The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Fuyong Song - One of the best experts on this subject based on the ideXlab platform.
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Activation of PINK1-Parkin-dependent mitophagy in Tri-ortho-cresyl phosphate-treated Neuro2a cells.
Chemico-biological interactions, 2019Co-Authors: Yu Wang, Ruirui Kou, Keqin Xie, Cuiqin Zhang, Zhenyu Shen, Fuyong SongAbstract:Abstract 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.
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Activation of mitochondria-mediated apoptotic pathway in tri-ortho-cresyl phosphate-induced Delayed Neuropathy.
Neurochemistry international, 2013Co-Authors: Chaoshuang Zou, Ruirui Kou, Yuan Gao, Keqin Xie, Fuyong SongAbstract: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.
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The role of calcium activated neutral protease in Organophosphate-Induced Delayed Neuropathy
Zhonghua lao dong wei sheng zhi ye bing za zhi = Zhonghua laodong weisheng zhiyebing zazhi = Chinese journal of industrial hygiene and occupational di, 2013Co-Authors: Ruirui Kou, Keqin Xie, Fuyong SongAbstract:有机磷化合物除可抑制胆碱酯酶活力引起急性中毒外,还能在人类和敏感动物中诱发迟发性神经病(organophosphorus ester induced Delayed Neuropathy,OPIDN)o OPIDN的特点是在有机磷化合物急性中毒后1～3周开始出现症状,首发症状多为四肢远端感觉异常,逐渐发展为共济失调与运动性肌无力,严重者可瘫痪[1-2].关于OPIDN的发生机制,早在上世纪70年代Johnson[3]提出OPIDN的发生与神经病靶酯酶(Neuropathy target esterase,NTE)活力抑制有关.在1990年,Abou-donia和Lapadula[4]出OPIDN的发生可能与钙及钙调蛋白依赖性蛋白激酶Ⅱ(calcium/calmodulin-dependent protein kinaseⅡ,Ca/CaM kinaseⅡ)介导的神经元细胞骨架异常磷酸化有关.然而,支持上述两种学说的研究仅仅表明NTE、Ca/CaM kinaseⅡ与OPIDN之间存在相关性,它们之间的因果关系始终没有确立。
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Calcium-dependent neutral cysteine protease and Organophosphate-Induced Delayed Neuropathy
Chemico-Biological Interactions, 2012Co-Authors: Fuyong Song, Keqin XieAbstract:A few organophosphorus compounds (OPs) can cause toxic Neuropathy known as organophosphorus ester-induced Delayed Neuropathy (OPIDN). Although the incidents of OPIDN have been documented for over a century, its molecular mechanisms underlying the axonopathy are still unclear. Recently, increasing evidences suggest that proteases are closely associated with OPIDN. Herein, we have summarized the roles of calcium-dependent cysteine proteases (calpains) in OPIDN. The activation of calpains should be an early molecular event during the onset and development of OPIDN. However, the understanding of the mechanism underlying the disruption of Ca2+ homeostasis and the activation of calpain by neurotoxic OPs is still limited. Therefore, a better understanding of molecular mechanisms that can prevent the disturbance in cellular Ca2+ homeostasis can facilitate to establish the novel therapeutic strategies for OPIDN.
