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Project description:Injured neurons in the adult mammalian central nervous system often die and seldom regenerate axons. To uncover transcriptional pathways that could ameliorate these disappointing responses, we analyzed three interventions that increase survival and regeneration of mouse retinal ganglion cells (RGCs) following optic nerve crush (ONC) injury, albeit not to a clinically useful extent. We assessed gene expression in each of 46 RGC types by single-cell transcriptomics following ONC and treatment. We also compared RGCs that regenerated with those that survived but did not regenerate. Each intervention enhanced survival of most RGC types, but type-independent axon regeneration required manipulation of multiple pathways. Distinct computational methods converged on separate sets of genes selectively expressed by RGCs likely to be dying, surviving, or regenerating. Overexpression of genes associated with the regeneration program enhanced both survival and axon regeneration in vivo, indicating that mechanistic analysis can be used to identify novel therapeutic strategies.
| S-EPMC9391321 | biostudies-literature
Project description:Neurons of the central nervous system (CNS) display only a limited ability to survive and regenerate their axons after an injury. In mice, 85% of retinal ganglion cells (RGCs) die within 2 weeks of axotomy by optic nerve crush (ONC) and only few survivors regenerate axons. In the past years, a multitude of interventions have been identified to improve RGC survival and regeneration after an injury, however, each only protects a subset of neurons and stimulates axon regrowth in an even smaller set.. Here, we sought out to elucidate the molecular mechanisms underlying this selective responsiveness and investigated genes regulated by three well established survival and regeneration-promoting interventions – activation of the MTOR pathway via deletion of its inhibitor Pten, activation of the Jak/Stat-pathway by deletion of its endogenous inhibitor Socs3, and overexpression of the neurotrophic cytokine CNTF. Analysis of the transcriptomes from >125,000 single RGCs at various time points after ONC showed that while broad survival of all RGC types could be induced with each intervention, type-independent axon regeneration was only overcome with the manipulation of multiple pathways. Those RGCs were able to mitigate the injury response and simultaneously upregulated survival and regeneration associated programs (prior and after injury). Four independent ways of analysis identified these programs to be differentially regulated among RGCs, with distinct signatures for degenerating, surviving and regenerating cells. Finally, testing some genes associated with the regeneration-program in vivo identified potential future therapeutic targets to promote neuroprotection and axonal regeneration.
2022-06-28 | GSE202154 | GEO
Project description:Neurons of the central nervous system (CNS) display only a limited ability to survive and regenerate their axons after an injury. In mice, 85% of retinal ganglion cells (RGCs) die within 2 weeks of axotomy by optic nerve crush (ONC) and only few survivors regenerate axons. In the past years, a multitude of interventions have been identified to improve RGC survival and regeneration after an injury, however, each only protects a subset of neurons and stimulates axon regrowth in an even smaller set.. Here, we sought out to elucidate the molecular mechanisms underlying this selective responsiveness and investigated genes regulated by three well established survival and regeneration-promoting interventions – activation of the MTOR pathway via deletion of its inhibitor Pten, activation of the Jak/Stat-pathway by deletion of its endogenous inhibitor Socs3, and overexpression of the neurotrophic cytokine CNTF. Analysis of the transcriptomes from >125,000 single RGCs at various time points after ONC showed that while broad survival of all RGC types could be induced with each intervention, type-independent axon regeneration was only overcome with the manipulation of multiple pathways. Those RGCs were able to mitigate the injury response and simultaneously upregulated survival and regeneration associated programs (prior and after injury). Four independent ways of analysis identified these programs to be differentially regulated among RGCs, with distinct signatures for degenerating, surviving and regenerating cells. Finally, testing some genes associated with the regeneration-program in vivo identified potential future therapeutic targets to promote neuroprotection and axonal regeneration.
2022-06-28 | GSE201254 | GEO
Project description:Overlapping transcriptional programs promote survival and axonal regeneration of injured retinal ganglion cells
| PRJNA834803 | ENA
Project description:Overlapping transcriptional programs promote survival and axonal regeneration of injured retinal ganglion cells [1]
| PRJNA830507 | ENA
Project description:Overlapping transcriptional programs promote survival and axonal regeneration of injured retinal ganglion cells [2]
| PRJNA834807 | ENA
Project description:Neuritin 1 (Nrn1) is an extracellular glycophosphatidylinositol-linked protein that stimulates axonal plasticity, dendritic arborization and synapse maturation in the central nervous system (CNS). The purpose of this study was to evaluate the neuroprotective and axogenic properties of Nrn1 on axotomized retinal ganglion cells (RGCs) in vitro and on the in vivo optic nerve crush (ONC) mouse model. Axotomized cultured RGCs treated with recombinant hNRN1 significantly increased survival of RGCs by 21% (n=6-7, P<0.01) and neurite outgrowth in RGCs by 141% compared to controls (n=15, P<0.05). RGC transduction with AAV2-CAG-hNRN1 prior to ONC promoted RGC survival (450%, n=3-7, P<0.05) and significantly preserved RGC function by 70% until 28 days post crush (dpc) (n=6, P<0.05) compared with the control AAV2-CAG-green fluorescent protein transduction group. Significantly elevated levels of RGC marker, RNA binding protein with multiple splicing (Rbpms; 73%, n=5-8, P<0.001) and growth cone marker, growth-associated protein 43 (Gap43; 36%, n=3, P<0.01) were observed 28 dpc in the retinas of the treatment group compared with the control group. Significant increase in Gap43 (100%, n=5-6, P<0.05) expression was observed within the optic nerves of the AAV2-hNRN1 group compared to controls. In conclusion, Nrn1 exhibited neuroprotective, regenerative effects and preserved RGC function on axotomized RGCs in vitro and after axonal injury in vivo. Nrn1 is a potential therapeutic target for CNS neurodegenerative diseases.
