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ROS after nerve injury A. DHE fluorescence increases in DRG neurons 12 hours after SNC and remains elevated until 24 hours but not at 3 or 7 days compared to sham. Nerve delivery of NAC at the time of the crush blocks DHE fluorescence increase in DRG after SNC. Scale bar: 150µm B. Bar graphs show quantification of DHE fluorescence intensity after sham, SNC or SNC+NAC compared to Sham for each time point. Data is expressed as mean fold change of fluorescence intensity ± s.e.m. normalized vs Sham 12h. N= 3 animals per condition. (***p<0.001) indicate significant difference with respect to Sham 12h (ANOVA followed by Bonferroni test, p<0.0001). C. Hydro-Cy3 fluorescence increases in DRG neurons 12 hours after SNC while nerve delivery of NAC or DPI at the time of the crush block Hydro-Cy3 fluorescence increase in DRG 12 hours after SNC. Scale bar: 150µm. D. Bar graphs show quantification of Hydro-Cy3 fluorescence intensity after sham, SNC, SNC+NAC or SNC+DPI compared to Sham. Data is expressed as mean fold change of fluorescence intensity ± s.e.m. normalized vs Sham. N= 6 animals per condition. (***p=0.0005) indicate significant difference with respect to Sham (ANOVA followed by Bonferroni test, p<0.0001). Source data for B and D are provided in Supplementary Table 5.
Source publication
Reactive oxygen species (ROS) contribute to tissue damage and remodelling mediated by the inflammatory response after injury. Here we show that ROS, which promote axonal dieback and degeneration after injury, are also required for axonal regeneration and functional recovery after spinal injury. We find that ROS production in the injured sciatic ner...
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Citations
... Specifically, 47.5% of the injury-responsive promoters showed binding sites for cohesin, while only 27.3% showed binding sites for CTCF (SI Appendix, Fig. S1A). Interestingly, genes with cohesin binding sites were enriched for biological processes associated with regenerative ability including nervous system development, neuronal differentiation, axon projection and guidance, microtubule organization, axon transport, and synapse organization (13,31,32) (SI Appendix, Fig. S1B). ...
... In naive condition, Rad21 deletion induced the downregulation of genes involved in neuronal-specific functions, such as ion transport and neurotransmitter signalling ( Fig. 2A, first column). In agreement with previous findings (15,27,31,32,39,40), in WT neurons nerve injury triggered regenerative pathways as shown by the expression of genes involved in transcription, immune regulation, nervous system developmental processes, signal transduction, cytoskeleton remodelling, circadian rhythms, axonogenesis, angiogenesis, cell adhesion, reactive oxygen species signalling, and downregulation of genes involved in ion transport and synaptic transmission ( Fig. 2A, second column, and SI Appendix, Fig. S7C). However, in RAD21 depleted neurons most of the genes belonging to regenerative pathways either failed to be activated at all by injury, were induced at lower levels, or were downregulated compared to WT neurons ( Fig. 2A, third and fourth columns). ...
... The distance between the "within domains" and "between domains" curves was strongly decreased indicating a loss of the chromatin contacts in cohesin-depleted neurons (Fig. 3B). We then normalized and balanced Downregulated genes residing in genomic domains that were lost or showed a reduction in strength in Rad21 KO neurons were enriched for regenerative pathways, such as axon extension and guidance, nervous system development, neuronal differentiation, circadian rhythm, angiogenesis, actin cytoskeleton remodelling (15,31,32,39,40) (Fig. 4A). The previously identified 579 cohesin-dependent genes, including several RAGs, were preferentially found within domains that were lost or showed a reduction in strength (Fig. 4B-D). ...
