Retinoic acid breakdown is required for proximodistal positional identity during axolotl limb regeneration
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PROVIDER: PRJNA1138466 | ENA |
REPOSITORIES: ENA
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Project description:Regenerating limbs retain their proximodistal (PD) positional identity following amputation. This positional identity is encoded genetically by PD patterning genes, which instruct blastema cells to regenerate the appropriate PD limb segment. Retinoic acid (RA) is known to specify proximal limb identity, but how RA concentration is established in the blastema is unknown. Here, we show that RA breakdown via CYP26B1 is essential for determining the RA concentration within blastemas. CYP26B1 inhibition molecularly reprograms distal blastemas into a proximal identity, phenocopying the effects of administering excess RA. We identify Shox as an RA responsive gene that is differentially expressed between proximally and distally amputated blastemas. Ablation of Shox results in shortened limbs with proximal skeletal elements that fail to undergo endochondral ossification. These results suggest that PD positional identity is determined by RA degradation and that targets of RA have a critical role in skeletal element formation during limb regeneration.
2024-07-22 | GSE272731 | GEO
Project description:We know little about the control of positional information (PI) during axolotl limb regeneration which ensures that the limb regenerates exactly what was amputated and the work reported here investigates this phenomenon. Retinoic acid administration changes the PI in a proximal direction so that a complete limb can be regenerated from a hand. Rather that identifying all the genes altered by RA treatment of the limb, we have eliminated many off-target effects by using retinoic acid receptor selective agonists. We firstly identify the receptor involved in this respecification process as RARα and secondly identify the genes involved by RNA sequencing of the RARα-treated blastemal mesenchyme. We find 1177 up-regulated genes and 1403 down-regulated genes which could be identified using the axolotl genome. These include several genes known to be involved in retinoic acid metabolism and in patterning. Since positional in-formation is thought to be a property of the cell surface of blastemal cells when we examine our dataset with an emphasis on this aspect, we find the top canonical pathway is integrin signaling. In the extracellular matrix compartment, we find an MMP and several collagens are up-regulated and several cell membrane genes and secretory factors are also up-regulated. This provides data for future testing of the function of these candidates in the control of PI during limb regeneration.
2021-08-20 | GSE182296 | GEO
Project description:Retinoic acid receptors and the control of positional information in the regenerating axolotl limb
| PRJNA755711 | ENA
Project description:Humans and other tetrapods are considered to require apical-ectodermal-ridge, AER, cells for limb development, and AER-like cells are suggested to be re-formed to initiate limb regeneration. Paradoxically, the presence of AER in the axolotl, the primary regeneration model organism, remains controversial. Here, by leveraging a single-cell transcriptomics-based multi-species atlas, composed of axolotl, human, mouse, chicken, and frog cells, we first established that axolotls contain cells with AER characteristics. Surprisingly, further analyses and spatial transcriptomics revealed that axolotl limbs do not fully re-form AER cells during regeneration. Moreover, the axolotl mesoderm displays part of the AER machinery, revealing a novel program for limb (re)growth. These results clarify the debate about the axolotl AER and the extent to which the limb developmental program is recapitulated during regeneration.
2023-09-20 | GSE243225 | GEO
Project description:Discovery of genes driving axolotl limb regeneration has been challenging due to limited genomic resources. We assembled 42 RNA-Seq samples totaling approximately 1.3 billion 100 base paired-end reads using Trinity (Grabherr M.G. et al, Nature Biotechnology, 2011; Haas B.J. et al, Nature Protocols, 2013): https://github.com/trinityrnaseq/trinityrnaseq/wiki). We created a transcriptome with complete sequence information for most axolotl genes, identified transcriptional profiles that distinguish blastemas from differentiated limb tissues, and uncovered functional roles for cirbp and kazald1 in limb regeneration.
