• Here we review recent insights into the biophysical, biochemical, and epigenetic processes that underlie regenerative healing in amphibians, focusing particularly on tail and limb regeneration in Xenopus . (frontiersin.org)
  • We examined the bioelectric properties (resting potential gradients in the epidermis) of Xenopus laevis froglets undergoing hindlimb amputation and observed that the contralateral (undamaged) limb exhibits apparent depolarization signals immediately after the opposite hindlimb is amputated. (biologists.com)
  • This type of regeneration is rare among vertebrates but does occur in the African clawed frog Xenopus laevis , traditionally a model organism for the study of early development. (biomedcentral.com)
  • Xenopus tadpoles can regenerate their tails, limb buds and the lens of the eye, although the ability of the latter two organs to regenerate diminishes with advancing developmental stage. (biomedcentral.com)
  • Activation of this transgene blocks regeneration of the tail and limb of Xenopus tadpoles. (biomedcentral.com)
  • Gene Ontology analysis showed that genes involved in embryonic development and growth are significantly over-represented in regenerating early hindlimb buds and that successful regeneration in the Xenopus hindlimb correlates with the induction of stress response pathways. (biomedcentral.com)
  • Gene over-expression analyses in Xenopus limb and tail regeneration have indicated that successful regeneration requires the re-activation of developmental FGF or BMP signalling pathways [ 8 - 12 ]. (biomedcentral.com)
  • We have developed a heat shock inducible transgenic line ( N1 ) of Xenopus in which the BMP antagonist Noggin can be induced at a specific time during either development or regeneration, repressing BMP signalling [ 10 , 12 ]. (biomedcentral.com)
  • Just as plant cells respond to injury by undergoing callus formation via dedifferentiation, some animal models dedifferentiate their cells to form blastema, which are analogous to plant calluses, after limb amputation. (wikipedia.org)
  • In mammals, a limb amputation or spinal cord transection is followed by inflammation and fibrotic scarring that leaves the animal with a permanent disability. (frontiersin.org)
  • The wound epithelium of N1 transgenic hindlimb buds, which forms over the cut surface of the limb bud after amputation, does not transition normally into the distal thickened apical epithelial cap. (biomedcentral.com)
  • N1 transgenic hindlimbs, which do not regenerate, do not form an apical epithelial cap or cone shaped blastema following amputation. (biomedcentral.com)
  • Appendage regeneration, particularly of the tadpole tail, has been widely studied before, during and after this period. (frontiersin.org)
  • We have used this line to show that BMP function is not only required for appendage regeneration but that it is specifically needed to generate a proliferating blastema while being dispensable for wound healing [ 12 ]. (biomedcentral.com)
  • Injuries that sever tissues such as the limb or spinal cord are met with radically different outcomes among vertebrates. (frontiersin.org)
  • It is well-established that early embryonic signaling pathways are critical for growth and patterning of new tissue during regeneration. (frontiersin.org)
  • The complete integumentary organ system (IOS) regeneration and scarless wound healing mechanism, which occurs in specific species, body sites and developmental stages, clearly shows that mechanical stress signals and immune responses play important roles in determining the wound healing mode. (mdpi.com)
  • In urodele amphibians such as axolotls and newts, the same injury is followed by scarless regenerative healing that can fully restore both the lost tissue and its function (reviewed in Tanaka, 2016 ). (frontiersin.org)
  • Elegant experiments using heat-shock inducible expression of inhibitory proteins have further refined these observations to establish epistatic relationships, in which BMP acts upstream of Wnt, which in turn acts upstream of FGF during regeneration of the limb bud and tail ( Lin and Slack, 2008 ). (frontiersin.org)
  • While it can be induced in a laboratory setting through processes like direct reprogramming and the production of induced pluripotent stem cells, endogenous dedifferentiation processes also exist as a component of wound healing mechanisms. (wikipedia.org)
  • The mechanism by which dedifferentiation occurs has not been completely illuminated. (wikipedia.org)
  • The pathways discussed below are found to be closely related to dedifferentiation and regeneration in some species. (wikipedia.org)
  • Because not one pathway has been elucidated as necessary for all dedifferentiation and regeneration, it is possible that the mechanism functions differently in different species. (wikipedia.org)
  • Epimorphic regeneration can be thought of as occurring in two phases: wound healing and cell proliferation. (biomedcentral.com)
  • Regeneration-competent wound healing of amphibian appendages is generally rapid and involves covering the wound surface with a specialised epidermis lacking a basement membrane and dermis [ 3 , 4 ]. (biomedcentral.com)