The in vivo three-dimensional genomic architecture of adult mature neurons at homeostasis and after medically relevant perturbations such as axonal injury remains elusive. Here we address this knowledge gap by mapping the three-dimensional chromatin architecture and gene expression programme at homeostasis and after sciatic nerve injury in wild-type and cohesin-deficient mouse sensory dorsal root ganglia neurons via combinatorial Hi-C and RNA-seq. We find that cohesin is required for the full induction of the regenerative transcriptional program, by organising 3D genomic domains required for the activation of regenerative genes. Importantly, loss of cohesin results in disruption of chromatin architecture at regenerative genes and severely impaired nerve regeneration. Together, these data provide an original three-dimensional chromatin map of adult sensory neurons in vivo and demonstrate a role for cohesin-dependent chromatin interactions in neuronal regeneration.
... After a cerebral cortex injury, the damaged neurons may trigger the rapid expression of early response genes through the promoter region DSBs, thereby facilitating nerve repair [42]. Reactive oxygen species (ROS) are a direct factor that induces DSBs [41] and are necessary for the regeneration of axons and synapses of damaged sensory neurons [65], while the mitochondrial membrane is an important site for intracellular ROS generation [40]. ...
Background
The repair of peripheral nerve injury poses a clinical challenge, necessitating further investigation into novel therapeutic approaches. In recent years, bone marrow mesenchymal stromal cell (MSC)-derived mitochondrial transfer has emerged as a promising therapy for cellular injury, with reported applications in central nerve injury. However, its potential therapeutic effect on peripheral nerve injury remains unclear.
Methods
We established a mouse sciatic nerve crush injury model. Mitochondria extracted from MSCs were intraneurally injected into the injured sciatic nerves. Axonal regeneration was observed through whole-mount nerve imaging. The dorsal root ganglions (DRGs) corresponding to the injured nerve were harvested to test the gene expression, reactive oxygen species (ROS) levels, as well as the degree and location of DNA double strand breaks (DSBs).
Results
The in vivo experiments showed that the mitochondrial injection therapy effectively promoted axon regeneration in injured sciatic nerves. Four days after injection of fluorescently labeled mitochondria into the injured nerves, fluorescently labeled mitochondria were detected in the corresponding DRGs. RNA-seq and qPCR results showed that the mitochondrial injection therapy enhanced the expression of Atf3 and other regeneration-associated genes in DRG neurons. Knocking down of Atf3 in DRGs by siRNA could diminish the therapeutic effect of mitochondrial injection. Subsequent experiments showed that mitochondrial injection therapy could increase the levels of ROS and DSBs in injury-associated DRG neurons, with this increase being correlated with Atf3 expression. ChIP and Co-IP experiments revealed an elevation of DSB levels within the transcription initiation region of the Atf3 gene following mitochondrial injection therapy, while also demonstrating a spatial proximity between mitochondria-induced DSBs and CTCF binding sites.
Conclusion
These findings suggest that MSC-derived mitochondria injected into the injured nerves can be retrogradely transferred to DRG neuron somas via axoplasmic transport, and increase the DSBs at the transcription initiation regions of the Atf3 gene through ROS accumulation, which rapidly release the CTCF-mediated topological constraints on chromatin interactions. This process may enhance spatial interactions between the Atf3 promoter and enhancer, ultimately promoting Atf3 expression. The up-regulation of Atf3 induced by mitochondria further promotes the expression of downstream regeneration-associated genes and facilitates axon regeneration.
... The oxidative inactivation of PTEN by ROS has also been demonstrated to play a significant positive role in those physiological processes demanding cell growth [34]. It can promote cardiac remodeling [35], neuronal regeneration [36], immune response [37], glucose metabolism [38], and myogenesis [39]. However, within the cellular environment, H 2 O 2 can be eliminated by thiol proteins from the Prx family. ...
... also been demonstrated to play a significant positive role in those physiological processes demanding cell growth [34]. It can promote cardiac remodeling [35], neuronal regeneration [36], immune response [37], glucose metabolism [38], and myogenesis [39]. However, within the cellular environment, H2O2 can be eliminated by thiol proteins from the Prx family. ...