2016-12-15 | GSE92429 | GEO
Project description:Amputation of the axolotl forelimb results in the formation of a blastema, a transient tissue where progenitor cells accumulate prior to limb regeneration. Connective tissue (CT) – skeleton, periskeleton, tendon, dermis, interstitial cells – contributes the vast majority of cells that populate the blastema, however it is unclear how individual CT cells may reprogram their fate in order to rebuild the tetrapod limb. Here we use a combination of Cre-loxP reporter lineage tracking and single-cell (sc) RNA-seq to molecularly track, for the first time, adult CT cell heterogeneity and its transition to a limb blastema state. We uncover a multi-phasic molecular program where CT cell types found in the uninjured adult limb revert to a relatively homogenous progenitor state that participates in inflammation and extracellular matrix disassembly prior to proliferation, establishment of positional information, and ultimately re-differentiation. While the early regeneration transcriptome states are unique to the blastema, the later stages recapitulate embryonic limb development. Notably, we do not find evidence of a pre-existing blastema-like precursor nor limb bud-like progenitors in the uninjured adult tissue. However, we find that distinct CT subpopulations in the adult limb differentially contribute to proximal and distal portions of the regenerated limb. Together, our data illuminates molecular and cellular reprogramming during complex organ regeneration in a vertebrate.
2018-09-27 | GSE106269 | GEO
Project description:Here we report the results of a robust microarray experiment that examined the first 28 days of axolotl forelimb regeneration. At each of 20 post-amputation time points, we estimated gene expression for 10 replicate RNA samples that were isolated from 1m of heterogeneous tissue collected from the distal limb tip. The distal 1.0mm of heterogeneous tissue from regenerating limb tip were removed and used for RNA extraction. 10 samples were collected for each of 20 time points.
2015-04-20 | E-GEOD-67118 | biostudies-arrayexpress
Project description:Regeneration of complex multi-tissue structures, such as limbs, requires the coordinated effort of multiple cell types. In axolotl limb regeneration, the wound epidermis and blastema have been extensively studied via histology, grafting, and bulk-tissue RNA-sequencing. However, studying the contributions of these tissues is hindered due to limited information regarding the molecular identity of the cell types in regenerating limbs. By performing unbiased single-cell RNA-sequencing on over 25,000 cells from axolotl limbs, we identify a plethora of cellular diversity within epidermal, mesenchymal, and hematopoietic lineages in homeostatic and regenerating limbs. We identify regeneration-induced genes, develop putative trajectories for blastema cell differentiation, and propose the molecular identity and origin of fibroblast-derived blastema progenitor cells residing in homeostatic limbs. This work will enable application of molecular techniques to assess the contribution of these populations to limb regeneration. It will also facilitate work aimed at identifying transcripts and cells critical for limb regeneration.
2018-10-25 | GSE121737 | GEO
Project description:Here we report the results of a robust microarray experiment that examined the first 28 days of axolotl forelimb regeneration. At each of 20 post-amputation time points, we estimated gene expression for 10 replicate RNA samples that were isolated from 1m of heterogeneous tissue collected from the distal limb tip.
2015-04-20 | GSE67118 | GEO
Project description:Identifying the genetic program that induces limb regeneration in salamanders is an important resource for regenerative medicine, which currently lacks tools to promote regeneration of functional body structures. The genetic network underlying limb regeneration has been elusive due to the complexity of the injury response that occurs concomitant to blastema formation. Here we performed parallel expression profile time courses of non-regenerative lateral wounds versus amputated limbs in axolotl. We show that limb regeneration occurs in three distinguishable phases--early wound healing followed by a transition phase leading to establishment of the limb development program. By focusing on the transition phase, we identified 93 strictly regeneration-associated genes involved in oxidative stress response, chromatin modification, epithelial development and limb development. The specific expression of the genes was confirmed by in situ hybridization. Regeneration-specific expression databases are critical resources for understanding how regeneration-relevant phenotypes can be induced from adult cells Regeneration of the axolotl forelimb lower arm was compared with the healing of a deep lateral injury in a high density timecourse (uncut, 3h, 6h, 9h, 12h, 24h, 36h, 52h, 72h, 120h, 168h, 288h and 528h after injury). Three independent biological replicates were performed using separate cluches of animals. Amputated and lateral wound samples were made as matched contralateral samples of four pooled animals per timepoint.
2013-01-01 | E-GEOD-36451 | biostudies-arrayexpress