Document Detail

Amputation-induced reactive oxygen species are required for successful Xenopus tadpole tail regeneration.
Jump to Full Text
MedLine Citation:
PMID:  23314862     Owner:  NLM     Status:  MEDLINE    
Understanding the molecular mechanisms that promote successful tissue regeneration is critical for continued advancements in regenerative medicine. Vertebrate amphibian tadpoles of the species Xenopus laevis and Xenopus tropicalis have remarkable abilities to regenerate their tails following amputation, through the coordinated activity of numerous growth factor signalling pathways, including the Wnt, Fgf, Bmp, Notch and TGF-β pathways. Little is known, however, about the events that act upstream of these signalling pathways following injury. Here, we show that Xenopus tadpole tail amputation induces a sustained production of reactive oxygen species (ROS) during tail regeneration. Lowering ROS levels, using pharmacological or genetic approaches, reduces the level of cell proliferation and impairs tail regeneration. Genetic rescue experiments restored both ROS production and the initiation of the regenerative response. Sustained increased ROS levels are required for Wnt/β-catenin signalling and the activation of one of its main downstream targets, fgf20 (ref. 7), which, in turn, is essential for proper tail regeneration. These findings demonstrate that injury-induced ROS production is an important regulator of tissue regeneration.
Nick R Love; Yaoyao Chen; Shoko Ishibashi; Paraskevi Kritsiligkou; Robert Lea; Yvette Koh; Jennifer L Gallop; Karel Dorey; Enrique Amaya
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Video-Audio Media     Date:  2013-01-13
Journal Detail:
Title:  Nature cell biology     Volume:  15     ISSN:  1476-4679     ISO Abbreviation:  Nat. Cell Biol.     Publication Date:  2013 Feb 
Date Detail:
Created Date:  2013-02-04     Completed Date:  2013-03-29     Revised Date:  2014-06-10    
Medline Journal Info:
Nlm Unique ID:  100890575     Medline TA:  Nat Cell Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  222-8     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Animals, Genetically Modified
Antioxidants / pharmacology
Cell Proliferation* / drug effects
Enzyme Inhibitors / pharmacology
Fibroblast Growth Factors / metabolism
Gene Expression Regulation
Hydrogen Peroxide / metabolism
Larva / metabolism
NADPH Oxidase / antagonists & inhibitors,  genetics,  metabolism
Oligonucleotides, Antisense / metabolism
Reactive Oxygen Species / metabolism*
Regeneration* / drug effects
Tail / drug effects,  embryology,  metabolism*,  surgery
Time Factors
Wnt Proteins / metabolism
Wnt Signaling Pathway
Xenopus Proteins / metabolism
Xenopus laevis / embryology,  genetics,  metabolism*,  surgery
beta Catenin / metabolism
Grant Support
082450//Wellcome Trust; 092096//Wellcome Trust; //Biotechnology and Biological Sciences Research Council; //Wellcome Trust
Reg. No./Substance:
0/Antioxidants; 0/Enzyme Inhibitors; 0/Oligonucleotides, Antisense; 0/Reactive Oxygen Species; 0/Wnt Proteins; 0/Xenopus Proteins; 0/beta Catenin; 0/beta-catenin protein, Xenopus; 0/fibroblast growth factor 20, Xenopus; 62031-54-3/Fibroblast Growth Factors; BBX060AN9V/Hydrogen Peroxide; EC Oxidase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Full Text
Journal Information
Journal ID (nlm-journal-id): 100890575
Journal ID (pubmed-jr-id): 21417
Journal ID (nlm-ta): Nat Cell Biol
Journal ID (iso-abbrev): Nat. Cell Biol.
ISSN: 1465-7392
ISSN: 1476-4679
Article Information
Download PDF

nihms-submitted publication date: Day: 10 Month: 7 Year: 2013
Electronic publication date: Day: 13 Month: 1 Year: 2013
Print publication date: Month: 2 Year: 2013
pmc-release publication date: Day: 01 Month: 8 Year: 2013
Volume: 15 Issue: 2
First Page: 222 Last Page: 228
PubMed Id: 23314862
ID: 3728553
DOI: 10.1038/ncb2659
ID: EMS53733

