AIM: To verify whether P-glycoprotein (P-gp) could induce cell resistance to apoptosis by inhibiting caspase-8 and caspase-3.METHODS: Human KB cells, either drug-sensitive or with multidrug resistance (MDR) phenotype ...AIM: To verify whether P-glycoprotein (P-gp) could induce cell resistance to apoptosis by inhibiting caspase-8 and caspase-3.METHODS: Human KB cells, either drug-sensitive or with multidrug resistance (MDR) phenotype caused by overexpression of P-gp (KBv200 cells), were treated with anti-Fas (CH-11 monoclonal antibody) to induce apoptosis.Cytotoxicity was detected by MTT assay. Symptoms of cell death were assessed by morphological observation after Hoechst33258 staining, activation of caspase-8 and caspase-3 was measured by Western blotting.RESULTS: Compared with KB cells, the resistance of KBv200 cells to VCR (vincristine) was about 51-fold higher.Anti-Fas (CH-11) induced cytotoxicity and apoptosis in both sensitive KB cells and MDR phenotype KBv200cells. The IC50 of CH-11 in KB cells was similar to that in KBv200 cells. CH-11 induced similar apoptotic rates in both KB cells and KBv200 cells, which could be classified as caspase-dependent apoptotic pathway. Verapamil (VRP) did not affect CH-11-mediated apoptosis in KBv200 cells.CONCLUSION: Expression of P-glycoprotein does not induce resistance to caspase-8 and -3 activation or antiFas-induced cell apoptosis.展开更多
Two-state folding and down-hill folding are two kinds of protein folding dynamics for small single domain proteins.Here we apply molecular dynamics(MD)simulation to the two-state protein GB1 and down-hill folding prot...Two-state folding and down-hill folding are two kinds of protein folding dynamics for small single domain proteins.Here we apply molecular dynamics(MD)simulation to the two-state protein GB1 and down-hill folding protein gpW to reveal the relationship of their free energy landscape and folding/unfolding dynamics.Results from the steered MD simulations show that gpW is much less mechanical resistant than GB1,and the unfolding process of gpW has more variability than that of GB1 according to their force-extension curves.The potential of mean force(PMF)of GB1 and gpW obtained by the umbrella sampling simulations shows apparent difference:PMF of GB1 along the coordinate of extension exhibits a kink transition point where the slope of PMF drops suddenly,while PMF of gpW increases with extension smoothly,which are consistent with two-state folding dynamics of GB1 and downhill folding dynamics of gpW,respectively.Our results provide insight to understand the fundamental mechanism of different folding dynamics of twostate proteins and downhill folding proteins.展开更多
基金Supported by the Natural Science Foundation of Guangdong Province,No.021813National Natural Science Foundation of China,No.30371659
文摘AIM: To verify whether P-glycoprotein (P-gp) could induce cell resistance to apoptosis by inhibiting caspase-8 and caspase-3.METHODS: Human KB cells, either drug-sensitive or with multidrug resistance (MDR) phenotype caused by overexpression of P-gp (KBv200 cells), were treated with anti-Fas (CH-11 monoclonal antibody) to induce apoptosis.Cytotoxicity was detected by MTT assay. Symptoms of cell death were assessed by morphological observation after Hoechst33258 staining, activation of caspase-8 and caspase-3 was measured by Western blotting.RESULTS: Compared with KB cells, the resistance of KBv200 cells to VCR (vincristine) was about 51-fold higher.Anti-Fas (CH-11) induced cytotoxicity and apoptosis in both sensitive KB cells and MDR phenotype KBv200cells. The IC50 of CH-11 in KB cells was similar to that in KBv200 cells. CH-11 induced similar apoptotic rates in both KB cells and KBv200 cells, which could be classified as caspase-dependent apoptotic pathway. Verapamil (VRP) did not affect CH-11-mediated apoptosis in KBv200 cells.CONCLUSION: Expression of P-glycoprotein does not induce resistance to caspase-8 and -3 activation or antiFas-induced cell apoptosis.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874309,11474237,and 11574310)the 111 Project,China(Grant No.B16029).
文摘Two-state folding and down-hill folding are two kinds of protein folding dynamics for small single domain proteins.Here we apply molecular dynamics(MD)simulation to the two-state protein GB1 and down-hill folding protein gpW to reveal the relationship of their free energy landscape and folding/unfolding dynamics.Results from the steered MD simulations show that gpW is much less mechanical resistant than GB1,and the unfolding process of gpW has more variability than that of GB1 according to their force-extension curves.The potential of mean force(PMF)of GB1 and gpW obtained by the umbrella sampling simulations shows apparent difference:PMF of GB1 along the coordinate of extension exhibits a kink transition point where the slope of PMF drops suddenly,while PMF of gpW increases with extension smoothly,which are consistent with two-state folding dynamics of GB1 and downhill folding dynamics of gpW,respectively.Our results provide insight to understand the fundamental mechanism of different folding dynamics of twostate proteins and downhill folding proteins.
