Exosome-shuttled FTO from BM-MSCs contributes to cancer malignancy and chemoresistance in acute myeloid leukemia by inducing m6A-demethylation: A nano-based investigation.

Although bone marrow mesenchymal stem cells (BM-MSCs)-derived exosomes have been reported to be closely associated with acute myeloid leukemia (AML) progression and chemo-resistance, but its detailed functions and molecular mechanisms have not been fully delineated. Besides, serum RNA m6A demethylase fat mass and obesity-associated protein (FTO)-containing exosomes are deemed as important indicators for cancer progression, and this study aimed to investigate the role of BM-MSCs-derived FTO-exosomes in regulating the malignant phenotypes of AML cells. Here, we verified that BM-MSCs-derived exosomes delivered FTO to promote cancer aggressiveness, stem cell properties and Cytosine arabinoside (Ara-C)-chemoresistance in AML cells, and the underlying mechanisms were also uncovered. Our data suggested that BM-MSCs-derived FTO-exo demethylated m6A modifications in the m6A-modified LncRNA GLCC1 to facilitate its combination with the RNA-binding protein Hu antigen R (HuR), which further increased the stability and expression levels of LncRNA GLCC1. In addition, LncRNA GLCC1 was verified as an oncogene to facilitate cell proliferation and enhanced Ara-C-chemoresistance in AML cells. Further experiments confirmed that demethylated LncRNA GLCC1 served as scaffold to facilitate the formation of the IGF2 mRNA binding protein 1 (IGF2BP1)-c-Myc complex, which led to the activation of the downstream tumor-promoting c-Myc-associated signal pathways. Moreover, our rescuing experiments validated that the promoting effects of BM-MSCs-derived FTO-exo on cancer aggressiveness and drug resistance in AML cells were abrogated by silencing LncRNA GLCC1 and c-Myc. Thus, the present firstly investigated the functions and underlying mechanisms by which BM-MSCs-derived FTO-exo enhanced cancer aggressiveness and chemo-resistance in AML by modulating the LncRNA GLCC1-IGF2BP1-c-Myc signal pathway, and our work provided novel biomarkers for the diagnosis, treatment and therapy of AML in clinic.

m6A genotypes and prognostic signature for assessing the prognosis of patients with acute myeloid leukemia.

BACKGROUND: N6-methyladenosine (m6A) has been confirmed to function critically in acute myeloid leukemia (AML) progression. Hitherto, the subtyping and prognostic predictive significance of m6A-correlated genes in AML is unclear. METHOD: From The Cancer Genome Atlas (TCGA-LAML), Therapeutically Applicable Research to Generate Effective Treatments (TARGET-AML) and Gene Expression Omnibus (GEO, GSE71014) databases, we collected the sequencing data of AML patients. The batch effect was removed via limma package for TCGA-LAML and TARGET-AML, and the aggregated samples were AML cohorts. Samples in the AML cohort identified m6A models in AML by consensus clustering based on 23-m6A-related modulators. M6A-related differentially expressed genes (m6ARDEGs) influencing the overall survival (OS) of AML were determined by performing differential expression analysis and univariate COX analysis, and consensus-based clustering was utilized to access AML molecular subtypes. LASSO and multivariate COX analyses were performed to obtain the optimized m6ARDEGs to construct the m6A Prognostic Risk Score (m6APR_Score). Whether the model was robust was evaluated according to Kaplan-Meier (K-M) and receiver operator characteristic (ROC) curves. Further, the abundance of immune cell infiltration was explored in different m6A modification patterns and molecular subtypes and m6APR_Score groupings. Finally, nomogram was constructed to predict OS in AML. Quantitative real-time polymerase chain reaction (RT-qPCR) and cell counting kit-8 (CCK-8) assay were used to validate the genes in m6APR_Score in AML cells. RESULTS: The m6A models (m6AM1, m6AM2, m6AM3) and molecular subtypes (C1, C2, C3) were identified in the AML cohort, exhibiting different prognosis and immunoreactivity. We recognized novel prognostic biomarkers of AML such as CD83, NRIP1, ACSL1, METTL7B, OGT, and C4orf48. AML patients were grouped into high-m6APR_Score and low-m6APR_Score groups, with the later group showing a better prognosis than former one. Both the AML cohort and the validation cohort GSE71014 demonstrated excellent prediction. Finally, the nomogram accurately predicted the survival of patients suffering from AML. Further, the decision curves showed that both nomogram and m6APR_Score showed excellent prediction. It was confirmed in vitro experiments that mRNA expressions of NRIP1, ACSL1, METTL7B and OGT were elevated, while CD83 and C4orf48 mRNA expressions downregulated in AML cells. A significant increase in the viability of U937 and THP-1 cell lines after inhibition of CD83, while siMETTL7B had contrast results. CONCLUSION: Our study demonstrated that m6APR_Score and CD83, NRIP1, ACSL1, METTL7B, OGT, and C4orf48 potentially provided novel and promising prognostic support for AML patients.