Amputation-induced reactive oxygen species (ROS) are required for successful Xenopus tadpole tail regeneration
Nick R. Love12
Yaoyao Chen124
Shoko Ishibashi12
Paraskevi Kritsiligkou1
Robert Lea12
Yvette Koh12
Jennifer L. Gallop3
Karel Dorey12
Enrique Amaya12
1Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
2The Healing Foundation Centre, Michael Smith Building, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
3The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN United Kingdom
Correspondence: Correspondence should be addressed to EA
4Present address: Wellcome Trust Centre for Stem Cell Research, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR
AUTHOR CONTRIBUTIONS NL designed and carried out most of the experiments in this study and co-wrote the manuscript. YC established the HyPerYFP assay in Xenopus, generated spib morpants, and assisted in many of the other experiments in the study. SI generated the cyba constructs, and PK generated the pHlourin constructs. KD performed western blot analyses on the tagged cyba constructs and helped prepare the manuscript. YK performed the C1-blastomere injections and cell-tracking analysis of the inflammatory cells. RL performed the whole-mount in situ hybridizations and whole-mount immunohistochemistry experiments. JG generated the initial finding that the antioxidant MC-186 could be used to lower ROS in Xenopus. EA supervised the project, aided with embryo experiments, and co-wrote the manuscript.

To better understand the genetic and molecular mechanisms underlying Xenopus tropicalis tadpole tail regeneration, we recently performed a microarray screen examining gene expression during regeneration, which uncovered a number of coordinately upregulated genes involved in the production of ROS and H2O22. Indeed, H2O2 and other ROS, traditionally viewed as harmful to cells, are now appreciated to have pleiotropic biological effects on various cellular processes, many of which could play roles during tissue regeneration 8, 9. This prompted us to examine the production and role of ROS during vertebrate tail regeneration in Xenopus tadpoles.

We first sought to determine whether there was a change in ROS levels following Xenopus tadpole tail amputation and during the subsequent tail regeneration process. To image ROS in vivo, we used the ratiometric reporter fluorophore HyPerYFP 10. This YFP variant possesses an oxidative sensitive OxyR domain that, following oxidation, causes a reversible conformational change in HyPerYFP and marked change in fluorescence excitation, a reaction that is particularly sensitive to H2O2 over other ROS 10. Hence, a simple calculation of the HyPerYFP oxidized 490nm/reduced 402nm excitation ratio provides an in vivo assay of intracellular H2O2 or closely related ROS 11,12. We generated several Xenopus laevis transgenic lines that express HyPerYFP ubiquitously from the CMV promoter, and the F0 founders successfully passed their transgenes to the F1 generation (Figure 1a, Supplementary Figure S1a) 13. To assess any changes in H2O2 during regeneration, we amputated the tails of F1 or F2 HyPerYFP transgenic tadpoles, and found a marked increase in intracellular H2O2 following tail amputation (Figure 1b). Interestingly, the H2O2 levels remained high during the entire tail regeneration process, which lasts several days (Figure 1b). Titrations with exogenous H2O2 during tail regeneration suggested that regenerating tissues maintain a sustained level of intracellular H2O2 concentrations between 50μM and 200μM (Supplementary Fig. S1b).

To confirm these findings, we sought other means to detect ROS in regenerative tissue in vivo. Using the H2O2 sensitive fluorogenic dyes 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate (CM-H2DCFDA) and superoxide (−O2) sensitive dihydroethidium (DHE) 14, we obtained similar results to those we obtained using the HyPerYFP probe (Supplementary Fig. S1c). Given that an increase in pH can lead to a change in the HyperYFP ratio 10, we next used a pH sensitive probe, pHluorin 15 and found that regenerating tails do not possess a pH level above 8.0 that would have generated a false-positive increased HyPerYFP ratio (Supplementary Fig. S1d). Together, these data and the HyPerYFP imaging results provide compelling evidence that tadpole tail regeneration is associated with a sustained presence of relatively high levels of H2O2 and/or other related ROS.

Previous reports in zebrafish have shown that epidermal injury results in the production of H2O2, which acts as a chemoattractant for inflammatory cells 11, 12. Consistent with these reports, we found that epidermal wounding also caused an increase in ROS levels at the injury site, which remained elevated until wound healing was complete (Supplementary Fig. S2).

Given that tadpole tail amputation induces a massive recruitment of inflammatory cells to the site of injury 13 and inflammatory cells are known to produce high levels of ROS 9, 16, we asked whether the increase in ROS was due to the recruitment of inflammatory cells. Two pieces of experimental evidence argued against this possibility. First, we labeled the inflammatory cells of HyPerYFP transgenic tadpoles with RFP (see Methods) and found that the increase in ROS levels peaked within one hour post-amputation (hpa), while the major recruitment of inflammatory cells did not begin until 2 hpa (Figure 2a, Supplementary Video). Second, tadpoles with diminished inflammatory cells (morphants for spib, a transcription factor required for primitive myeloid cell development 17; Figure 2c), showed no significant difference in the HyPerYFP ratios versus control morphant tadpoles following tail amputation (Figure 2d, e). These two sets of data strongly suggest that the sustained ROS levels during tail regeneration are largely produced by non-inflammatory wound resident cells, a finding consistent with previous reports examining zebrafish epidermal wounding 11.

