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Wang C, Peng R, Yuan X, Liu S, Xu S, Li Y, Zhang Z, Zeng M, Hu L, Zou F. Cellular and molecular responses-mediated by DjMEK1/2 are necessary for planarian regeneration. Int J Biol Macromol 2020; 164:3751-3761. [PMID: 32888997 DOI: 10.1016/j.ijbiomac.2020.08.209] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 08/26/2020] [Accepted: 08/27/2020] [Indexed: 01/23/2023]
Abstract
The planarian flatworm is an ideal model to study the regeneration due to its robust regenerative ability. A variety of cellular response activities have been reported to be involved in the regeneration process, including the mitogen-activated protein kinase (MAPK) signaling. However, the mechanism of MAPK pathway in regenerative responses is still unclear. In this study, we employed the planarian, Dugesia japonica, as the model to investigate the function of MAP-extracellular signal-regulated kinase (MEK), an important component of MAPK signaling pathway, in the regeneration process. We found that MEK was required for the missing tissue response after several amputation and subsequent regeneration. MEK not only affected the size of blastema in the early stage of regeneration by regulating stem cell proliferation, but also determined the planarian's regeneration through balancing cell proliferation and apoptosis. In addition, the activation of Wnt pathway partially rescued regenerative defects induced by inhibition of MEK. Taken together, our results highlight a crucial role of MEK signaling in the planarian regeneration.
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Affiliation(s)
- Chao Wang
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China
| | - Rui Peng
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China
| | - Xieyong Yuan
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China
| | - Shengpeng Liu
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China
| | - Shutao Xu
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China
| | - Yan Li
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China
| | - Zhenhua Zhang
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China
| | - Min Zeng
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China
| | - Lanlin Hu
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China
| | - Fangdong Zou
- Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, Sichuan, PR China.
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Ma K, Zhang Y, Song G, Wu M, Chen G. Identification of Autophagy-Related Gene 7 and Autophagic Cell Death in the Planarian Dugesia japonica. Front Physiol 2018; 9:1223. [PMID: 30233400 PMCID: PMC6131670 DOI: 10.3389/fphys.2018.01223] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 08/14/2018] [Indexed: 12/21/2022] Open
Abstract
Planarians undergo continuous body size remodeling under starvation or during regeneration. This process likely involves autophagy and autophagic cell death, but this hypothesis is supported by few studies. To test this hypothesis, we cloned and characterized autophagy-related gene 7 (Atg7) from the planarian Dugesia japonica (DjAtg7). The full-length cDNA of DjAtg7 measures 2272 bp and includes a 2082-bp open reading frame encoding 693 amino acids with a molecular weight of 79.06 kDa. The deduced amino acid sequence of DjAtg7 contains a conserved ATP-binding site and a catalytic active site of an E1-like enzyme belonging to the ATG7 superfamily. DjAtg7 transcripts are mainly expressed in intestinal tissues of the intact animals. After amputation, DjAtg7 was highly expressed at the newly regenerated intestinal branch on days 3-7 of regeneration and in the old tissue of the distal intestinal branch on day 10 of regeneration. However, knockdown of DjAtg7 by RNAi did not affect planarian regeneration and did not block autophagosome formation, which indicates that autophagy is more complex than previously expected. Interestingly, TEM clearly confirmed that autophagy and autophagic cell death occurred in the old tissues of the newly regenerated planarians and clearly revealed that the dying cell released vesicles containing cellular cytoplasmic contents into the extracellular space. Therefore, the autophagy and autophagic cell death that occurred in the old tissue not only met the demand for body remodeling but also met the demand for energy supply during planarian regeneration. Collectively, our work contributes to the understanding of autophagy and autophagic cell death in planarian regeneration and body remodeling.
