Interleukin-4 （IL-4） promotes lymphocyte survival and protects primary lymphomas from apoptosls. Previous studies reported differential requirements for the signal transducer and activator of transcription 6 （STAT6...Interleukin-4 （IL-4） promotes lymphocyte survival and protects primary lymphomas from apoptosls. Previous studies reported differential requirements for the signal transducer and activator of transcription 6 （STAT6） and IRS2/phosphati-dylinositol 3 kinase （PI-3K） signaling pathways in mediating the IL-4-induced protection from Fas-mediated apoptosis. In this study, we characterized IL-4-activated signals that suppress anti-IgM-mediated apoptosis and growth arrest of CH31, a model B-cell lymphoma line. In CH31, anti-IgM treatment leads to the loss of mitochondrial membrane poten-tial, phospho-Akt, phospho-CDK2, and c-myc protein. These losses are followed by massive induction of p27^Kip1 protein expression, cell cycle arrest, and apoptosis. Strikingly, IL-4 treatment prevented or reversed these changes. Furthermore, IL-4 suppressed the activation of caspases 9 and 3, and, in contrast to previous reports, induced the phosphorylation （de-activation） of BAD. IL-4 treatment also induced expression of BclxL, a STAT6-dependent gene. Pharmacologic inhibitors and dominant inhibitory forms of PI-3K and Akt abrogated the anti-apoptotic function of IL-4. These results suggest that the IL-4 receptor activates several signaling pathways, with the Akt pathway playing a major role in suppression of the apoptotic program activated by anti-IgM.展开更多
In order to explore the expression of PI-3K in T lymphocytes of asthmatic rats and the relationship between PI-3K and activation of T lymphocytes, 24 Wistar rats were randomly divided into 4 groups： normal control gr...In order to explore the expression of PI-3K in T lymphocytes of asthmatic rats and the relationship between PI-3K and activation of T lymphocytes, 24 Wistar rats were randomly divided into 4 groups： normal control group, asthmatic one-week group, asthmatic two-week group and asthmatic four-week group. T cells were purified from blood of each rat and the expression of PI-3K was observed by immunocytochemical fluorescence staining, the serniquantitative fluorescence intensity was measured by HPIAS-2000 analytic software, and the expression of IL-4 in supernatants was detected by ELISA. The results showed that the fluorescence intensity of T lymphocytes in asthmatic groups was significantly higher than that in normal control （P〈0.001）, indicating that the expression of PI-3K in T lymphocytes of asthmatic rats was significantly higher than that in those of normal controls, and the difference between acute and chronic stage asthmatic groups was significant （P〈0.05）. The expression levels of IL-4 protein in supernatants of asthmatic T lymphocytes were significantly higher than those in the normal controls （P〈0.05）. There was a significant positive correlation between the expression of PI-3K in T lymphocytes and the IL-4 protein expression in supernatants （r=0.583, P〈0.01）. It was suggested that PI-3K signal pathway may participate in the processes of activation and other cytological effects of asthmatic T lymphocytes, thus may play an important roles in the pathogenesis of asthma.展开更多
文摘Interleukin-4 （IL-4） promotes lymphocyte survival and protects primary lymphomas from apoptosls. Previous studies reported differential requirements for the signal transducer and activator of transcription 6 （STAT6） and IRS2/phosphati-dylinositol 3 kinase （PI-3K） signaling pathways in mediating the IL-4-induced protection from Fas-mediated apoptosis. In this study, we characterized IL-4-activated signals that suppress anti-IgM-mediated apoptosis and growth arrest of CH31, a model B-cell lymphoma line. In CH31, anti-IgM treatment leads to the loss of mitochondrial membrane poten-tial, phospho-Akt, phospho-CDK2, and c-myc protein. These losses are followed by massive induction of p27^Kip1 protein expression, cell cycle arrest, and apoptosis. Strikingly, IL-4 treatment prevented or reversed these changes. Furthermore, IL-4 suppressed the activation of caspases 9 and 3, and, in contrast to previous reports, induced the phosphorylation （de-activation） of BAD. IL-4 treatment also induced expression of BclxL, a STAT6-dependent gene. Pharmacologic inhibitors and dominant inhibitory forms of PI-3K and Akt abrogated the anti-apoptotic function of IL-4. These results suggest that the IL-4 receptor activates several signaling pathways, with the Akt pathway playing a major role in suppression of the apoptotic program activated by anti-IgM.
文摘In order to explore the expression of PI-3K in T lymphocytes of asthmatic rats and the relationship between PI-3K and activation of T lymphocytes, 24 Wistar rats were randomly divided into 4 groups： normal control group, asthmatic one-week group, asthmatic two-week group and asthmatic four-week group. T cells were purified from blood of each rat and the expression of PI-3K was observed by immunocytochemical fluorescence staining, the serniquantitative fluorescence intensity was measured by HPIAS-2000 analytic software, and the expression of IL-4 in supernatants was detected by ELISA. The results showed that the fluorescence intensity of T lymphocytes in asthmatic groups was significantly higher than that in normal control （P〈0.001）, indicating that the expression of PI-3K in T lymphocytes of asthmatic rats was significantly higher than that in those of normal controls, and the difference between acute and chronic stage asthmatic groups was significant （P〈0.05）. The expression levels of IL-4 protein in supernatants of asthmatic T lymphocytes were significantly higher than those in the normal controls （P〈0.05）. There was a significant positive correlation between the expression of PI-3K in T lymphocytes and the IL-4 protein expression in supernatants （r=0.583, P〈0.01）. It was suggested that PI-3K signal pathway may participate in the processes of activation and other cytological effects of asthmatic T lymphocytes, thus may play an important roles in the pathogenesis of asthma.
