FOXO3a involvement in the release of TNF-α stimulated by ATP in spinal cord astrocytes

Temporal profiling and validation of oxidative stress-related genes in spinal cord injury

Oxidative stress (OS) plays a pivotal role in the pathogenesis of spinal cord injury (SCI), yet its underlying mechanisms remain elusive. In this study, we explored the OS phenotype in a rat model of SCI. Subsequently, comprehensive bioinformatic analyses were conducted on microarray data pertaining to SCI (GSE45006). Notably, KEGG enrichment analysis revealed a pronounced enrichment of pivotal pathways, namely MAPK, FoxO, Apoptosis, NF-κB, TNF, HIF-1, and Chemokine across distinct phases of SCI. Furthermore, GO enrichment analysis highlighted the significance of biological processes including response to hypoxia, response to decrease oxygen levels, response to reactive oxygen species, cellular response to oxidative stress, reactive oxygen species metabolic process, and regulation of neuron death in the context of OS following SCI. Notably, our study underscores the prominence of nine genes, namely Itgb1, Itgam, Fn1, Icam1, Cd44, Cxcr4, Ptprc, Tlr4, and Tlr2 as OS key genes in SCI, consistently expressed in both the acute phase (1, 3, 7 days) and sub-acute phase (14 days). Subsequently, the relative mRNA expression of these key genes in different time points (1, 3, 7, 14 days) post-SCI. Finally, leveraging the DsigDB database, we predicted ten potential compounds potentially targeting OS and facilitating the repair of SCI, thus providing novel insights into the mechanisms underlying OS and identifying potential therapeutic targets for SCI.

IL-13 and FOXO3 genes polymorphisms regulate IgE levels in asthmatic patients

Immunoglobulin E (IgE) serves a crucial role in the pathogenesis of several allergic disorders, and elevated levels of total serum IgE have been associated with asthma. IgE is responsible for the release of several asthma-associated inflammatory mediators from mast cells, such as histamine and prostaglandins. The aim of the present study was to assess the association of interleukin (IL)-13 single nucleotide polymorphism (SNP) rs20541 and forkhead box O3a (FOXO3a) SNP rs13217795 with IgE levels in asthmatic patients and a healthy control group. Genetic polymorphism analysis of SNPs was performed using PCR/restriction fragment length polymorphism. Total serum IgE levels were measured using an ELISA kit. Genotypes were grouped into three models: Co-dominant, dominant and recessive. Major and minor alleles for IL-13 SNP rs20541 and FOXO3a SNP rs13217795 were C and T, whereas for IL-13, they were G and A, respectively. There was a significant association between the IL-13 rs20541 SNP and the total IgE serum levels, in which pure minor alleles were associated with a significant reduction (~5x lower) in IgE serum levels compared with the major alleles in asthmatic subjects and to a lesser extent in the control subjects. Additionally, the FOXO3a rs13217795 SNP was associated with a significant increase in total IgE levels (~5x higher) in the asthmatic patients compared with the control subjects. In conclusion, the present study confirmed that there was a significant association between the IL-13 SNP rs20541 and asthma, and an association between the FOXO3a SNP rs13217795 with asthma pathogenicity in Jordanian subjects.

Histological and Biochemical Changes in Adult Male Rat Liver after Spinal Cord Injury with Evaluation of the Role of Granulocyte-Colony Stimulating Factor

Spinal cord injury (SCI) is a devastating disease leading to motor disability. Metabolic dysfunction is another complication of SCI. Thus, we aimed to study the effect of SCI on the histological and biochemical structure of the liver in adult male rats and to delineate the role of post-injury administration of G-CSF. Thirty adult male Sprague-Dawley rats were assigned into three groups: Group I; control (18 rats subdivided equally into three subgroups), and 12 rats underwent SCI and were divided into an SCI group II and G-SCF-treated group III. Twenty-one days post-injury, liver sections were processed for light and electron microscopic examinations and immunohistochemical staining for PCNA and CD68 antibodies. The biochemical assay was carried out for detection of serum levels of ALT, AST, total proteins, albumin, total cholesterol, triglycerides, HDL-c, GSH and MDA. Liver tissue levels of GPx and MDA as well as semiquantitative RT-PCR analysis of hepatic cytokine expression were also conducted. In the SCI group, results showed liver tissue damage in the form of lipid infiltration, blood vessel congestion, vacuolated cells with apoptotic nuclei and increased collagen deposition. Increased CD68-positive macrophages and a decreased number of PCNA-positive cells was detected. Moreover, liver enzymes, total cholesterol and triglycerides were increased while serum albumin, total proteins and HDL-c were decreased in the SCI group. Oxidative stress and increased expression of inflammatory cytokines were detected. Administration of G-CSF induced significant liver improvement with retained liver function by anti-inflammatory, immune-modulatory and antioxidant mechanisms.