Synergistic effects on oxidative stress, apoptosis and necrosis resulting from combined toxicity of three commonly used pesticides on HepG2 cells.

The widespread use of pesticides performs a vital role in safeguarding crop yields and quality, providing the opportunity for multiple pesticides to co-exist, which poses a significant potential risk to human health. To assess the toxic effects caused by exposures to individual pesticides (chlorpyrifos, carbofuran and acetamiprid), binary combinations and ternary combinations, individual and combined exposure models were developed using HepG2 cells and the types of combined effects of pesticide mixtures were assessed using concentration addition (CA), independent action (IA) and combination index (CI) models, respectively, and the expression of biomarkers related to oxidative stress, apoptosis and cell necrosis was further examined. Our results showed that both individual pesticides and mixtures exerted toxic effects on HepG2 cells. The CI model indicated that the toxic effects of pesticide mixtures exhibited synergistic effects. The results of the lactate dehydrogenase (LDH) release and apoptosis assay revealed that the pesticide mixture increased the release of LDH and apoptosis levels. Moreover, our results also showed that individual pesticides and mixtures disrupted redox homeostasis and that pesticide mixtures produced more intense oxidative stress effects. In conclusion, we have illustrated the enhanced combined toxicity of pesticide mixtures by in-vitro experiments, which provides a theoretical basis and scientific basis for further toxicological studies.

The therapeutic potential of berberine chloride against SARM1-dependent axon degeneration in acrylamide-induced neuropathy.

Chronic acrylamide (ACR) intoxication causes typical pathology of axon degeneration. Moreover, sterile-α and toll/interleukin 1 receptor motif-containing protein 1 (SARM1), the central executioner of the programmed axonal destruction process under various insults, is up-regulated in ACR neuropathy. However, it remains unclear whether inhibitors targeting SARM1 are effective or not. Among all the pharmacological antagonists, berberine chloride (BBE), a natural phytochemical and the first identified non-competitive inhibitor of SARM1, attracts tremendous attention. Here, we observed the protection of 100 µM BBE against ACR-induced neurites injury (2 mM ACR, 24 hr) in vitro, and further evaluated the neuroprotective effect of BBE (100 mg/kg p.o. three times a week for 4 weeks) in ACR-intoxicated rats (40 mg/kg i.p. three times a week for 4 weeks). The expression of SARM1 was also detected. BBE intervention significantly inhibited the overexpression of SARM1, ameliorated axonal degeneration, alleviated pathological changes in the sciatic nerve and spinal cord, and improved neurobehavioral symptoms in ACR-poisoned rats. Thus, BBE exhibits a strong neuroprotective effect against the SARM1-dependent axon destruction in ACR neuropathy. Meanwhile, our study underscores the need for appropriate inhibitor selection in diverse situations that would benefit from blocking the SARM1-dependent axonal destruction pathway.

Allyl methyl trisulfide protected against LPS-induced acute lung injury in mice via inhibition of the NF-κB and MAPK pathways.

