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Rojas S, Barghouth PG, Karabinis P, Oviedo NJ. The DNA Methyltransferase DMAP1 is Required for Tissue Maintenance and Planarian Regeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.10.588909. [PMID: 38645093 PMCID: PMC11030423 DOI: 10.1101/2024.04.10.588909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
The precise regulation of transcription is required for embryonic development, adult tissue turnover, and regeneration. Epigenetic modifications play a crucial role in orchestrating and regulating the transcription of genes. These modifications are important in the transition of pluripotent stem cells and their progeny. Methylation, a key epigenetic modification, influences gene expression through changes in histone tails and direct DNA methylation. Work in different organisms has shown that the DNA methyltransferase-1-associated protein (DMAP1) may associate with other molecules to repress transcription through DNA methylation. Thus, DMAP1 is a versatile protein implicated in a myriad of events, including pluripotency maintenance, DNA damage repair, and tumor suppression. While DMAP1 has been extensively studied in vitro, its complex regulation in the context of the adult organism remains unclear. To gain insights into the possible roles of DMAP1 at the organismal level, we used planarian flatworms that possess remarkable regenerative capabilities driven by pluripotent stem cells called neoblast. Our findings demonstrate the evolutionary conservation of DMAP1 in the planarian Schmidtea mediterranea. Functional disruption of DMAP1 through RNA interference revealed its critical role in tissue maintenance, neoblast differentiation, and regeneration in S. mediterranea. Moreover, our analysis unveiled a novel function for DMAP1 in regulating cell death in response to DNA damage and influencing the expression of axial polarity markers. Our findings provide a simplified paradigm for studying DMAP1's epigenetic regulation in adult tissues.
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Affiliation(s)
- Salvador Rojas
- Department of Molecular & Cell Biology, University of California, Merced, CA, 95343
| | - Paul G. Barghouth
- Department of Molecular & Cell Biology, University of California, Merced, CA, 95343
| | - Peter Karabinis
- Department of Molecular & Cell Biology, University of California, Merced, CA, 95343
| | - Néstor J. Oviedo
- Department of Molecular & Cell Biology, University of California, Merced, CA, 95343
- Health Sciences Research Institute, University of California, Merced, CA, 95343
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2
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Davidian D, LeGro M, Barghouth PG, Rojas S, Ziman B, Maciel EI, Ardell D, Escobar AL, Oviedo NJ. Restoration of DNA integrity and cell cycle by electric stimulation in planarian tissues damaged by ionizing radiation. J Cell Sci 2022; 135:274829. [PMID: 35322853 PMCID: PMC9264365 DOI: 10.1242/jcs.259304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 03/05/2022] [Indexed: 10/18/2022] Open
Abstract
Exposure to high levels of ionizing γ-radiation leads to irreversible DNA damage and cell death. Here, we establish that exogenous application of electric stimulation enables cellular plasticity to reestablish stem cell activity in tissues damaged by ionizing radiation. We show that sub-threshold direct current stimulation (DCS) rapidly restores pluripotent stem cell populations previously eliminated by lethally γ-irradiated tissues of the planarian flatworm Schmidtea mediterranea. Our findings reveal that DCS enhances DNA repair, transcriptional activity, and cell cycle entry in post-mitotic cells. These responses involve rapid increases in cytosolic [Ca2+] through the activation of L-type Cav channels and intracellular Ca2+ stores leading to the activation of immediate early genes and ectopic expression of stem cell markers in postmitotic cells. Overall, we show the potential of electric current stimulation to reverse the damaging effects of high dose γ-radiation in adult tissues. Furthermore, our results provide mechanistic insights describing how electric stimulation effectively translates into molecular responses capable of regulating fundamental cellular functions without the need for genetic or pharmacological intervention.
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Affiliation(s)
- Devon Davidian
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Melanie LeGro
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Paul G Barghouth
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Salvador Rojas
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Benjamin Ziman
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Eli Isael Maciel
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - David Ardell
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Health Sciences Research Institute, University of California, Merced, USA
| | - Ariel L Escobar
- Department of Bioengineering, University of California, Merced, USA.,Health Sciences Research Institute, University of California, Merced, USA
| | - Néstor J Oviedo
- Department of Molecular & Cell Biology, University of California, Merced, USA.,Health Sciences Research Institute, University of California, Merced, USA
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3
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Barghouth PG, Rojas S, O'Dell LR, Betancourt AM, Oviedo NJ. Analysis of DNA Double-Stranded Breaks Using the Comet Assay in Planarians. Methods Mol Biol 2022; 2450:479-491. [PMID: 35359324 PMCID: PMC9761910 DOI: 10.1007/978-1-0716-2172-1_25] [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: 06/14/2023]
Abstract
Comet assay provides the opportunity to detect and characterize DNA strand breaks. Cellular lysing followed by embedding in agarose slide is used to visualize under an electrical current migration patterns corresponding to DNA fragments of different sizes. Here we describe the process of detecting and characterizing DNA damage by Comet assay on planarians, which is a model organism commonly used to understand the process of whole-body regeneration, stem cell regulation, and adult tissue maintenance.
