Exposure of naive murine CD4 + T lymphocytes to superantigen such as staphylococcal enterotoxin B (SEB) induces a strong proliferative response. Prolonged exposure or subsequent restimulation of the responding T cell ...Exposure of naive murine CD4 + T lymphocytes to superantigen such as staphylococcal enterotoxin B (SEB) induces a strong proliferative response. Prolonged exposure or subsequent restimulation of the responding T cell population with SEB leads to the apoptotic events of activation-induced cell death (AICD). The signaling mechanism responsible for the AICD is a target of intensive investigation. However, the precise downstream signaling pathways of SEB-induced AICD remains unclear. Our results here show that the sequential activation of caspase-1/ICE-like and caspase-3/CPP32-like cysteine proteases probably plays a role in the signaling transduction of SEB-induced AICD, but caspase-3/CPP32-like proteases activation does not depend on caspase-1-like proteases activation. Herbimycin A, a specific inhibitor of protein tyrosine kinases, inhibit caspase-3/CPP32-like cysteine proteases activation. However, it does not prevent DNA fragmentation of CD4 + T cells apoptosis induced by SEB. These results indicate that protein tyrosine kinases pathway is probably involved in the signaling transduction of CD4 + T cells apoptosis induced by SEB and “crosstalks” with the pathway of caspase-3/CPP32-like proteases activation.展开更多
Objective To identlfy the member of the caspase famlly proteases involved in Y-radiation-inducedapoptosis in HL-60 cells and to study the expression or the caspase gene in normal, apoptotic cells and in immortal tumor...Objective To identlfy the member of the caspase famlly proteases involved in Y-radiation-inducedapoptosis in HL-60 cells and to study the expression or the caspase gene in normal, apoptotic cells and in immortal tumor cells. Methods By using degenerate oligonucleotide primers encoding the highly conserved peptides that were present in all known caspases, we performed RT-PCR on poly(A)RNA from γ-radiation-induced apoptotic HL-6o cells.Caspase-3 mRNA in apoptotic HL-6o cells and in human tumor cell lines was analyzed by Northern blot. Results The amplified DNA fragment was identiried with caspase-3 cDNA by cloning and sequencing. The Northern blot analysis of caspase-3 mRNA of different human tumor cell lines showed that the caspase-3 gene transcript was more highly expressed in leukemia cell lines and the SH-SY5Y cell line than in HeLa and MCF-7 cells. It was more highly expressed in the radiation-induced apoptotic HL-6o cells than in control HL-6o cells. Conclusion These results indicated that caspase-3 was involved in γ-radiation-induced apoptosis in HL-6o cells. The high level of expression or caspase-3 may aid efforts to understand the insensitivity of some tumor cells to radlation, their inherent ability to survive, and apoptosis展开更多
基金This study was supported by a grant from the Natural Science Foundation of China (No.30070703)
文摘Exposure of naive murine CD4 + T lymphocytes to superantigen such as staphylococcal enterotoxin B (SEB) induces a strong proliferative response. Prolonged exposure or subsequent restimulation of the responding T cell population with SEB leads to the apoptotic events of activation-induced cell death (AICD). The signaling mechanism responsible for the AICD is a target of intensive investigation. However, the precise downstream signaling pathways of SEB-induced AICD remains unclear. Our results here show that the sequential activation of caspase-1/ICE-like and caspase-3/CPP32-like cysteine proteases probably plays a role in the signaling transduction of SEB-induced AICD, but caspase-3/CPP32-like proteases activation does not depend on caspase-1-like proteases activation. Herbimycin A, a specific inhibitor of protein tyrosine kinases, inhibit caspase-3/CPP32-like cysteine proteases activation. However, it does not prevent DNA fragmentation of CD4 + T cells apoptosis induced by SEB. These results indicate that protein tyrosine kinases pathway is probably involved in the signaling transduction of CD4 + T cells apoptosis induced by SEB and “crosstalks” with the pathway of caspase-3/CPP32-like proteases activation.
基金The National Natural Science Foundation Committee(No. 39770823)
文摘Objective To identlfy the member of the caspase famlly proteases involved in Y-radiation-inducedapoptosis in HL-60 cells and to study the expression or the caspase gene in normal, apoptotic cells and in immortal tumor cells. Methods By using degenerate oligonucleotide primers encoding the highly conserved peptides that were present in all known caspases, we performed RT-PCR on poly(A)RNA from γ-radiation-induced apoptotic HL-6o cells.Caspase-3 mRNA in apoptotic HL-6o cells and in human tumor cell lines was analyzed by Northern blot. Results The amplified DNA fragment was identiried with caspase-3 cDNA by cloning and sequencing. The Northern blot analysis of caspase-3 mRNA of different human tumor cell lines showed that the caspase-3 gene transcript was more highly expressed in leukemia cell lines and the SH-SY5Y cell line than in HeLa and MCF-7 cells. It was more highly expressed in the radiation-induced apoptotic HL-6o cells than in control HL-6o cells. Conclusion These results indicated that caspase-3 was involved in γ-radiation-induced apoptosis in HL-6o cells. The high level of expression or caspase-3 may aid efforts to understand the insensitivity of some tumor cells to radlation, their inherent ability to survive, and apoptosis
