A proliferation gradient between proximal and msxb-expressing distal blastema directs zebrafish fin regeneration

Development ◽  
2002 ◽  
Vol 129 (11) ◽  
pp. 2607-2617 ◽  
Author(s):  
Alex Nechiporuk ◽  
Mark T. Keating
Keyword(s):  
High Rate ◽  
Proliferating Cells ◽  
Homogeneous Population ◽  
Fin Regeneration ◽  
New Model ◽  
Blastema Formation ◽  
Phosphohistone H3 ◽  
Slow Cycling ◽  
Early Regeneration ◽  
Regeneration Blastema

Previous studies of zebrafish fin regeneration led to the notion that the regeneration blastema is a homogeneous population of proliferating cells. Here, we show that the blastema consists of two components with markedly distinct proliferation properties. During early blastema formation, proliferating cells are evenly distributed. At the onset of regenerative outgrowth, however, blastemal cells are partitioned into two domains. Proximal blastemal cells proliferate at a high rate, shifting from a median G2 of more than 6 hours to approximately 1 hour. By contrast, the most distal blastemal cells do not proliferate. There is a gradient of proliferation between these extremes. Using bromodeoxyuridine incorporation and anti-phosphohistone H3 labeling, we find a 50-fold difference in proliferation across the gradient that extends approximately 50 μm, or ten cell diameters. We show that during early regeneration, proliferating blastemal cells express msxb, a homeodomain transcriptional repressor. While msxb is widely expressed among proliferating cells during blastema formation, its expression becomes restricted to a small number of non-proliferating, distal blastemal cells during regenerative outgrowth. Bromodeoxyuridine pulse-chase experiments show that distal and proximal blastemal cells are formed from proliferating, msxb-positive blastemal cells, not from preexisting slow-cycling cells. These data support the idea that blastema formation results from dedifferentiation of intraray mesenchymal cells. Based on these findings, we propose a new model of zebrafish fin regeneration in which the function of non-proliferating, msxb-expressing, distal blastemal cells is to specify the boundary of proliferation and provide direction for regenerative outgrowth.

scholarly journals Regeneration of the flatworm Prosthiostomum siphunculus (Polycladida, Platyhelminthes)

2020 ◽  
Author(s):  
Tamara Schadt ◽  
Veronika Prantl ◽  
Alexandra L Grosbusch ◽  
Philip Bertemes ◽  
Bernhard Egger
Keyword(s):  
Stem Cell ◽  
Wound Closure ◽  
The Other ◽  
Regeneration Capacity ◽  
Proliferating Cells ◽  
Free Living ◽  
Cell Dynamics ◽  
Head Regeneration ◽  
The Brain ◽  
Regeneration Blastema

Abstract Fueled by the discovery of head regeneration in triclads (planarians) two and a half centuries ago, flatworms have been the focus of regeneration research. But not all flatworms can regenerate equally well and to obtain a better picture of the characteristics and evolution of regeneration in flatworms other than planarians, the regeneration capacity and stem cell dynamics during regeneration in the flatworm order Polycladida are studied. Here, we show that as long as the brain remained at least partially intact, the polyclad Prosthiostomum siphunculus was able to regenerate submarginal eyes, cerebral eyes, pharynx, intestine and sucker. In the complete absence of the brain only wound closure was observed but no regeneration of missing organs. Amputated parts of the brain could not be regenerated. The overall regeneration capacity of P. siphunculus is a good fit for category III after a recently established system, in which most polyclads are currently classified. Intact animals showed proliferating cells in front of the brain which is an exception compared with most of the other free-living flatworms that have been observed so far. Proliferating cells could be found within the regeneration blastema, similar to all other flatworm taxa except triclads. No proliferation was observed in epidermis and pharynx. In pulse-chase experiments, the chased cells were found in all regenerated tissues and thereby shown to differentiate and migrate to replace the structures lost upon amputation.

scholarly journals The Fish Family Poeciliidae as a Model to Study the Evolution and Diversification of Regenerative Capacity in Vertebrates

2021 ◽  
Vol 9 ◽  
Author(s):  
Diego Safian ◽  
Geert F. Wiegertjes ◽  
Bart J. A. Pollux
Keyword(s):  
Molecular Mechanisms ◽  
Reproductive Traits ◽  
Model System ◽  
Animal Kingdom ◽  
Regenerative Capacity ◽  
Fish Family ◽  
Fin Regeneration ◽  
New Model ◽  
Fish Fins ◽  
Livebearing Fish