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Changes in beclin-1 and micro-calpain expression in tri-ortho-cresyl phosphate-induced Delayed Neuropathy
Toxicology letters, 2012Co-Authors: Fuyong Song, Chaoshuang Zou, Xiaoying Han, Tao Zeng, Cui-li Zhang, Keqin XieAbstract:Abstract Tri-ortho-cresyl phosphate (TOCP) can cause toxic Neuropathy known as Organophosphate-Induced Delayed Neuropathy (OPIDN), which is pathologically characterized by the swollen axon containing aggregations of neurofilaments, microtubules, and multivesicular vesicles. Autophagy is a self-degradative process which plays a housekeeping role in removing misfolded proteins and damaged organelles. The current study was designed to investigate the possible roles of autophagy in the pathogenesis of OPIDN. Adult hens were treated with a dose of 750 mg/kg TOCP by gavage, or injected subcutaneously with 60 mg/kg phenylmethanesulfonyl fluoride (PMSF) dissolved in DMSO 24 h earlier and subsequently treated with TOCP, then sacrificed on the time-points of 0, 1, 5, 10, and 21 days after dosing of TOCP respectively. The levels of beclin-1 and μ-calpain in tibial nerves and spinal cords were determined by immunoblotting. The results showed that in both tissues TOCP increased the expression of μ-calpain while decreased that of beclin-1. When given before TOCP administration, PMSF pretreatment could protect hens against the Delayed Neuropathy. In the meantime, pretreatment with PMSF reduced calpain expression below basal and increased beclin-1 expression above basal in tibial nerve, whereas it simply returned calpain and beclin-1 expression to their basal levels in spinal cord. In conclusion, the intoxication of TOCP was associated with a significant change of beclin-1 in hen nervous tissues, which suggested that disruption of autophagy-regulated machinery in neurons might be involved in the pathogenesis of OPIDN.
Keqin Xie - One of the best experts on this subject based on the ideXlab platform.
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Activation of PINK1-Parkin-dependent mitophagy in Tri-ortho-cresyl phosphate-treated Neuro2a cells.
Chemico-biological interactions, 2019Co-Authors: Yu Wang, Ruirui Kou, Keqin Xie, Cuiqin Zhang, Zhenyu Shen, Fuyong SongAbstract:Abstract 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.
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Activation of mitochondria-mediated apoptotic pathway in tri-ortho-cresyl phosphate-induced Delayed Neuropathy.
Neurochemistry international, 2013Co-Authors: Chaoshuang Zou, Ruirui Kou, Yuan Gao, Keqin Xie, Fuyong SongAbstract: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.
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The role of calcium activated neutral protease in Organophosphate-Induced Delayed Neuropathy
Zhonghua lao dong wei sheng zhi ye bing za zhi = Zhonghua laodong weisheng zhiyebing zazhi = Chinese journal of industrial hygiene and occupational di, 2013Co-Authors: Ruirui Kou, Keqin Xie, Fuyong SongAbstract:有机磷化合物除可抑制胆碱酯酶活力引起急性中毒外,还能在人类和敏感动物中诱发迟发性神经病(organophosphorus ester induced Delayed Neuropathy,OPIDN)o OPIDN的特点是在有机磷化合物急性中毒后1～3周开始出现症状,首发症状多为四肢远端感觉异常,逐渐发展为共济失调与运动性肌无力,严重者可瘫痪[1-2].关于OPIDN的发生机制,早在上世纪70年代Johnson[3]提出OPIDN的发生与神经病靶酯酶(Neuropathy target esterase,NTE)活力抑制有关.在1990年,Abou-donia和Lapadula[4]出OPIDN的发生可能与钙及钙调蛋白依赖性蛋白激酶Ⅱ(calcium/calmodulin-dependent protein kinaseⅡ,Ca/CaM kinaseⅡ)介导的神经元细胞骨架异常磷酸化有关.然而,支持上述两种学说的研究仅仅表明NTE、Ca/CaM kinaseⅡ与OPIDN之间存在相关性,它们之间的因果关系始终没有确立。
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Calcium-dependent neutral cysteine protease and Organophosphate-Induced Delayed Neuropathy
Chemico-Biological Interactions, 2012Co-Authors: Fuyong Song, Keqin XieAbstract:A few organophosphorus compounds (OPs) can cause toxic Neuropathy known as organophosphorus ester-induced Delayed Neuropathy (OPIDN). Although the incidents of OPIDN have been documented for over a century, its molecular mechanisms underlying the axonopathy are still unclear. Recently, increasing evidences suggest that proteases are closely associated with OPIDN. Herein, we have summarized the roles of calcium-dependent cysteine proteases (calpains) in OPIDN. The activation of calpains should be an early molecular event during the onset and development of OPIDN. However, the understanding of the mechanism underlying the disruption of Ca2+ homeostasis and the activation of calpain by neurotoxic OPs is still limited. Therefore, a better understanding of molecular mechanisms that can prevent the disturbance in cellular Ca2+ homeostasis can facilitate to establish the novel therapeutic strategies for OPIDN.
