Project description:Previous studies indicated that macrophages play a role during lens regeneration in newts, but their function has not been tested experimentally. Here we generated a transgenic newt reporter line in which macrophages can be visualized in vivo. Using this new tool, we analyzed the location of macrophages during lens regeneration. We uncovered early gene expression changes using bulk RNAseq in two newt species, Notophthalmus viridescens and Pleurodeles waltl. Next, we used clodronate liposomes to deplete macrophages, which inhibited lens regeneration in both newt species. Macrophage depletion induced the formation of scar-like tissue, an increased and sustained inflammatory response, an early decrease in iris pigment epithelial cell (iPEC) proliferation and a late increase in apoptosis. Some of these phenotypes persisted for at least 100 days and could be rescued by exogenous FGF2. Re-injury alleviated the effects of macrophage depletion and re-started the regeneration process. Together, our findings highlight the importance of macrophages in facilitating a pro-regenerative environment in the newt eye, helping to resolve fibrosis, modulating the overall inflammatory landscape and maintaining the proper balance of early proliferation and late apoptosis.
Project description:Previous studies indicated that macrophages play a role during lens regeneration in newts, but their function has not been tested experimentally. Here we generated a transgenic newt reporter line in which macrophages can be visualized in vivo. Using this new tool, we analyzed the location of macrophages during lens regeneration. We uncovered early gene expression changes using bulk RNAseq in two newt species, Notophthalmus viridescens and Pleurodeles waltl. Next, we used clodronate liposomes to deplete macrophages, which inhibited lens regeneration in both newt species. Macrophage depletion induced the formation of scar-like tissue, an increased and sustained inflammatory response, an early decrease in iris pigment epithelial cell (iPEC) proliferation and a late increase in apoptosis. Some of these phenotypes persisted for at least 100 days and could be rescued by exogenous FGF2. Re-injury alleviated the effects of macrophage depletion and re-started the regeneration process. Together, our findings highlight the importance of macrophages in facilitating a pro-regenerative environment in the newt eye, helping to resolve fibrosis, modulating the overall inflammatory landscape and maintaining the proper balance of early proliferation and late apoptosis.
Project description:The adult vertebrate red spotted newt is a champion of regeneration, demonstrating an amazing ability to regenerate damaged organs and tissues back to an uninjured state without the formation of scar or reduction in function. By developing a novel cardiac resection strategy, our group recently demonstrated that newt hearts could morphologically and functionally regenerate, without scarring, within a period of 2-3 months following injury. MicroRNAs (miRs) have been widely publicized as essential post-transcriptional gene regulators in a variety of biological processes, including regeneration. We have conducted a microarray screen for vertebrate miRs, with several candidate miRs showing significant differential expression at important time-points following injury to the newt heart. The newt microRNA expression between uninjured hearts and regenerating hearts, 7 and 21 days post-injury (dpi), was compared by microarray analysis. Three paired samples were analyzed: Uninjured, 7dpi and 21dpi newt hearts. Three arrays were hybridized comparing two-paired samples each time.
Project description:The adult vertebrate red spotted newt is a champion of regeneration, demonstrating an amazing ability to regenerate damaged organs and tissues back to an uninjured state without the formation of scar or reduction in function. By developing a novel cardiac resection strategy, our group recently demonstrated that newt hearts could morphologically and functionally regenerate, without scarring, within a period of 2-3 months following injury. MicroRNAs (miRs) have been widely publicized as essential post-transcriptional gene regulators in a variety of biological processes, including regeneration. We have conducted a microarray screen for vertebrate miRs, with several candidate miRs showing significant differential expression at important time-points following injury to the newt heart. The newt microRNA expression between uninjured hearts and regenerating hearts, 7 and 21 days post-injury (dpi), was compared by microarray analysis.
Project description:Surgical removal of the lens from larval Xenopus laevis results in a rapid transdifferention of central corneal cells to form a new lens. The trigger for this process is understood to be an induction event arising from the unprecedented contact between the cornea and the vitreous humour that occurs following lens removal. The identity of this trigger is unknown. Here, we have used a functional transgenic approach to show that BMP signalling is required for lens regeneration and a microarray approach to identify genes that are upregulated specifically during this process. Analysis of the array data strongly implicates Wnt signalling and Pitx transcription factors in this process. Pluripotency genes, in contrast, are not upregulated, supporting the idea that corneal cells transdifferentiate without returning to a stem cell state. Furthermore, several genes from the array were expressed in the forming lens during embryogenesis. One of these, nipsnap1, is a known direct target of BMP signalling. We suggest that, as with tail regeneration, activation of multiple developmental signalling pathways could drive lens regeneration from the cornea. Three biological replicates of each of three sample types were analysed. For each replicate, lens tissue (L) was derived from 5 lenses dissected from stage 50 tadpoles. Similarly, 7-8 corneas dissected from stage 50 tadpoles from which the lens had been removed 3 days previously were pooled for each biologocal replicate (R). These samples should contain tissue that is changing from cornea to lens, to regenerate the missing lens. Finally, 7-8 corneas from eyes of tadpoles at the same stage that had the cornea lifetd but the lens left in place 3 days earlier were pooled for each biological replicate (sham operated corneas, designated S).
Project description:Surgical removal of the lens from larval Xenopus laevis results in a rapid transdifferention of central corneal cells to form a new lens. The trigger for this process is understood to be an induction event arising from the unprecedented contact between the cornea and the vitreous humour that occurs following lens removal. The identity of this trigger is unknown. Here, we have used a functional transgenic approach to show that BMP signalling is required for lens regeneration and a microarray approach to identify genes that are upregulated specifically during this process. Analysis of the array data strongly implicates Wnt signalling and Pitx transcription factors in this process. Pluripotency genes, in contrast, are not upregulated, supporting the idea that corneal cells transdifferentiate without returning to a stem cell state. Furthermore, several genes from the array were expressed in the forming lens during embryogenesis. One of these, nipsnap1, is a known direct target of BMP signalling. We suggest that, as with tail regeneration, activation of multiple developmental signalling pathways could drive lens regeneration from the cornea.
Project description:We have developed a standardized and reproducible heart resection/regeneration model system in the red-spotted newt. In order to ascertain the involvement of microRNAs in this amazing process, we made and sequenced cDNA libraries for microRNAs in order to provide sequence data that we could use in further quantitative and qualitative studies. We constructed small RNA cDNA libraries for uninjured (Uninj), 7dpi and 21dpi heart samples, which were sequenced using Illumina-Solexa technology at SciLifeLabs (Stockholm, Sweden).