The capacity of regenerating a new structure after losing an old one is a major challenge in the animal kingdom. Fish have emerged as an interesting model to study regeneration due to their high and diverse regenerative capacity. To date, most efforts have focused on revealing the mechanisms underlying fin regeneration, but information on why and how this capacity evolves remains incomplete. Here, we propose the livebearing fish family Poeciliidae as a promising new model system to study the evolution of fin regeneration. First, we review the current state of knowledge on the evolution of regeneration in the animal kingdom, with a special emphasis on fish fins. Second, we summarize recent advances in our understanding of the mechanisms behind fin regeneration in fish. Third, we discuss potential evolutionary pressures that may modulate the regenerative capacity of fish fins and propose three new theories for how natural and sexual selection can lead to the evolution of fin regeneration: (1) signaling-driven fin regeneration, (2) predation-driven fin regeneration, and (3) matrotrophy-suppressed fin regeneration. Finally, we argue that fish from the family Poeciliidae are an excellent model system to test these theories, because they comprise of a large variety of species in a well-defined phylogenetic framework that inhabit very different environments and display remarkable variation in reproductive traits, allowing for comparative studies of fin regeneration among closely related species, among populations within species or among individuals within populations. This new model system has the potential to shed new light on the underlying genetic and molecular mechanisms driving the evolution and diversification of regeneration in vertebrates.

Delayed Development of Limbal Stem Cell Deficiency Following Chemical Injury—Pathogenesis and Therapeutic Strategies

2013 ◽  
Vol 06 (02) ◽  
pp. 101
Author(s):  
Tamar Kadar ◽  
Shlomit Dachir ◽  
Vered Horwitz ◽  
Adina Amir ◽  
◽  
...  
Keyword(s):  
Stem Cell ◽  
Sulfur Mustard ◽  
Rabbit Model ◽  
Therapeutic Window ◽  
Epithelial Stem Cells ◽  
Proliferating Cells ◽  
Ocular Surgery ◽  
Cytotoxic Effects ◽  
Warfare Agents ◽  
Slow Cycling

Limbal epithelial stem cell deficiency (LSCD) occurs as a result of damage to the limbal epithelial stem cells (ESC) population. It may derive from direct destructive loss of the ESC (common chemical burn), and/or from dysfunction of the SC niche, leading to delayed death of the cells. This review focuses on delayed-onset LSCD, induced by antineoplastic chemicals, such as mitomycin C, 5-fluorouracil, and mustards, in terms of pathogenesis and management. These agents are used in ocular surface chemotherapy, in ocular surgery procedures, and as warfare agents, and target proliferating cells as slow-cycling cells, such as the ESC, are relatively resistant. Although the mechanism of the delayed loss of ESC is not entirely clear, we have shown, in the rabbit model, pathologic alterations in the limbal stroma, following the application of sulfur mustard, suggesting that dysfunction of the niche triggers the death of the SC later on. The absence of direct cytotoxic effects of these agents on the ESC, indicates a therapeutic window for prevention of the delayed LSCD.

scholarly journals Large-scale analysis of the genes involved in fin regeneration and blastema formation in the medaka, Oryzias latipes

2004 ◽  
Vol 121 (7-8) ◽  
pp. 861-872 ◽  
Author(s):  
Rei Katogi ◽  
Yuki Nakatani ◽  
Tadasu Shin-i ◽  
Yuji Kohara ◽  
Keiji Inohaya ◽  
...  
Keyword(s):  
Large Scale ◽  
Oryzias Latipes ◽  
Scale Analysis ◽  
Fin Regeneration ◽  
Blastema Formation ◽  
Large Scale Analysis

The chemokine SDF-1 regulates blastema formation during zebrafish fin regeneration

2006 ◽  
Vol 216 (10) ◽  
pp. 635-639 ◽  
Author(s):  
Pascale Dufourcq ◽  
Sophie Vriz
Keyword(s):  
Fin Regeneration ◽  
Blastema Formation

scholarly journals Calcineurin controls proximodistal blastema polarity in zebrafish fin regeneration

2020 ◽  
Vol 118 (2) ◽  
pp. e2009539118
Author(s):  
Zigang Cao ◽  
Yunlong Meng ◽  
Fanghua Gong ◽  
Zhaopeng Xu ◽  
Fasheng Liu ◽  
...  
Keyword(s):  
Molecular Switch ◽  
Adult Zebrafish ◽  
Fin Regeneration ◽  
Cut Edge ◽  
Calcineurin Inhibition ◽  
Regeneration Blastema

