Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Retinoic acid breakdown is required for proximodistal positional identity during axolotl limb regeneration

ABSTRACT: 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.

ORGANISM(S): Ambystoma mexicanum

PROVIDER: GSE272731 | GEO | 2024/07/22

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Expression data from regenerating axolotl forelimbs

Project description:Salamanders are capable of regenerating amputated limbs by generating a mass of lineage-restricted cells called a blastema. Blastemas only generate structures distal to their origin unless treated with retinoic acid (RA), which results in proximodistal (PD) limb duplications. Little is known about the transcriptional network that regulates PD duplication. In this study, we identified expression patterns that explain PD duplication including upregulation of proximal homeobox gene expression and silencing of distal-associated genes whereas limb truncation was associated with disrupted skeletal differentiation. Overall, mechanisms were identified that regulate RAR’s multifaceted roles in the salamander limb including regulation of skeletal patterning during epimorphic regeneration, skeletal tissue differentiation during regeneration, and homeostatic regeneration of intact limbs.

2017-01-10 | GSE93303 | GEO

Tig1 regulates proximo-distal identity during salamander limb regeneration

Project description:Salamander limb regeneration is an accurate process which gives rise exclusively to the missing structures, irrespective of the amputation level. This suggests that cells in the stump have an awareness of their spatial location, a property termed ‘positional identity’. Little is known about how positional identity is encoded, in salamanders or other biological systems. Through single-cell RNAseq analysis, we identified Tig1/RARRES1 as a potential determinant of proximal identity. Tig1 encodes a conserved cell surface molecule, is regulated by retinoic acid and exhibits a graded expression along the proximo-distal axis of the limb. Its overexpression leads to regeneration defects in the distal elements and elicits proximal displacement of blastema cells, while its neutralisation blocks proximo-distal cell surface interactions. Critically, Tig1 reprogrammes distal cells to a proximal identity, upregulating Prod1 and inhibiting HoxA13 and distal transcriptional networks. Thus, Tig1 is a central cell surface determinant of proximal identity in the salamander limb.

2022-01-30 | GSE184948 | GEO

Meis genes regulate RA/FGF signaling to control multiple steps of limb development

Project description:Vertebrate limbs develop by integrating signals that control patterning along three main orthogonal axes. Flank-produced retinoic acid (RA) is initially required for limb induction and establishment of the apical ectodermal ridge (AER), a distal signaling center that produces fibroblast growth factors (FGFs), which are essential for limb growth and distalization. Once the AER is established, RA:FGF antagonism determines the restricted expression of a set of genes that control limb proximodistal patterning. Essential for this antagonism is the activation by FGF of the RA-degrading enzyme CYP26B1 in the distal limb bud. In addition, sonic hedgehog produced from the zone of polarizing activity (ZPA) is essential for distal limb anteroposterior patterning and contributes to RA reduction by cooperating in CYP26B1 activation. Meis transcription factors are expressed in the proximal limb bud, are activated by RA and can regulate proximodistal limb development; however, the mechanisms underlying their activity remain unknown. Here we studied Meis function in the mouse limb bud through Meis2 conditional overexpression and elimination of Meis1 and Meis2. We found that Meis activity is first required for limb bud initiation and the proper establishment of the AER and ZPA signaling centers, and subsequently for the development of proximal limb structures. Functional genomic analyses reveal that Meis is an important conveyor of the RA:FGF antagonism through the regulation of components of the RA and FGF signaling pathways, including CYP26B1. In addition, Meis regulates a set of proximal limb genes controlling proximodistal patterning and differentiation. Our work reveals a regulatory module essential for limb patterning and potentially co-opted in other patterning processes involving RA:FGF antagonism.

2018-09-25 | GSE51374 | GEO

Single-cell analysis uncovers convergence of cell identities during axolotl limb regeneration

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

Chromatin states at homeoprotein loci distinguish axolotl limb segments prior to regeneration [RNA-seq]

Project description:The salamander limb regenerates only the missing portion. Each limb segment can only form segments equivalent to- or more distal to their own identity, relying on a property termed “positional information”. How positional information is encoded in limb cells has been unknown. By cell-type-specific chromatin profiling of upper arm, lower arm, and hand, we found segment-specific levels of histone H3K27me3 at limb homeoprotein gene loci but not their upstream regulators, constituting an intrinsic segment information code. During regeneration, regeneration-specific regulatory elements became active prior to the re-appearance of developmental regulatory elements. This means that, in the hand segment, the permissive chromatin state of the hand homeoprotein gene HoxA13 engages with regeneration regulatory elements, bypassing the upper limb program. We performed Differential Gene expression analysis using data obtained from RNA-seq of two mature limb segments (mature arm vs hand). Therefore, we performed libraries from the mature arm and 5, 9, 13 dpa regenerating arm blastema.

2023-04-10 | GSE217593 | GEO

Single cell RNA sequencing of adult regenerating mouse digit tips

Project description:Innate regeneration following digit tip amputation is one of the few examples of epimorphic regeneration in mammals. Digit tip regeneration is mediated by the blastema, the same structure invoked during limb regeneration in some lower vertebrates. By genetic lineage analyses in mice, the digit tip blastema has been defined as a population of heterogeneous, lineage restructed progenitor cells. These previous studies, however, do not comprehensively evaluate blastema heterogeneity or address lineage restruction of closely related cell types. Here we report single cell RNA sequencing of over 38,000 cells from mouse digit tip blastemas and unamputated control digit tips and generate an atlas of the cell types participating in digit tip regeneration.

2020-02-24 | GSE143888 | GEO

Variant PRC1 competes with retinoic acid-related signals to repress Meis2 in distal forelimb bud

Project description:Suppression of Meis genes in the distal limb bud is required for Proximal-Distal (PD) specification of the forelimb. Polycomb group (PcG) factors play a role in downregulation of retinoic acid (RA)-related signals in the distal forelimb bud, causing Meis repression. It is, however, not known if downregulation of RA-related signals and PcG-mediated proximal genes repression are functionally linked. Here, we reveal that PcG factors and RA-related signals antagonize each other to polarize Meis2 expression along the PD axis. With mathematical modeling and simulation, we propose that PcG factors are required to adjust the threshold for RA-related signaling to regulate Meis2 expression. Finally, we show that a variant Polycomb repressive complex 1 (PRC1), incorporating PCGF3 and PCGF5, represses Meis2 expression in the distal limb bud. Taken together, we reveal a previously unknown link between PcG proteins and downregulation of RA-related signals to mediate the phase transition of Meis2 transcriptional status during forelimb patterning.

2018-09-07 | GSE105206 | GEO

bmp4 RNAi gene expression profiling

Project description:Regeneration is a widespread phenomenon that often requires formation of a new tissue outgrowth at wounds called a blastema. Identifying the key signals that trigger blastema formation is therefore fundamental for understanding the mechanistic basis of regeneration. We uncovered a role for the wound epidermis in regeneration initiation in planarians. The gene equinox is expressed within hours of injury in the planarian wound epidermis and encodes a secreted protein conserved in many phyla. Following equinox inhibition, animals failed to form blastemas, reset positional information, and upregulate stem cell (neoblast) proliferation at wounds. Associated with these defects was an inability to maintain wound-induced gene expression. We propose that activation of equinox in the wound epidermis initiates planarian regeneration.

2021-09-04 | GSE179291 | GEO

Single cell gene expression profiling using 10x v3

2021-09-04 | GSE179290 | GEO

equinox RNAi gene expression profiling

2021-09-04 | GSE179293 | GEO