The effects of a novel immunosuppressive agent FTY720 on proliferation inhibition and apoptosis of acute leukemia cell lines HL 60 and U937, and the role of extracelluar regulated protein kinase (ERK) in the course o...The effects of a novel immunosuppressive agent FTY720 on proliferation inhibition and apoptosis of acute leukemia cell lines HL 60 and U937, and the role of extracelluar regulated protein kinase (ERK) in the course of proliferation inhibition and apoptosis induced by FTY720 were studied. The proliferation inhibition rate of HL 60 and U937 cells by various concentrations of FTY720 was detected by MTT assay. Cell apoptosis was detected by DNA fragment analysis and flow cytometry. The phosphorylated ERK1/2 protein expression was observed by Western blotting. The change of intracellular distribution of ERK1/2 protein was identified by SP immunohistochemical staining. The results showed that FTY720 could inhibit the growth of HL 60 and U937 cells effectively in a dose dependent manner. After incubation with FTY720 for 24 h, apoptosis was observed in HL 60 and U937 cells. The intracellular expression of phosphorylated ERK1/2 protein was also down regulated and the distribution of ERK1/2 protein in cell nuclear was reduced during FTY720 induced apoptosis. So, that FTY720 inhibited ERK1/2 phosphorylation might mediate the role of FTY720 induced apoptosis and proliferation inhibition of leukemia cells.展开更多
In order to investigate the regulative function of telom erase and phosphorylated (acti- vated) extracelluar regulated protein kinase (ERK) 1and 2 in the leukemic cell lines HL - 6 0 and K5 6 2 proliferation inhibit...In order to investigate the regulative function of telom erase and phosphorylated (acti- vated) extracelluar regulated protein kinase (ERK) 1and 2 in the leukemic cell lines HL - 6 0 and K5 6 2 proliferation inhibition and apoptosis,three chemotherapeutic drugs Harringtonine(HRT) , Vincristine(VCR) and Etoposide(Vp16 ) were selected as inducers.The proliferation inhibition rate was detected by MTT m ethod,the cell cycle and cell apoptosis was analyzed by flow cytometry and the telom erase activity was detected by the telom eric repeat am plification protocol(TRAP) assay and bioluminescence analysis method.The phosphorylated ERK 1/ 2 protein expression was detected by western blot method.The results showed that HRT,VCR and Vp16 could inhibit cell proliferation,induce apoptosis,inhibit telomerase activity and down- regulate the protein expres- sion of phosphorylated ERK.Itwas suggested that ERK signal transduction pathway was involved in the down- regulation of telomerase activity and the onset of apoptosis in the leukem ic cells treat- ed by HRT,VCR and Vp16 .展开更多
Sinorhizobium meliloti nifA is important in fixing nitrogen during symbiosis. A nifA null mutant induces small white invalid nodules in the roots of host plant. The additional phenotypic alterations associated with th...Sinorhizobium meliloti nifA is important in fixing nitrogen during symbiosis. A nifA null mutant induces small white invalid nodules in the roots of host plant. The additional phenotypic alterations associated with the disruption of the nifA gene are reported in this study. Under a free-living state, S. meliloti nifA mutant reduces its ability to swarm on a half-solid plate. Interestingly, the AHL （Acylhomoserine lactones） contents in the nifA mutant are lower than that of the wild type during the lag phase, whereas it is reversed in the logarithmic and stationary phases. Quantitative spectrophotometric assays reveal that the total amount of extracellular proteins of the nifA mutant are lower than that of the wild type. In addition, the mutant abolishes its nodulation competitive ability during symbiosis. These findings indicate that NifA plays a regulatory role in multiple cellular processes in S. meliloti.展开更多
文摘The effects of a novel immunosuppressive agent FTY720 on proliferation inhibition and apoptosis of acute leukemia cell lines HL 60 and U937, and the role of extracelluar regulated protein kinase (ERK) in the course of proliferation inhibition and apoptosis induced by FTY720 were studied. The proliferation inhibition rate of HL 60 and U937 cells by various concentrations of FTY720 was detected by MTT assay. Cell apoptosis was detected by DNA fragment analysis and flow cytometry. The phosphorylated ERK1/2 protein expression was observed by Western blotting. The change of intracellular distribution of ERK1/2 protein was identified by SP immunohistochemical staining. The results showed that FTY720 could inhibit the growth of HL 60 and U937 cells effectively in a dose dependent manner. After incubation with FTY720 for 24 h, apoptosis was observed in HL 60 and U937 cells. The intracellular expression of phosphorylated ERK1/2 protein was also down regulated and the distribution of ERK1/2 protein in cell nuclear was reduced during FTY720 induced apoptosis. So, that FTY720 inhibited ERK1/2 phosphorylation might mediate the role of FTY720 induced apoptosis and proliferation inhibition of leukemia cells.
文摘In order to investigate the regulative function of telom erase and phosphorylated (acti- vated) extracelluar regulated protein kinase (ERK) 1and 2 in the leukemic cell lines HL - 6 0 and K5 6 2 proliferation inhibition and apoptosis,three chemotherapeutic drugs Harringtonine(HRT) , Vincristine(VCR) and Etoposide(Vp16 ) were selected as inducers.The proliferation inhibition rate was detected by MTT m ethod,the cell cycle and cell apoptosis was analyzed by flow cytometry and the telom erase activity was detected by the telom eric repeat am plification protocol(TRAP) assay and bioluminescence analysis method.The phosphorylated ERK 1/ 2 protein expression was detected by western blot method.The results showed that HRT,VCR and Vp16 could inhibit cell proliferation,induce apoptosis,inhibit telomerase activity and down- regulate the protein expres- sion of phosphorylated ERK.Itwas suggested that ERK signal transduction pathway was involved in the down- regulation of telomerase activity and the onset of apoptosis in the leukem ic cells treat- ed by HRT,VCR and Vp16 .
基金This work was supported by the National Grand Fundamental Research 973 Project (No. 2001CB108901)National Science Foundation of China (No. 30400267).
文摘Sinorhizobium meliloti nifA is important in fixing nitrogen during symbiosis. A nifA null mutant induces small white invalid nodules in the roots of host plant. The additional phenotypic alterations associated with the disruption of the nifA gene are reported in this study. Under a free-living state, S. meliloti nifA mutant reduces its ability to swarm on a half-solid plate. Interestingly, the AHL （Acylhomoserine lactones） contents in the nifA mutant are lower than that of the wild type during the lag phase, whereas it is reversed in the logarithmic and stationary phases. Quantitative spectrophotometric assays reveal that the total amount of extracellular proteins of the nifA mutant are lower than that of the wild type. In addition, the mutant abolishes its nodulation competitive ability during symbiosis. These findings indicate that NifA plays a regulatory role in multiple cellular processes in S. meliloti.