To address the role of ROS during tail regeneration, we decreased ROS levels following amputation using several methods. We first used two chemicals that target the NADPH Oxidase (NOX) enzyme complexes, a major source of cellular ROS 9 (Supplementary Fig. S3). We found that 2μM diphenyleneiodonium (DPI), a flavoprotein inhibitor, which targets the NOX subunit 18, 19 and 200μM apocynin (APO), which disrupts the assembly of the NOX complex 20, significantly reduced ROS levels by 12 hpa (Figure 3a; see Supplemental Fig. S3 for chemical structures and putative modes of action of the three inhibitors). Given that DPI and APO may have off target effects 19, 21, we used 5-50 times lower concentration of these inhibitors than others have used for similar experiments 11, 21. In addition, we used a different method of lowering ROS, namely the therapeutic anti-oxidant and free radical scavenger MCI-186, (tradename Edaravone) 22, 23. We found that 200μM MCI-186 also reduced ROS levels, although to a lesser extent than DPI or APO (Figure 3a). Notably, lowering amputation-induced ROS levels using these inhibitors resulted in an impairment of tail regeneration, as evidenced by shorter tail length at 72 hpa (Figure 3b). However, the failure of tail regeneration in ROS inhibitor treated tadpoles at 72 hpa could have simply been due to a delay in the regeneration program. To address this possibility, we cultured tadpoles following amputation for three days under ROS inhibition and then moved the tadpoles into fresh medium without the inhibitors until day 7 post-amputation, the time period needed for completion of tail regeneration (Figure 3c) 13. This analysis showed that DPI or APO treatment over the first 3 days post-amputation (dpa) effectively precluded the regeneration program from reinitiating, even if the inhibitors were removed thereafter. In contrast, MCI-186, which had the least lowering effect on the HyPerYFP ratio, impaired or delayed regeneration while present, but in its absence, regeneration resumed such that after 7 days, the regenerated tails were largely similar to those in the DMSO treated controls (Figure 3c). These data suggested that NOX complex activity is required for the initiation of the regeneration program in the first 3 days post amputation, and regeneration is unable to recover thereafter, while the antioxidant scavenger merely delays the regeneration program while present.

We next sought to rescue the defects of ROS inhibitor treated tadpoles by the addition of exogenous H2O2 to the media. However, combining ROS inhibitors with prolonged, systemic exposure to H2O2, even as low as 50uM, for time periods longer than 24hours was toxic to tadpoles, thus precluding us from attempting regeneration phenotypic rescue experiments with exogenous H2O2. Given the difficulty we encountered attempting to rescue the chemical inhibitor derived phenotypes with exogenous H2O2, we turned to genetic perturbation approaches aimed at inhibiting NOX-mediated ROS production during tail regeneration. Our previous micro-array data suggested that the expression levels of cytochrome b-245 alpha polypeptide, cyba (also known as p22phox, a necessary subunit in NOX complexes 1, 2, and 4; Supplementary Figure S3b) 24, more than trebled following amputation and remained upregulated throughout regeneration (array target Str.15394.1.S1_at, 13). We confirmed the expression of cyba in newly amputated and regenerative tissue using RT-PCR and in situ hybridization (Supplementary Fig. S4). We then generated an antisense morpholino oligonucleotide (MO) designed to block the translation of cyba and, because antibodies recognizing the Xenopus cyba homologue are not available, we confirmed the efficacy of the MO using a C-terminal tagged cyba-FLAG epitope fusion construct (Figure 4a). Additionally, we generated an N-terminal myc-tagged version of cyba that was insensitive to the cyba MO knockdown effect, for use as a rescue construct (Figure 4b).

We injected 20ng of the cyba atg MO with 250pg of either rfp or myc-cyba mRNA into fertilized embryos and assessed the post-amputation ROS production and the regenerative response (Figure 4c,d). HyPerYFP imaging revealed that cyba morphants had ~33% reduction in amputation-induced ROS,, a loss that was rescued by co-injecting the morpholino insensitive N-terminal myc-tagged cyba variant. Notably, the decrease in ROS in cyba morphants correlated with a marked decrease in regenerative bud tissue formation, an effect that was partially rescued using myc-cyba coexpression (Figure 4d). These data show that a portion of the amputation-induced ROS increase is mediated by the NOX-cyba complex, and that the regenerative response requires this enzymatic source of ROS.