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Affiliation(s)
- Paul G Barghouth
- Department of Molecular & Cell Biology, University of California, Merced, CA, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA, USA
| | - Salvador Rojas
- Department of Molecular & Cell Biology, University of California, Merced, CA, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA, USA
| | - Lacey R O'Dell
- Department of Molecular & Cell Biology, University of California, Merced, CA, USA
| | - Andrew M Betancourt
- Department of Molecular & Cell Biology, University of California, Merced, CA, USA
| | - Néstor J Oviedo
- Department of Molecular & Cell Biology, University of California, Merced, CA, USA.
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA, USA.
- Health Sciences Research Institute, University of California, Merced, CA, USA.
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4
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Sahu S, Sridhar D, Abnave P, Kosaka N, Dattani A, Thompson JM, Hill MA, Aboobaker A. Ongoing repair of migration-coupled DNA damage allows planarian adult stem cells to reach wound sites. eLife 2021; 10:e63779. [PMID: 33890575 PMCID: PMC8104965 DOI: 10.7554/elife.63779] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 04/22/2021] [Indexed: 12/21/2022] Open
Abstract
Mechanical stress during cell migration may be a previously unappreciated source of genome instability, but the extent to which this happens in any animal in vivo remains unknown. We consider an in vivo system where the adult stem cells of planarian flatworms are required to migrate to a distal wound site. We observe a relationship between adult stem cell migration and ongoing DNA damage and repair during tissue regeneration. Migrating planarian stem cells undergo changes in nuclear shape and exhibit increased levels of DNA damage. Increased DNA damage levels reduce once stem cells reach the wound site. Stem cells in which DNA damage is induced prior to wounding take longer to initiate migration and migrating stem cell populations are more sensitive to further DNA damage than stationary stem cells. RNAi-mediated knockdown of DNA repair pathway components blocks normal stem cell migration, confirming that active DNA repair pathways are required to allow successful migration to a distal wound site. Together these findings provide evidence that levels of migration-coupled-DNA-damage are significant in adult stem cells and that ongoing migration requires DNA repair mechanisms. Our findings reveal that migration of normal stem cells in vivo represents an unappreciated source of damage, which could be a significant source of mutations in animals during development or during long-term tissue homeostasis.
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Affiliation(s)
- Sounak Sahu
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - Divya Sridhar
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - Prasad Abnave
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | | | - Anish Dattani
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - James M Thompson
- CRUK/MRC Oxford Institute for Radiation Oncology, ORCRB Roosevelt Drive, University of OxfordOxfordUnited Kingdom
| | - Mark A Hill
- CRUK/MRC Oxford Institute for Radiation Oncology, ORCRB Roosevelt Drive, University of OxfordOxfordUnited Kingdom
| | - Aziz Aboobaker
- Department of Zoology, University of OxfordOxfordUnited Kingdom
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5
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Whole planarian chromosome squash. STAR Protoc 2021; 2:100257. [PMID: 33490976 PMCID: PMC7809184 DOI: 10.1016/j.xpro.2020.100257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Whole planarian chromosome squash allows researchers to qualitatively analyze chromosome integrity. Treatment with colchicine is used to halt dividing cells within metaphase and does not require amputation or tissue puncturing. In combination with acetic-orcein, a stain-fixative for chromosomes, this strategy is suitable for animals with friable tissues caused by drug treatment, radiation, and RNA interference phenotypes. The whole planarian squash method presented here is a minimally invasive procedure that facilitates simultaneous analysis of chromosomal integrity in control and experimental animals. For complete details on the use and execution of this protocol, please refer to Peiris et al. (2016).
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6
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Davidian D, Ziman B, Escobar AL, Oviedo NJ. Direct Current Electric Stimulation Alters the Frequency and the Distribution of Mitotic Cells in Planarians. Bioelectricity 2021; 3:77-91. [PMID: 34476379 DOI: 10.1089/bioe.2020.0026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Background: The use of direct current electric stimulation (DCS) is an effective strategy to treat disease and enhance body functionality. Thus, treatment with DCS is an attractive biomedical alternative, but the molecular underpinnings remain mostly unknown. The lack of experimental models to dissect the effects of DCS from molecular to organismal levels is an important caveat. Here, we introduce the planarian flatworm Schmidtea mediterranea as a tractable organism for in vivo studies of DCS. We developed an experimental method that facilitates the application of direct current electrical stimulation to the whole planarian body (pDCS). Materials and Methods: Planarian immobilization was achieved by combining treatment with anesthesia, agar embedding, and low temperature via a dedicated thermoelectric cooling unit. Electric currents for pDCS were delivered using pulled glass microelectrodes. The electric potential was supplied through a constant voltage power supply. pDCS was administered up to six hours, and behavioral and molecular effects were measured by using video recordings, immunohistochemistry, and gene expression analysis. Results: The behavioral immobilization effects are reversible, and pDCS resulted in a redistribution of mitotic cells along the mediolateral axis of the planarian body. The pDCS effects were dependent on the polarity of the electric field, which led to either increase in reductions in mitotic densities associated with the time of pDCS. The changes in mitotic cells were consistent with apparent redistribution in gene expression of the stem cell marker smedwi-1. Conclusion: The immobilization technique presented in this work facilitates studies aimed at dissecting the effects of exogenous electric stimulation in the adult body. Treatment with DCS can be administered for varying times, and the consequences evaluated at different levels, including animal behavior, cellular and transcriptional changes. Indeed, treatment with pDCS can alter cellular and transcriptional parameters depending on the polarity of the electric field and duration of the exposure.
