AIM: To prove anthrax lethal toxin(Le Tx) blocks the mitogen activated protein kinases(MAPKs) activation by degrading the MAPK/ERK kinases(MEKs) to suppress vascular endothelial growth factor(VEGF) secretion.METHODS: ...AIM: To prove anthrax lethal toxin(Le Tx) blocks the mitogen activated protein kinases(MAPKs) activation by degrading the MAPK/ERK kinases(MEKs) to suppress vascular endothelial growth factor(VEGF) secretion.METHODS: Human adult retinal pigmented epithelium(ARPE) cells were cultured and treated with normal glucose, high glucose or high glucose with Le Tx for additional 24, 48 or 72 h for viable cell count. Total RNA from the ARPE was isolated for reverse transcription polymerase chain reaction(RT-PCR). The conditioned medium of ARPE cells treated in different group for 48 h was filtered and diluted to detect the concentration of VEGF by enzyme-linked immunosorbant assays.Evaluate the role of MEK/MAPK pathway in the secretion of VEGF by immunoblotting. RESULTS: In this study, we proved high glucose induced activation of the MAPK extracellular signal-regulated kinase(ERK1/2) and p38 in the ARPE cell line was blocked by anthrax Le Tx. Le Tx also inhibited high glucose induced ARPE cell over proliferation.CONCLUSION: Le Tx suppressed high glucose induced VEGF over secretion in the ARPE cells, mainly through a post-translational mechanism.展开更多
The responses of macrophages to Bacillus anthracis infection are important for the survival of the host,since macrophages are required for the germination of B.anthracis spores in lymph nodes,and macrophage death exac...The responses of macrophages to Bacillus anthracis infection are important for the survival of the host,since macrophages are required for the germination of B.anthracis spores in lymph nodes,and macrophage death exacerbates anthrax lethal toxin(LeTx)-induced organ collapse.To elucidate the mechanism of macrophage cell death induced by LeTx,we performed a genetic screen to search for genes associated with LeTx-induced macrophage cell death.RAW264.7 cells,a macrophage-like cell line sensitive to LeTx-induced death,were randomly mutated and LeTx-resistant mutant clones were selected.AMP deaminase 3(AMPD3),an enzyme that converts AMP to IMP,was identified to be mutated in one of the resistant clones.The requirement of AMPD3 in LeTxinduced cell death of RAW 264.7 cells was confirmed by the restoration of LeTx sensitivity with ectopic reconstitution of AMPD3 expression.AMPD3 deficiency does not affect LeTx entering cells and the cleavage of mitogen-activated protein kinase kinase(MKK)by lethal factor inside cells,but does impair an unknown downstream event that is linked to cell death.Our data provides new information regarding LeTx-induced macrophage death and suggests that there is a key regulatory site downstream of or parallel to MKK cleavage that controls the cell death in LeTx-treated macrophages.展开更多
基金Supported by National Natural Science Foundation of China (No.81170855)
文摘AIM: To prove anthrax lethal toxin(Le Tx) blocks the mitogen activated protein kinases(MAPKs) activation by degrading the MAPK/ERK kinases(MEKs) to suppress vascular endothelial growth factor(VEGF) secretion.METHODS: Human adult retinal pigmented epithelium(ARPE) cells were cultured and treated with normal glucose, high glucose or high glucose with Le Tx for additional 24, 48 or 72 h for viable cell count. Total RNA from the ARPE was isolated for reverse transcription polymerase chain reaction(RT-PCR). The conditioned medium of ARPE cells treated in different group for 48 h was filtered and diluted to detect the concentration of VEGF by enzyme-linked immunosorbant assays.Evaluate the role of MEK/MAPK pathway in the secretion of VEGF by immunoblotting. RESULTS: In this study, we proved high glucose induced activation of the MAPK extracellular signal-regulated kinase(ERK1/2) and p38 in the ARPE cell line was blocked by anthrax Le Tx. Le Tx also inhibited high glucose induced ARPE cell over proliferation.CONCLUSION: Le Tx suppressed high glucose induced VEGF over secretion in the ARPE cells, mainly through a post-translational mechanism.
基金supported by grants from the National Institutes of Health of the USA(Nos.AI41637 and AI68896)the National Natural Science Foundation of China(Grant Nos.30830092,30921005,91029304,and 81061160512)+1 种基金the National Basic Research Program(973 Program)(Grant No.2009CB522200)the Science Planning Program of Fujian Province(Grant No.2009J1010).
文摘The responses of macrophages to Bacillus anthracis infection are important for the survival of the host,since macrophages are required for the germination of B.anthracis spores in lymph nodes,and macrophage death exacerbates anthrax lethal toxin(LeTx)-induced organ collapse.To elucidate the mechanism of macrophage cell death induced by LeTx,we performed a genetic screen to search for genes associated with LeTx-induced macrophage cell death.RAW264.7 cells,a macrophage-like cell line sensitive to LeTx-induced death,were randomly mutated and LeTx-resistant mutant clones were selected.AMP deaminase 3(AMPD3),an enzyme that converts AMP to IMP,was identified to be mutated in one of the resistant clones.The requirement of AMPD3 in LeTxinduced cell death of RAW 264.7 cells was confirmed by the restoration of LeTx sensitivity with ectopic reconstitution of AMPD3 expression.AMPD3 deficiency does not affect LeTx entering cells and the cleavage of mitogen-activated protein kinase kinase(MKK)by lethal factor inside cells,but does impair an unknown downstream event that is linked to cell death.Our data provides new information regarding LeTx-induced macrophage death and suggests that there is a key regulatory site downstream of or parallel to MKK cleavage that controls the cell death in LeTx-treated macrophages.
