Dynamic membrane depolarization is an early regulator of ependymoglial cell response to spinal cord injury in axolotl
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ABSTRACT:
ORGANISM(S): Ambystoma mexicanum
PROVIDER: GSE71934 | GEO | 2016/01/03
SECONDARY ACCESSION(S): PRJNA292499
REPOSITORIES: GEO
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Project description:Salamanders, such as the Mexican axolotl, are some of the few vertebrates fortunate in their ability to regenerate diverse structures after injury. Unlike mammals they are able to regenerate a fully functional spinal cord after injury. However, the early signals required to initiate a pro-regenerative response after spinal cord injury is not well understood. To address this question we developed a spinal cord injury model in axolotls and used in vivo imaging of ion sensitive dyes and determined that spinal cord injury induces a rapid and dynamic change in the resting membrane potential of ependymoglial cells. Prolonged depolarization of ependymoglial cells after injury inhibits glial cell proliferation and subsequent axon regeneration. Using transcriptional profiling we identified c-Fos as a key voltage sensitive early response gene that is expressed specifically in the ependymoglial cells after injury. This data establishes that dynamic changes in the membrane potential after injury are essential for regulating the specific spatiotemporal expression of c-Fos that is critical for promoting faithful spinal cord regeneration in axolotl. All axolotls used in these experiments were bred in the axolotl facility at the University of Minnesota under the IACUC protocol #1201A08381. Axolotls of 2â3 cm were used for all in vivo experiments, and animals were kept in separate containers and fed daily with artemia; water was changed daily. Animals were anesthetized in 0.01% p-amino benzocaine (Sigma) before microinjection was performed. Experimental Design: Ivermectin injection Ivermectin or vehicle only (water) was pressure injected into the central canal of the spinal cord, and this was visualized by the addition of Fast Green into the solution. Directly after injection, a portion of the spinal cord was surgically removed and the animals were placed back into water in individual containers. One day post injury (1dpi) animals were anesthetized again and the area of the injury was removed. Tissue from 10 animals were pooled for each microarray replicate.
2016-07-05 | E-GEOD-71934 | biostudies-arrayexpress
Project description:Salamanders, such as the Mexican axolotl, are some of the few vertebrates fortunate in their ability to regenerate diverse structures after injury. Unlike mammals they are able to regenerate a fully functional spinal cord after injury. Throughout human life, many cells and certain tissues, such as hair follicle stem cells and liver, can be continuously replaced to maintain functional integrity in response to normal daily wear and tear. However, the human response to more serious tissue damage is limited to relatively primitive wound healing, whereby collagenous scar tissue fills the injury site, assuring the tissue’s structural integrity but often resulting in a debilitating loss of functionality. In contrast many vertebrates, including axolotls, have remarkable regenerative capacity including the functional regeneration of full thickness wounds. Here, we have identified a novel role for SALL4 in regulating collagen transcriptional after injury that is essential to ensure perfect skin regeneration in axolotl.
2017-03-07 | GSE79299 | GEO
Project description:Salamanders have the remarkable ability to functionally regenerate after spinal cord transection. In response to injury, GFAP+ glial cells in the axolotl spinal cord proliferate and migrate to replace the missing neural tube and create a permissive environment for axon regeneration. Molecular pathways that regulate the pro-regenerative axolotl glial cell response are poorly understood. Here we show axolotl glial cells up-regulate AP-1cFos/JunB after injury, which promotes a pro-regenerative glial cell response. Axolotl glial cells directly repress c-Jun expression via up-regulation of miR-200a. Inhibition of miR-200a during regeneration causes defects in axonal regrowth and transcriptomic analysis revealed that miR-200a inhibition leads to differential regulation of genes involved with reactive gliosis, the glial scar, ECM remodeling and axon guidance. This work identifies a novel role for miR-200a in inhibiting reactive gliosis in glial cell in axolotl during spinal cord regeneration
2019-03-19 | GSE122939 | GEO
Project description:Endogenous bioelectric signaling via changes in cellular resting potential (Vmem) is a key regulator of patterning during regeneration and embryogenesis in numerous model systems. Depolarization of Vmem has been functionally implicated in de-differentiation, tumorigenesis, anatomical re-specification, and appendage regeneration. However, no unbiased analyses have been performed to understand genome-wide transcriptional responses to Vmem change in vivo. Moreover, it is unknown which genes or gene networks represent conserved targets of bioelectrical signaling across different patterning contexts and species. Here, we use microarray analysis to comparatively analyze transcriptional responses to specific Vmem depolarization. We compare the response of the transcriptome during embryogenesis (Xenopus development), regeneration (Axolotl regeneration), and stem cell differentiation (human mesenchymal stem cells in culture) to identify common