lntracellular redox homeostasis plays a critical role in determining tumor cells' sensitivity to drug-induced apoptosis. Here we investigated the role of thioredoxin-1 (TRX1), a key component of redox regulation, i...lntracellular redox homeostasis plays a critical role in determining tumor cells' sensitivity to drug-induced apoptosis. Here we investigated the role of thioredoxin-1 (TRX1), a key component of redox regulation, in arsenic trioxide (AS2O3)-induced apoptosis. Over-expression of wild-type TRX1 in HepG2 cells led to the inhibition of As2O3-induced cytochrome c (cyto c) release, caspase activation and apoptosis, and down-regulation of TRX1 expression by RNAi sensitized HepG2 cells to As2O3-induced apoptosis. Interestingly, mutation of the active site of TRX1 from Cys^32/35 to Ser^32/35 converted this molecule from an apoptotic protector to an apoptotic promoter. In an effort to understand the mechanisms of this conversion, we used isolated mitochondria from mouse liver and found that recombinant wild-type TRX1 could protect mitochondria from the apoptotic changes. In contrast, the mutant form of TRX1 alone elicited mitochondria-related apoptotic changes, including the mitochondrial permeability transition pore (mPTP) opening, loss of mitochondrial membrane potential, and cyto c release from mitochondria. These apoptotic effects were inhibited by cyclosporine A (CsA), indicating that mutant TRX1 targeted to mPTP. Alteration of TRX1 from its reduced form to oxidized form in vivo by 2,4-dinitrochlorobenzene (DNCB), a specific inhibitor ofTRX reductase, also sensitized HepG2 cells to As203-induced apoptosis. These data suggest that TRX1 plays a central role in regulating apoptosis by blocking cyto c release, and inactivation of TRX1 by either mutation or oxidization of the active site cysteines may sensitize tumor cells to As2O3-induced apoptosis.展开更多
Objective:Alzheimer’s disease( AD) is the most common neurodegenerative disorder which is characterized by amyloid-β( Aβ) aggradation in the brain and impairment of cognitive function. Thioredoxin-1( Trx-1) is a re...Objective:Alzheimer’s disease( AD) is the most common neurodegenerative disorder which is characterized by amyloid-β( Aβ) aggradation in the brain and impairment of cognitive function. Thioredoxin-1( Trx-1) is a redox regulating protein,and plays roles in resisting the oxidative stress and protecting neurons. Our previous study found that Trx-1 improved the cognitive function of Parkinson’s Disease( PD) mice. Geranylgeranylacetone( GGA) is an antiulcer drug and induces the expression of Trx-1 in vivo and in vitro. However,whether Trx-1 improves cognitive functions in mice of APP/PS1 or GGA protects SH-SY5 Y cells from cytotoxicity induced by Aβ is still unknown. The objective of present is to investigate the roles of Trx-1 and GGA in inhibiting neurotoxicity of Aβ. Methods:We used MTT assay to test the cell viability induced by Aβ(25-35) and western blot to detect the expression of Trx-1 in SH-SY5 Y cells. Trx-1 overexpression transgenic mice were hybridized with APP/PS1 transgenic mice to get control,Trx-1,Tx-1/APP/PS1 and APP/PS1 mice. Then we used Morris water maze,high plus maze and object recognition test to detect the cognitive function of different kinds of mice. We also used RT-PCR and western blot to test the mRNA level and expression of Trx-1,APP,PS1 and Aβ. Results:In our present study,we demonstrated that Aβ(25-35) decreased the cell viability and the expression of Trx-1 in SH-SY5 Y cells. The cell viability and the expression of Trx-1 were reversed by GGA. Our results showed that the escape latency in APP/PS1 mice was longer when compared with the Trx-1/APP/PS1 mice in Morris water maze and high plus maze. Whereas navigational experiments in Morris water maze result showed that the total number of crossings and the percentage of time spent in the target quadrant were significantly decreased in APP/PS1 mice when compared to Trx-1/APP/PS1 mice. Object recognition test the discrimination index was significantly decreased in APP/PS1 mice when compared with Trx-1/APP/PS1 mice. The mRNA levels and the expression of APP,PS1 and Aβ were decreased in Trx-1/APP/PS1 mice when compared to APP/PS1 mice. Conclusion:These results suggest that GGA protects SH-SY5 Y cells from cytotoxicity induced by Aβ(25-35) and restored the expression of Trx-1. Trx-1 overexpression improves cognitive function of APP/PS1 mice. Trx-1 may be a potential therapeutic target for the clinical management of AD.展开更多