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Affiliation(s)
- Devon Davidian
- Department of Molecular & Cell Biology and University of California Merced, Merced, California, USA
| | - Benjamin Ziman
- Department of Molecular & Cell Biology and University of California Merced, Merced, California, USA
| | - Ariel L Escobar
- Department of Bioengineering, University of California Merced, Merced, California, USA
| | - Néstor J Oviedo
- Department of Molecular & Cell Biology and University of California Merced, Merced, California, USA
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7
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Ziman B, Barghouth PG, Maciel EI, Oviedo NJ. TRAF-like Proteins Regulate Cellular Survival in the Planarian Schmidtea mediterranea. iScience 2020; 23:101665. [PMID: 33134895 PMCID: PMC7586133 DOI: 10.1016/j.isci.2020.101665] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 07/31/2020] [Accepted: 10/07/2020] [Indexed: 12/12/2022] Open
Abstract
Tissue homeostasis relies on the timely renewal of cells that have been damaged or have surpassed their biological age. Nonetheless, the underlying molecular mechanism coordinating tissue renewal is unknown. The planarian Schmidtea mediterranea harbors a large population of stem cells that continuously divide to support the restoration of tissues throughout the body. Here, we identify that TNF Receptor Associated Factors (TRAFs) play critical roles in cellular survival during tissue repair in S. mediterranea. Disruption with RNA-interference of TRAF signaling results in rapid morphological defects and lethality within 2 weeks. The TRAF phenotype is accompanied by an increased number of mitoses and cell death. Our results also reveal TRAF signaling is required for proper regeneration of the nervous system. Taken together, we find functional conservation of TRAF-like proteins in S. mediterranea as they act as crucial regulators of cellular survival during tissue homeostasis and regeneration.
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Affiliation(s)
- Benjamin Ziman
- Department of Molecular and Cell Biology, University of California, Merced, CA 95343, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA 95343, USA
| | - Paul G. Barghouth
- Department of Molecular and Cell Biology, University of California, Merced, CA 95343, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA 95343, USA
| | - Eli Isael Maciel
- Department of Molecular and Cell Biology, University of California, Merced, CA 95343, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA 95343, USA
| | - Néstor J. Oviedo
- Department of Molecular and Cell Biology, University of California, Merced, CA 95343, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA 95343, USA
- Health Sciences Research Institute, University of California, Merced, CA 95343, USA
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8
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Salvetti A, Gambino G, Rossi L, De Pasquale D, Pucci C, Linsalata S, Degl'Innocenti A, Nitti S, Prato M, Ippolito C, Ciofani G. Stem cell and tissue regeneration analysis in low-dose irradiated planarians treated with cerium oxide nanoparticles. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 115:111113. [DOI: 10.1016/j.msec.2020.111113] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/17/2020] [Accepted: 05/20/2020] [Indexed: 12/21/2022]
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9
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Shiroor DA, Bohr TE, Adler CE. Injury Delays Stem Cell Apoptosis after Radiation in Planarians. Curr Biol 2020; 30:2166-2174.e3. [PMID: 32386527 DOI: 10.1016/j.cub.2020.03.054] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 02/17/2020] [Accepted: 03/20/2020] [Indexed: 12/31/2022]
Abstract
Stem cells are continuously exposed to multiple stresses, including radiation and tissue injury. As central drivers of tissue repair and regeneration, it is necessary to understand how their behavior is influenced by these stressors. Planarians have an abundant population of stem cells that are rapidly eliminated after radiation exposure via apoptosis. Low doses of radiation eliminate the majority of these stem cells, allowing a few to remain [1]. Here, we combine radiation with injury to define how stem cells respond to tissue damage. We find that a variety of injuries induced within a defined window of time surrounding radiation cause stem cells to outlast those in uninjured animals. Injury stimulates localized cell death adjacent to wounds [2], in the same regions where stem cells persist. This persistence occurs in the absence of proliferation. Instead, stem cells are retained near the wound due to delayed apoptosis, which we quantify by combining fluorescence-activated cell sorting (FACS) with annexin V staining. Pharmacological inhibition of the mitogen-activated protein (MAP) kinase extracellular signal-regulated kinase (ERK) prevents stem cell persistence after injury, implicating wound-induced ERK activity in this response. By combining radiation with injury, our work reveals a novel connection between dying cells and stem cells that remain. Furthermore, the ability to induce stem cell persistence after radiation provides a paradigm to study mechanisms that may contribute to unanticipated consequences of injury, such as tumorigenesis.
