult organisms, a process of utmost interest for regenerative medicine. Animals like Hydra and planarians, which maintain their shape and fitness thanks to a highly dynamic homeostasis, offer a useful paradigm to study adult organizers in steady-state conditions. Beside the homeostatic context, these model systems also offer the possibility to study how organizers form de novo from somatic adult tissues. Both extracellular matrix remodeling and caspase activation play a key role in this transition, acting as promoters of organizer formation in the vicinity of the wound. Their respective roles and the crosstalk between them just start to be deciphered.
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Affiliation(s)
- Matthias C Vogg
- Department of Genetics and Evolution, Institute of Genetics and Genomics in Geneva (IGe3), Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Yvan Wenger
- Department of Genetics and Evolution, Institute of Genetics and Genomics in Geneva (IGe3), Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Brigitte Galliot
- Department of Genetics and Evolution, Institute of Genetics and Genomics in Geneva (IGe3), Faculty of Sciences, University of Geneva, Geneva, Switzerland.
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73
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Hill EM, Petersen CP. Wnt/Notum spatial feedback inhibition controls neoblast differentiation to regulate reversible growth of the planarian brain. Development 2015; 142:4217-29. [PMID: 26525673 DOI: 10.1242/dev.123612] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 10/27/2015] [Indexed: 12/20/2022]
Abstract
Mechanisms determining final organ size are poorly understood. Animals undergoing regeneration or ongoing adult growth are likely to require sustained and robust mechanisms to achieve and maintain appropriate sizes. Planarians, well known for their ability to undergo whole-body regeneration using pluripotent adult stem cells of the neoblast population, can reversibly scale body size over an order of magnitude by controlling cell number. Using quantitative analysis, we showed that after injury planarians perfectly restored brain:body proportion by increasing brain cell number through epimorphosis or decreasing brain cell number through tissue remodeling (morphallaxis), as appropriate. We identified a pathway controlling a brain size set-point that involves feedback inhibition between wnt11-6/wntA/wnt4a and notum, encoding conserved antagonistic signaling factors expressed at opposite brain poles. wnt11-6/wntA/wnt4a undergoes feedback inhibition through canonical Wnt signaling but is likely to regulate brain size in a non-canonical pathway independently of beta-catenin-1 and APC. Wnt/Notum signaling tunes numbers of differentiated brain cells in regenerative growth and tissue remodeling by influencing the abundance of brain progenitors descended from pluripotent stem cells, as opposed to regulating cell death. These results suggest that the attainment of final organ size might be accomplished by achieving a balance of positional signaling inputs that regulate the rates of tissue production.
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Affiliation(s)
- Eric M Hill
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Christian P Petersen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA Robert Lurie Comprehensive Cancer Center, Northwestern University, Evanston, IL 60208, USA
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74
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Adler CE, Sánchez Alvarado A. Types or States? Cellular Dynamics and Regenerative Potential. Trends Cell Biol 2015; 25:687-696. [PMID: 26437587 DOI: 10.1016/j.tcb.2015.07.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 07/13/2015] [Accepted: 07/29/2015] [Indexed: 01/31/2023]
Abstract
Many of our organs can maintain and repair themselves during homeostasis and injury, as a result of the action of tissue-specific, multipotent stem cells. However, recent evidence from mammalian systems suggests that injury stimulates dramatic plasticity, or transient changes in cell potential, in both stem cells and more differentiated cells. Planarian flatworms possess abundant stem cells, making them an exceptional model for understanding the cellular behavior underlying homeostasis and regeneration. Recent discoveries of cell lineages and regeneration-specific events provide an initial framework for unraveling the complex cellular contributions to regeneration. In this review, we discuss the concept of cellular plasticity in the context of planarian regeneration, and consider the possibility that pluripotency may be a transient, probabilistic state exhibited by stem cells.
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Affiliation(s)
- Carolyn E Adler
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA; Current address: Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
| | - Alejandro Sánchez Alvarado
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA; Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815-6789, USA.
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75
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Tiras HP, Gudkov SV, Emelyanenko VI, Aslanidi KB. Intrinsic chemiluminescence of neoblasts in the course of planarian regeneration. Biophysics (Nagoya-shi) 2015. [DOI: 10.1134/s000635091505022x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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76
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Taranis Protects Regenerating Tissue from Fate Changes Induced by the Wound Response in Drosophila. Dev Cell 2015; 34:119-28. [DOI: 10.1016/j.devcel.2015.04.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/25/2015] [Accepted: 04/23/2015] [Indexed: 12/15/2022]
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77
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Tejada-Romero B, Carter JM, Mihaylova Y, Neumann B, Aboobaker AA. JNK signalling is necessary for a Wnt- and stem cell-dependent regeneration programme. Development 2015; 142:2413-24. [PMID: 26062938 DOI: 10.1242/dev.115139] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 06/03/2015] [Indexed: 12/23/2022]
Abstract
Regeneration involves the integration of new and old tissues in the context of an adult life history. It is clear that the core conserved signalling pathways that orchestrate development also play central roles in regeneration, and further study of conserved signalling pathways is required. Here we have studied the role of the conserved JNK signalling cascade during planarian regeneration. Abrogation of JNK signalling by RNAi or pharmacological inhibition blocks posterior regeneration and animals fail to express posterior markers. While the early injury-induced expression of polarity markers is unaffected, the later stem cell-dependent phase of posterior Wnt expression is not established. This defect can be rescued by overactivation of the Hh or Wnt signalling pathway to promote posterior Wnt activity. Together, our data suggest that JNK signalling is required to establish stem cell-dependent Wnt expression after posterior injury. Given that Jun is known to be required in vertebrates for the expression of Wnt and Wnt target genes, we propose that this interaction may be conserved and is an instructive part of planarian posterior regeneration.
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Affiliation(s)
- Belen Tejada-Romero
- Department of Zoology, Tinbergen Building, South Parks Road, University of Oxford, Oxford OX1 3PS, UK
| | - Jean-Michel Carter
- Department of Zoology, Tinbergen Building, South Parks Road, University of Oxford, Oxford OX1 3PS, UK
| | - Yuliana Mihaylova
- Department of Zoology, Tinbergen Building, South Parks Road, University of Oxford, Oxford OX1 3PS, UK
| | - Bjoern Neumann
- Department of Zoology, Tinbergen Building, South Parks Road, University of Oxford, Oxford OX1 3PS, UK
| | - A Aziz Aboobaker
- Department of Zoology, Tinbergen Building, South Parks Road, University of Oxford, Oxford OX1 3PS, UK
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78
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Correction: JNK controls the onset of mitosis in planarian stem cells and triggers apoptotic cell death required for regeneration and remodeling. PLoS Genet 2015; 11:e1005132. [PMID: 25860912 PMCID: PMC4393315 DOI: 10.1371/journal.pgen.1005132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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