| S-EPMC4669798 | biostudies-other
Project description:Injury to the axons of retinal ganglion cells (RGCs) is a key pathological event in glaucomatous neurodegeneration. The transcription factors JUN (the target of the c-Jun N-terminal kinases, JNKs) and DDIT3/CHOP (a mediator of the endoplasmic reticulum stress response) have been shown to control the majority of proapoptotic signaling after mechanical axonal injury in RGCs and in other models of neurodegeneration. The downstream transcriptional networks controlled by JUN and DDIT3, which are critical for RGC death, however, are not well defined. To determine these networks, RNA was isolated from the retinas of wild-type mice and mice deficient in Jun, Ddit3, and both Jun and Ddit3 three days after mechanical optic nerve crush injury (CONC). RNA-sequencing data analysis was performed and immunohistochemistry was used to validate potential transcriptional signaling changes after axonal injury. This study identified downstream transcriptional changes after injury including both neuronal survival and proinflammatory signaling that were attenuated to differing degrees by loss of Ddit3, Jun, and Ddit3/Jun. These data suggest proinflammatory signaling in the retina might be secondary to activation of pro-death pathways in RGCs after acute axonal injury. These results determine the downstream transcriptional networks important for apoptotic signaling which may be important for ordering and staging the pro-degenerative signals after mechanical axonal injury.
| S-EPMC8927149 | biostudies-literature
Project description:BackgroundIn addition to rescuing injured retinal ganglion cells (RGCs) by stimulating the intrinsic growth ability of damaged RGCs in various retinal/optic neuropathies, increasing evidence has shown that the external microenvironmental factors also play a crucial role in restoring the survival of RGCs by promoting the regrowth of RGC axons, especially inflammatory factors. In this study, we aimed to screen out the underlying inflammatory factor involved in the signaling of staurosporine (STS)-induced axon regeneration and verify its role in the protection of RGCs and the promotion of axon regrowth.MethodsWe performed transcriptome RNA sequencing for STS induction models in vitro and analyzed the differentially expressed genes. After targeting the key gene, we verified the role of the candidate factor in RGC protection and promotion of axon regeneration in vivo with two RGC-injured animal models (optic nerve crush, ONC; retinal N-methyl-D-aspartate, NMDA damage) by using cholera toxin subunit B anterograde axon tracing and specific immunostaining of RGCs.ResultsWe found that a series of inflammatory genes expressed upregulated in the signaling of STS-induced axon regrowth and we targeted the candidate CXCL2 gene since the level of the chemokine CXCL2 gene elevated significantly among the top upregulated genes. We further demonstrated that intravitreal injection of rCXCL2 robustly promoted axon regeneration and significantly improved RGC survival in ONC-injured mice in vivo. However, different from its role in ONC model, the intravitreal injection of rCXCL2 was able to simply protect RGCs against NMDA-induced excitotoxicity in mouse retina and maintain the long-distance projection of RGC axons, yet failed to promote significant axon regeneration.ConclusionsWe provide the first in vivo evidence that CXCL2, as an inflammatory factor, is a key regulator in the axon regeneration and neuroprotection of RGCs. Our comparative study may facilitate deciphering the exact molecular mechanisms of RGC axon regeneration and developing high-potency targeted drugs.
| S-EPMC10280836 | biostudies-literature
Project description:As axon damage and retinal ganglion cell (RGC) loss lead to blindness, therapies that increase RGC survival and axon regrowth have direct clinical relevance. Given that NFκB signaling is critical for neuronal survival and may regulate neurite growth, we investigated the therapeutic potential of NFκB signaling in RGC survival and axon regeneration. Although both NFκB subunits (p65 and p50) are present in RGCs, p65 exists in an inactive (unphosphorylated) state when RGCs are subjected to neurotoxic conditions. In this study, we used a phosphomimetic approach to generate DNA coding for an activated (phosphorylated) p65 (p65mut), then employed an adeno-associated virus serotype 2 (AAV2) to deliver the DNA into RGCs. We tested whether constitutive p65mut expression prevents death and facilitates neurite outgrowth in RGCs subjected to transient retinal ischemia or optic nerve crush (ONC), two models of neurotoxicity. Our data indicate that RGCs treated with AAV2-p65mut displayed a significant increase in survival compared to controls in ONC model (77 ± 7% vs. 25 ± 3%, P-value = 0.0001). We also found protective effect of modified p65 in RGCs of ischemic retinas (55 ± 12% vs. 35 ± 6%), but not to a statistically significant degree (P-value = 0.14). We did not detect a difference in axon regeneration between experimental and control animals after ONC. These findings suggest that increased NFκB signaling in RGCs attenuates retinal damage in animal models of neurodegeneration, but insignificantly impacts axon regeneration.
| S-EPMC5138106 | biostudies-literature