Microglia suppress Ascl1-induced retinal regeneration in mice.
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE161394 | GEO | 2020/12/30
REPOSITORIES: GEO
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Project description:Müller glia can serve as a source for retinal regeneration in some non-mammalian vertebrates. Recently we found that this process can be induced in mouse Müller glia after injury, by combining transgenic expression of the proneural transcription factor Ascl1 and the HDAC inhibitor TSA. However, new neurons are only generated from a subset of Müller glia in this model, and identifying factors that limit Ascl1-mediated MG reprogramming could potentially make this process more efficient, and potentially useful clinically. One factor that limits neurogenesis in some non-mammalian vertebrates is the STAT pathway activation that occurs in Müller glia in response to injury. In this report, we tested whether injury induced STAT activation hampers the ability of Ascl1 to reprogram Müller glia into retinal neurons. Using a STAT inhibitor, in combination with our previously described reprogramming paradigm, we found a large increase in the ability of Müller glia to generate neurons, similar to those we described previously. Single-cell RNA-seq showed that the progenitor-like cells derived from Ascl1-expressing Müller glia have a higher level of STAT signaling than those that become neurons. Using Ascl1 ChIP-seq and DNase-seq, we found that developmentally inappropriate Ascl1 binding sites (that were unique to the overexpression context) had enrichment for the STAT binding motif. This study provides evidence that STAT pathway activation reduces the efficiency of Ascl1-mediated reprogramming in Müller glia, potentially by directing Ascl1 to developmentally inappropriate targets.
2019-11-01 | GSE135414 | GEO
Project description:Non-mammalian vertebrates have a robust ability to regenerate injured retinal neurons from Müller glia cells (MG) that activate the proneural factor Achaete-scute homolog 1 (Ascl1/Mash1) and de-differentiate into progenitors cells. In contrast, mammalian MG have a limited regenerative response and fail to upregulate Ascl1 after injury. To test whether Ascl1 could restore a neurogenic potential to mammalian MG, we over-expressed Ascl1 in dissociated mouse MG cultures and intact retinal explants. Ascl1-infected MG upregulate retinal progenitor-specific genes, while downregulating glial genes. Furthermore, Ascl1 remodeled the chromatin at its targets from a repressive to active configuration. MG-derived progenitors differentiated into cells that exhibited neuronal morphologies, expressed retinal subtype-specific neuronal markers, and displayed neuron-like physiological responses. These results indicate that a single transcription factor, Ascl1, can produce a neurogenic state in mature Muller glia. Expresssion profiling was used to determine the genes that were changed after Ascl1 infection of P12 cultured Müller glia compared with those present in P0 progenitors and P7-P21 Müller glia Retinas were dissociated and FAC-sorted from Hes5-GFP mice at P0, P7, P10, P14 or P21 and submitted for profiling. WT Retinas were dissociated at P12, grown for 1 week in culture, and infected with lentiviruses expressing Ascl1 or GFP for four days. Total RNA was extracted and submitted for profiling.
2013-04-06 | E-GEOD-45835 | biostudies-arrayexpress
Project description:Non-mammalian vertebrates have a robust ability to regenerate injured retinal neurons from Müller glia cells (MG) that activate the proneural factor Achaete-scute homolog 1 (Ascl1/Mash1) and de-differentiate into progenitors cells. In contrast, mammalian MG have a limited regenerative response and fail to upregulate Ascl1 after injury. To test whether Ascl1 could restore a neurogenic potential to mammalian MG, we over-expressed Ascl1 in dissociated mouse MG cultures and intact retinal explants. Ascl1-infected MG upregulate retinal progenitor-specific genes, while downregulating glial genes. Furthermore, Ascl1 remodeled the chromatin at its targets from a repressive to active configuration. MG-derived progenitors differentiated into cells that exhibited neuronal morphologies, expressed retinal subtype-specific neuronal markers, and displayed neuron-like physiological responses. These results indicate that a single transcription factor, Ascl1, can produce a neurogenic state in mature Muller glia. Expresssion profiling was used to determine the genes that were changed after Ascl1 infection of P12 cultured Müller glia compared with those present in P0 progenitors and P7-P21 Müller glia
2013-04-06 | GSE45835 | GEO
Project description:Regeneration of neurons has enormous implications for human health and is a topic of interest both from the biological and translational perspective. The retina poses an excellent system to study the potential of replacing neurons following injury and the impact different lesions can have on this process. We have established mouse models where proneural transcription factors are expressed in Müller glia to stimulate neurogenesis, which is analogous to how zebrafish regenerate the retina after injury. Our previous studies have shown that Müller glia overexpressing either Ascl1 or Ascl1-Atoh1 will respond to inner retinal damage, caused by a neurotoxic dose of NMDA, by acquiring a progenitor-like state and giving rise to bipolar cells or retinal ganglion-like cells, respectively. It was not known however whether neurogenesis would still occur if the retina suffered outer retinal injury and if the timing of injury relative to the expression of proneural factors was critical for the process. To address these questions, we explored whether timing or mode of injury affect the induced neurogenesis from MG. We show that reprogramming MG with Ascl1 is not impacted by the mode or timing of injury, since all paradigms resulted in similar ratios of new bipolar neurons. By contrast, MG that express Ascl1-Atoh1 respond to outer retinal damage by producing a new type of retinal ganglion-like cell that is not generated after NMDA injury. Therefore, although the fate of reprogrammed neurons is mostly dictated by the proneural transcription factors, there is a context-dependent effect of the injured retinal microenvironment.
