Unlike oleate and linoleate, palmitate induced mitochondrialapoptosis in GL15 glioblastoma cells. Decrease in membranepotential in a subpopulation of mitochondria of palmitate-treatedcells was revealed using the 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide probe. Thediminished ability to reduce a tetrazolium salt indicated animpairment of mitochondrial function. Up to 50% cytochrome c(cyt c) was detached from the inner mitochondrial membraneand released outside mitochondria in palmitate-treated cells,whereas no release was detected after oleate and linoleatetreatments. Cyt c release into the cytosol was followed bycaspase 3 activation. Released cyt c and caspase 3 activitywere not affected by neutral and acid sphingomyelinaseinhibitors and by the inhibitor of serine palmitoyltransferasecycloserine, indicating that apoptosis was independent of theceramide pathway, nor the mitochondrial pro-apoptotic AIF orBcl-2/Bax factors appeared to be involved in the effect. Utilizationof palmitate by GL15 cells altered phospholipid composition.Cardiolipin (CL), the lipid involved in cyt c interaction withthe inner mitochondrial membrane, was decreased and highlysaturated. This produced an imbalance in hydrophilic/hydrophobicinteractions underlying the anchorage of cyt c, byweakening the hydrophobic component and facilitatingdetachment of the protein and activation of downstream processes.The primary role of CL was explored by supplying GL15with exogenous CL through a fusion process of CL liposomeswith cell plasma membrane. Fused CL moved to mitochondria,as detected by nonylacridine orange probe. Enrichment ofmitochondrial membranes with CL prior to palmitate treatmentof cells caused decreased cyt c release and caspase 3 activity.
Loss of cardiolipin in palmitate-treated GL15 glioblastoma cells favors cytochrome c release from mitochondria leading to apoptosis
SCIACCALUGA, Miriam;
2008-01-01
Abstract
Unlike oleate and linoleate, palmitate induced mitochondrialapoptosis in GL15 glioblastoma cells. Decrease in membranepotential in a subpopulation of mitochondria of palmitate-treatedcells was revealed using the 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide probe. Thediminished ability to reduce a tetrazolium salt indicated animpairment of mitochondrial function. Up to 50% cytochrome c(cyt c) was detached from the inner mitochondrial membraneand released outside mitochondria in palmitate-treated cells,whereas no release was detected after oleate and linoleatetreatments. Cyt c release into the cytosol was followed bycaspase 3 activation. Released cyt c and caspase 3 activitywere not affected by neutral and acid sphingomyelinaseinhibitors and by the inhibitor of serine palmitoyltransferasecycloserine, indicating that apoptosis was independent of theceramide pathway, nor the mitochondrial pro-apoptotic AIF orBcl-2/Bax factors appeared to be involved in the effect. Utilizationof palmitate by GL15 cells altered phospholipid composition.Cardiolipin (CL), the lipid involved in cyt c interaction withthe inner mitochondrial membrane, was decreased and highlysaturated. This produced an imbalance in hydrophilic/hydrophobicinteractions underlying the anchorage of cyt c, byweakening the hydrophobic component and facilitatingdetachment of the protein and activation of downstream processes.The primary role of CL was explored by supplying GL15with exogenous CL through a fusion process of CL liposomeswith cell plasma membrane. Fused CL moved to mitochondria,as detected by nonylacridine orange probe. Enrichment ofmitochondrial membranes with CL prior to palmitate treatmentof cells caused decreased cyt c release and caspase 3 activity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