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Changes in beclin-1 and micro-calpain expression in tri-ortho-cresyl phosphate-induced Delayed Neuropathy
Toxicology letters, 2012Co-Authors: Fuyong Song, Chaoshuang Zou, Xiaoying Han, Tao Zeng, Cui-li Zhang, Keqin XieAbstract:Abstract Tri-ortho-cresyl phosphate (TOCP) can cause toxic Neuropathy known as Organophosphate-Induced Delayed Neuropathy (OPIDN), which is pathologically characterized by the swollen axon containing aggregations of neurofilaments, microtubules, and multivesicular vesicles. Autophagy is a self-degradative process which plays a housekeeping role in removing misfolded proteins and damaged organelles. The current study was designed to investigate the possible roles of autophagy in the pathogenesis of OPIDN. Adult hens were treated with a dose of 750 mg/kg TOCP by gavage, or injected subcutaneously with 60 mg/kg phenylmethanesulfonyl fluoride (PMSF) dissolved in DMSO 24 h earlier and subsequently treated with TOCP, then sacrificed on the time-points of 0, 1, 5, 10, and 21 days after dosing of TOCP respectively. The levels of beclin-1 and μ-calpain in tibial nerves and spinal cords were determined by immunoblotting. The results showed that in both tissues TOCP increased the expression of μ-calpain while decreased that of beclin-1. When given before TOCP administration, PMSF pretreatment could protect hens against the Delayed Neuropathy. In the meantime, pretreatment with PMSF reduced calpain expression below basal and increased beclin-1 expression above basal in tibial nerve, whereas it simply returned calpain and beclin-1 expression to their basal levels in spinal cord. In conclusion, the intoxication of TOCP was associated with a significant change of beclin-1 in hen nervous tissues, which suggested that disruption of autophagy-regulated machinery in neurons might be involved in the pathogenesis of OPIDN.
Chaoshuang Zou - One of the best experts on this subject based on the ideXlab platform.
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Activation of mitochondria-mediated apoptotic pathway in tri-ortho-cresyl phosphate-induced Delayed Neuropathy.
Neurochemistry international, 2013Co-Authors: Chaoshuang Zou, Ruirui Kou, Yuan Gao, Keqin Xie, Fuyong SongAbstract: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.
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Changes in beclin-1 and micro-calpain expression in tri-ortho-cresyl phosphate-induced Delayed Neuropathy
Toxicology letters, 2012Co-Authors: Fuyong Song, Chaoshuang Zou, Xiaoying Han, Tao Zeng, Cui-li Zhang, Keqin XieAbstract:Abstract Tri-ortho-cresyl phosphate (TOCP) can cause toxic Neuropathy known as Organophosphate-Induced Delayed Neuropathy (OPIDN), which is pathologically characterized by the swollen axon containing aggregations of neurofilaments, microtubules, and multivesicular vesicles. Autophagy is a self-degradative process which plays a housekeeping role in removing misfolded proteins and damaged organelles. The current study was designed to investigate the possible roles of autophagy in the pathogenesis of OPIDN. Adult hens were treated with a dose of 750 mg/kg TOCP by gavage, or injected subcutaneously with 60 mg/kg phenylmethanesulfonyl fluoride (PMSF) dissolved in DMSO 24 h earlier and subsequently treated with TOCP, then sacrificed on the time-points of 0, 1, 5, 10, and 21 days after dosing of TOCP respectively. The levels of beclin-1 and μ-calpain in tibial nerves and spinal cords were determined by immunoblotting. The results showed that in both tissues TOCP increased the expression of μ-calpain while decreased that of beclin-1. When given before TOCP administration, PMSF pretreatment could protect hens against the Delayed Neuropathy. In the meantime, pretreatment with PMSF reduced calpain expression below basal and increased beclin-1 expression above basal in tibial nerve, whereas it simply returned calpain and beclin-1 expression to their basal levels in spinal cord. In conclusion, the intoxication of TOCP was associated with a significant change of beclin-1 in hen nervous tissues, which suggested that disruption of autophagy-regulated machinery in neurons might be involved in the pathogenesis of OPIDN.