2023-12-13 | GSE250019 | GEO
Project description:Loss of neurons in the neural retina is a leading cause of vision loss. Retinal regeneration in zebrafish is attributed to Müller glia, which are activated, adopt a stem cell-like state, proliferate, and generate new neurons. Despite the same endogenous Müller glia being present in all vertebrates including humans, Müller glia activation in mammals leads to glial scarring instead of neurogenesis. Therefore, understanding Müller glia cellular states and molecular processes during zebrafish regeneration may allow us to improve mammalian regeneration. Since only a subset of Müller glia activate following neuron loss, we asked whether a specialised subset of Müller glia might be genetically primed for activation. Single-cell RNA sequencing (sc-RNAseq) from integrated zebrafish Müller glia samples reveals heterogeneity of gene expression across the quiescent Müller glia pool with 4 main clusters emerging, two of which are genetically similar. Labelling for key differentially expressed markers identified that these main clusters correlated with glia spatially distributed across dorsal, central and ventral retina. Using a genetically driven, chemically induced nitroreductase approach, three distinct photoreceptor types were ablated: the long (Lws2), short wavelength-sensitive (Sws2) and rod (Xops) photoreceptors, which also differ in their abundance. As expected, histological analysis of the three injuries and sc-RNAseq data for the two cone photoreceptor ablations identified common genetic program involved in the transition of Müller glia quiescence to activation, and differential responses to injury related to either injury extent or subtype of photoreceptor targeted. Interestingly, despite differences in the distributed across the retina, biased activation of Müller glia was observed in dorsal and central regions. Gene ontology analysis revealed that these injury-responsive dorsal and central Müller glia express genes related to dorsal/ventral pattern formation, growth factor activity, and regulation of developmental process. Müller glia upregulated genes related to homeostasis as well as certain AP-1 and injury-responsive transcription factors, followed by expression of genes involved in cell cycle, chromatin remodeling, and microtubule organisation. Prior to cell cycle entry, Müller glia show a transient upregulation of genes involved in gliogenesis, and Notch signalling. These findings enhance our understanding of heterogeneous states of quiescent Müller glia, and how these differences relate to activation and regeneration potential following neural ablation. A comparison of the distinct quiescent Müller glia with glia states in mammals will reveal key molecular pathways that could be targeted for improved mammalian neural regeneration.
2023-08-21 | GSE218107 | GEO
Project description:Many retinal diseases lead to the loss of retinal neurons and cause visual impairment. The adult mammalian retina has little capacity for regeneration. By contrast, teleost fish functionally regenerate their retina following injury, and Müller glia (MG) are the source of regenerated neurons. The proneural transcription factor Ascl1 is upregulated in MG after retinal damage in zebrafish and is necessary for regeneration. Although Ascl1 is not expressed in mammalian MG after injury, forced expression of Ascl1 in mouse MG induces a neurogenic state in vitro and in vivo after NMDA (N-methyl-d-aspartate) damage in young mice. However, by postnatal day 16, mouse MG lose neurogenic capacity, despite Ascl1 overexpression. Loss of neurogenic capacity in mature MG is accompanied by reduced chromatin accessibility, suggesting that epigenetic factors limit regeneration. Here we show that MG-specific overexpression of Ascl1, together with a histone deacetylase inhibitor, enables adult mice to generate neurons from MG after retinal injury. The MG-derived neurons express markers of inner retinal neurons, synapse with host retinal neurons, and respond to light. Using an assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq), we show that the histone deacetylase inhibitor promotes accessibility at key gene loci in the MG, and allows more effective reprogramming. Our results thus provide a new approach for the treatment of blinding retinal diseases.