We next wished to examine potential regenerative mechanisms that might be affected by the ROS produced following tail amputation and during regeneration. Intriguingly, previous reports had linked NOX-mediated H2O2 production with cell proliferation and growth factor signaling 25-28. During Xenopus tail regeneration, a localized increase in cell proliferation in the injured and regenerating tail occurs at 24-36hpa, and these proliferating cells can be assayed by the presence of phospho-histone H3 (pH3), a marker for mitotic cells 2, 29. To ask whether ROS production was necessary for cell proliferation during tail regeneration, we returned to the use of chemical inhibitors for these experiments due to the transient nature of Xenopus morpholino injections 30. Treatment of regenerating tails with DPI and APO, and, to a lesser extent MCI-186, significantly decreased cell proliferation as assayed by pH3 staining at 36hours post-amputation (Figure 5a) and thus suggested a potential defect in growth factor signaling within these inhibitor treated tadpole tails.

Wnt and FGF signalling have been associated with increased cell proliferation during tissue regeneration 31-33. To assess the dynamics of ROS and Wnt/β-catenin signaling during tail regeneration, we utilized a X. tropicalis Wnt/β-catenin signaling reporter line, which uses multimerized TCF optimal promoter (TOP) sites to drive the expression of destabilized GFP (dsGFP) (fluorescent protein half-life of 2hrs) 34. We observed an absence of Wnt/β-catenin signaling at the wound site immediately after amputation, which was followed by a sustained activation of Wnt/β-catenin signaling from 24hpa, as assayed by the expression of the destabilized GFP reporter (Supplementary Figure S5a). Indeed, we found that inhibiting ROS production via DPI, APO, or MCI-186 treatment starting from amputation until 36hpa resulted in a marked decreased in Wnt∕β~ catenin signaling, as evidenced by decreased Wnt/β-catenin directed dsGFP fluorescence (Figure 5b).

A previous report had shown that H2O2 modulates Wnt/β-catenin signaling in vitro via nucleoredoxin (n×n), a small redox sensitive protein from the thiorodoxin family 35. Using in situ hybridization, we found that n×n was expressed during tail regeneration (Supplementary Fig. S5b). Though we have not specifically addressed the role of n×n during tail regeneration in this study, its expression provides a putative molecule linking changes in ROS levels with alterations in Wnt/β-catenin signaling activity.

fgf20 is a direct transcriptional target Wnt/β-catenin signaling 7 and it is markedly upregulated during X. laevis tail regeneration 3. Furthermore, our previous microarray analysis showed that fgf20 was the most highly upregulated fgf gene during X. tropicalis tail regeneration 2. We confirmed this upregulation by whole-mount in situ hybridization, where we detected high expression levels of fgf20 in the regenerative bud tissue, starting from 12hpa (Supplementary Figure S5c). Notably, we found that the expression of fgf20 was decreased in tadpoles treated with the ROS inhibitors, DPI, APO, or MCI (Figure 5c, d). Given that fgf20 is a major transcriptional target of Wnt/β-catenin signaling in Xenopus, these results further suggest that amputation-induced ROS are required for Wnt/β-catenin signaling in the early and intermediate stages of tail regeneration.

We then asked whether fgf20, one of many fgfs expressed during tail regeneration 3, 13, was itself necessary for tadpole tail regeneration. In zebrafish, fgf20 has been shown to be essential for the formation of regenerative blastema tissue following tail fin amputation 31, however, its role during Xenopus tadpole tail regeneration had not been addressed. To address the role of fgf20 in the regenerative response, we designed two antisense morpholinos targeting two separate splice junctions in X. tropicalis fgf20 (Supplementary Fig. S5c), and we found that both morpholinos were similarly efficient in reducing fgf20 transcript levels as assayed by RT-PCR (Figure 5d). Following tail amputation, fgf20 morphant tadpoles were able to heal the wound at the amputation site, but they failed to mount a full regenerative response. More specifically, we noted a significant defect in the regeneration of the axial tissues of the tail, corresponding to the tissue that expresses fgf20, and overall tail regrowth was significantly reduced in fgf20 versus control morphants tadpoles (Figure 5e,f). These data show that fgf20 function is required for the regeneration of the axial tissues of the tail, but not for the healing and regeneration of the epidermal tissues.

