Influence Of Cytchrome C On Apoptosis Induced By Baculovirus In Insect Spodoptera Litura Cells

Previous results have shown that an elevation of cytchrome c in the cytosol and a corresponding decrease in the mitochondrial in the apoptotic process induced by Syngrapha falcifera multiple nuclear polyhedrosis virus(SfaMNPV)in Spodoptera litura cell line(SL-1).In this study we further investigate the influence of cytchrome c on apoptosis induced by baculovirus in insect cells.The main results were as follows:Under the flow cytometry assay, the effect of SfaMNPV without and with CSA on mitochondrial membrane potential( Δψ m) was investigated by Rh-123 staining of cells.The Rh-123 fluorescent intensity in SL-1 cells was reduced in time-dependent manner. The effects of SfaMNPV without and with CSA on apoptosis-related potein cytcwas investigated by western blotting.Also, cytcwas released from mitochondrial to cytosolic after induction for 4h.However, when the cells treated by SfaMNPV with 30μ m CSA the mitochondrial membrane potential and cytcin the mitochondrial fraction generally remained stable. The data indicate that the release of cytcrelated with the permeability of mitochondrial membrane.An activation of capase3 in SfaMNPV-induced cells was determined in AC-DEVD-AFC as substrate. At 4h post infection an activity of caspase-3 was measured and gradually increased with time extension. Western blotting assay showed the level of 32KD procaspase-3 of cytosol fraction obtained from apoptotic cells declined in equal time points. However, caspase-3 activity produced a little change during the time period of study when the cells treated by SfaMNPV with 30μm CSA. DNA fragmentation assay did not showed the ladder pattern and DAPI staining confirmed no morphological alterations of cells, when the cells infected with SfaMNPV in presence of 30μm CSA. The results demonstrated CSA inhibited caspase-3 activity and SL-1 cell apoptosis by inhibition release of cytcin SfaMNPV-induced insect cell apoptosis.These data indicate that cytchrome c play a key rolr in SfaMNPV-induced apoptosis in S.litura cells and establish a connection between cytchrome c release and subsequent caspase activation in insect cells.