Developmentally upregulated transcriptional elongation factor a like 3 suppresses axon regeneration after optic nerve injury.
TL;DR: In this paper, the authors found that Transcriptional Elongation Factor A Like 3 (Tceal3) is developmentally upregulated in retinal ganglion cell (RGCs) projection CNS neurons, and suppresses their capacity to regenerate axons after injury.
About: This article is published in Neuroscience Letters.The article was published on 2021-09-21 and is currently open access. It has received 5 citations till now. The article focuses on the topics: Axon & PI3K/AKT/mTOR pathway.
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TL;DR: In this paper , the authors used single cell RNA-seq (scRNA-seq) and immunohistology to investigate whether post-injury born oligodendrocytes incorporate into the glial scar after optic nerve injury.
Abstract: ABSTRACT Failure of central nervous system projection neurons to spontaneously regenerate long-distance axons underlies irreversibility of white matter pathologies. A barrier to axonal regenerative research is that the axons regenerating in response to experimental treatments stall growth before reaching post-synaptic targets. Here, we test the hypothesis that the interaction of regenerating axons with live oligodendrocytes, which were absent during developmental axon growth, contributes to stalling axonal growth. To test this hypothesis, first, we used single cell RNA-seq (scRNA-seq) and immunohistology to investigate whether post-injury born oligodendrocytes incorporate into the glial scar after optic nerve injury. Then, we administered demyelination-inducing cuprizone and stimulated axon regeneration by Pten knockdown (KD) after optic nerve crush. We found that post-injury born oligodendrocyte lineage cells incorporate into the glial scar, where they are susceptible to the demyelination diet, which reduced their presence in the glial scar. We further found that the demyelination diet enhanced Pten KD-stimulated axon regeneration and that localized cuprizone injection promoted axon regeneration. We also present a resource for comparing the gene expression of scRNA-seq-profiled normal and injured optic nerve oligodendrocyte lineage cells.
3 citations
TL;DR: In this article , the authors used a new method for capturing specifically the rare long-distance axon-regenerating RGCs, and also compared their transcriptomes with embryonic RGC, to answer these questions.
Abstract: ABSTRACT Central nervous system projection neurons fail to spontaneously regenerate injured axons. Targeting developmentally regulated genes in order to reactivate embryonic intrinsic axon growth capacity or targeting pro-growth tumor suppressor genes such as Pten promotes long-distance axon regeneration in only a small subset of injured retinal ganglion cells (RGCs), despite many RGCs regenerating short-distance axons. A recent study identified αRGCs as the primary type that regenerates short-distance axons in response to Pten inhibition, but the rare types which regenerate long-distance axons, and cellular features that enable such response, remained unknown. Here, we used a new method for capturing specifically the rare long-distance axon-regenerating RGCs, and also compared their transcriptomes with embryonic RGCs, in order to answer these questions. We found the existence of adult non-α intrinsically photosensitive M1 RGC subtypes that retained features of embryonic cell state, and showed that these subtypes partially dedifferentiated towards an embryonic state and regenerated long-distance axons in response to Pten inhibition. We also identified Pten inhibition-upregulated mitochondria-associated genes, Dynlt1a and Lars2, which promote axon regeneration on their own, and thus present novel therapeutic targets.
2 citations
TL;DR: In this article, the authors used single cell RNA-seq (scRNA-seq) and immunohistological analysis to investigate whether post-injury born oligodendrocytes integrate into the glial scar.
Abstract: The failure of mature central nervous system (CNS) projection neurons to regenerate axons over long distances drastically limits the recovery of functions lost after various CNS injuries and diseases. A major barrier in axon regeneration research is that, in most neurons, the axonal regenerative response to experimental treatments stalls before the axons reach their post-synaptic targets. Here, we tested the hypothesis that premature de novo myelination of the injured axons that are experimentally stimulated to regenerate stalls their growth, even after the glial scar is bypassed. To test this hypothesis, we used single cell RNA-seq (scRNA-seq) and immunohistological analysis to investigate whether post-injury born oligodendrocytes integrate into the glial scar. We also used a multiple sclerosis model of demyelination concurrently with the stimulation of axon regeneration by Pten knockdown (KD) in projection neurons after traumatic optic nerve injury. We found that post-injury born oligodendrocytes integrate into the glial scar, where they are susceptible to the demyelination treatment, which prevented premature myelination, and thereby enhanced Pten KD-stimulated axon regeneration. We also present a website for comparing the gene expression of scRNA-seq-profiled optic nerve oligodendrocytes under physiological and pathophysiological conditions. SIGNIFICANCE STATEMENT Myelin debris from degenerating axons along with reactive astrocytes in the glial scar inhibit CNS axon regeneration. However, even with the recently developed experimental approaches which activate axons to regenerate passed the glial scar, almost all axons still stall growth before reaching their post-synaptic targets. Here, we show that post-injury born oligodendrocytes integrate into the glial scar, and that other than myelin debris, live oligodendrocytes prematurely myelinating the regenerating axons inhibit growth, even if the axons have already regenerated passed the glial scar.
1 citations
TL;DR: In this article , the authors analyzed by scRNA-seq retinal microglia and macrophages, and found that Rbpms+ subpopulations of retinal min-glia/macrophages confounded identification of RGCs.