Allyl methyl trisulfide (AMTS) is one major lipid-soluble organosulfur compound of garlic. Previous studies have reported the potential therapeutic effect of garlic on acute lung injury (ALI) or its severe condition acute respiratory distress syndrome (ARDS), but the specific substances that exert the regulatory effects are still unclear. In this study, we investigate the protective effects of AMTS on lipopolysaccharide (LPS)-induced ALI mice and explored the underlying mechanisms. In vivo experiments, ICR mice were pretreated with 25-100 mg/kg AMTS for 7 days and followed by intratracheal instillation of LPS (1.5 mg/kg). The results showed that AMTS significantly attenuated LPS-induced deterioration of lung pathology, demonstrated by ameliorative edema and protein leakage, and improved pulmonary histopathological morphology. Meanwhile, the expression of inflammatory mediators and the infiltration of inflammation-regulation cells induced by LPS were also inhibited. In vitro experiments also revealed that AMTS could alleviate inflammation response and inhibit the exaggeration of macrophage M1 polarization in LPS-induced RAW264.7 cells. Mechanistically, we identified that AMTS treatment could attenuate the LPS-induced elevation of protein expression of p-IκBα, nuclear NF-κB-p65, COX2, iNOS, p-P38, p-ERK1/2, and p-JNK. Collectively, these data suggest that AMTS could attenuate LPS-induced ALI and the molecular mechanisms should be related to the suppression of the NF-κB and MAPKs pathways.

Calpain-mediated cleavage of mitochondrial fusion/fission proteins in acetaminophen-induced mice liver injury.

Mitochondrial dysfunction was considered to be a critical event in acetaminophen (APAP) -induced hepatotoxicity. Recent studies suggest that abnormal mitochondrial dynamics contributes to mitochondrial dysfunction in APAP-induced liver injury, yet the underlying mechanisms responsible for deregulated mitochondrial dynamics remains elusive. In this study, C57BL/6 mice were used to establish a model of acute liver injury via intraperitoneal (i.p.) injection with overdose of APAP. Furthermore, calpain intervention experiments were achieved by the inhibitors ALLN or calpeptin. The activity of serum enzymes and pathological changes of APAP-treated mice were evaluated, and the critical molecules in mitochondrial dynamics and calpain degradative pathway were determined by electron microscopy, immunoblot and calpain activity kit. The results demonstrated that APAP overdose resulted in a severe liver injury, mitochondrial damage and an obvious cleavage of fusion/fission proteins. Meanwhile, the activation of calpain degradative machinery in liver were observed following APAP. By contrast, pretreatment of calpain inhibitors significantly inhibited the activation of calpains. Our further investigation found that ALLN or calpeptin administration significantly suppresses the changes of mitochondrial dynamics in APAP-treated mice and finally protected against APAP-induced hepatoxicity. Overall, these results suggest that calpain-mediated cleavage of mitochondrial dynamics proteins was involved in the pathogenic process of mitochondrial dysfunction and thus present a potential molecular coupling APAP-induced hepatotoxicity.

Mitophagy protects against acetaminophen-induced acute liver injury in mice through inhibiting NLRP3 inflammasome activation.

Mitochondrial dysfunction was considered as a critical event involved in acetaminophen (APAP)-induced acute liver injury. Mitophagy is a type of autophagy responsible for the selective removal of damaged mitochondria. However, the exact role and possible mechanism of mitophagy in APAP-induced hepatotoxicity remains largely unknown. In this study, C57/BL6 mice were used to establish a model of acute liver injury via intraperitoneal (i.p.) injection with different doses of APAP. Furthermore, autophagy intervention experiments were achieved by the administration of rapamycin (RAPA) or chloroquine (CQ) one hour prior to dosing 300 mg/kg APAP. The activity of serum enzymes and pathological changes of APAP-treated mice were evaluated, and the critical molecules in mitophagy and NLRP3 inflammasome pathway were determined by electron microscopy, immunoblot, immunofluorescence and real-time PCR. The results demonstrated that APAP overdose resulted in an activation of PINK1/Parkin-mediated mitophagy in mice liver. Moreover, the expression of the critical molecules in NF-kB and NLRP3 inflammasome signaling pathway were markedly increased by APAP. Our further investigation found that pretreatment with RAPA protected against APAP-induced hepatoxicity in mice. Notably, RAPA significantly inhibited the activation of NF-kB and NLRP3 inflammasome and the production of IL-1ß in APAP-treated mice. By contrast, pretreatment with CQ further enhanced NLRP3 inflammasome signaling pathway. Taken together, these results indicated that activation of PINK1/Parkin-mediated mitophagy protects against APAP-induced acute liver injury in mice through inhibiting inflammasome activation. Therefore, mitophagy may represent a promising therapeutic target for APAP-induced liver injury.