networks across model species that are associated with depolarization. Both sub-network enrichment and PANTHER analyses identified a number of key genetic modules as targets of Vmem change, and also revealed important (well-conserved) commonalities in bioelectric signal transduction, despite highly diverse experimental contexts and species. Depolarization regulates specific transcriptional networks across all three germ layers (ectoderm, mesoderm and endoderm) such as cell differentiation and apoptosis, and this information will be used for developing mechanistic models of bioelectric regulation of patterning. Moreover, our analysis reveals that Vmem change regulates transcripts related to important disease pathways such as cancer and neurodegeneration, which may represent novel targets for emerging electroceutical therapies. All axolotls used in these experiments were bred in the axolotl facility at the University of Minnesota under the IACUC protocol #1201A08381. Axolotls of 2â3 cm were used for all in vivo experiments, and animals were kept in separate containers and fed daily with artemia; water was changed daily. Animals were anesthetized in 0.01% p-amino benzocaine (Sigma) before microinjection was performed. There were 9 microarrays conducted, and these were ivermectin-treated (n=3). Experimental Design: Ivermectin injection Ivermectin or vehicle only (water) was pressure injected into the central canal of the spinal cord, and this was visualized by the addition of Fast Green into the solution. Directly after injection, a portion of the spinal cord was surgically removed and the animals were placed back into water in individual containers. One day post injury (1dpi) animals were anesthetized again and the area of the injury was removed. Tissue from 10 animals were pooled for each microarray replicate. Mature - Uninjured spinal cord tissue Sc Crush- spinal cord tissue 1 day after injury Ivermectin - Ivermectin injected spinal cord tissue 1 day after injury.
2016-07-03 | E-GEOD-72096 | biostudies-arrayexpress
Project description:Salamanders have the remarkable ability to functionally regenerate after spinal cord transection. In response to injury, GFAP+ glial cells in the axolotl spinal cord proliferate and migrate to replace the missing neural tube and create a permissive environment for axon regeneration. In this paper we show that miR-200a acts to repress expression of Brachyury in sox2 positive progenitor cells in the axoltol spinal cord after spinal cord injury but after tail amputation when multiple tissue types must be regenerated then mir-200a is downregualted allowing progenitor cells in the spinal cord to naturally become bipotent progenitors which can give rise to muscle and neural cell types. When miR-200a is inhibited after spinal cord injury then these cells also express BRachyury cna can form muscle.
2022-02-10 | GSE196098 | GEO
Project description:Among the vertebrates, teleost and urodele amphibians are capable of regenerating their central nervous system. We have used crush injury method on zebrafish spinal cord, which is a common mammalian mode of injury in spinal cord. To identify the molecular mechanisms of the underlying cellular events during regeneration of zebrafish spinal cord, we have employed high density oligonucleotide microarrays and profiled the temporal transcriptome dynamics during the entire phenomenon. A total of 3842 genes expressed differentially with significant fold changes during spinal cord regeneration. Cluster analysis revealed event specific dynamic expression of genes related to inflammation, cell death, cell migration, cell proliferation, neurogenesis, neural patterning and axonal regrowth. We have also validated the expression pattern of 14 genes (which include inflammatory regulators, cell cycle regulators, pattern forming genes and signaling molecules) by different methodologies. Spatio-temporal analysis of STAT3 expression suggested its possible function in controlling inflammation and cell proliferation. Genes involved in the proliferating neural progenitors and their dorso-ventral patterning (sox2 and dbx2) are differentially expressed. Injury induced cell proliferation is controlled by many cell cycle regulators and some of them also show their common expression in other regenerating systems like fin, heart and retina. We also reported unusual expression pattern of certain pathway genes like one carbon folate metabolism and N-glycan biosynthesis which have not been reported during regeneration of spinal cord. Genes like stat3, socs3, atf3, mmp9 and sox11, which are known to control peripheral nervous system (PNS) regeneration in mammals, are also upregulated in zebrafish spinal cord injury (SCI) thus creating PNS like environment after injury. Our study provides a comprehensive genetic blue print of diverse cellular response(s) during regeneration of zebrafish spinal cord that could be used to induce successful regeneration in mammals. The spinal cord has been injured by crushing dorso-ventrally for 1 sec with a number 5 Dumont forceps at the level of 15th/16th vertebrae. Later the wound were sealed by placing a suture. Both spinal cord injured and sham operated fish were allowed to regenerate and the progress of regeneration was observed after 1, 3, 7, 10 and 15 days of injury. Zebrafishes were anesthetized deeply for 5 minutes in 0.1% tricaine (MS222; Sigma, USA) and approximately 1mm length of spinal cord both rostrally and caudally from injury epicenter were dissected out from 50-60 fishes in each batch and pooled for RNA extraction.