Phosphatase and tensin homolog (PTEN) is a negative regulator of the phosphoinositide 3-kinases/protein kinase B (PI3K/AKT) signaling pathway. Notably, its active site contains a cysteine residue that is susceptible to oxidation by hydrogen peroxide (H 2 O 2). This oxidation inhibits the phosphatase function of PTEN, critically contributing to the activation of the PI3K/AKT pathway. Upon the stimulation of cell surface receptors, the activity of NADPH oxidase (NOX) generates a transient amount of H 2 O 2 , serving as a mediator in this pathway by oxidizing PTEN. The mechanism underlying this oxidation, occurring despite the presence of highly efficient and abundant cellular oxidant-protecting and reducing systems, continues to pose a perplexing conundrum. Here, we demonstrate that the presence of bicarbonate (HCO 3 −) promoted the rate of H 2 O 2-mediated PTEN oxidation, probably through the formation of peroxymonocarbonate (HCO 4 −), and consequently potentiated the phosphorylation of AKT. Acetazolamide (ATZ), a carbonic anhydrase (CA) inhibitor, was shown to diminish the oxidation of PTEN. Thus, CA can also be considered as a modulator in this context. In essence, our findings consolidate the crucial role of HCO 3 − in the redox regulation of PTEN by H 2 O 2 , leading to the presumption that HCO 4 − is a signaling molecule during cellular physiological processes.
... Understanding the regulation and function of NADPH oxidase is an active area of research because of its potential therapeutic implications. In recent results presented by Hervera et al., it has been shown that NOX2 present in macrophage secreted exosomes was involved in the regulation of axonal regeneration of injured axons; therefore, NOX regulation may serve as potential factor in regenerative medicine (Hervera et al., 2018). ...
Extracellular vesicles (EVs) are a type of cytoplasmic vesicles secreted by a variety of cells. EVs originating from cells have been known to participate in cell communication, antigen presentation, immune cell activation, tolerance induction, etc. These EVs can also carry the active form of Nicotinamide Adenine Dinucleotide Phosphate Oxidase Hydrogen (NADPH) oxidase, which is very essential for the production of reactive oxygen species (ROS) and that can then modulate processes such as cell regeneration. The aim of this study is to characterize the EVs isolated from U-937 and THP-1 cells, identify the NADPH oxidase (NOX) isoforms, and to determine whether EVs can modulate NOX4 and NOX2 in monocytes and macrophages. In our study, isolated EVs of U-937 were characterized using dynamic light scattering (DLS) spectroscopy and immunoblotting. The results showed that the exogenous addition of differentiation agents (either phorbol 12-myristate 13-acetate (PMA) or ascorbic acid) or the supplementation of EVs used in the study did not cause any stress leading to alterations in cell proliferation and viability. In cells co-cultured with EVs for 72 h, strong suppression of NOX4 and NOX2 is evident when monocytes transform into macrophagic cells. We also observed lower levels of oxidative stress measured using immunoblotting and electron paramagnetic resonance spectroscopy under the EVs co-cultured condition, which also indicates that EVs might contribute significantly by acting as an antioxidant source, which agrees with previous studies that hypothesized the role of EVs in therapeutics. Therefore, our results provide evidence for NOX regulation by EVs in addition to its role as an antioxidant cargo.
... Antioxidant-related enzymes have been classified as biomarkers of oxidative stress, meaning that they are imbalanced when ROS production exceeds the limit of detoxification capacity, to assess the impact on fish health through stress and immune responses (Liu et al. 2015;Tan et al. 2018;Bodega et al. 2019). CAT, GPx, GR, and Keap1 are the main antioxidant enzymes of ROS detoxification that can sustain physiological homeostasis in an antioxidant defense network (Hervera et al. 2018;Shi et al. 2021). Oligochitosan may improve antioxidant performance and reduce oxidative stress damage by inhibiting and eliminating the accumulation of excess free radicals in the body by enhancing endogenous antioxidant activity (Liu et al. 2009). ...