Sleep Deprivation Selectively Down-Regulates Astrocytic 5-HT2B Receptors and Triggers Depressive-Like Behaviors via Stimulating P2X7 Receptors in Mice

Chronic loss of sleep damages health and disturbs the quality of life. Long-lasting sleep deprivation (SD) as well as sleep abnormalities are substantial risk factors for major depressive disorder, although the underlying mechanisms are not clear. Here, we showed that chronic SD in mice promotes a gradual elevation of extracellular ATP, which activates astroglial P2X₇ receptors (P2X₇Rs). Activated P2X₇Rs, in turn, selectively down-regulated the expression of 5-HT_2B receptors (5-HT_2BRs) in astrocytes. Stimulation of P2X₇Rs induced by SD selectively suppressed the phosphorylation of AKT and FoxO3a in astrocytes, but not in neurons. The over-expression of FoxO3a in astrocytes inhibited the expression of 5-HT_2BRs. Down-regulation of 5-HT_2BsRs instigated by SD suppressed the activation of STAT3 and relieved the inhibition of Ca²⁺-dependent phospholipase A2. This latter cascade promoted the release of arachidonic acid and prostaglandin E2. The depression-like behaviors induced by SD were alleviated in P2X₇R-KO mice. Our study reveals the mechanism underlying chronic SD-induced depression-like behaviors and suggests 5-HT_2BRs as a key target for exploring therapeutic strategies aimed at the depression evoked by sleep disorders.

Chemical characteristics and cytoprotective activities of polysaccharide fractions from Athyrium Multidentatum (Doll.) Ching

Five polysaccharide fractions (PS-1, PS-2, PS-3, PS-4 and PS-5) were successfully isolated from Athyrium Multidentatum (Doll.) Ching by anion-exchange column chromatography. Their in vitro cytoprotective activities and the underlying mechanisms were explored in this paper. Chemical analysis suggested that the five polysaccharide fractions were heteropolysaccharides with different molecular weights and monosaccharide compositions. Treatment with these polysaccharide fractions could increase cell viabilities, superoxide dismutase/catalase activities, nitric oxide contents, mitochondrial membrane potential levels and Bcl-2/Bax ratios, and reduce cell apoptosis, intracellular reactive oxygen species production and malondialdehyde contents in H2O2-damaged cells. Moreover, these polysaccharide fractions enhanced the mRNA expression levels of PI3K, Akt, FOXO3a, Nrf2 and HO-1 and PS-4 exhibited the most powerful effects on the mRNA expression of these genes. Current findings suggested that the polysaccharide fractions decreased H2O2-induced apoptosis of HUVECs. The activation of PI3K/Akt/FOXO3a and Nrf2/HO-1 signaling pathways might be involved in the protective mechanisms of the active fractions. The polysaccharides might be one of the key bioactive ingredients of Athyrium Multidentatum (Doll.) Ching for the treatment of oxidative damage.

Tetrahydrocurcumin protects against spinal cord injury and inhibits the oxidative stress response by regulating FOXO4 in model rats

It has been reported that tetrahydrocurcumin has hypoglycemic, hypolipidemic, anti-metastasis, anticancer and anti-depressant pharmacological effects, and its antioxidative, hypoglycemic and hypolipidemic properties are better than those of curcumin. The present study assessed whether tetrahydrocurcumin exerts a neuroprotective effect against spinal cord injury (SCI) and investigated the underlying mechanisms. In a rat model of SCI, tetrahydrocurcumin enhanced the average Basso-Beattie-Bresnahan scores, inhibited water accumulation in the spinal cord and decreased inflammatory factors. Furthermore, oxidative stress and apoptosis (caspase-3 activity and B-cell lymphoma 2-associated X protein levels) were also suppressed in SCI rats treated with tetrahydrocurcumin. Tetrahydrocurcumin effectively decreased the gene expression of matrix metalloproteinase-3 and -13, as well as cyclooxygenase-2, promoted the phosphorylation of Akt and enhanced the protein expression of forkhead box (FOX)O4 in SCI rats. The present study delineates that tetrahydrocurcumin protects against SCI and inhibits the oxidative stress response by regulating the FOXO4 in SCI model rats.