Planarian flatworms regenerate their heads and tails from anterior or posterior wounds and this regenerative blastema polarity is controlled by Wnt/β-catenin signaling. It is well known that a regeneration blastema of appendages of vertebrates such as fish and amphibians grows distally. However, it remains unclear whether a regeneration blastema in vertebrate appendages can grow proximally. Here, we show that a regeneration blastema in zebrafish fins can grow proximally along the proximodistal axis by calcineurin inhibition. We used fin excavation in adult zebrafish to observe unidirectional regeneration from the anterior cut edge (ACE) to the posterior cut edge (PCE) of the cavity and this unidirectional regeneration polarity occurs as the PCE fails to build blastemas. Furthermore, we found that calcineurin activities in the ACE were greater than in the PCE. Calcineurin inhibition induced PCE blastemas, and calcineurin hyperactivation suppressed fin regeneration. Collectively, these findings identify calcineurin as a molecular switch to specify the PCE blastema of the proximodistal axis and regeneration polarity in zebrafish fin.

scholarly journals Innovative mechanism of public administration modernization in Ukraine

2019 ◽  
pp. 83-89
Author(s):  
Ljubov Fedulova
Keyword(s):  
Sustainable Development ◽  
Public Administration ◽  
System Approach ◽  
Point Of View ◽  
High Rate ◽  
Public Authorities ◽  
The Sustainable Development ◽  
New Model ◽  
Business Entities ◽  
Management Institutions

The high rate of global development of economic processes is increasingly strengthening the global nature of the sustainable development concept, which is characterized by the interconnection of environmental, economic, social and institutional problems that are increasingly exacerbated by rapidly changing technological, geopolitical and other factors. In this context, it is necessary to see comprehensive provision and continuous support of sustainable development, which provides for coordinated actions and interaction of governments, business entities, non-profit organizations and society as a whole. Their effective implementation is possible through the creation of an appropriate institutional system, where management institutions occupy one of the key places. The subject of the research is the essence and features of the innovative mechanism for implementing modernization processes in the system of public administration. The purpose of writing the article is to justify the need to develop and implement an innovative mechanism to form a new model of public administration in Ukraine, define its components from the standpoint of system approach and the development of proposals for the promising directions of its implementation. The methodology of the research is the principles of innovation and public administration theories, the concept of service state. On the basis of the system approach, the paper identifies the components of the innovative mechanism of public administration modernization that influence the nature of the decentralization process in Ukraine. Using the methods of statistical and expert analysis, the problems of decentralization in the country are determined. The methods of structuring and synthesis  underpin the developed proposals for strengthening the role of the innovative public administration mechanism in ensuring economic growth and solving social problems. The results of the research is the assessment of progress in decentralization in Ukraine and identification of problems that complicate the achievement of goals and require increased efforts of public authorities to solve problems accumulated in society from the standpoint of innovative approach. Conclusions. The modern Ukrainian economy needs specific, different from the traditional economy approaches to define the objectives of forming a new model of public administration in terms of introducing an innovative mechanism to accelerate the process of developing relations between public authorities and civil society participants. Particular attention is needed for the methodology in developing the components of reforming the public administration innovative mechanism and determining the relationship between them from the point of view of the system approach as well as elaborating tools for their implementation in order to increase the level of manageability in the process of providing citizens with high-quality public services.

Mps1 defines a proximal blastemal proliferative compartment essential for zebrafish fin regeneration

Development ◽  
2002 ◽  
Vol 129 (22) ◽  
pp. 5141-5149
Author(s):  
Kenneth D. Poss ◽  
Alex Nechiporuk ◽  
Ann M. Hillam ◽  
Stephen L. Johnson ◽  
Mark T. Keating
Keyword(s):  
Tissue Regeneration ◽  
Positional Cloning ◽  
Molecular Mechanisms ◽  
Mitotic Checkpoint ◽  
Temperature Sensitive ◽  
Fin Regeneration ◽  
And Function ◽  
Regeneration Blastema

One possible reason why regeneration remains enigmatic is that the dominant organisms used for studying regeneration are not amenable to genetic approaches. We mutagenized zebrafish and screened for temperature-sensitive defects in adult fin regeneration. The nightcap mutant showed a defect in fin regeneration that was first apparent at the onset of regenerative outgrowth. Positional cloning revealed that nightcapencodes the zebrafish orthologue of mps1, a kinase required for the mitotic checkpoint. mps1 expression was specifically induced in the proximal regeneration blastema, a group of cells that normally proliferate intensely during outgrowth. The nightcap mutation caused severe defects in these cells. However, msxb-expressing blastemal cells immediately distal to this proliferative region did not induce mps1and were retained in mutants. These results indicate that the proximal blastema comprises an essential subpopulation of the fin regenerate defined by the induction and function of Mps1. Furthermore, we show that molecular mechanisms of complex tissue regeneration can now be dissected using zebrafish genetics.

