AIM: To investigate the roles of PLCγ2 and PKCα in TPA-induced apoptosis of gastric cancer cells.METHODS: Human gastric cancer cell line MGC80-3 was used. Protein expression levels of PLCγ2 and PKCα were detected ...AIM: To investigate the roles of PLCγ2 and PKCα in TPA-induced apoptosis of gastric cancer cells.METHODS: Human gastric cancer cell line MGC80-3 was used. Protein expression levels of PLCγ2 and PKCα were detected by Western blot. Protein localization of PLCγ2 and PKCα was shown by immunofluoscence analysis under laserscanning confocal microscope. Apoptotic morphology was observed by DAPI fluorescence staining, and apoptotic index was counted among 1 000 cells randomly.RESULTS: Treatment of gastric cancer cells MGC80-3 with TPA not only up-regulated expression of PLC-γ2 protein,but also induced PLC-γ2 translocation from the cytoplasm to the nucleus. However, this process was not directly associated with apoptosis induction. Further investigation showed that PKCa translocation from the cytoplasm to the nucleus was correlated with initiation of apoptosis. To explore the inevitable linkage between PLC-γ2 and PKCα during apoptosis induction,PLC inhibitor U73122 was used to block PLC-γ2 translocation,in which neither stimulating PKCα translocation nor inducing apoptosis occurred in MGC80-3 cells. However, when U73122treated cells were exposed to TPA, not only PLC-γ2, but also PKCα was redistributed. On the other hand, when cells were treated with PKC inhibitor alone, PLC-γ2 protein was still located in the cytoplasm. However, redistribution of PLC-γ2 protein occurred in the presence of TPA, no matter whether PKC inhibitor existed or not.CONCLUSION: PLC-γ2 translocation is critical in transmitting TPA signal to its downstream molecule PKCα. As an effector,PKCα directly promotes apoptosis of MGC80-3 cells.Therefore, protein translocation of PLCγ2 and PKCα is critical event in the process of apoptosis induction.展开更多
Objective To investigate the inhibitory mechanism of emodin on lipopolysaccharide (LPS)-induced nitric oxide (NO) generation in rat peritoneal macrophages. Methods NO production and iNOS expression were measured throu...Objective To investigate the inhibitory mechanism of emodin on lipopolysaccharide (LPS)-induced nitric oxide (NO) generation in rat peritoneal macrophages. Methods NO production and iNOS expression were measured through nitrite assay and Western blotting assay, respectively. NF-κB activity and nuclei P65 expression were estimated by dual-luciferase and Western blotting assay, respectively. Intracellular free Ca2+ ([Ca2+]i) was detected using the ratiometric fluorescent calcium indicator dye, Fura-2, and a microspectrofluorometer. PLC-γ phosporylation was analyzed by Western blotting assay. Results First, emodin was found playing active roles in suppressing LPS-induced NF-κB activation in rat peritoneal macrophages. Second, emodin down-regulated transient [Ca2+]i and could increase in NF-κB upstream signal. Finally, emodin suppressed phosphorylation of PLC-γ by LPS stimulation in the upstream of [Ca2+]i. Conclusion Suppression of PLC-γ phosphorylation is involved in emodin inhibiting NO generation by LPS stimulation in rat peritoneal macrophages.展开更多
基金the National Natural Science Foundation of China(No.30170477)the National Outstanding Youth Science Foundation of China(No.39825502)the Natural Science Foundation of Fujian Province(C0110004)
文摘AIM: To investigate the roles of PLCγ2 and PKCα in TPA-induced apoptosis of gastric cancer cells.METHODS: Human gastric cancer cell line MGC80-3 was used. Protein expression levels of PLCγ2 and PKCα were detected by Western blot. Protein localization of PLCγ2 and PKCα was shown by immunofluoscence analysis under laserscanning confocal microscope. Apoptotic morphology was observed by DAPI fluorescence staining, and apoptotic index was counted among 1 000 cells randomly.RESULTS: Treatment of gastric cancer cells MGC80-3 with TPA not only up-regulated expression of PLC-γ2 protein,but also induced PLC-γ2 translocation from the cytoplasm to the nucleus. However, this process was not directly associated with apoptosis induction. Further investigation showed that PKCa translocation from the cytoplasm to the nucleus was correlated with initiation of apoptosis. To explore the inevitable linkage between PLC-γ2 and PKCα during apoptosis induction,PLC inhibitor U73122 was used to block PLC-γ2 translocation,in which neither stimulating PKCα translocation nor inducing apoptosis occurred in MGC80-3 cells. However, when U73122treated cells were exposed to TPA, not only PLC-γ2, but also PKCα was redistributed. On the other hand, when cells were treated with PKC inhibitor alone, PLC-γ2 protein was still located in the cytoplasm. However, redistribution of PLC-γ2 protein occurred in the presence of TPA, no matter whether PKC inhibitor existed or not.CONCLUSION: PLC-γ2 translocation is critical in transmitting TPA signal to its downstream molecule PKCα. As an effector,PKCα directly promotes apoptosis of MGC80-3 cells.Therefore, protein translocation of PLCγ2 and PKCα is critical event in the process of apoptosis induction.
文摘Objective To investigate the inhibitory mechanism of emodin on lipopolysaccharide (LPS)-induced nitric oxide (NO) generation in rat peritoneal macrophages. Methods NO production and iNOS expression were measured through nitrite assay and Western blotting assay, respectively. NF-κB activity and nuclei P65 expression were estimated by dual-luciferase and Western blotting assay, respectively. Intracellular free Ca2+ ([Ca2+]i) was detected using the ratiometric fluorescent calcium indicator dye, Fura-2, and a microspectrofluorometer. PLC-γ phosporylation was analyzed by Western blotting assay. Results First, emodin was found playing active roles in suppressing LPS-induced NF-κB activation in rat peritoneal macrophages. Second, emodin down-regulated transient [Ca2+]i and could increase in NF-κB upstream signal. Finally, emodin suppressed phosphorylation of PLC-γ by LPS stimulation in the upstream of [Ca2+]i. Conclusion Suppression of PLC-γ phosphorylation is involved in emodin inhibiting NO generation by LPS stimulation in rat peritoneal macrophages.