Protective effect of leptin-mediated caveolin-1 expression on neurons after spinal cord injury

Spinal cord injury (SCI) causes long-term disability and has no effective clinical treatment. After SCI, extracellular adenosine triphosphate (ATP) leads to an influx of extracellular Ca²⁺, and this Ca²⁺ overload causes neuronal toxicosis and apoptosis. The biological functions of leptin have been widely investigated in the central nervous system. In this study, we discovered that the administration of leptin could improve locomotor recovery following SCI. The aim of this study was to determine the neuroprotective mechanism of leptin in vivo and in vitro. The neuronal apoptosis and Ca²⁺ imaging signal induced by ATP were suppressed by leptin, due to elevated caveolin-1 expression. In vivo two-photon observations revealed that leptin reduced the neuronal Ca²⁺ imaging signal in the exposed spinal cords of live Thy1-YFP mice. In conclusion, leptin promotes locomotor functional recovery and suppresses neuronal impairment after SCI, suggesting that leptin has a promising clinical therapeutic value for treatment of SCI.

Tanshinone IIA Attenuates Insulin Like Growth Factor 1 -Induced Cell Proliferation in PC12 Cells through the PI3K/Akt and MEK/ERK Pathways

The insulin like growth factor 1 (IGF-1) and its receptor (IGF-1R) facilitate tumor proliferation and progression. Tanshinone IIA (TSN) is an active diterpene quinone isolated from the roots of the herbal plant Salvia miltiorrhiza. TSN inhibits the proliferation of various types of cancer cells but its role in the IGF-1R-induced proliferation of pheochromocytoma (PC12) cells and the potential mechanisms are largely unknown. This study aims to investigate the anti-proliferative effect of TSN in PC12 cells and its role on IGF-1R signaling transduction. PC12 cells were treated with IGF-1 with or without TSN, methyl thiazolytetrazolium (MTT) assay, and cell counting kit-8 and flow cytometry were used to evaluate the proliferation of PC12 cells. The role of TSN on the apoptosis of PC12 cells were detected by flow cytometry as well. The effects of TSN and IGF-1 on the phosphorylation of IGF-1R, protein kinase B (Akt), extracellular-signal related kinase 1/2 (ERK1/2) and other downstream targets were analyzed by Western blotting analysis. Our results showed that IGF-1 promoted the growth of PC12 cells in a dose-dependent manner and increased the phosphorylation of IGF-1R, whereas TSN attenuated the effect of IGF-1. Interestingly, TSN did not induce cell apoptosis in PC12 cells. Moreover, TSN attenuated the phosphorylation of Akt and ERK1/2 induced by IGF-1, and the phosphorylation of glycogen synthase kinase-3β, forkhead box O3a (FOXO3a) and c-Raf were also inhibited by TSN. Furthermore, TSN inhibited cell growth induced by IGF-1 and blocked the activation of IGF-1R in SH-SY5Y cells. Taken together, TSN has an inhibitory effect on the proliferation of PC12 cells via down-regulation of the phosphorylated IGF-1R and its downstream signaling.

Overexpression of HIPK2 attenuates spinal cord injury in rats by modulating apoptosis, oxidative stress, and inflammation

HIPK2 is considered to be a tumor suppressor. It also has been implicated in several functions such as apoptosis and inflammation that are linked to spinal cord injury (SCI). However, whether HIPK2 ameliorates the neurological pain of SCI remains unclear. Here, we investigated the effects of HIPK2 on neurological function, oxidative stress, levels of inflammatory cytokines and expression of Bcl-2/Bax in an SCI model. Firstly, we evaluated the therapeutic effects of HIPK2 on neurological pain in the SCI rat using the Basso, Beattie and Bresnahan scores and H & E staining. Overexpression of HIPK2 significantly elevated the levels of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF), and reduced the mRNA expression of Nogo-A and RhoA in SCI rats. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays showed that overexpression of HIPK2 significantly reduced the number of apoptotic cells. Overexpression of HIPK2 also decreased expression of Bax and Caspase-3 and elevated expression of Bcl-2 in the SCI model, indicating that HIPK2 exhibited its protective activity by inhibiting SCI-induced apoptosis. Then, we measured the serum concentrations of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX). We also determined the mRNA and protein levels of nuclear factor-κB p65 unit, tumor necrosis factor-α (TNF-α), and interleukin (IL)-1β. HIPK2 overexpression reduced oxidative stress and the levels of inflammatory cytokines compared with SCI control animals. Additionally, acetylation of HIPK2 was reduced in SCI rats. Overexpression of HIPK2 could enhance autophagy by elevating the expression of Beclin-1 and LC3-II while autophagy is regarded as a beneficial regulator to improve spinal cord injury. Together, overexpression of HIPK2 improved contusive SCI induced pain by modulating oxidative stress, Bcl‑2 and Bax signaling, and inflammation, and also regulating autophagy.