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Affiliation(s)
- Divya A Shiroor
- Department of Molecular Medicine, Cornell University of Veterinary Medicine, 930 Campus Road, Ithaca, NY 14853, USA
| | - Tisha E Bohr
- Department of Molecular Medicine, Cornell University of Veterinary Medicine, 930 Campus Road, Ithaca, NY 14853, USA
| | - Carolyn E Adler
- Department of Molecular Medicine, Cornell University of Veterinary Medicine, 930 Campus Road, Ithaca, NY 14853, USA.
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10
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Wouters A, Ploem JP, Langie SAS, Artois T, Aboobaker A, Smeets K. Regenerative responses following DNA damage - β-catenin mediates head regrowth in the planarian Schmidtea mediterranea. J Cell Sci 2020; 133:jcs237545. [PMID: 32107291 DOI: 10.1242/jcs.237545] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 02/09/2020] [Indexed: 12/12/2022] Open
Abstract
Pluripotent stem cells hold great potential for regenerative medicine. Increased replication and division, such is the case during regeneration, concomitantly increases the risk of adverse outcomes through the acquisition of mutations. Seeking for driving mechanisms of such outcomes, we challenged a pluripotent stem cell system during the tightly controlled regeneration process in the planarian Schmidtea mediterranea Exposure to the genotoxic compound methyl methanesulfonate (MMS) revealed that despite a similar DNA-damaging effect along the anteroposterior axis of intact animals, responses differed between anterior and posterior fragments after amputation. Stem cell proliferation and differentiation proceeded successfully in the amputated heads, leading to regeneration of missing tissues. Stem cells in the amputated tails showed decreased proliferation and differentiation capacity. As a result, tails could not regenerate. Interference with the body-axis-associated component β-catenin-1 increased regenerative success in tail fragments by stimulating proliferation at an early time point. Our results suggest that differences in the Wnt signalling gradient along the body axis modulate stem cell responses to MMS.
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Affiliation(s)
- Annelies Wouters
- Zoology, Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Jan-Pieter Ploem
- Zoology, Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Sabine A S Langie
- Vito Health, 2400 Mol, Belgium
- Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Tom Artois
- Zoology, Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Aziz Aboobaker
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Karen Smeets
- Zoology, Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
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11
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Barghouth PG, Karabinis P, Venegas A, Oviedo NJ. Poly(ADP-Ribose) Polymerase-3 Regulates Regeneration in Planarians. Int J Mol Sci 2020; 21:E875. [PMID: 32013251 PMCID: PMC7038108 DOI: 10.3390/ijms21030875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 01/27/2020] [Indexed: 11/20/2022] Open
Abstract
Protein ADP-ribosylation is a reversible post-translational modification (PTM) process that plays fundamental roles in cell signaling. The covalent attachment of ADP ribose polymers is executed by PAR polymerases (PARP) and it is essential for chromatin organization, DNA repair, cell cycle, transcription, and replication, among other critical cellular events. The process of PARylation or polyADP-ribosylation is dynamic and takes place across many tissues undergoing renewal and repair, but the molecular mechanisms regulating this PTM remain mostly unknown. Here, we introduce the use of the planarian Schmidtea mediterranea as a tractable model to study PARylation in the complexity of the adult body that is under constant renewal and is capable of regenerating damaged tissues. We identified the evolutionary conservation of PARP signaling that is expressed in planarian stem cells and differentiated tissues. We also demonstrate that Smed-PARP-3 homolog is required for proper regeneration of tissues in the anterior region of the animal. Furthermore, our results demonstrate, Smed-PARP-3(RNAi) disrupts the timely location of injury-induced cell death near the anterior facing wounds and also affects the regeneration of the central nervous system. Our work reveals novel roles for PARylation in large-scale regeneration and provides a simplified platform to investigate PARP signaling in the complexity of the adult body.
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Affiliation(s)
- Paul G. Barghouth
- Department of Molecular and Cell Biology, University of California, Merced, CA 95340, USA; (P.G.B.); (P.K.); (A.V.)
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA 95340, USA
| | - Peter Karabinis
- Department of Molecular and Cell Biology, University of California, Merced, CA 95340, USA; (P.G.B.); (P.K.); (A.V.)
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA 95340, USA
| | - Andie Venegas
- Department of Molecular and Cell Biology, University of California, Merced, CA 95340, USA; (P.G.B.); (P.K.); (A.V.)
| | - Néstor J. Oviedo
- Department of Molecular and Cell Biology, University of California, Merced, CA 95340, USA; (P.G.B.); (P.K.); (A.V.)
