Dataset Information

Epidermal-Derived Hedgehog Signaling Drives Mesenchymal Proliferation during Digit Tip Regeneration.

ABSTRACT: Hand injuries often result in significant functional impairments and are rarely completely restored. The spontaneous regeneration of injured appendages, which occurs in salamanders and newts, for example, has been reported in human fingertips after distal amputation, but this type of regeneration is rare in mammals and is incompletely understood. Here, we study fingertip regeneration by amputating murine digit tips, either distally to initiate regeneration, or proximally, causing fibrosis. Using an unbiased microarray analysis, we found that digit tip regeneration is significantly associated with hair follicle differentiation, Wnt, and sonic hedgehog (SHH) signaling pathways. Viral over-expression and genetic knockouts showed the functional significance of these pathways during regeneration. Using transgenic reporter mice, we demonstrated that, while both canonical Wnt and HH signaling were limited to epidermal tissues, downstream hedgehog signaling (through Gli) occurred in mesenchymal tissues. These findings reveal a mechanism for epidermal/mesenchyme interactions, governed by canonical hedgehog signaling, during digit regeneration. Further research into these pathways could lead to improved therapeutic outcomes after hand injuries in humans.

SUBMITTER: Maan ZN

PROVIDER: S-EPMC8467649 | biostudies-literature | 2021 Sep

REPOSITORIES: biostudies-literature

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Epidermal-Derived Hedgehog Signaling Drives Mesenchymal Proliferation during Digit Tip Regeneration.

Maan Zeshaan N ZN Rinkevich Yuval Y Barrera Janos J Chen Kellen K Henn Dominic D Foster Deshka D Bonham Clark Andrew CA Padmanabhan Jagannath J Sivaraj Dharshan D Duscher Dominik D Hu Michael M Yan Kelley K Januszyk Michael M Longaker Michael T MT Weissman Irving L IL Gurtner Geoffrey C GC

Journal of clinical medicine 20210920 18

Hand injuries often result in significant functional impairments and are rarely completely restored. The spontaneous regeneration of injured appendages, which occurs in salamanders and newts, for example, has been reported in human fingertips after distal amputation, but this type of regeneration is rare in mammals and is incompletely understood. Here, we study fingertip regeneration by amputating murine digit tips, either distally to initiate regeneration, or proximally, causing fibrosis. Using ...[more]

PMID: 34575372

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Project description:Purpose: Repair of distal phalanx amputation is widely studied and thought to occur through a regenerative process. Single-cell RNA sequencing (scRNA) has greatly improved the ability to characterize the cells that are involved in regeneration and abnormal healing of bone and soft tissue. Given the disorganized architecture of digit tip “regenerated” bone and its common progenitor cell to the pathologic process of heterotopic ossification, we hypothesized that digit tip repair after injury follows a program of aberrant wound repair rather than true regeneration of normal bone tissue. Methods: ScRNA data of mouse digit tip amputation (DTA) and embryonic limb development (EMB) was downloaded from NBCI GEO data base ascension number GSE135985. Additionally, scRNA data from heterotopic ossification (HO) was downloaded from GSE126060. HO, DTA, and EMB datasets were clustered individually. HO was merged and aligned with EMB and DT in separate analyses. Cells expressing the mesenchymal progenitor cell (MPC) marker Pdgfra, which we have shown to differentiate into HO and others have shown to differentiate into bone after DTA, were identified and analyzed in the HO-DTA and HO-EMB datasets. Monocle 2, Seurat 3.1.1, and Pearson correlation analysis were used for analysis and visualization. Immunostaining for markers present in DTA (ACAN, FBN-2, LTBP2) was performed on sections collected from a murine model of traumatic HO in Pdgfra-CreER;TdTomato mice induced with tamoxifen one-week prior to HO-forming injury. Results: MPC clusters from DTA and HO and from EMB and HO were aligned and projected using UMAP to compare transcription profiles. Across the timepoints, MPCs in the DTA and HO occupy similar regions of the UMAP plot, while MPCs in EMB and HO occupy largely independent regions, with only overlap at the latest time points. Using Monocle 2, cells were placed on a virtual timeline based on similarities in transcription. MPCs from DTA and HO meet at the same location on the trajectory following injury. In the EMB to HO comparison, cells only occupy similar regions of the trajectory at post-natal day 3 suggesting that bone is formed by different pathways. To understand correlations between time points, transcriptomes were also compared by Pearson analysis. MPCs following HO and DTA injuries occupy similar regions of the plot while MPCs in EMB and HO only occupy similar regions of the correlation plot at P3. Markers previously identified to be upregulated in MPCs in DTA were also upregulated in MPCs in HO by both scRNA and immunofluorescent histology. Conclusions: Cells responsible for bone repair following DTA show similar transcriptional profiles as MPCs in traumatic HO and dissimilar to MPCs in EMB. Furthermore, MPCs in both digit tip repair and HO follow trajectories that do not overlap with embryonic limb development. Thus, we demonstrate for the first time, that the process following DTA is not truly regeneration and follows programs of aberrant repair as seen in HO.

Dataset Information

Epidermal-Derived Hedgehog Signaling Drives Mesenchymal Proliferation during Digit Tip Regeneration.

Publications

Epidermal-Derived Hedgehog Signaling Drives Mesenchymal Proliferation during Digit Tip Regeneration.

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