The PI3K/Akt/FOXO3a pathway regulates regeneration following spinal cord injury in adult rats through TNF-α and p27kip1 expression

The aim of the present study was to elucidate the expression and role of the phosphatidylinositol 3‑kinase (PI3K)/Akt/forkhead box O3 (FOXO3a) pathway in the regeneration of the spinal cord following spinal cord injury (SCI), and its regulatory effect on tumor necrosis factor (TNF)-α and cyclin-dependent kinase inhibitor 1B (p27kip1) expression. Firstly, in a Sprague-Dawley rat model of SCI, western blot analysis revealed that the protein levels of PI3K, phosphorylated Akt and FOXO3a were markedly inhibited compared with those in the sham control group. In vitro experiments were also conducted, in which primary dissociated cultures of rat dorsal spinal cord cells were induced with lipopolysaccharide (LPS; 4 µg/ml). The downregulation of PI3K using LY294002 markedly suppressed cell viability, reduced the protein levels of FOXO3a and p27kip1, and increased TNF-α protein production in the LPS-induced spinal cord cells. In addition, when the LPS-induced spinal cord cells were infected with FOXO3a adenoviral vectors, the overexpression of FOXO3 markedly promoted cell proliferation, activated p27kip1 protein levels and inhibited TNF-α protein production in the spinal cord cells. These results suggest that the PI3K/Akt/FOXO3a pathway regulates regeneration following SCI in adult rats via its modulatory effects on TNF-α and p27kip1 expression.

Mechanism of depression as a risk factor in the development of Alzheimer's disease: the function of AQP4 and the glymphatic system

BACKGROUND

Many studies have indicated that a history of depression increases the risk of developing Alzheimer's disease (AD); however, the potential pathogenestic mechanism by which depression functions as a high risk factor for AD remains unknown. Recently, a "cerebral lymphatic system" referred to as "glymphatic system" has been demonstrated to be responsible for neuronal extracellular waste protein clearance via a paravascular pathway. However, the function of glymphatic pathway has not been determined in depressive disorders.

METHODS

The present study used an animal model of chronic unpredictable mild stress (CUMS) to determine the function of glymphatic pathway by using fluorescence tracers. Immunohistochemistry was used to assess the accumulation of endogenous mouse and exogenous human amyloid beta 42 (Aβ42) in CUMS-treated mice with or without treatment with antidepressant fluoxetine.

FINDINGS

Glymphatic pathway circulation was impaired in mice treated with CUMS; moreover, glymphatic pathway dysfunction suppressed Aβ42 metabolism, because the accumulation of endogenous and exogenous Aβ42 was increased in the brains of the CUMS-treated mice. However, treatment with fluoxetine reversed these destructive effects of CUMS on glymphatic system. In anhedonic mice, the expression of the water channel aquaporin 4 (AQP4), a factor in glymphatic pathway dysfunction, was down-regulated in cortex and hippocampus.

CONCLUSION

The dysfunction of glymphatic system suggested why a history of depression may be a strong risk factor for AD in anhedonic mice. We hope our study will contribute to an understanding of the risk mechanism of depressive disorder in the development of AD and the mechanisms of antidepressant therapies in AD.

Astrocytes: Integrative Regulators of Neuroinflammation in Stroke and Other Neurological Diseases

Astrocytes regulate neuroinflammatory responses after stroke and in other neurological diseases. Although not all astrocytic responses reduce inflammation, their predominant function is to protect the brain by driving the system back to homeostasis after injury. They receive multidimensional signals within the central nervous system and between the brain and the systemic circulation. Processing this information allows astrocytes to regulate synapse formation and maintenance, cerebral blood flow, and blood-brain barrier integrity. Similarly, in response to stroke and other central nervous system disorders, astrocytes detect and integrate signals of neuronal damage and inflammation to regulate the neuroinflammatory response. Two direct regulatory mechanisms in the astrocyte arsenal are the ability to form both physical and molecular barriers that seal the injury site and localize the neuroinflammatory response. Astrocytes also indirectly regulate the inflammatory response by affecting neuronal health during the acute injury and axonal regrowth. This ability to regulate the location and degree of neuroinflammation after injury, combined with the long time course of neuroinflammation, makes astrocytic signaling pathways promising targets for therapies.