Oligochitosan (OCS) has many vital bioactive functions; however, its underlying mechanisms in the liver of hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatu ♂) are not well studied. A comprehensive study is currently focused on the systematic effects of OCS on hybrid grouper liver, particularly their effects on transcriptome profiles, toxicity, and apoptosis. With the control diet supplemented with OCS at different dosages (0, 200, 400, 800, or 1600 mg/kg), the 30-day feeding trial was randomized to 360 fish in triplicate. The findings revealed that liver and body weight are not impacted by OCS after a 4-week feeding trial. To characterize the liver transcriptome by high-throughput sequencing, KEGG analysis showed that OCS feeding activated apoptosis-related signaling pathways. The five DEG levels, namely CYC, GADD45, PAI1, CDKN1A, and BCL2L1, were downregulated in apoptosis-related pathways for clarifying the transcriptomic data. To elucidate the immune responses stimulated by OCS by qRT-PCR, inflammation-associated cytokines’ mRNA expression levels, such as TNF-α and IL-1β, were significantly upregulated in the 800 mg/kg group in contrast to the control. At the same time, OCS significantly improved antioxidant capacity by significantly decreasing apoptosis-related genes’ expression and considerably enhancing CAT and GPx expression. To further test the antibacterial ability of OCS-fed hybrid groupers, the liver morphology of hybrid groupers was significantly improved after infection with Vibrio harvey, and apoptosis was significantly reduced in grouper liver according to TUNEL results. Overall, appropriate dietary OCS could improve immune responses and attenuate apoptosis-related signaling pathways in the liver of hybrid grouper, thus playing a role in bacterial resistance.
... In recent years, many methods have been developed and advanced to treat peripheral nerve injuries [5], such as autologous nerve grafting technique [6], nerve conduits, among others. However, these methods often yield suboptimal results and each of them has drawbacks [7]. Therefore, it is crucial to conduct further investigation into the underlying mechanisms of PNI, making this a highly relevant area of study. ...
... Reactive oxygen species (ROS) are a type of oxidizing agents that contain unpaired electrons [6]. Under normal circumstances, they are generated and cleared by the intracellular redox system in a balanced manner [7]. Abnormal ROS accumulation, triggered by tissue damage and the inflammatory response, leads to the progression of inflammation, injury, and ultimately cell death [19]. ...
Background
Peripheral nerve injury (PNI) is commonly observed in clinical practice, yet the underlying mechanisms remain unclear. This study investigated the correlation between the expression of a Ras-related protein Rab32 and pyroptosis in rats following PNI, and potential mechanisms have been explored by which Rab32 may influence Schwann cells pyroptosis and ultimately peripheral nerve regeneration (PNR) through the regulation of Reactive oxygen species (ROS) levels.
Methods
The authors investigated the induction of Schwann cell pyroptosis and the elevated expression of Rab32 in a rat model of PNI. In vitro experiments revealed an upregulation of Rab32 during Schwann cell pyroptosis. Furthermore, the effect of Rab32 on the level of ROS in mitochondria in pyroptosis model has also been studied. Finally, the effects of knocking down the Rab32 gene on PNR were assessed, morphology, sensory and motor functions of sciatic nerves, electrophysiology and immunohistochemical analysis were conducted to assess the therapeutic efficacy.
Results
Silencing Rab32 attenuated PNI-induced Schwann cell pyroptosis and promoted peripheral nerve regeneration. Furthermore, our findings demonstrated that Rab32 induces significant oxidative stress by damaging the mitochondria of Schwann cells in the pyroptosis model in vitro.
Conclusion
Rab32 exacerbated Schwann cell pyroptosis in PNI model, leading to delayed peripheral nerve regeneration. Rab32 can be a potential target for future therapeutic strategy in the treatment of peripheral nerve injuries.
... This increased status persists for 24 h post-injury, after which the ROS levels gradually return to baseline at later time points, specifically at 3 and 7 days. 61 The ROS-responsive drug release profile of the drug-loaded nanomicelle Taz@PMet NPs is depicted in Figure 2O. Notably, the drug release rate was faster in the medium with a higher concentration of H 2 O 2 . ...
... Excessive ROS can induce serious oxidative stress, resulting in DNA, lipid, and protein oxidative damage [8,9]. This also triggers widespread secondary injuries like axonal demyelination and neuronal cell necrosis [10]. Concurrently, an inflammatory response mediated by microglia gets activated due to excessive ROS [11]. ...