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Changes in autophagy-related protein levels in nervous tissues of hens with tri-ortho-cresyl phosphate-induced Delayed Neuropathy
Zhonghua lao dong wei sheng zhi ye bing za zhi = Zhonghua laodong weisheng zhiyebing zazhi = Chinese journal of industrial hygiene and occupational di, 2012Co-Authors: Chaoshuang Zou, Ruirui Kou, Yuan Gao, Keqin Xie, Fuyong SongAbstract: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. Key words: three-o-cresyl phosphate; Organophosphate-Induced Delayed Neuropathy; Autophagy-related protein
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Reduction of retrograde axonal transport associated-proteins motor proteins, dynein and dynactin in the spinal cord and cerebral cortex of hens by tri-ortho-cresyl phosphate (TOCP).
Neurochemistry international, 2011Co-Authors: Fuyong Song, Chaoshuang Zou, Xiaoying Han, Tao Zeng, Cui-li Zhang, Keqin XieAbstract:Tri-ortho-cresyl phosphate (TOCP) can cause a type of neurotoxicity known as Organophosphate-Induced Delayed Neuropathy (OPIDN). The characteristic axonal swelling containing aggregations of neurofilaments, microtubules, and multivesicular vesicles is consistent with a disturbance of axonal transport. We hypothesized that there existed a disturbance of molecular motor in the pathogenesis of OPIDN. In the present study, adult hens were treated with a dosage of 750 mg/kg TOCP by gavage, or pretreated 24h earlier with phenylmethanesulfonyl fluoride (PMSF) and subsequently with TOCP, then sacrificed on the time-points of 0, 1, 5, 10, and 21 days after dosing of TOCP, respectively. The level of kinesin-1, dynein, and dynactin in spinal cords and cerebral cortexes of hens was determined. Immunoblotting analysis showed a progressive decline of dynein and dynactin in spinal cords after dosing TOCP. Furthermore, a significant reduction in dynactin and dynein was observed in cerebral cortexes at several time-points post dosing TOCP. In contrast, no significant changes of kinesin-1 were observed throughout the period of experiment. When given before TOCP administration, PMSF could inhibit TOCP-induced motor protein disruption, while it protected hens against the Delayed Neuropathy. In conclusion, the reduction of the motor proteins, dynein and dynactin, might be associated with the disruption of retrograde neuronal axonal transport in OPIDN.
Ping-an Chang - One of the best experts on this subject based on the ideXlab platform.
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Motor neuron diseases and neurotoxic substances: a possible link?
Chemico-biological interactions, 2009Co-Authors: Ping-an ChangAbstract:The motor neuron diseases (MNDs) are a group of related neurodegenerative diseases that cause the relative selective progressive death of motor neurons. Exploring the molecular mechanisms underlying MND phenotypes has been hampered by their multifactorial nature and high incidence of sporadic cases, although genetic factors are considered to play a considerable role at present. However, environmental factors, especial exposure to neurotoxic substances, could induce neurotoxicity with the same phenotypes of specific MNDs. Organophosphate-Induced Delayed Neuropathy (OPIDN) is a neurodegenerative disorder characterized by ataxia and progression to paralysis, with a concomitant distal axonal degeneration and secondary demyelination of central and peripheral axons. The inhibition and subsequent aging of Neuropathy target esterase (NTE) by organophosphate has been proposed to be the initiating event in OPIDN. NTE is characterized to be a lysophospholipase/phospholipase B mostly in the nervous system to regulate phospholipid homeostasis. Brain-specific deletion of mouse NTE contributes to the behavioral defects characterized by neuronal loss. Recently, mutations in human NTE have also been shown to cause a hereditary spastic paraplegia called NTE-related motor neuron disorder with the same characteristics of OPIDN, which supported the role of NTE abnormalities in OPIDN, and raised the possibility that NTE pathway disturbances contribute to other MNDs. Together with the identified association of paraoxonase polymorphisms with amyotrophic lateral sclerosis, there is a possibility that neurotoxic substances contribute to MND in genetically vulnerable people by gene-environment interactions.