2012-12-01 | E-GEOD-39295 | biostudies-arrayexpress
Project description:The axolotl is an animal with remarkable regenerative abilities, making it an ideal model for studying potential regenerative therapies in mammals, including humans. However, the molecular mechanisms involved in regeneration remain unclear. We conducted a transcriptomic analysis of juvenile axolotls' limbs and their blastema and compared the results with aged axolotls that failed to regenerate after amputation. We identified a set of genes involved in cell differentiation, transcriptional regulation, cartilage development, bone morphogenesis, and extracellular matrix remodeling. Four highly expressed genes (FSTL1, ADAMTS17, GPX7, and CTHRC1) were identified in regenerating tissue, but underexpressed in aged axolotls. Structural and homology analysis showed that these genes are conserved and have important roles in development, bone morphogenesis, and cartilage formation. Our findings propose a novel set of key axolotl genes involved in tissue regeneration that could be a starting point for further studies in other vertebrates.
2024-11-27 | GSE237864 | GEO
Project description:An outstanding mystery in biology is why some species, such as the axolotl, can regenerate tissues whereas mammals cannot1. Here, we demonstrate that rapid activation of protein synthesis is a unique feature of the injury response critical for limb regeneration in the axolotl (Ambystoma mexicanum). By applying polysome sequencing, we identify hundreds of transcripts, including antioxidants and ribosome components that are selectively activated at the level of translation from pre-existing messenger RNAs in response to injury. By contrast, protein synthesis is not activated in response to non-regenerative digit amputation in the mouse. We identify the mTORC1 pathway as a key upstream signal that mediates tissue regeneration and translational control in the axolotl. We discover unique expansions in mTOR protein sequence among urodele amphibians. By engineering an axolotl mTOR (axmTOR) in human cells, we show that these changes create a hypersensitive kinase that allows axolotls to maintain this pathway in a highly labile state primed for rapid activation. This change renders axolotl mTOR more sensitive to nutrient sensing, and inhibition of amino acid transport is sufficient to inhibit tissue regeneration. Together, these findings highlight the unanticipated impact of the translatome on orchestrating the early steps of wound healing in a highly regenerative species and provide a missing link in our understanding of vertebrate regenerative potential.
2023-05-08 | GSE185593 | GEO
Project description:Defining conserved molecular pathways in animal models of successful cardiac regeneration could yield insight into why adult mammals have inadequate cardiac regeneration after injury. Here we describe a cross-species transcriptomic screen to identify evolutionarily conserved pathways in the early events of cardiac regeneration in three species that can regenerate myocardium after a major injury. In this study, we performed RNA-seq on regenerating hearts from three model organisms - axolotl, zebrafish and mouse. Apical resection was performed to amputate ~10 - 20% of the left ventricle in all three model organisms. Following resection, hearts were harvested at 12, 24 and 48 hours post-resection and subjected to RNA-seq. RNA-seq on sham controls (no ventricular amputation) was used as interanal control. This approach revealed upregulation of inflammatory genes in all three organisms during regeneration. Furthermore, upregulation of Complement 5a receptor1 (C5aR1) expression in the regenerating hearts of zebrafish, axolotls and mice was observed.
2018-02-01 | GSE108493 | GEO
Project description:Amphibians such as the salamanders and the African clawed frog Xenopus are great models for regeneration studies because they can fully regenerate their lost organs. While axolotl can regenerate damaged organs throughout its lifetime, Xenopus has a limited regeneration capacity after metamorphosis. The ecotropic viral integrative factor 5 (Evi5), a cell-cycle-regulated protein that prevents cells from entering mitosis prematurely, is of great interest for it is highly upregulated in the limb blastema of axolotls, but its expression level remains unchanged in the fibroblastema of postmetamorphic frogs. Yet, its role in regeneration competent context in Xenopus has not been fully analyzed. Here we show that Evi5 is also upregulated in Xenopus tadpoles after limb and tail amputation, as it is in axolotls. Down-regulation of Evi5 with morpholino antisense oligos (Mo) impairs wound healing and blastema formation in limbs and tails in both axolotls and Xenopus tadpoles, suggesting a conserved function for Evi5 in regeneration. Using skin punch as a healing model we show that Evi5 is also involved in cell migration during wound healing. RNA-sequencing analysis shows that in addition to reduced signaling of Lepr, Pdgfa, Gdf5, evi5 Mo also downregulate lysine demethylases kdm6b and kdm7a, which are also required for limb regeneration. Thus, our results demonstrate that Evi5 plays a critical role in the regeneration of multiple systems in amphibians.
2022-11-24 | GSE218034 | GEO