Disordered reactive oxygen/nitrogen species are a common occurrence in various diseases, which usually cause cellular oxidative damage and inflammation. Despite the wide range of applications for biomimetic nanoparticles with antioxidant or anti-inflammatory properties, designs that seamlessly integrate these two abilities with a synergistic effect in a simple manner are seldom reported. In this study, we developed a novel PEI-Mn composite nanoparticle (PM NP) using a chelation method, and the curcumin was loaded onto PM NPs via metal–phenol coordination to form PEI-Mn@curcumin nanoparticles (PMC NPs). PMC NPs possessed excellent dispersibility and cytocompatibility, was engineered to serve as an effective nanozyme, and exhibited specific SOD-like and CAT-like activities. In addition, the incorporation of curcumin granted PMC NPs the ability to effectively suppress the expression of inflammatory cytokines in microglia induced by LPS. As curcumin also has antioxidant properties, it further amplified the synergistic efficiency of ROS scavenging. Significantly, PMC NPs effectively scavenged ROS triggered by H2O2 in SIM-A9 microglia cells and Neuro-2a cells. PMC NPs also considerably mitigated DNA and lipid oxidation in Neuro-2a cells and demonstrated an increase in cell viability under various H2O2 concentrations. These properties suggest that PMC NPs have significant potential in addressing excessive ROS and inflammation related to neural diseases.
... The activation of AKT and its downstream cascades are proved to be related to variety of cancers [30]. Besides, studies also indicate that the elevated AKT activity through oxidative inactivation of PTEN can yield benefits in particular physiological processes that require cell growth such as cardiac remodeling following ischemia [31], neuronal regeneration [32], immune response [33], insulin-related metabolism [34], and myogenesis [35]. Within the cellular environment, H2O2 can be eliminated by thiol proteins from the Prx family. ...
Phosphatase and tensin homolog (PTEN) is a negative regulator of the phosphoinositide 3-kinases/protein kinase B (PI3K/AKT) signaling pathway. Notably, its active site harbors a cysteine residue that is susceptible to oxidation by hydrogen peroxide (H2O2). This oxidation inhibits the phosphatase function of PTEN, critically contributing to the activation of the PI3K/AKT pathway. Upon stimulation of cell surface receptors, the activity of NADPH oxidase 2 (NOX2) generates a transient amount of H2O2, serving as a mediator in this pathway by oxidizing PTEN. The mechanism underlying this oxidation, occurring despite the presence of highly efficient and abundant cellular oxidant-protecting and reducing systems, continues to pose a perplexing conundrum. Here, we demonstrate that the presence of bicarbonate (HCO3-) promoted the rate of H2O2-mediated PTEN oxidation, probably through the formation of peroxymonocarbonate (HCO4-), consequently potentiated the phosphorylation of AKT. In essence, our findings consolidate the crucial role of HCO3- in the redox regulation of PTEN by H2O2, lead to the presumption regarding HCO4- as a signaling molecule during cellular physiological processes.
... The downregulation of PTEN, mediated by NOX2 activity in association with nerve injury, leads to increased activation of the PI3K/AKT pathway, promoting neuron outgrowth. The PTEN oxidative inactivation following nerve injury plays an important role in regulating nerve regeneration and is, therefore, a prospective mechanism in the study of neuronal pathology [107]. ...
Phosphatase and tensin homolog (PTEN) is a tumor suppressor due to its ability to regulate cell survival, growth, and proliferation by downregulating the PI3K/AKT signaling pathway. In addition, PTEN plays an essential role in other physiological events associated with cell growth demands, such as ischemia-reperfusion, nerve injury, and immune responsiveness. Therefore, recently, PTEN inhibition has emerged as a potential therapeutic intervention in these situations. Increasing evidence demonstrates that reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), are produced and required for the signaling in many important cellular processes under such physiological conditions. ROS have been shown to oxidize PTEN at the cysteine residue of its active site, consequently inhibiting its function. Herein, we provide an overview of studies that highlight the role of the oxidative inhibition of PTEN in physiological processes.