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Identification and characterization of chicken Neuropathy target esterase.
Gene, 2009Co-Authors: Ping-an Chang, Ding-xin Long, Quan Sun, Fang-zhou SongAbstract:Neuropathy target esterase (NTE) was proposed as the initial target during the process of Organophosphate-Induced Delayed Neuropathy (OPIDN) and adult hens are the animal model of OPIDN. However, little has been known about the sequence and characteristics of chicken NTE. Here, we firstly identified the full length cDNA of chicken NTE (cNTE), which contained an open reading frame of 3966 nucleotides encoding 1321 amino acids. Chicken NTE had two distinct regions, one was the regulatory domain (cNTER) and the other was the catalytic domain (cNEST). Over-expression of cNTER in mammalian cells did not show any NTE activity, whereas cNEST had NTE activity. Cells expressing cNTER tagged with green fluorescent protein (GFP) showed accumulation of cNTER-GFP in an endoplasmic reticulum-like localization pattern. In addition, macroautophagy and the proteasome pathways were found to be involved in the degradation of cNTER, but not cNEST. These results first showed that cNTE was an ER-anchored protein and degraded by macroautophagy as well as the proteasome.
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Degradation of Neuropathy target esterase by the macroautophagic lysosomal pathway.
Life sciences, 2008Co-Authors: Ding-xin Long, Ping-an Chang, Yu-jie Liang, Lin YangAbstract:Neuropathy target esterase (NTE) was proposed as the initial target during the process of Organophosphate-Induced Delayed Neuropathy (OPIDN) in humans and some sensitive animals. NTE was recently identified as a novel phospholipase B that is anchored to the cytoplasmic side of the endoplasmic reticulum. However, little is known about the degradation of NTE. In this study, we have investigated the role of the macroautophagic-lysosomal pathway in NTE degradation in neuronal and non-neuronal cells. Macroautophagy inhibitors and activators were used to interrupt the lysosomal pathway, and NTE protein level was followed using western blotting analysis. A fluorescent microscopy assay was used to determine the co-localization of NTE and lysosomes. Western blotting analysis showed that the macroautophagy inhibitors 3-methyladenine and ammonium chloride increased the levels of a heterologously expressed NTE-GFP fusion protein as well as endogenous NTE. Starvation had the opposite effect. The role of macroautophagy in NTE degradation was further supported by the co-localization of exogenous NTE with lysosomes in starved COS7 cells. Furthermore, the contribution of NTE activity and protein domains to the degradation of NTE by macroautophagy was investigated, showing that both the transmembrane and regulatory domains played a role in the degradation of NTE and that the catalytic domain, and thus NTE activity, was not involved. Our findings clearly demonstrate, for the first time, that the macroautophagy/lysosome pathway plays a role in controlling NTE quantity, providing a further understanding of the function of NTE.
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Degradation of Neuropathy target esterase by the macroautophagic lysosomal pathway.