1 citations
TL;DR: In this paper , the authors analyzed developmental and subtype-specific expression of Collapsin Response mediator proteins (Crmps) in retinal ganglion cells (RGCs), tested whether overexpressing Crmp1, Crmp4, or Crmp5 in RGCs through localized intralocular AAV2 delivery promotes axon regeneration after optic nerve injury in vivo, and characterized developmental co-regulation of gene-concept networks associated with Crmps.
References
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TL;DR: Recent advances in understanding of the mTOR pathway are reviewed and pharmacological approaches to treat human pathologies linked to mTOR deregulation are discussed.
5,792 citations
TL;DR: ‘weighted-nearest neighbor’ analysis is introduced, an unsupervised framework to learn the relative utility of each data type in each cell, enabling an integrative analysis of multiple modalities.
Abstract: The simultaneous measurement of multiple modalities, known as multimodal analysis, represents an exciting frontier for single-cell genomics and necessitates new computational methods that can define cellular states based on multiple data types. Here, we introduce ‘weighted-nearest neighbor’ analysis, an unsupervised framework to learn the relative utility of each data type in each cell, enabling an integrative analysis of multiple modalities. We apply our procedure to a CITE-seq dataset of hundreds of thousands of human white blood cells alongside a panel of 228 antibodies to construct a multimodal reference atlas of the circulating immune system. We demonstrate that integrative analysis substantially improves our ability to resolve cell states and validate the presence of previously unreported lymphoid subpopulations. Moreover, we demonstrate how to leverage this reference to rapidly map new datasets, and to interpret immune responses to vaccination and COVID-19. Our approach represents a broadly applicable strategy to analyze single-cell multimodal datasets, including paired measurements of RNA and chromatin state, and to look beyond the transcriptome towards a unified and multimodal definition of cellular identity. Availability Installation instructions, documentation, tutorials, and CITE-seq datasets are available at http://www.satijalab.org/seurat
2,924 citations
TL;DR: The manipulation of intrinsic growth control pathways as a therapeutic approach to promote axon regeneration after CNS injury is suggested.
Abstract: The failure of axons to regenerate is a major obstacle for functional recovery after central nervous system (CNS) injury. Removing extracellular inhibitory molecules results in limited axon regeneration in vivo. To test for the role of intrinsic impediments to axon regrowth, we analyzed cell growth control genes using a virus-assisted in vivo conditional knockout approach. Deletion of PTEN (phosphatase and tensin homolog), a negative regulator of the mammalian target of rapamycin (mTOR) pathway, in adult retinal ganglion cells (RGCs) promotes robust axon regeneration after optic nerve injury. In wild-type adult mice, the mTOR activity was suppressed and new protein synthesis was impaired in axotomized RGCs, which may contribute to the regeneration failure. Reactivating this pathway by conditional knockout of tuberous sclerosis complex 1, another negative regulator of the mTOR pathway, also leads to axon regeneration. Thus, our results suggest the manipulation of intrinsic growth control pathways as a therapeutic approach to promote axon regeneration after CNS injury.
1,397 citations
TL;DR: In this article, the authors show that simultaneous deletion of PTEN and SOCS3 enables robust and sustained axon regeneration in adult central nervous system (CNS) and further reveal concurrent activation of mTOR and STAT3 pathways as key for sustaining long-distance axon regeneration in adult CNS.
Abstract: A formidable challenge in neural repair in the adult central nervous system (CNS) is the long distances that regenerating axons often need to travel in order to reconnect with their targets. Thus, a sustained capacity for axon regeneration is critical for achieving functional restoration. Although deletion of either phosphatase and tensin homologue (PTEN), a negative regulator of mammalian target of rapamycin (mTOR), or suppressor of cytokine signalling 3 (SOCS3), a negative regulator of Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway, in adult retinal ganglion cells (RGCs) individually promoted significant optic nerve regeneration, such regrowth tapered off around 2 weeks after the crush injury. Here we show that, remarkably, simultaneous deletion of both PTEN and SOCS3 enables robust and sustained axon regeneration. We further show that PTEN and SOCS3 regulate two independent pathways that act synergistically to promote enhanced axon regeneration. Gene expression analyses suggest that double deletion not only results in the induction of many growth-related genes, but also allows RGCs to maintain the expression of a repertoire of genes at the physiological level after injury. Our results reveal concurrent activation of mTOR and STAT3 pathways as key for sustaining long-distance axon regeneration in adult CNS, a crucial step towards functional recovery.
610 citations
TL;DR: In this paper, a method for promoting CNS axon regeneration was proposed, comprising of inhibiting the expression or activity in a neuron of one or more of the members of the Kruppel-like transcription factor (KLF) family that suppress axon growth (e.g., KLF 1, 2, 3, 4, 5, 6, 9, 12, 13, 14, 15 and/or 16), and stimulating the expression and activity of neurons of the KLF family that promote axon expansion.
Abstract: This invention relates, e.g., to a method for promoting CNS axon regeneration, comprising (1) inhibiting the expression or activity in a neuron of one or more of the members of the Kruppel-like transcription factor (KLF) family that suppress axon growth (e.g., KLF 1, 2, 3, 4, 5, 9, 12, 13, 14, 15 and/or 16), and/or (2) stimulating the expression or activity in a neuron of one or more of the members of the KLF family that promote axon growth (e.g., KLF 6 and/or 7).
517 citations