Thus, our data show that Xenopus tadpole tail regeneration requires the sustained production of H2O2 or closely related ROS, especially during the first 72 hours following amputation. ROS are likely to have pleiotropic effects on cellular physiology, including metabolism, motility, proliferation and signaling, due to the potential global effects that oxidation might incur on protein function 8, 9. In our study, we focused on Wnt signaling and cell proliferation due to the known role that oxidation has on these aspects of cell biology and their previously established roles during tail regeneration. Our finding that a change in ROS levels is required for proper Wnt signaling during tadpole tail regeneration is particularly interesting. It is generally recognized that Wnt signaling plays a critical role in almost every studied regeneration system, from Hydra to mammals, yet very little is known about what controls the activation of Wnt signalling following injury 36, 37. Thus, our work suggests that increased production of ROS plays a critical role in facilitating Wnt signalling following injury, and thus allows the regeneration program to commence. Given the ubiquitous role of Wnt signalling in regenerative events 37, this finding is intriguing as it might provide a general mechanism for injury induced Wnt signalling activation across all regeneration systems, and furthermore, manipulating ROS may provide a means to induce the activation of a regenerative program in those cases where regeneration is normally limited.


FN3COMPETING FINANCIAL INTERESTS The authors declare no competing financial interests.


We thank Philip Niethammer for the pCS2+ HyperYFP construct, the University of Manchester Bioimaging Facility for guidance with imaging, and Roberto Paredes and Yutaka Matsubayashi for advice with statistical analyses. We also thank Nancy Papalopulu and Chris Thompson for comments on the manuscript. This work was supported by a Wellcome Trust Program Grant (E.A.), a Wellcome Trust Career Development Fellowship (J.G.), a Wellcome Trust PhD Studentship (P.K.), and grants from the BBSRC (K.D.), The Healing Foundation (N.L., Y.C., E.A.), and The National Science Foundation (N.L.).

