Project description:Purpose: This study aims to the downstream transcriptional networks controlled by JUN and DDIT which are critical for RGC death Methods: 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), and was subjected to RNA-sequecing. Results: This study identified downstream transcriptional changes after injury included both neuronal survival and pro-inflammatory signaling that were attenuated to differing degrees by loss of Ddit3, Jun, and Ddit3/Jun. Conclusion: These data suggest pro-inflammatory 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.
Project description:Purpose: The purpose of this study was to use RNA-seq to investigate the molecular mechanisms of damage in the early stages of the response to axonal injury, before the onset of RGC death. Methods: 12-week-old wild-type (WT) mice were used in this study. The experiment group underwent an optic nerve crush (ONC) procedure to induce axonal injury in the right eye, and the control group underwent a sham procedure. Retinal mRNA profiles were generated by deep sequencing, in triplicate, using IlluminaHiseq2000. The sequence reads were analyzed by CLC genomics workbench and R software. qRT–PCR validation was performed using TaqMan assays. Results: Using an optimized data analysis workflow, we mapped about 66 million sequence reads per sample to the mouse genome (build mm9). Differential gene expression analysis showed that endoplasmic reticulum stress-related genes and antioxidative response-related genes have been shown to be significantly upregulated 2 days after ONC. Conclusions: Our study represents the first detailed analysis of retinal transcriptomes in the early stages after axonal injury. Our results indicated that ER stress plays a key role under these conditions. Furthermore, the antioxidative defense and immune responses occurred concurrently in the early stages after axonal injury. We believe that our study will lead to a better understanding of and insight into the molecular mechanisms underlying RGC death after axonal injury. Retinal mRNA profiles of 12 week-old wild type (WT) after ONC or sham were generated by deep sequencing, in triplicate, using Illumina Hiseq2000.
Project description:We used optic nerve injury as a model to study early signaling events in the neuronal soma following axonal injury. Optic nerve injury results in the selective death of retinal ganglion cells (RGCs). The time course of cell death takes place over a period of days with the earliest detection of RGC death at about 48 hr post injury. We hypothesized that in the period immediately following axonal injury, there are changes in the soma that signal surrounding glia and neurons and that start programmed cell death. In the current study, we investigated early changes in cellular signaling and gene expression that occur within the first 6 hrs post optic nerve injury. We detected differences in phosphoproteins and gene expression within this time period that we used to interpret temporal events. Our studies revealed that the entire retina has been signaled by the RGC soma within 30 min after optic nerve injury and that pathways that modulate cell death are likely to be active in RGCs within 6 hrs following axonal injury Experiment Overall Design: In the treated animals, axons of the optic nerve were crushed with fine forceps for 10 sec, 1 mm posterior to the globe, under direct visualization, within an intact meningeal sheath. Controls were contralateral eyes from the same animals in each group that had not been injured. After 6 hr eyes were enucleated and processed for tissue sectionin
Project description:We used optic nerve injury as a model to study early signaling events in the neuronal soma following axonal injury. Optic nerve injury results in the selective death of retinal ganglion cells (RGCs). The time course of cell death takes place over a period of days with the earliest detection of RGC death at about 48 hr post injury. We hypothesized that in the period immediately following axonal injury, there are changes in the soma that signal surrounding glia and neurons and that start programmed cell death. In the current study, we investigated early changes in cellular signaling and gene expression that occur within the first 6 hrs post optic nerve injury. We detected differences in phosphoproteins and gene expression within this time period that we used to interpret temporal events. Our studies revealed that the entire retina has been signaled by the RGC soma within 30 min after optic nerve injury and that pathways that modulate cell death are likely to be active in RGCs within 6 hrs following axonal injury Keywords: Stress Response
Project description:Purpose: The purpose of this study was to use RNA-seq to investigate the molecular mechanisms of damage in the early stages of the response to axonal injury, before the onset of RGC death. Methods: 12-week-old wild-type (WT) mice were used in this study. The experiment group underwent an optic nerve crush (ONC) procedure to induce axonal injury in the right eye, and the control group underwent a sham procedure. Retinal mRNA profiles were generated by deep sequencing, in triplicate, using IlluminaHiseq2000. The sequence reads were analyzed by CLC genomics workbench and R software. qRT–PCR validation was performed using TaqMan assays. Results: Using an optimized data analysis workflow, we mapped about 66 million sequence reads per sample to the mouse genome (build mm9). Differential gene expression analysis showed that endoplasmic reticulum stress-related genes and antioxidative response-related genes have been shown to be significantly upregulated 2 days after ONC. Conclusions: Our study represents the first detailed analysis of retinal transcriptomes in the early stages after axonal injury. Our results indicated that ER stress plays a key role under these conditions. Furthermore, the antioxidative defense and immune responses occurred concurrently in the early stages after axonal injury. We believe that our study will lead to a better understanding of and insight into the molecular mechanisms underlying RGC death after axonal injury.
Project description:Retinal ganglion cells (RGCs) convey the major output of information collected from the eye to the brain. RGCs are irreversibly lost when injured in degenerative diseases such as glaucoma; this failure can be partially reversed by eliminating the retinal mobile zinc (Zn2+) and leads to substantial axon regeneration. ZnT3 conditional knockout in retinal amacrine cells blocks the synaptic transport of Zn2+, which promotes RGC survival and axonal regeneration in optic nerve jinjury (ONC). Here, we conducted an mRNA sequencing of flow cytometry-isolated RGCs 3 days after optic nerve injury with or without ZnT3 expression in retinal amacrine cells.
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.
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.
Project description:Local mRNA translation mediates the adaptive responses of axons to extrinsic signals but direct evidence that it occurs in mammalian CNS axons in vivo is scant. We developed an axon-TRAP-RiboTag approach in mouse that allows deep-sequencing analysis of ribosome-bound mRNAs in the retinal ganglion cell axons of the developing and adult retinotectal projection in vivo. The embryonic-to-postnatal axonal translatome comprises an evolving subset of enriched genes with axon-specific roles suggesting distinct steps in axon wiring, such as elongation, pruning and synaptogenesis. Adult axons, remarkably, have a complex translatome with strong links to axon survival, neurotransmission and neurodegenerative disease. Translationally co-regulated mRNA subsets share common upstream regulators, and novel sequence elements generated by alternative splicing that promote axonal mRNA translation. Our results indicate that intricate regulation of compartment-specific mRNA translation in mammalian CNS axons supports the formation and maintenance of neural circuits in vivo. The profiling of ribosome-bound mRNAs in mouse retinal ganglion cell axons at 4 different developmental stages