Activation of PINK1-Parkin-dependent mitophagy in Tri-ortho-cresyl phosphate-treated Neuro2a cells.

Tri-ortho-cresyl phosphate (TOCP) is a typical organophosphorus compound that can cause organophosphate-induced delayed neuropathy (OPIDN), which is pathologically characterized by axonal degeneration. Nowadays, mitochondrial dysfunction is regarded as a potential mechanism contributing to OPIDN progress. Mitophagy, a selective type of autophagy, is required to segregate damaged mitochondria from healthy mitochondrial networks and deliver them to lysosome for degradation. This research was designed to investigate the role of mitophagy in axon degeneration following TOCP administration in an in vitro model. Differentiated neuro2a (N2a) cells were divided into four groups and treated with 0, 5, 10, and 20 µM TOCP for 24 h, respectively. The critical proteins in PINK1-Parkin-dependent mitophagy including LC3, P62, PINK1, Parkin, mitochondrial proteins, and autophagic receptors were detected by immunoblotting and immunofluorescence. After TOCP treatment, increased level of ROS in N2a cells revealed a significant mitochondria damage. Meanwhile, it was observed that much more PINK1, Parkin, and LC3-II were translocated to the mitochondria. Furthermore, immunofluorescence analysis demonstrated that the co-localization of Parkin and LC3 was significantly increased. These results suggested that PINK1-Parkin dependent mitophagy pathway in N2a cells was activated by TOCP treatment. In addition, P62, a major autophagic receptor, was markedly accumulated on the mitochondria, which indicated that P62 might play a critical role in facilitating mitophagy under TOCP-induced axonal degeneration. Taken together, our results suggest that TOCP exposure resulted in the activation of PINK1-Parkin-dependent mitophagy in N2a cells. Mitophagy may act as a positively reactive mode in eliminating dysfunctional mitochondria and therefore protect neurons against TOCP neurotoxicity.

Diallyl sulfide treatment protects against acetaminophen-/carbon tetrachloride-induced acute liver injury by inhibiting oxidative stress, inflammation and apoptosis in mice.

The purpose of the present study was to investigate the effects and underlying mechanisms of diallyl sulfide (DAS), an organosulfur compound extracted from garlic, on drug-induced or chemical-induced liver injury caused by acetaminophen (APAP) or carbon tetrachloride (CCl4) in mice. DAS (100, 200, or 400 µmol kg-1) was orally administered 1 hour before APAP or CCl4 intraperitoneal injection, and the serum and liver tissue were collected 24 hours after APAP or CCl4 exposure. The serum aminotransferase activities and liver histopathological examination showed that DAS exhibited obvious hepatoprotective effects against acute liver injury induced by APAP or CCl4. In addition, exposure to APAP or CCl4 resulted in an increased content of malonaldehyde as well as a decreased ratio of reduced to oxidized glutathione, and a decreased level of superoxide dismutase and catalase activity in the liver (p < 0.05); however, pretreatment with DAS restored the perturbations of the antioxidant system in the liver. Beyond that, DAS pretreatment reduced the APAP-/CCl4-induced increase in phosphorylation of inhibitor of kappa B alpha (IκBα) and p65 subunit of nuclear factor kappa B (NF-κB) expression in the cytoplasm and nucleus in the liver. DAS pretreatment also decreased the excessive level of TNF-α caused by APAP or CCl4 in serum (p < 0.05). Moreover, DAS pretreatment regulated the expression of cleaved caspase 3, Bax and Bcl-2 in the liver and suppressed APAP-/CCl4-induced hepatocyte apoptosis. In conclusion, DAS exhibits hepatoprotective effects against drug-induced and chemical-induced liver injuries induced by APAP or CCl4 in mice, probably due to its ability to reduce hepatic oxidative stress and inhibit inflammatory injury and hepatocyte apoptosis.