Life Sciences, 2008Co-Authors: Ding-xin Long, Ping-an Chang, Yu-jie Liang, Lin YangAbstract:Abstract Aims Neuropathy target esterase (NTE) was proposed as the initial target during the process of Organophosphate-Induced Delayed Neuropathy (OPIDN) in humans and some sensitive animals. NTE was recently identified as a novel phospholipase B that is anchored to the cytoplasmic side of the endoplasmic reticulum. However, little is known about the degradation of NTE. In this study, we have investigated the role of the macroautophagic-lysosomal pathway in NTE degradation in neuronal and non-neuronal cells. Main methods Macroautophagy inhibitors and activators were used to interrupt the lysosomal pathway, and NTE protein level was followed using western blotting analysis. A fluorescent microscopy assay was used to determine the co-localization of NTE and lysosomes. Key findings Western blotting analysis showed that the macroautophagy inhibitors 3-methyladenine and ammonium chloride increased the levels of a heterologously expressed NTE-GFP fusion protein as well as endogenous NTE. Starvation had the opposite effect. The role of macroautophagy in NTE degradation was further supported by the co-localization of exogenous NTE with lysosomes in starved COS7 cells. Furthermore, the contribution of NTE activity and protein domains to the degradation of NTE by macroautophagy was investigated, showing that both the transmembrane and regulatory domains played a role in the degradation of NTE and that the catalytic domain, and thus NTE activity, was not involved. Significance Our findings clearly demonstrate, for the first time, that the macroautophagy/lysosome pathway plays a role in controlling NTE quantity, providing a further understanding of the function of NTE.
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Molecular cloning and expression analysis of cDNA ends of chicken Neuropathy target esterase.
Chemico-biological interactions, 2007Co-Authors: Ping-an Chang, Quan Sun, Fang-zhou SongAbstract:Neuropathy target esterase (NTE) was proposed as the initial target during the process of Organophosphate-Induced Delayed Neuropathy (OPIDN) in human and some sensitive animals. Adult hens are usually the animal model for experimental studies of OPIDN. However, little is known about the sequence and characteristics of chicken NTE. We report here the cloning of the 5' and 3' cDNA ends of chicken NTE through rapid amplification of cDNA ends (RACE) and their expression profiles in different tissues with northern blotting. The cloned 3' cDNA end of chicken NTE is 801 base pair (bp) in length with an open reading frame (ORF) of 379 bp. It contains a termination codon (TAG) and a 422-nucleotide noncoding sequence with the polyA sequence (GenBank accession no. DQ126678). The chicken NTE 5' cDNA end is 665 bp in length with an ORF of 552 bp. It contains an initiation codon (ATG) and a 113-bp untranslated region (GenBank accession no. DQ126677). The deduced proteins from 5' and 3' cDNA ends have a high degree of homology to humans and mouse NTE at the amino acid level. Chicken NTE is suggested to be a transmembrane protein by the transmembrane helix prediction of the deduced N-terminal sequence. The chicken NTE gene is expressed as a 4.5k b transcript in different tissues, including brain, kidney, liver and testis. Moreover, the mRNA expression of chicken NTE is highest in brain, and the mRNA levels of chicken NTE in testis, kidney and liver are about 75%, 47% and 24% of that in brain, respectively. These results should be helpful in cloning chicken full-length NTE gene.
Paul Glynn - One of the best experts on this subject based on the ideXlab platform.
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Axonal degeneration and Neuropathy target esterase.
Arhiv za higijenu rada i toksikologiju, 2007Co-Authors: Paul GlynnAbstract:This brief review summarizes recent observations which suggest a possible mechanism for Organophosphate-Induced Delayed Neuropathy (OPIDN). Neuropathy target esterase (NTE) has been shown to deacylate endoplasmic reticulum (ER) membrane phosphatidylcholine (PtdCho). Raised levels of PtdCho are present in the brains of Swiss cheese/NTE mutant Drosophila together with abnormal membrane structures, axonal and dendritic degeneration and neural cell loss. Similar vacuolated pathology is found in the brains of mice with brain-specific deletion of the NTE gene and, in old age, these mice show clinical and histopathological features of Neuropathy resembling those in wild-type mice chronically dosed with tri-ortho-cresylphosphate. It is suggested that OPIDN results from the loss of NTE's phospholipase activity which in turn causes ER malfunction and perturbation of axonal transport and glial-axonal interactions.