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Affiliation(s)
| | | | | | | | - Guangwen Chen
- College of Life Sciences, Henan Normal University, Xinxiang, China
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Su H, Sureda-Gomez M, Rabaneda-Lombarte N, Gelabert M, Xie J, Wu W, Adell T. A C-terminally truncated form of β-catenin acts as a novel regulator of Wnt/β-catenin signaling in planarians. PLoS Genet 2017; 13:e1007030. [PMID: 28976975 PMCID: PMC5643146 DOI: 10.1371/journal.pgen.1007030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 10/16/2017] [Accepted: 09/17/2017] [Indexed: 12/12/2022] Open
Abstract
β-Catenin, the core element of the Wnt/β-catenin pathway, is a multifunctional and evolutionarily conserved protein which performs essential roles in a variety of developmental and homeostatic processes. Despite its crucial roles, the mechanisms that control its context-specific functions in time and space remain largely unknown. The Wnt/β-catenin pathway has been extensively studied in planarians, flatworms with the ability to regenerate and remodel the whole body, providing a ‘whole animal’ developmental framework to approach this question. Here we identify a C-terminally truncated β-catenin (β-catenin4), generated by gene duplication, that is required for planarian photoreceptor cell specification. Our results indicate that the role of β-catenin4 is to modulate the activity of β-catenin1, the planarian β-catenin involved in Wnt signal transduction in the nucleus, mediated by the transcription factor TCF-2. This inhibitory form of β-catenin, expressed in specific cell types, would provide a novel mechanism to modulate nuclear β-catenin signaling levels. Genomic searches and in vitro analysis suggest that the existence of a C-terminally truncated form of β-catenin could be an evolutionarily conserved mechanism to achieve a fine-tuned regulation of Wnt/β-catenin signaling in specific cellular contexts. The Wnt signaling pathway is essential for proper intercellular communication in every developmental process since it controls basic cellular events as cell fate or proliferation. The key element of the Wnt signaling is β-catenin, which controls the transcription of multiple genes in the Wnt receiving cell. A main level of regulation of the Wnt/β-catenin signaling occurs in the cytoplasm, where β-catenin protein levels depend on the activity of the β-catenin destruction complex. However, once it reaches the nucleus, β-catenin transcriptional activity requires a fine-tuned regulation to enable the multiple context-specific responses that it performs. These nuclear mechanisms that regulate the Wnt/β-catenin signaling remain poorly understood. Here we report the existence of C-terminal truncated forms of β-catenin in planarians (β-cat3 and 4), which, in vitro, do not show transactivation activity and compete with the canonical planarian β-catenin (β-cat1), thus acting as competitor inhibitors. Functional analyses in planarians indicate that β-cat4 acts as a negative regulator of β-cat1 during planarian eye photoreceptor specification. We provide evidence to suggest that this novel mechanism for the regulation of nuclear β-catenin activity could be conserved across animal evolution.
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Affiliation(s)
- Hanxia Su
- MOE Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Miquel Sureda-Gomez
- Departament de Genètica, Microbiologia i Estadística,Facultat de Biologia, Universitat de Barcelona and Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Catalunya, Spain
| | - Neus Rabaneda-Lombarte
- Departament de Genètica, Microbiologia i Estadística,Facultat de Biologia, Universitat de Barcelona and Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Catalunya, Spain
| | - Maria Gelabert
- Departament de Genètica, Microbiologia i Estadística,Facultat de Biologia, Universitat de Barcelona and Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Catalunya, Spain
| | - Jianlei Xie
- MOE Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Wei Wu
- MOE Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Teresa Adell
- Departament de Genètica, Microbiologia i Estadística,Facultat de Biologia, Universitat de Barcelona and Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Catalunya, Spain
- * E-mail:
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Nishimura O, Hosoda K, Kawaguchi E, Yazawa S, Hayashi T, Inoue T, Umesono Y, Agata K. Unusually Large Number of Mutations in Asexually Reproducing Clonal Planarian Dugesia japonica. PLoS One 2015; 10:e0143525. [PMID: 26588467 PMCID: PMC4654569 DOI: 10.1371/journal.pone.0143525] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/05/2015] [Indexed: 11/21/2022] Open
Abstract
We established a laboratory clonal strain of freshwater planarian (Dugesia japonica) that was derived from a single individual and that continued to undergo autotomous asexual reproduction for more than 20 years, and we performed large-scale genome sequencing and transcriptome analysis on it. Despite the fact that a completely clonal strain of the planarian was used, an unusually large number of mutations were detected. To enable quantitative genetic analysis of such a unique organism, we developed a new model called the Reference Gene Model, and used it to conduct large-scale transcriptome analysis. The results revealed large numbers of mutations not only outside but also inside gene-coding regions. Non-synonymous SNPs were detected in 74% of the genes for which valid ORFs were predicted. Interestingly, the high-mutation genes, such as metabolism- and defense-related genes, were correlated with genes that were previously identified as diverse genes among different planarian species. Although a large number of amino acid substitutions were apparently accumulated during asexual reproduction over this long period of time, the planarian maintained normal body-shape, behaviors, and physiological functions. The results of the present study reveal a unique aspect of asexual reproduction.
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Affiliation(s)
- Osamu Nishimura
- Global COE Program: Evolution and Biodiversity, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Japan
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Japan
| | - Kazutaka Hosoda
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Japan
| | - Eri Kawaguchi
- Global COE Program: Evolution and Biodiversity, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Japan
| | - Shigenobu Yazawa
- Global COE Program: Evolution and Biodiversity, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Japan
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Japan
- Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Tetsutaro Hayashi
- Center for Developmental Biology, RIKEN, 2-2-3 Minatojima-Nakamachi, Chuo-ku, Kobe, Hyogo, Japan
- Advanced Center for Computing and Communication, RIKEN, 2–1 Hirosawa, Wako, Saitama, Japan
| | - Takeshi Inoue
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Japan
| | - Yoshihiko Umesono
- Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo, Japan
| | - Kiyokazu Agata
- Global COE Program: Evolution and Biodiversity, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Japan
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Japan
- * E-mail:
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Ma C, Gao Y, Chai G, Su H, Wang N, Yang Y, Li C, Miao D, Wu W. Djrho2 is involved in regeneration of visual nerves in Dugesia japonica. J Genet Genomics 2010; 37:713-23. [DOI: 10.1016/s1673-8527(09)60089-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2010] [Revised: 06/27/2010] [Accepted: 07/02/2010] [Indexed: 01/03/2023]
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