Diallyl sulfide protects against lipopolysaccharide/d-galactosamine-induced acute liver injury by inhibiting oxidative stress, inflammation and apoptosis in mice.

The effects of diallyl sulfide (DAS) and the potential mechanisms were investigated on lipopolysaccharide (LPS)/d-galactosamine (D-GalN)-induced acute liver injury in mice. DAS (50, 100, 200 µmol/kg) were orally given 1 h prior to LPS (10 µg/kg)/D-GalN (500 mg/kg) intraperitoneal injection. Serum and liver were collected at 8 h after LPS/D-GalN treatment. DAS Pretreatment reduced the activities of serum aminotransferase and attenuated histopathological damage in LPS/D-GalN-induced liver injury. Additionally, LPS/D-GalN-induced liver oxidative stress was ameliorated by DAS pretreatment, as evidenced by the decreased content of MDA and increased level of GSH, SOD, CAT in liver. Moreover, LPS/D-GalN-induced the excessive levels of TNF-α, IL-1ß and MCP-1 in serum and liver was decreased by DAS pretreatment. Furthermore, DAS pretreatment attenuated LPS/D-GalN-induced hepatocyte apoptosis, as evidenced by TUNEL staining and protein expression of cleaved caspase3, Bax and Bcl-2 in liver. DAS also up-regulated the expression of p-PI3K p85 and p-Akt in a dose-dependent manner, and Akt inhibitor MK-2206 weakened the inhibitory effect of DAS on hepatocyte apoptosis induced by LPS/D-GalN. In conclusion, the results suggest that DAS exerts the protective effect on LPS/GalN-induced acute liver injury, and this effects possibly by suppressing oxidative stress, inflammation and regulating hepatocyte apoptosis via the PI3K/Akt pathway.

Tributyltin exposure induces gut microbiome dysbiosis with increased body weight gain and dyslipidemia in mice.

Gut microbiome dysbiosis plays a profound role in the pathogenesis of obesity and tributyltin (TBT) has been found as an environmental obesogen. However, whether TBT could disturb gut microbiome and the relationship between obesity induced by TBT exposure and alteration in gut microbiota are still unknown. In order to assess the association between them, mice were exposed to TBTCl (50 µg kg-1) once every three days from postnatal days (PNDs) 24 to 54. The results demonstrated that TBT exposure resulted in increased body weight gain, lager visceral fat accumulation and dyslipidemia in male mice on PND 84. Correspondingly, 16S rRNA gene sequencing revealed that TBT treatment decreased gut microbial species and perturbed the microbiome composition in mice. Furthermore, Pearson's corelation coefficient analysis showed a significantly negative correlation between the body weight and the alpha diversity of gut microbiome. These results suggested that TBT exposure could induce gut microbiome dysbiosis in mice, which might contribute to the obesity pathogenesis.

Tributyltin reduces the levels of serum adiponectin and activity of AKT and induces metabolic syndrome in male mice.