- Quantitative and Systems Biology Graduate Program, University of California, Merced, CA 95340, USA
- Health Sciences Research Institute, University of California, Merced, CA 95340, USA
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12
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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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13
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Ermakov AM, Ermakova ON, Popov AL, Manokhin AA, Ivanov VK. Opposite effects of low intensity light of different wavelengths on the planarian regeneration rate. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2019; 202:111714. [PMID: 31830733 DOI: 10.1016/j.jphotobiol.2019.111714] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 10/11/2019] [Accepted: 11/14/2019] [Indexed: 02/06/2023]
Abstract
Planarian freshwater flatworms have the unique ability to regenerate due to stem cell activity. The process of regeneration is extremely sensitive to various factors, including light radiation. Here, the effect of low-intensity LED light of different wavelengths on regeneration, stem cell proliferation and gene expression associated with these processes was studied. LED matrices with different wavelengths (red (λmax = 635 nm), green (λmax = 520 nm) and blue (λmax = 463 nm), as well as LED laser diodes (red (λmax = 638.5 nm), green (λmax = 533 nm) and blue (λmax = 420 nm), were used in the experiments. Computer-assisted morphometry, whole-mount immunocytochemical study and RT-PCR were used to analyze the biological effects of LED light exposure on the planarian regeneration in vivo. It was found that a one-time exposure of regenerating planarians with low-intensity red light diodes stimulated head blastema growth in a dose-dependent manner (up to 40%). The green light exposure of planarians resulted in the opposite effect, showing a reduced head blastema growth rate by up to 21%. The blue light exposure did not lead to any changes in the rate of head blastema growth. The maximum effects of light exposure were observed at a dose of 175.2 mJ/cm2. No significant differences were revealed in the dynamics of neoblasts' (planarian stem cells) proliferation under red and green light exposure. However, the RT-PCR gene expression analysis of 46 wound-induced genes revealed their up-regulation upon red LED light exposure, and down-regulation upon green light exposure. Thus, we have demonstrated that the planarian regeneration process is rather sensitive to the effects of low-intensity light radiation of certain wavelengths, the biological activity of red and green light being dictated by the different expression of the genes regulating transcriptional activity.
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Affiliation(s)
- A M Ermakov
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia
| | - O N Ermakova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia
| | - A L Popov
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia
| | - A A Manokhin
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Oblast 142290, Russia
| | - V K Ivanov
- Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia.
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14
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Maciel EI, Jiang C, Barghouth PG, Nobile CJ, Oviedo NJ. The planarian Schmidtea mediterranea is a new model to study host-pathogen interactions during fungal infections. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2019; 93:18-27. [PMID: 30571995 PMCID: PMC6333478 DOI: 10.1016/j.dci.2018.12.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/07/2018] [Accepted: 12/11/2018] [Indexed: 05/06/2023]
Abstract
Candida albicans is one of the most common fungal pathogens of humans. Currently, there are limitations in the evaluation of C. albicans infection in existing animal models, especially in terms of understanding the influence of specific infectious stages of the fungal pathogen on the host. We show that C. albicans infects, grows and invades tissues in the planarian flatworm Schmidtea mediterranea, and that the planarian responds to infection by activating components of the host innate immune system to clear and repair host tissues. We study different stages of C. albicans infection and demonstrate that planarian stem cells increase division in response to fungal infection, a process that is likely evolutionarily conserved in metazoans. Our results implicate MORN2 and TAK1/p38 signaling pathways as possible mediators of the host innate immune response to fungal infection. We propose the use of planarians as a model system to investigate host-pathogen interactions during fungal infections.
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Affiliation(s)
- Eli Isael Maciel
- Department of Molecular & Cell Biology, University of California, Merced, USA; Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Cen Jiang
- Department of Molecular & Cell Biology, University of California, Merced, USA; Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Paul G Barghouth
- Department of Molecular & Cell Biology, University of California, Merced, USA; Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Clarissa J Nobile
- Department of Molecular & Cell Biology, University of California, Merced, USA; Health Sciences Research Institute, University of California, Merced, USA.
| | - Néstor J Oviedo
- Department of Molecular & Cell Biology, University of California, Merced, USA; Health Sciences Research Institute, University of California, Merced, USA.
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15
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Stevens AS, Wouters A, Ploem JP, Pirotte N, Van Roten A, Willems M, Hellings N, Franken C, Koppen G, Artois T, Plusquin M, Smeets K. Planarians Customize Their Stem Cell Responses Following Genotoxic Stress as a Function of Exposure Time and Regenerative State. Toxicol Sci 2019; 162:251-263. [PMID: 29145667 DOI: 10.1093/toxsci/kfx247] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Aiming to in vivo characterize the responses of pluripotent stem cells and regenerative tissues to carcinogenic stress, we employed the highly regenerative organism Schmidtea mediterranea. Its broad regenerative capacities are attributable to a large pool of pluripotent stem cells, which are considered key players in the lower vulnerability toward chemically induced carcinogenesis observed in regenerative organisms. Schmidtea mediterranea is, therefore, an ideal model to study pluripotent stem cell responses with stem cells residing in their natural environment. Including microenvironmental alterations is important, as the surrounding niche influences the onset of oncogenic events. Both short- (3 days) and long-term (17 days) exposures to the genotoxic carcinogen methyl methanesulfonate (50 µM) were evaluated during homeostasis and animal regeneration, two situations that render altered cellular niches. In both cases, MMS-induced DNA damage was observed, which provoked a decrease in proliferation on the short term. The outcome of DNA damage responses following long-term exposure differed between homeostatic and regenerating animals. During regeneration, DNA repair systems were more easily activated than in animals in homeostasis, where apoptosis was an important outcome. Knockdown experiments confirmed the importance of DNA repair systems during carcinogenic exposure in regenerating animals as knockdown of rad51 induced a stem cell-depleted phenotype, after regeneration was completed.