文摘lntracellular redox homeostasis plays a critical role in determining tumor cells' sensitivity to drug-induced apoptosis. Here we investigated the role of thioredoxin-1 (TRX1), a key component of redox regulation, in arsenic trioxide (AS2O3)-induced apoptosis. Over-expression of wild-type TRX1 in HepG2 cells led to the inhibition of As2O3-induced cytochrome c (cyto c) release, caspase activation and apoptosis, and down-regulation of TRX1 expression by RNAi sensitized HepG2 cells to As2O3-induced apoptosis. Interestingly, mutation of the active site of TRX1 from Cys^32/35 to Ser^32/35 converted this molecule from an apoptotic protector to an apoptotic promoter. In an effort to understand the mechanisms of this conversion, we used isolated mitochondria from mouse liver and found that recombinant wild-type TRX1 could protect mitochondria from the apoptotic changes. In contrast, the mutant form of TRX1 alone elicited mitochondria-related apoptotic changes, including the mitochondrial permeability transition pore (mPTP) opening, loss of mitochondrial membrane potential, and cyto c release from mitochondria. These apoptotic effects were inhibited by cyclosporine A (CsA), indicating that mutant TRX1 targeted to mPTP. Alteration of TRX1 from its reduced form to oxidized form in vivo by 2,4-dinitrochlorobenzene (DNCB), a specific inhibitor ofTRX reductase, also sensitized HepG2 cells to As203-induced apoptosis. These data suggest that TRX1 plays a central role in regulating apoptosis by blocking cyto c release, and inactivation of TRX1 by either mutation or oxidization of the active site cysteines may sensitize tumor cells to As2O3-induced apoptosis.
文摘Objective:Alzheimer’s disease( AD) is the most common neurodegenerative disorder which is characterized by amyloid-β( Aβ) aggradation in the brain and impairment of cognitive function. Thioredoxin-1( Trx-1) is a redox regulating protein,and plays roles in resisting the oxidative stress and protecting neurons. Our previous study found that Trx-1 improved the cognitive function of Parkinson’s Disease( PD) mice. Geranylgeranylacetone( GGA) is an antiulcer drug and induces the expression of Trx-1 in vivo and in vitro. However,whether Trx-1 improves cognitive functions in mice of APP/PS1 or GGA protects SH-SY5 Y cells from cytotoxicity induced by Aβ is still unknown. The objective of present is to investigate the roles of Trx-1 and GGA in inhibiting neurotoxicity of Aβ. Methods:We used MTT assay to test the cell viability induced by Aβ(25-35) and western blot to detect the expression of Trx-1 in SH-SY5 Y cells. Trx-1 overexpression transgenic mice were hybridized with APP/PS1 transgenic mice to get control,Trx-1,Tx-1/APP/PS1 and APP/PS1 mice. Then we used Morris water maze,high plus maze and object recognition test to detect the cognitive function of different kinds of mice. We also used RT-PCR and western blot to test the mRNA level and expression of Trx-1,APP,PS1 and Aβ. Results:In our present study,we demonstrated that Aβ(25-35) decreased the cell viability and the expression of Trx-1 in SH-SY5 Y cells. The cell viability and the expression of Trx-1 were reversed by GGA. Our results showed that the escape latency in APP/PS1 mice was longer when compared with the Trx-1/APP/PS1 mice in Morris water maze and high plus maze. Whereas navigational experiments in Morris water maze result showed that the total number of crossings and the percentage of time spent in the target quadrant were significantly decreased in APP/PS1 mice when compared to Trx-1/APP/PS1 mice. Object recognition test the discrimination index was significantly decreased in APP/PS1 mice when compared with Trx-1/APP/PS1 mice. The mRNA levels and the expression of APP,PS1 and Aβ were decreased in Trx-1/APP/PS1 mice when compared to APP/PS1 mice. Conclusion:These results suggest that GGA protects SH-SY5 Y cells from cytotoxicity induced by Aβ(25-35) and restored the expression of Trx-1. Trx-1 overexpression improves cognitive function of APP/PS1 mice. Trx-1 may be a potential therapeutic target for the clinical management of AD.