Leptin suppresses adenosine triphosphate-induced impairment of spinal cord astrocytes

Spinal cord injury (SCI) causes long-term disability and has no clinically effective treatment. After SCI, adenosine triphosphate (ATP) may be released from neuronal cells and astrocytes in large amounts. Our previous studies have shown that the extracellular release of ATP increases the phosphorylation of cytosolic phospholipase A2 (cPLA2 ) and triggers the rapid release of arachidonic acid (AA) and prostaglandin E2 (PGE2) via the stimulation of epidermal growth factor receptor (EGFR) and the downstream phosphorylation of extracellular-regulated protein kinases 1 and 2. Leptin, a glycoprotein, induces the activation of the Janus kinase (JAK2)/signal transducers and activators of transcription-3 (Stat3) pathway via the leptin receptor. In this study, we found that 1) prolonged leptin treatment suppressed the ATP-stimulated release of AA and PGE2 from cultured spinal cord astrocytes; 2) leptin elevated the expression of caveolin-1 (Cav-1) via the JAK2/Stat3 signaling pathway; 3) Cav-1 blocked the interaction between Src and EGFR, thereby inhibiting the phosphorylation of EGFR and cPLA2 and attenuating the release of AA or PGE2; 4) pretreatment with leptin decreased ;he level of apoptosis and the release of interleukin-6 from cocultured neurons and astrocytes; and 5) leptin improved the recovery of locomotion in mice after SCI. Our results highlight leptin as a promising therapeutic agent for SCI. © 2016 Wiley Periodicals, Inc.

Thoracic 9 Spinal Transection-Induced Model of Muscle Spasticity in the Rat: A Systematic Electrophysiological and Histopathological Characterization

The development of spinal hyper-reflexia as part of the spasticity syndrome represents one of the major complications associated with chronic spinal traumatic injury (SCI). The primary mechanism leading to progressive appearance of muscle spasticity is multimodal and may include loss of descending inhibitory tone, alteration of segmental interneuron-mediated inhibition and/or increased reflex activity to sensory input. Here, we characterized a chronic thoracic (Th 9) complete transection model of muscle spasticity in Sprague-Dawley (SD) rats. Isoflurane-anesthetized rats received a Th9 laminectomy and the spinal cord was transected using a scalpel blade. After the transection the presence of muscle spasticity quantified as stretch and cutaneous hyper-reflexia was identified and quantified as time-dependent changes in: i) ankle-rotation-evoked peripheral muscle resistance (PMR) and corresponding electromyography (EMG) activity, ii) Hoffmann reflex, and iii) EMG responses in gastrocnemius muscle after paw tactile stimulation for up to 8 months after injury. To validate the clinical relevance of this model, the treatment potency after systemic treatment with the clinically established anti-spastic agents baclofen (GABAB receptor agonist), tizanidine (α2-adrenergic agonist) and NGX424 (AMPA receptor antagonist) was also tested. During the first 3 months post spinal transection, a progressive increase in ankle rotation-evoked muscle resistance, Hoffmann reflex amplitude and increased EMG responses to peripherally applied tactile stimuli were consistently measured. These changes, indicative of the spasticity syndrome, then remained relatively stable for up to 8 months post injury. Systemic treatment with baclofen, tizanidine and NGX424 led to a significant but transient suppression of spinal hyper-reflexia. These data demonstrate that a chronic Th9 spinal transection model in adult SD rat represents a reliable experimental platform to be used in studying the pathophysiology of chronic spinal injury-induced spasticity. In addition a consistent anti-spastic effect measured after treatment with clinically effective anti-spastic agents indicate that this model can effectively be used in screening new anti-spasticity compounds or procedures aimed at modulating chronic spinal trauma-associated muscle spasticity.