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Affiliation(s)
- An-Sofie Stevens
- Zoology: Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Annelies Wouters
- Zoology: Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Jan-Pieter Ploem
- Zoology: Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Nicky Pirotte
- Zoology: Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Andromeda Van Roten
- Zoology: Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Maxime Willems
- Laboratory of Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Ghent University, 9000 Ghent, Belgium.,Laboratory of Environmental Toxicology & Aquatic Ecology, Ghent University, 9000 Ghent, Belgium
| | - Niels Hellings
- Biomedical Research Institute, Hasselt University, 3590 Diepenbeek, Belgium
| | - Carmen Franken
- Environmental Risk and Health Unit, Flemish Institute for Technological Research (VITO), 2400 Mol, Belgium
| | - Gudrun Koppen
- Environmental Risk and Health Unit, Flemish Institute for Technological Research (VITO), 2400 Mol, Belgium
| | - Tom Artois
- Zoology: Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Michelle Plusquin
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Karen Smeets
- Zoology: Biodiversity and Toxicology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium
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16
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DNA damage and tissue repair: What we can learn from planaria. Semin Cell Dev Biol 2018; 87:145-159. [PMID: 29727725 DOI: 10.1016/j.semcdb.2018.04.013] [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: 01/30/2018] [Revised: 04/22/2018] [Accepted: 04/30/2018] [Indexed: 12/21/2022]
Abstract
Faithful renewal of aging and damaged tissues is central to organismal lifespan. Stem cells (SCs) generate the cellular progeny that replenish adult tissues across the body but this task becomes increasingly compromised over time. The age related decline in SC-mediated tissue maintenance is a multifactorial event that commonly affects genome integrity. The presence of DNA damage in SCs that are under continuous demand to divide poses a great risk for age-related disorders such as cancer. However, performing analysis of SCs with genomic instability and the DNA damage response during tissue renewal present significant challenges. Here we introduce an alternative experimental system based on the planaria flatworm Schmidtea mediterranea to address at the organismal level studies intersecting SC-mediated tissue renewal in the presence of genomic instability. Planaria have abundant SCs (neoblasts) that maintain high rates of cellular turnover and a variety of molecular tools have been developed to induce DNA damage and dissect how neoblasts respond to this stressor. S. mediterranea displays high evolutionary conservation of DNA repair mechanisms and signaling pathways regulating adult SCs. We describe genetically induced-DNA damage models and highlight body-wide signals affecting cellular decisions such as survival, proliferation, and death in the presence of genomic instability. We also discuss transcriptomic changes in the DNA damage response during injury repair and propose DNA repair as key component of tissue regeneration. Additional studies using planaria will provide insights about mechanisms regulating survival and growth of cells with DNA damage during tissue renewal and regeneration.
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17
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Thiruvalluvan M, Barghouth PG, Tsur A, Broday L, Oviedo NJ. SUMOylation controls stem cell proliferation and regional cell death through Hedgehog signaling in planarians. Cell Mol Life Sci 2018; 75:1285-1301. [PMID: 29098326 PMCID: PMC7083543 DOI: 10.1007/s00018-017-2697-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 10/21/2017] [Accepted: 10/24/2017] [Indexed: 12/15/2022]
Abstract
Mechanisms underlying anteroposterior body axis differences during adult tissue maintenance and regeneration are poorly understood. Here, we identify that post-translational modifications through the SUMO (Small Ubiquitin-like Modifier) machinery are evolutionarily conserved in the Lophotrocozoan Schmidtea mediterranea. Disruption of SUMOylation in adult animals by RNA-interference of the only SUMO E2 conjugating enzyme Ubc9 leads to a systemic increase in DNA damage and a remarkable regional defect characterized by increased cell death and loss of the posterior half of the body. We identified that Ubc9 is mainly expressed in planarian stem cells (neoblasts) but it is also transcribed in differentiated cells including neurons. Regeneration in Ubc9(RNAi) animals is impaired and associated with low neoblast proliferation. We present evidence indicating that Ubc9-induced regional cell death is preceded by alterations in transcription and spatial expression of repressors and activators of the Hedgehog signaling pathway. Our results demonstrate that SUMOylation acts as a regional-specific cue to regulate cell fate during tissue renewal and regeneration.
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Affiliation(s)
- Manish Thiruvalluvan
- Department of Molecular and Cell Biology, University of California, 5200 North Lake Road, Merced, CA, 95343, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Paul G Barghouth
- Department of Molecular and Cell Biology, University of California, 5200 North Lake Road, Merced, CA, 95343, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, USA
| | - Assaf Tsur
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Limor Broday
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Néstor J Oviedo
- Department of Molecular and Cell Biology, University of California, 5200 North Lake Road, Merced, CA, 95343, USA.