Tributyltin (TBT), a proven environmental obesogen, functions as a nanomolar agonist of the peroxisome proliferator activated receptor-γ (PPARγ). However, the adverse effects of TBT on metabolism are incompletely understood. In this study, male ICR mice were administered TBT (5 and 50 µg·kg-1 ) by an intraperitoneal injection once every 3 days for 30 days from 28 days of age and bred for another 30 days after the last administration of TBT. We analyzed the effects of these exposures on the fat depot weights, serum lipid profile, serum leptin and adiponectin, hepatic lipid accumulation, and activity of AKT in the liver and skeletal muscle isolated from mice 8 mins after receiving an insulin injection. Pubertal exposure to TBTCl resulted in a higher body weight, increased epididymal and liver fat accumulation, hyperlipidemia, an elevated low-density lipoprotein/high-density lipoprotein ratio, serum adiponectin deficiency, worse glucose tolerance, and lower insulin-dependent AKT phosphorylation in the liver and muscle in mice. These results showed that TBT exposure induced peripheral insulin resistance and metabolic syndrome in mice.

Activation of p62-keap1-Nrf2 antioxidant pathway in the early stage of acetaminophen-induced acute liver injury in mice.

Acetaminophen (APAP) overdose can cause severe liver failure even death. Nearly half of drug-induced liver injury is attributed to APAP in the US and many European countries. Oxidative stress has been validated as a critical event involved in APAP-induced liver failure. p62/SQSTM1, a selective autophagy adaptor protein, is reported to regulate Nrf2-ARE antioxidant pathway in response to oxidative stress. However, the exact role of p62-keap1-Nrf2 antioxidant pathway in APAP-induced hepatotoxicity remains unknown. In the present study, the dose-response and time-course model in C57/BL6 mice were established by intraperitoneal injection of APAP. The results of serum alanine/aspartate aminotransferases (ALT/AST) and histological examination demonstrated that APAP overdose resulted in the severe liver injury. In the meantime, the levels of p62, phospho-p62 and nuclear Nrf2 were significantly increased by APAP in mice liver, suggesting an activation of p62-keap1-Nrf2 pathway. In addition, the expression of GSTA1 mRNA was increased in a dose-dependent manner, while the mRNA levels of HO-1 and GCLC were decreased with the increase of APAP dose. Our further investigation found that expression of HO-1 and GCLC peaked at 3 h∼6 h, and then were decreased gradually. Taken together, these results indicated that p62-keap1-Nrf2 antioxidant pathway was primarily activated in the early stage of APAP hepatotoxicity, which might play a protective role in the process of APAP-induced acute liver injury.

Carbon disulfide activates p62-Nrf2-keap1 pathway in rat nerve tissues.

Oxidative stress is associated with the pathogenesis of carbon disulfide (CS2) induced polyneuropathy. The nuclear factor erythroid 2-related factor 2 (Nrf2) plays a critical role in protecting cells against oxidative stress. However, whether there exists a Nrf2-mediated antioxidative machinery in CS2-induced neuropathy has not been elucidated. In the present study, male wistar rats were randomly divided into three experimental groups and one control group. The rats in experimental groups were treated with CS2 by gavage at dosages of 200, 400 and 600mg/kg/day respectively, six times per week for 6 weeks. Nrf2-keap1 antioxidative pathway and p62-related kinase signaling in rat nerve tissues was examined by western blotting and real-time PCR. The results demonstrated that CS2 treatment resulted in Nrf2 translocation from the cytosol to the nucleus in rat spinal cords. In the meantime, the expression of antioxidative enzymes such as NAD(P)H quinone oxidoreductase-1, heme oxygenase-1, and glutamate-cysteine ligase was significantly increased. Furthermore, CS2 treatment increased the level of p62 and its phosphorylation status, while decreased the level of keap1. In addition, CS2 also lead to the activation of CAMKK2 and ULK1 kinase signaling in rat spinal cords and sciatic nerves. Taken together, our results indicated that CS2 intoxication was associated with the activation of Nrf2-ARE antioxidative machinery, which might play a protective role against CS2-induced neuronal damage.

[Changes in expression of motor protein for axonal transport in nerve tissues of carbon disulfide-intoxicated rats].

