Cathepsin D mediates cytochrome c release and caspase activation in human fibroblast apoptosis induced by staurosporine.
There is increasing evidence that proteases other than caspases, for example, the lysosomal cathepsins B, D and L, are involved in apoptotic cell death. In the present study, we present data that suggest a role for cathepsin D in staurosporine-induced apoptosis in human foreskin fibroblasts. Cathepsin D and cytochrome c were detected partially released to the cytosol after exposure to 0.1 muM staurosporine for 1 h. After 4 h, activation of caspase-9 and -3 was initiated and later caspase-8 activation and a decrease in full-length Bid were detected. Pretreatment of cells with the cathepsin D inhibitor, pepstatin A, prevented cytochrome c release and caspase activation, and delayed cell death. These results imply that cytosolic cathepsin D is a key mediator in staurosporine-induced apoptosis. Analysis of the relative sequence of apoptotic events indicates that, in this cell type, cathepsin D acts upstream of cytochrome c release and caspase activation.
Division of Pathology II, Faculty of Health Sciences, Linköping University, S-58185 Linköping, Sweden. lotta.johansson@inr.liu.se
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D017209:Apoptosis / Q000502:physiology*; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D002402:Cathepsin D / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D010436:Pepstatins / Q000494:pharmacology; D019311:Staurosporine / Q000494:pharmacology*
D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D010436:Pepstatins; D045304:Cytochromes c; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D002402:Cathepsin D; D019311:Staurosporine; C031375:pepstatin