- Quantitative and Systems Biology Graduate Program, University of California, Merced, USA.
- Health Sciences Research Institute, University of California, Merced, USA.
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18
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Alam MS, Moriyama H, Matsumoto M. Inhibition of Dr-dut gene causes DNA damage in planarian. Mol Reprod Dev 2018; 85:188-196. [PMID: 29405473 DOI: 10.1002/mrd.22952] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 12/27/2017] [Indexed: 02/02/2023]
Abstract
The DUT gene encodes Deoxyuridine triphosphatase (dUTPase), which is involved in nucleotide metabolism. dUTPase prevents uracil misincorporation in DNA by balancing the intracellular ratio between dUTP and dTTP. This study aimed to investigate the role of Dr-dut gene in the planarian Dugesia ryukyuensis by assessing the consequences of Dr-dut silencing on known phenomena, including regeneration following amputation and radiation damage. We functionally disrupted planarian Dr-dut mRNA by feeding RNAi-containing food to animals. Dr-dut RNAi resulted in the death of planarians in 28 days, and elevated double-stranded DNA breakage. Expression of the DNA damage response gene Dr-atm and the DNA repair genes Dr-rad51 and Dr-rad51c temporarily increased, and then decreased following the onset of feeding. When RNAi-treated planarians were amputated, both head and tail parts failed to regenerate, and the animals died in 25 and 29 days, respectively. Administration of 5-fluorouracil (5-FU) also resulted in death and DNA damage, and synergistically caused higher genotoxicity in planarian fed Dr-dut RNAi-containing food.
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Affiliation(s)
- Md Shahanoor Alam
- Department of Bioscience and Informatics, Keio University, Yokohama, Kanagawa, Japan
| | - Hideaki Moriyama
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Midori Matsumoto
- Department of Bioscience and Informatics, Keio University, Yokohama, Kanagawa, Japan
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19
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Levin M, Martyniuk CJ. The bioelectric code: An ancient computational medium for dynamic control of growth and form. Biosystems 2018; 164:76-93. [PMID: 28855098 PMCID: PMC10464596 DOI: 10.1016/j.biosystems.2017.08.009] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/20/2017] [Accepted: 08/22/2017] [Indexed: 12/19/2022]
Abstract
What determines large-scale anatomy? DNA does not directly specify geometrical arrangements of tissues and organs, and a process of encoding and decoding for morphogenesis is required. Moreover, many species can regenerate and remodel their structure despite drastic injury. The ability to obtain the correct target morphology from a diversity of initial conditions reveals that the morphogenetic code implements a rich system of pattern-homeostatic processes. Here, we describe an important mechanism by which cellular networks implement pattern regulation and plasticity: bioelectricity. All cells, not only nerves and muscles, produce and sense electrical signals; in vivo, these processes form bioelectric circuits that harness individual cell behaviors toward specific anatomical endpoints. We review emerging progress in reading and re-writing anatomical information encoded in bioelectrical states, and discuss the approaches to this problem from the perspectives of information theory, dynamical systems, and computational neuroscience. Cracking the bioelectric code will enable much-improved control over biological patterning, advancing basic evolutionary developmental biology as well as enabling numerous applications in regenerative medicine and synthetic bioengineering.
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Affiliation(s)
- Michael Levin
- Allen Discovery Center at Tufts University, Biology Department, Tufts University, 200 Boston Avenue, Suite 4600 Medford, MA 02155, USA.
| | - Christopher J Martyniuk
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida Genetics Institute, Interdisciplinary Program in Biomedical Sciences Neuroscience, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611, USA
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20
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Guo Q, Zhao G, Ni J, Guo Y, Zhang Y, Tian Q, Zhang S. Down-regulate of Djrfc2 causes tissues hypertrophy during planarian regeneration. Biochem Biophys Res Commun 2017; 493:1224-1229. [DOI: 10.1016/j.bbrc.2017.09.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 09/07/2017] [Indexed: 01/13/2023]
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21
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Sahu S, Dattani A, Aboobaker AA. Secrets from immortal worms: What can we learn about biological ageing from the planarian model system? Semin Cell Dev Biol 2017; 70:108-121. [PMID: 28818620 DOI: 10.1016/j.semcdb.2017.08.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 08/07/2017] [Accepted: 08/09/2017] [Indexed: 12/12/2022]
Abstract
Understanding how some animals are immortal and avoid the ageing process is important. We currently know very little about how they achieve this. Research with genetic model systems has revealed the existence of conserved genetic pathways and molecular processes that affect longevity. Most of these established model organisms have relatively short lifespans. Here we consider the use of planarians, with an immortal life-history that is able to entirely avoid the ageing process. These animals are capable of profound feats of regeneration fueled by a population of adult stem cells called neoblasts. These cells are capable of indefinite self-renewal that has underpinned the evolution of animals that reproduce only by fission, having disposed of the germline, and must therefore be somatically immortal and avoid the ageing process. How they do this is only now starting to be understood. Here we suggest that the evidence so far supports the hypothesis that the lack of ageing is an emergent property of both being highly regenerative and the evolution of highly effective mechanisms for ensuring genome stability in the neoblast stem cell population. The details of these mechanisms could prove to be very informative in understanding how the causes of ageing can be avoided, slowed or even reversed.