1. Slack JM,Lin G,Chen Y. The Xenopus tadpole: a new model for regeneration researchCell Mol Life SciYear: 200865546318030419
2. Love NR,et al. Genome-wide analysis of gene expression during Xenopus tropicalis tadpole tail regenerationBMC Dev BiolYear: 2011117022085734
3. Lin G,Slack JM. Requirement for Wnt and FGF signaling in Xenopus tadpole tail regenerationDev BiolYear: 200831632333518329638
4. Sugiura T,Tazaki A,Ueno N,Watanabe K,Mochii M. Xenopus Wnt-5a induces an ectopic larval tail at injured site, suggesting a crucial role for noncanonical Wnt signal in tail regenerationMech DevYear: 2009126566718977433
5. Beck CW,Christen B,Slack JM. Molecular pathways needed for regeneration of spinal cord and muscle in a vertebrateDev CellYear: 2003542943912967562
6. Ho DM,Whitman M. TGF-beta signaling is required for multiple processes during Xenopus tail regenerationDev BiolYear: 200831520321618234181
7. Chamorro MN,et al. FGF-20 and DKK1 are transcriptional targets of beta-catenin and FGF-20 is implicated in cancer and developmentEmbo JYear: 200524738415592430
8. Finkel T,Holbrook NJ. Oxidants, oxidative stress and the biology of ageingNatureYear: 200040823924711089981
9. Lambeth JD. NOX enzymes and the biology of reactive oxygenNat Rev ImmunolYear: 2004418118915039755
10. Belousov VV,et al. Genetically encoded fluorescent indicator for intracellular hydrogen peroxideNat MethodsYear: 2006328128616554833
11. Niethammer P,Grabher C,Look AT,Mitchison TJ. A tissue-scale gradient of hydrogen peroxide mediates rapid wound detection in zebrafishNatureYear: 200945999699919494811
12. Yoo SK,Starnes TW,Deng Q,Huttenlocher A. Lyn is a redox sensor that mediates leukocyte wound attraction in vivoNatureYear: 201148010911222101434
13. Love NR,et al. pTransgenesis: a cross-species, modular transgenesis resourceDevelopmentYear: 20111385451545822110059
14. Owusu-Ansah E,Yavari A,Mandal S,Banerjee U. Distinct mitochondrial retrograde signals control the G1-S cell cycle checkpointNat GenetYear: 20084035636118246068
15. Miesenbock G,De Angelis DA,Rothman JE. Visualizing secretion and synaptic transmission with pH-sensitive green fluorescent proteinsNatureYear: 19983941921959671304
16. West AP,et al. TLR signalling augments macrophage bactericidal activity through mitochondrial ROSNatureYear: 201147247648021525932
17. Costa RM,Soto X,Chen Y,Zorn AM,Amaya E. spib is required for primitive myeloid development in XenopusBloodYear: 20081122287229618594023
18. O’Donnell BV,Tew DG,Jones OT,England PJ. Studies on the inhibitory mechanism of iodonium compounds with special reference to neutrophil NADPH oxidaseBiochem JYear: 1993290Pt 141498439298
19. Kahles T,Brandes RP. NADPH oxidases as therapeutic targets in ischemic strokeCell Mol Life SciYear: 2012692345236322618244
20. Stefanska J,Pawliczak R. Apocynin: molecular aptitudesMediators InflammYear: 2008200810650719096513
21. Wind S,et al. Comparative pharmacology of chemically distinct NADPH oxidase inhibitorsBr J PharmacolYear: 201016188589820860666
22. Otomo E. Effect of a novel free radical scavenger, edaravone (MCI-186), on acute brain infarction. Randomized, placebo-controlled, double-blind study at multicentersCerebrovasc DisYear: 20031522222912715790
23. Yoneyama M,Kawada K,Gotoh Y,Shiba T,Ogita K. Endogenous reactive oxygen species are essential for proliferation of neural stem/progenitor cellsNeurochem IntYear: 20105674074619958807
24. Ambasta RK,et al. Direct interaction of the novel Nox proteins with p22phox is required for the formation of a functionally active NADPH oxidaseJ Biol ChemYear: 2004279459354594115322091
25. Le Belle JE,et al. Proliferative neural stem cells have high endogenous ROS levels that regulate self-renewal and neurogenesis in a PI3K/Akt-dependant mannerCell Stem CellYear: 20118597121211782
26. Sundaresan M,Yu ZX,Ferrans VJ,Irani K,Finkel T. Requirement for generation of H2O2 for platelet-derived growth factor signal transductionScience (New York, N.YYear: 1995270296299
27. Yanes O,et al. Metabolic oxidation regulates embryonic stem cell differentiationNat Chem BiolYear: 2010641141720436487
28. Dickinson BC,Peltier J,Stone D,Schaffer DV,Chang CJ. Nox2 redox signaling maintains essential cell populations in the brainNat Chem BiolYear: 2011710611221186346
29. Hendzel MJ,et al. Mitosis-specific phosphorylation of histone H3 initiates primarily within pericentromeric heterochromatin during G2 and spreads in an ordered fashion coincident with mitotic chromosome condensationChromosomaYear: 19971063483609362543
30. Nutt SL,Bronchain OJ,Hartley KO,Amaya E. Comparison of morpholino based translational inhibition during the development of Xenopus laevis and Xenopus tropicalisGenesisYear: 20013011011311477685
31. Whitehead GG,Makino S,Lien CL,Keating MT. fgf20 is essential for initiating zebrafish fin regenerationScience (New York, N.YYear: 200531019571960
32. Lee Y,Grill S,Sanchez A,Murphy-Ryan M,Poss KD. Fgf signaling instructs position-dependent growth rate during zebrafish fin regenerationDevelopmentYear: 20051325173518316251209
33. Stoick-Cooper CL,Moon RT,Weidinger G. Advances in signaling in vertebrate regeneration as a prelude to regenerative medicineGenes & developmentYear: 2007211292131517545465
34. Denayer T,Tran HT,Vleminckx K. Transgenic reporter tools tracing endogenous canonical Wnt signaling in XenopusMethods Mol BiolYear: 200846938140019109721
35. Funato Y,Michiue T,Asashima M,Miki H. The thioredoxin-related redox-regulating protein nucleoredoxin inhibits Wnt-beta-catenin signalling through dishevelledNat Cell BiolYear: 2006850150816604061
36. Galliot B,Chera S. The Hydra model: disclosing an apoptosis-driven generator of Wnt-based regenerationTrends Cell BiolYear: 20102051452320691596
37. Whyte JL,Smith AA,Helms JA. Wnt signaling and injury repairCold Spring Harb Perspect BiolYear: 20124a00807822723493

Article Categories:
  • Article

Previous Document:  Gene expression in bovine rumen epithelium during weaning identifies molecular regulators of rumen d...
Next Document:  SCFFbxw5 mediates transient degradation of actin remodeller Eps8 to allow proper mitotic progression...