OBJECTIVE: To study the changes in microtubule motor protein expression in the spinal cord and sciatic nerve of rats exposed to carbon disulfide, and to investigate the possible molecular mechanism of changes in axonal transport in carbon disulfide-induced peripheral neuropathy. METHODS: Healthy adult male Wistar rats were randomly divided into one control group and three experimental groups (10 rats per group). The rats in experimental groups were intoxicated by gavage of carbon disulfide at a dose of 200, 400, or 600 mg/kg 6 times a week for 6 consecutive weeks, while the rats in control group were given the same volume of corn oil by gavage. Animals were sacrificed after exposure, with nerve tissue separated. The levels of dynein, dynactin, and kinesin in the spinal cord and sciatic nerve were determined by Western blot. RESULTS: The content of dynein, dynactin, and kinesin in the sciatic nerve decreased significantly under exposure to carbon disulfide. The levels of dynein in the sciatic nerve were reduced by 23.47% and 33.34% at exposure doses of 400 and 600 mg/kg, respectively. The levels of dynactin in the sciatic nerve of the three experimental groups were reduced by 19.91%, 24.23%, and 41.30%, respectively. The level of kinesin was reduced by 25.98%under exposure to 600 mg/kg carbon disulfide. All the differences were statistically significant (P < 0.01). As compared with the control group, the 600 mg/kg group experienced a 28.24% decrease in level of dynactin in the spinal cord (P < 0.01), but no significant change was observed in the level of dynein or kinesin. CONCLUSION: Carbon disulfide has an impact on microtubule motor protein expression in nerve tissues, which might be involved in the development of carbon disulfide-induced peripheral neuropathy.

Activation of lysosomal degradative pathway in spinal cord tissues of carbon disulfide-treated rats.

Chronic exposure to carbon disulfide (CS2) can induce polyneuropathy in occupational worker and experimental animals, but underlying mechanism for CS2 neuropathy is currently unknown. In the present study, male Wistar rats were randomly divided into three experimental groups and one control group. The rats in experimental groups were treated with CS2 by gavage at dosages of 200, 400 and 600 mg/kg/day respectively, six times per week for 6 weeks. The formation of autophagosomes and lysosomes in motor neurons of rat spinal cord was observed by transmission electron microscopy, the level of autophagy-related proteins, lysosome-associated membrane protein 1 (LAMP-1), and cathepsin B in spinal cord tissues was determined by Western blot analysis, and the activity of cathepsin B was measured by fluorescence assay. The results demonstrated that the number of lysosomes in motor neurons was markedly increased in CS2-treated rats. In the meantime, the administration of CS2 significantly increased the level of microtubule-associated protein light chain 3-II (LC3-II), Atg1, UVRAG and LAMP-1 in rat spinal cord. Furthermore, the content and activity of cathepsin B in rat spinal cord also showed a significant elevation. Taken together, this study suggested that CS2 intoxication was associated with the activation of lysosomal degradative machinery, which might play a protective role against CS2-induced neuronal damage.

Involvement of autophagy in tri-ortho-cresyl phosphate- induced delayed neuropathy in hens.

Autophagy is a highly conserved cellular self-degradative process that plays a housekeeping role in removing aggregated proteins and damaged organelles. Our recent work has found that tri-ortho-cresyl phosphate (TOCP), a neuropathic organophosphate (OP), decreased the level of beclin 1 (a key molecule in the process of autophagy) in hen nerve tissues (Song et al., 2012). However, the role of autophagy in the pathogenesis of organophosphorus ester-induced delayed neuropathy (OPIDN) remains unclear. Here, we investigated whether dysfunctional autophagy was associated with the initiation and development of TOCP-induced delayed neuropathy. Adult hens were given a single dose of 750mg/kg TOCP (p.o.) and sacrificed on days 1, 5, 10, and 21 after dosing, respectively. The formation of autophagosomes in spinal cord motor neurons was observed by transmission electron microscopy, the level of autophagy-related proteins in hen spinal cords and tibial nerves was determined by Western blot analysis. The results demonstrated that the number of autophagosomes was markedly increased in the myelinated and unmyelinated axons of hen spinal cords after TOCP exposure. In the meantime, the level of two molecular markers for autophagy, microtubule-associated protein light chain-3 (LC3) and p62/SQSTM1 in hen nerve tissues was significantly decreased and increased, respectively. Furthermore, a marked reduction in autophagy-regulated proteins including ULK 1, AMBRA 1, ATG 5, ATG 7, ATG 12 and VPS34 expression was also observed. Our results suggested that the administration of TOCP resulted in a significant inhibition of autophagy activity in neurons, which might be associated with the pathogenesis of OPIDN.