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inhibition of neurite outgrowth in differentiating mouse n2a neuroblastoma cells by phenyl saligenin phosphate effects on map kinase erk 1 2 activation neurofilament heavy chain phosphorylation and Neuropathy target esterase activity
Biochemical Pharmacology, 2006Co-Authors: Alan J Hargreaves, Paul Glynn, Maxine J Fowler, Magdalini Sachana, John Flaskos, Mary Bountouri, Ian G C Coutts, Wayne Harris, Graham W McleanAbstract:Sub-lethal concentrations of the organophosphate phenyl saligenin phosphate (PSP) inhibited the outgrowth of axon-like processes in differentiating mouse N2a neuroblastoma cells (IC50 2.5 μM). A transient rise in the phosphorylation state of neurofilament heavy chain (NFH) was detected on Western blots of cell extracts treated with 2.5 μM PSP for 4 h compared to untreated controls, as determined by a relative increase in reactivity with monoclonal antibody Ta51 (anti-phosphorylated NFH) compared to N52 (anti-total NFH). However, cross-reactivity of PSP-treated cell extracts was lower than that of untreated controls after 24 h exposure, as indicated by decreased reactivity with both antibodies. Indirect immunofluorescence analysis with these antibodies revealed the appearance of neurofilament aggregates in the cell bodies of treated cells and reduced axonal staining compared to controls. By contrast, there was no significant change in reactivity with anti-a tubulin antibody B512 at either time point. The activation state of the MAP kinase ERK 1/2 increased significantly after PSP treatment compared to controls, particularly at 4 h, as indicated by increased reactivity with monoclonal antibody E-4 (anti-phosphorylated MAP kinase) but not with polyclonal antibody K-23 (anti-total MAP kinase). The observed early changes were concomitant with almost complete inhibition of the activity of Neuropathy target esterase (NTE), one of the proposed early molecular targets in Organophosphate-Induced Delayed Neuropathy (OPIDN).
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A mechanism for Organophosphate-Induced Delayed Neuropathy.
Toxicology letters, 2005Co-Authors: Paul GlynnAbstract:Abstract Neuropathy target esterase (NTE) reacts with those organophosphates, which cause paralysis with swelling and degeneration of distal parts of long nerves in the legs and spinal cord. Cloning of NTE cDNA allowed the generation of constitutive and brain-specific NTE-null mice: the former die by mid-gestation whereas the latter display age-dependent neurodegeneration. NTE is not required by dividing cells but is needed for survival of post-mitotic cells such as placental secondary giant cells and brain neurons. NTE is localised to the cytoplasmic face of the endoplasmic reticulum (ER) and catalyses the deacylation of ER-membrane phosphatidylcholine (PtdCho) to soluble products—glycerophosphocholine and fatty acids. PtdCho is the major phospholipid of eukaryotic cell membranes. Yeast mutants lacking NTE are viable because they maintain membrane homeostasis by reducing the rate of PtdCho synthesis. By contrast, brain neurons and glia in Drosophila NTE-null mutants accumulate PtdCho, have abnormal membrane structures, and finally undergo cell death. In the nervous system of susceptible vertebrates, neuropathic organophosphates will cause a transient loss of NTE activity, putatively disrupting membrane phospholipid homeostasis and ER functions including axonal transport and glial–axonal interaction: the distal parts of long axons will be particularly vulnerable to loss of these support functions.
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NTE: One target protein for different toxic syndromes with distinct mechanisms?
BioEssays : news and reviews in molecular cellular and developmental biology, 2003Co-Authors: Paul GlynnAbstract:Epidemics of Organophosphate-Induced Delayed Neuropathy (OPIDN) have paralysed thousands of people. This syndrome of nerve axon degeneration is initiated by organophosphates which react with Neuropathy target esterase (NTE). Dosing experiments with adult chickens raise the possibility that OPIDN is initiated by a gain-of-function mechanism. By contrast, loss of NTE function by mutation causes massive apoptosis in Drosophila brain. Now, Winrow et al. show that nte(-/-) mice die by mid-gestation, but nte(+/-) mice appear hyperactive and are more sensitive than wild-type mice to a fatal form of OP toxicity. Thus, different toxic syndromes may be initiated via a single target protein.