Zebrafish kit mutation reveals primary and secondary regulation of melanocyte development during fin stripe regeneration

Development ◽  
2000 ◽  
Vol 127 (17) ◽  
pp. 3715-3724 ◽  
Author(s):  
J.F. Rawls ◽  
S.L. Johnson
Keyword(s):  
Receptor Tyrosine Kinase ◽  
Mutational Analysis ◽  
Adult Zebrafish ◽  
Wild Type ◽  
Kit Mutation ◽  
Fin Regeneration ◽  
Normal Melanocyte ◽  
Kit Receptor ◽  
Early Regeneration ◽  
Secondary Mode

Fin regeneration in adult zebrafish is accompanied by re-establishment of the pigment stripes. To understand the mechanisms underlying fin stripe regeneration and regulation of normal melanocyte stripe morphology, we investigated the origins of melanocytes in the regenerating fin and their requirement for the kit receptor tyrosine kinase. Using pre-existing melanin as a lineage tracer, we show that most fin regeneration melanocytes develop from undifferentiated precursors, rather than from differentiated melanocytes. Mutational analysis reveals two distinct classes of regeneration melanocytes. First, an early regeneration class develops dependent on kit function. In the absence of kit function and kit-dependent melanocytes, a second class of melanocytes develops at later stages of regeneration. This late kit-independent class of regeneration melanocytes has little or no role in wild-type fin stripe development, thus revealing a secondary mode for regulation of fin stripes. Expression of melanocyte markers in regenerating kit mutant fins suggests that kit normally acts after mitf and before dct to promote development of the primary kit-dependent melanocytes. kit-dependent and kit-independent melanocytes are also present during fin stripe ontogeny in patterns similar to those observed during regeneration.

Effectiveness of Transcriptional CDK Inhibitors in Targeting Non-Proliferating CD34+CD38- AML Cells,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3482-3482
Author(s):  
Monica Pallis ◽  
Francis Burrows ◽  
Abigail Whittall ◽  
Claire Seedhouse ◽  
Nicholas Boddy ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Rna Polymerase Ii ◽  
Rna Synthesis ◽  
Cdk Inhibitors ◽  
Proliferating Cells ◽  
Median Percentage ◽  
Homogeneous Population ◽  
Quiescent Cells ◽  
Species Production

Abstract Abstract 3482 Quiescent cells conserve energy and are characterised by low RNA synthesis. In contrast, cancer cells are thought to be addicted to high RNA synthesis, particularly synthesis of survival molecules. We hypothesised that quiescent cancer cells, already low in RNA, would be sensitive to apoptosis induced by transcriptional cyclin-dependent kinase (CDK) inhibitors that further deplete RNA. We cultured the CD34+CD38- KG1a cell line continuously in the presence of an mTOR inhibitor, which maintained excellent viability and enriched the cells for quiescent stem cell features including low RNA content, low metabolism, low reactive oxygen species production and decreased size. Sensitivity to mitochondrial pore transition was similar in proliferating and quiescence-enriched cells, indicating that the basal mitochondrial apoptotic machinery is neither impaired nor improved. We treated quiescence-enriched cells for 48 hours with the nucleoside analogues ara-C, 5-azacytidine and clofarabine, the topoisomerase targeting agents daunorubicin, etoposide and irinotecan and three multikinase inhibitors with activity against transcriptional CDKs - flavopiridol, roscovotine and TG02. All of the agents used showed increased kill in the unmanipulated compared to the quiescence-enriched cells, emphasising the chemoresistant nature of quiescent cells. To put a value on the difficulty of eradicating the leukamic clone, we used the parameter 2 X IC50 (which theoretically would kill 100% cells in a totally homogeneous population). In quiescence-enriched cells, the percentage of cells killed at 2 X IC50 was roscovotine - 80%, TG02 – 72%, flavopiridol - 62%, 5-azacydidine - 61%, daunorubicin, clofarabine and irinotecan - 60%, etoposide - 58%, and for araC no IC50 for quiescence-enriched cells was reached at 20 times the IC50 of proliferating cells. The data show conclusively that, in this model, transcriptional CDK inhibitors outperformed the agents conventionally used in AML chemotherapy. We also showed that transcriptional CDK inhibitors induced serine 2 dephosphorylation of RNA polymerase II in equal measure in proliferating and quiescence- enriched cells. We have already shown that TGO2 targets primary CD34+CD38- cells in vitro (ASH 2010, abstract 1823). Here we also show that in four primary AML samples sensitive to roscovotine in vitro, the median percentage kill is greater in the CD34+CD38- subset, (which consists largely of quiescent cells and tends to contain the leukaemic stem cells,) than in the bulk cells (40.5% versus 19.5% kill at 2 micromolar roscovotine). We suggest that transcriptional CDK inhibitors may be a useful class of agent for targetting the occult quiescent CD34+CD38- cells thought to contribute to relapse in AML. Disclosures: Burrows: Tragara Pharmaceuticals: Employment.

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