  • Once the wound is healed, the cells of the stump must mobilise under the wound epidermis and begin the process of replacing lost tissues, by forming a proliferating blastema. (biomedcentral.com)
  • The pattern of depolarization matches that of the amputated limb and is correlated to the position and type of injury, revealing that information about damage is available to remote body tissues and is detectable non-invasively in vivo by monitoring the bioelectric state. (biologists.com)
  • Once BMP expression was restored, Msx1 expression was also restored, and regeneration proceeded.19 Similar studies have shown similar results in mouse digit tip regeneration. (wikipedia.org)
  • Using Affymetrix Gene Chip analysis, we have identified genes linked to regenerative success downstream of BMP signalling, including the BMP inhibitor Gremlin and the stress protein Hsp60 ( no blastema in zebrafish). (biomedcentral.com)
  • In recent years, interest in the possible molecular regulators of cell proliferation and differentiation in a wide range of regeneration models has grown significantly, but the cell kinetics of this process remain largely a mystery. (mdpi.com)
  • One concentrate inside the mechanism of neuronal death in AD would be the aberrant expression of cell cycle related proteins, this kind of as cdc2, cdk4, cyclin B1, and cyclin D, which med iate cell cycle progression, in vulnerable neurons from the AD brain, these molecules perform important roles in neuronal death related with several paradigms of neuronal death. (fgfrinhibitors.com)
  • For example, MMP, the matrix metalloproteinase, has shown up-regulated activity during early stages of limb regeneration. (wikipedia.org)
  • Regeneration of damaged body parts requires coordination of size, shape, location and orientation of tissue with the rest of the body. (biologists.com)
  • mitotically active cells of intact segments do not significantly contribute to the blastemal cellular sources. (mdpi.com)
  • Here we try to elucidate the cellular aspects of regeneration by EdU incorporation in intact and posteriorly amputated annelid Alitta virens using quantitative analysis. (mdpi.com)
  • The regeneration of a tissue intuitively recapitulates aspects of its embryonic development. (frontiersin.org)
  • Molecular evidence has validated multiple aspects of this parallel. (frontiersin.org)
  • Furthermore, the underlying mesenchyme remains rounded and does not expand to form a cone shaped blastema, a normal feature of successful regeneration. (biomedcentral.com)
  • Lowered Notch1 expression resulted in no tadpole tail regeneration, and induced Notch1 expression was able to partially rescue tail regeneration in the form of notochord and spinal cord (but very little musculature. (wikipedia.org)
  • Lizards present an intermediate character, with a capacity for extensive neurogenesis in the brain but defective spinal cord regeneration. (nature.com)
  • Figure 2: Neural progenitors in spinal cord development and regeneration. (nature.com)
  • During aging, numerous tissues exhibit a progressive decline in homeostasis and regeneration that results in tissue degeneration, malfunction and pathology. (mdpi.com)
  • Nevertheless, the mechanisms by which neuronal degeneration and death happen in AD and no matter whether they may be induced by Ab will not be wholly understood. (fgfrinhibitors.com)
  • The axolotl is one of the few tetrapods that are capable of regenerating complicated biological structures, such as complete limbs, throughout adulthood. (nih.gov)
  • Upon injury the axolotl generates a population of regeneration-competent limb progenitor cells known as the blastema, which will grow, establish pattern, and differentiate into the missing limb structures. (nih.gov)
  • However, it was also long known that lower vertebrate species are capable of impressive regeneration of CNS structures. (nature.com)
  • The pathways discussed below are found to be closely related to dedifferentiation and regeneration in some species. (wikipedia.org)
  • Because not one pathway has been elucidated as necessary for all dedifferentiation and regeneration, it is possible that the mechanism functions differently in different species. (wikipedia.org)
  • The profile of regenerating species could be consistent with the presence of regeneration in the ancestral vertebrate and loss during evolution. (nature.com)
  • Increasing cellular and molecular understanding of regeneration in different animal species coupled with studies of adult neurogenesis in mammals is providing a basis for addressing this question. (nature.com)
  • Understanding how these mechanisms impact on regenerative processes is essential to devise therapeutic approaches to improve tissue regeneration and extend healthspan. (mdpi.com)
  • Once BMP expression was restored, Msx1 expression was also restored, and regeneration proceeded.19 Similar studies have shown similar results in mouse digit tip regeneration. (wikipedia.org)
  • Lenhoff, H. M. & Lenhoff, S. G. in A History of Regeneration Research: Milestones in the Evolution of a Science (Ed. Dinsmore C. E.) (Cambridge University Press, Cambridge, 1991). (nature.com)