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Affiliation(s)
- Sounak Sahu
- Department of Zoology, South Parks Road, University of Oxford, Oxford OX1 3PS, UK
| | - Anish Dattani
- Department of Zoology, South Parks Road, University of Oxford, Oxford OX1 3PS, UK
| | - A Aziz Aboobaker
- Department of Zoology, South Parks Road, University of Oxford, Oxford OX1 3PS, UK.
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22
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Voura EB, Montalvo MJ, Dela Roca KT, Fisher JM, Defamie V, Narala SR, Khokha R, Mulligan ME, Evans CA. Planarians as models of cadmium-induced neoplasia provide measurable benchmarks for mechanistic studies. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2017; 142:544-554. [PMID: 28482323 DOI: 10.1016/j.ecoenv.2017.04.044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 04/02/2017] [Accepted: 04/19/2017] [Indexed: 06/07/2023]
Abstract
Bioassays of planarian neoplasia highlight the potential of these organisms as useful standards to assess whether environmental toxins such as cadmium promote tumorigenesis. These studies complement other investigations into the exceptional healing and regeneration of planarians - processes that are driven by a population of active stem cells, or neoblasts, which are likely transformed during planarian tumor growth. Our goal was to determine if planarian tumorigenesis assays are amenable to mechanistic studies of cadmium carcinogenesis. To that end we demonstrate, by examining both counts of cell populations by size, and instances of mitosis, that the activity of the stem cell population can be monitored. We also provide evidence that specific biomodulators can affect the potential of planarian neoplastic growth, in that an inhibitor of metalloproteinases effectively blocked the development of the lesions. From these results, we infer that neoblast activity does respond to cadmium-induced tumor growth, and that metalloproteinases are required for the progression of cancer in the planarian.
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Affiliation(s)
- Evelyn B Voura
- School of Science, Technology and Health Studies, Morrisville State College, 80 Eaton Street, Morrisville, New York 13408, USA.
| | - Melissa J Montalvo
- Department of Math and Science, Dominican College, 470 Western Highway South, Orangeburg, New York 10962, USA
| | - Kevin T Dela Roca
- Department of Math and Science, Dominican College, 470 Western Highway South, Orangeburg, New York 10962, USA
| | - Julia M Fisher
- Colgate University, 13 Oak Drive, Hamilton, New York 13346, USA
| | - Virginie Defamie
- Ontario Cancer Institute, University Health Network, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - Swami R Narala
- Ontario Cancer Institute, University Health Network, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - Rama Khokha
- Ontario Cancer Institute, University Health Network, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - Margaret E Mulligan
- Department of Math and Science, Dominican College, 470 Western Highway South, Orangeburg, New York 10962, USA
| | - Colleen A Evans
- Department of Math and Science, Dominican College, 470 Western Highway South, Orangeburg, New York 10962, USA
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23
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Lei K, Thi-Kim Vu H, Mohan RD, McKinney SA, Seidel CW, Alexander R, Gotting K, Workman JL, Sánchez Alvarado A. Egf Signaling Directs Neoblast Repopulation by Regulating Asymmetric Cell Division in Planarians. Dev Cell 2016; 38:413-29. [PMID: 27523733 DOI: 10.1016/j.devcel.2016.07.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 06/01/2016] [Accepted: 07/15/2016] [Indexed: 12/27/2022]
Abstract
A large population of proliferative stem cells (neoblasts) is required for physiological tissue homeostasis and post-injury regeneration in planarians. Recent studies indicate that survival of a few neoblasts after sublethal irradiation results in the clonal expansion of the surviving stem cells and the eventual restoration of tissue homeostasis and regenerative capacity. However, the precise mechanisms regulating the population dynamics of neoblasts remain largely unknown. Here, we uncovered a central role for epidermal growth factor (EGF) signaling during in vivo neoblast expansion mediated by Smed-egfr-3 (egfr-3) and its putative ligand Smed-neuregulin-7 (nrg-7). Furthermore, the EGF receptor-3 protein localizes asymmetrically on the cytoplasmic membrane of neoblasts, and the ratio of asymmetric to symmetric cell divisions decreases significantly in egfr-3(RNAi) worms. Our results not only provide the first molecular evidence of asymmetric stem cell divisions in planarians, but also demonstrate that EGF signaling likely functions as an essential regulator of neoblast clonal expansion.
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Affiliation(s)
- Kai Lei
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
| | - Hanh Thi-Kim Vu
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Ryan D Mohan
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
| | - Sean A McKinney
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Chris W Seidel
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | | | - Kirsten Gotting
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Jerry L Workman
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Alejandro Sánchez Alvarado
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
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