FOXO3a Gene Polymorphism Associated with Asthma in Indian Population

Asthma is a chronic inflammatory disorder delineated by a heightened immunological response due to environmental or genetic factors. Single nucleotide polymorphism studies have shown that FOXO3a plays a pivotal role in maintaining immunoregulation. Polymorphism in FOXO3a has been linked to inflammatory diseases such as chronic obstructive pulmonary disease (COPD), Rheumatoid Arthritis, and Crohn's disease suggesting that FOXO3a may be associated with asthma. Airway inflammation in asthma is characterized by activation of T helper type 2 (Th2) T cells and Foxo family members are reported to play critical roles in the suppression of T cell activation. Thus this study was undertaken to investigate an association between single nucleotide polymorphism of the FOXO3a (rs13217795, C>T transition) gene and asthma in Indian population. To our knowledge we are the first ones reporting an association between FOXO3a and asthma.

Extracellular ATP and other nucleotides-ubiquitous triggers of intercellular messenger release

Extracellular nucleotides, and ATP in particular, are cellular signal substances involved in the control of numerous (patho)physiological mechanisms. They provoke nucleotide receptor-mediated mechanisms in select target cells. But nucleotides can considerably expand their range of action. They function as primary messengers in intercellular communication by stimulating the release of other extracellular messenger substances. These in turn activate additional cellular mechanisms through their own receptors. While this applies also to other extracellular messengers, its omnipresence in the vertebrate organism is an outstanding feature of nucleotide signaling. Intercellular messenger substances released by nucleotides include neurotransmitters, hormones, growth factors, a considerable variety of other proteins including enzymes, numerous cytokines, lipid mediators, nitric oxide, and reactive oxygen species. Moreover, nucleotides activate or co-activate growth factor receptors. In the case of hormone release, the initially paracrine or autocrine nucleotide-mediated signal spreads through to the entire organism. The examples highlighted in this commentary suggest that acting as ubiquitous triggers of intercellular messenger release is one of the major functional roles of extracellular nucleotides. While initiation of messenger release by nucleotides has been unraveled in many contexts, it may have been overlooked in others. It can be anticipated that additional nucleotide-driven messenger functions will be uncovered with relevance for both understanding physiology and development of therapy.

Lentivirus-mediated inhibition of tumour necrosis factor-α improves motor function associated with PRDX6 in spinal cord contusion rats

The recovery of motor function in rats is inhibited following contusion spinal cord injury (cSCI). However, the mechanism of tumour necrosis factor α (TNF-α) in motor function after cSCI associated with peroxiredoxin 6 (PRDX6) remains unknown. We randomly divided rats into four groups: sham, cSCI, vector and lentivirus mediating TNF-α RNA interference (TNF-α-RNAi-LV) group. The Basso, Beattie, Bresnahan (BBB) scale was used to evaluate motor function. Real-time quantitative PCR (qRT-PCR) and western blotting were used to detect the expression of TNF-α and PRDX6, which were located in neurons using immunohistochemistry (IHC) and immunofluorescence. Subsequently, lentiviral-mediated TNF-α was used to determine the role of TNF-αand the relationship of PRDX6 and TNF-α in cSCI. After cSCI, the motor capability of hind limbs disappeared and was followed by recovery of function. IHC analysis indicated that TNF-α and PRDX6 were primarily located in spinal cord neurons. TNF-α interference significantly improved neural behaviour and increased expression of PRDX6. Our study suggests that inhibition of TNF-α can promote the recovery of motor function. The underlying mechanism of TNF-α-promoted motor function may be connected with the up-regulation of PRDX6. This provides a new strategy or target for the clinical treatment of SCI in future.

The regulation of Sox2 and Sox9 stimulated by ATP in spinal cord astrocytes

After spinal cord injury (SCI), the level of adenosine triphosphate (ATP) and extracellular matrix (ECM) is increased. Formation of the glial scar is a complex process that is primarily attributed to astrocytic proliferation, and the fibrotic scar results from ECM deposition. In our previous researches, ATP and fibronectin was able to separately stimulate the proliferation of astrocytes. Moreover, fibronectin increases the expression of P2Y1 receptor and offers more binding sites for ATP, which aggravates the proliferation. Meanwhile, ATP was also able to stimulate the release of interleukin (IL)-6 and tumor necrosis factor-α (TNF-α), but fibronectin does not. Recently, it has been reported that over-expressing P2Y1 receptor could promote the level of Sox9. However, the regulation of Sox genes by ATP is still little known in spinal cord astrocytes. In the present study, we discovered that ATP was able to increase the expression of Sox2 and Sox9; fibronectin did not have this direct function. Sox9 was only involved in the proliferation increased by ATP, and Sox2 influenced the release of IL-6 stimulated by ATP. Understanding the critical role of Sox2 and Sox9 mediated by ATP may provide a potential target for therapeutic intervention in spinal cord injury.