Activation of mitochondria-mediated apoptotic pathway in tri-ortho-cresyl phosphate-induced delayed neuropathy.

Previous studies suggest that abnormal neurons death has been implicated in organophosphate-induced delayed neuropathy (OPIDN). However, the precise mechanism of neuronal death in OPIDN remains largely unknown. In this study, adult hens were treated with a dosage of 750 mg/kg tri-ortho-cresyl phosphate (TOCP) by gavage, and then sacrificed on the time-points of 1, 5, 10, and 21 days after dosing TOCP, respectively. The apoptotic change of spinal cord neurons induced by TOCP was examined, and the role of mitochondria-mediated apoptosis of neurons during OPIDN was investigated. TUNEL assays showed that apoptotic neurons in hen spinal cords began to appear on day 5 following TOCP exposure. Immunohistochemistry and western blot analysis revealed a translocation of cytochrome C from mitochondria to cytoplasm after dosing TOCP. Moreover, the level of Bcl-2, Bcl-xl, Pro-caspase3 and Pro-caspase9 in hen spinal cord was significantly decreased, whereas that of Bax and cleaved-PARP was significantly elevated. Taken together, these findings indicate that the administration of TOCP can induce neuron apoptosis in hen spinal cords, which might be mediated by the activation of mitochondrial apoptotic pathway.

[Changes in autophagy-related protein levels in nervous tissues of hens with tri-ortho-cresyl phosphate-induced delayed neuropathy].

OBJECTIVE: To study the changes in the levels of autophagy-related proteins, Atg1, Atg5, and Beclin1, in organophosphate-induced delayed neuropathy (OPIDN) caused by tri-ortho-cresyl phosphate (TOCP), and to investigate the molecular pathogenic mechanism of OPIDN. METHODS: Thirty adult Roman hens were randomly and equally divided into control group and 1, 5, 10, and 21 d intoxication groups. Each hen in the intoxication group was administered TOCP by gavage at a single dose of 750 mg/kg, while each hen in the control group was administered the same volume of corn oil. The hens were killed at the corresponding time points, and their tibial nerves and spinal cords were collected. The levels of Atg1, Atg5, and Beclin1 in the tibial nerves and spinal cords were measured by immunoblotting. RESULTS: Compared with those in the control group, the levels of Atg1 in tibial nerves decreased by 29.8%, 64.4%, 43.5%, and 19.8% at 1, 5, 10, and 21 d, respectively, after intoxication ((P < 0.05); the levels of Atg5 in tibial nerves decreased by 36.8%, 49.6%, 51.2%, and 31.5% at 1, 5, 10, and 21 d, respectively, after intoxication (P < 0.05); the levels of Beclin1 in tibial nerves decreased by 68.5%, 66.3%, and 32.2% at 1, 5, and 10 d, respectively, after intoxication (P < 0.05). Compared with those in the control group, the levels of Atg1 in spinal cords decreased by 23.5%, 48.7%, and 20% at 1, 5, and 10 d, respectively, after intoxication (P < 0.05); the levels of Atg5 in spinal cords decreased by 32.7%, 51.5%, 47.3%, and 39.6% at 1, 5, 10, and 21 d, respectively, after intoxication (P < 0.05); the levels of Beclin1 in spinal cords decreased by 28.9%, 50.2%, 43.2%, and 28.3% at 1, 5, 10, and 21 d, respectively, after intoxication (P < 0.05). CONCLUSION: The intoxication of TOCP is associated with the significant changes in the levels of autophagy-related proteins in the nervous tissues of hens, which might be involved in the pathogenesis of OPIDN.