2021-01-10 | GSE164489 | GEO
Project description:Many neurodegenerative diseases cause degeneration of specific types of neurons. For example, glaucoma leads to death of retinal ganglion cells, leaving other neurons intact. Neurons are not regenerated in the adult mammalian central nervous system. However, in non-mammalian vertebrates, glial cells spontaneously reprogram into neural progenitors and replace neurons after injury. We have recently developed strategies to stimulate regeneration of functional neurons in the adult mouse retina by overexpressing the proneural factor Ascl1 in Müller glia. In this report, we test additional transcription factors (TFs) for their ability to direct regeneration to particular types of retinal neurons. We engineered mice to express different combinations of TFs in MG, including Ascl1, Pou4f2, Islet1 and Atoh1. Using IHC, scRNA-seq, scATAC-seq, and electrophysiology we find retinal ganglion-like cells can be regenerated in the damaged adult mouse retina in vivo with targeted overexpression of developmental RGC-transcription factors.
2022-09-15 | GSE211077 | GEO
Project description:Diseases and damage to the retina lead to losses in retinal neurons and eventual visual impairment. Although the mammalian retina has no inherent regenerative capabilities, fish have robust regeneration from Müller glia (MG). Recently, we have shown that driving expression of Ascl1 in adult mouse MG stimulates neurogenesis similar to fish regeneration. The regeneration observed in the mouse is limited in the variety of neurons that can be derived from MG; Ascl1-expressing MG primarily generate bipolar cells. To better understand the limits of MG-based regeneration in mouse retinas, we used ATAC- and RNA-seq to compare newborn progenitors with MG. Our analysis demonstrated striking similarities between MG and progenitors, with losses in regulatory motifs for neurogenesis genes. Young MG were found to have intermediate expression profiles and accessible DNA, which is mirrored in the ability of Ascl1 to direct bipolar neurogenesis in young MG. When comparing what makes bipolar and photoreceptor cells distinct from glial cells, we find that bipolar-specific accessible regions are more frequently linked to bHLH motifs and Ascl1 binding, indicating that Ascl1 preferentially binds to bipolar regions. Overall, our analysis indicates a loss of neurogenic gene expression and motif accessibility during glial maturation that may prevent efficient reprogramming.
2020-08-19 | GSE137318 | GEO
Project description:Regenerative neuroscience aims to stimulate endogenous repair mechanisms in the nervous system to replace neurons that have been lost from degenerative diseases or trauma. In the retina, many non-mammalian vertebrate species spontaneously regenerate retinal neurons from glial cells, through an injury-induced reprogramming of the cells to a retinal progenitor state. Recently, we have reported that engineering mouse Muller glia to express a retinal progenitor gene, the proneural transcription factor, Ascl1, is sufficient to stimulate neurogenesis in the glia to generate functional neurons. However, this process is inefficient and only a third of the Ascl1-expressing glia generate new neurons. Here we test whether proneural transcription factors of the Atoh1/7 class can further promote the neurogenic capacity of MG. We report that the combination of Ascl1:Atoh1 is remarkably efficient at stimulating neurogenesis (>80% expressing cells), even in the absence of retinal injury or TSA. We use electrophysiology and scRNA-seq to demonstrate that Ascl1:Atoh1 generates a diversity of retinal neuron types with the majority expressing characteristics of retinal ganglion cells. Overall, our results provide a proof-of-principle that transcription factors that are normally sequentially active in cell fate specification, can when combined, substantially improve glial reprogramming to neurons and expand the repertoire of cell fates that can be regenerated in the adult mouse retina. The ability to stimulate the neurogenic potential of glia in adult mice with high efficiency is a key step towards translation of this approach to repair the central nervous system.
2021-10-19 | GSE184286 | GEO
Project description:Here we performed a ChIP-seq experiment on a sample of adherent cultures of mouse neural stem cells (NS5 cell line) under normal growth conditions and upon short term activation (30 minutes) of an inducible version of the proneural factor Mash1/Ascl1 (Ascl1-ERT2). This resulted in the generation of a genome-wide map of Ascl1 binding to chromatin.
2015-02-16 | E-MTAB-2384 | biostudies-arrayexpress