title: Lysosome-mediated apoptosis is associated with cathepsin D-specific processing of bid at Phe24, Trp48, and Phe183.
abstract: Bax-mediated permeabilization of the outer mitochondrial membrane and release of apoptogenic factors into the cytosol are key events that occur during apoptosis. Likewise, apoptosis is associated with permeabilization of the lysosomal membrane and release of lysosomal cathepsins into the cytosol. This report identifies proteolytically active cathepsin D as an important component of apoptotic signaling following lysosomal membrane permeabilization in fibroblasts. Lysosome-mediated cell death is associated with degradation of Bax sequestering 14-3-3 proteins, cleavage of the Bax activator Bid, and translocation of Bax to mitochondria, all of which were cathepsin D-dependent. Processing of Bid could be reproduced by enforced lysosomal membrane permeabilization, using the lysosomotropic detergent O-methyl-serine dodecylamine hydrochloride (MSDH). We identified three cathepsin D-specific cleavage sites in Bid, Phe24, Trp48, and Phe183. Cathepsin D-cleaved Bid induced Bax-mediated release of cytochrome c from purified mitochondria, indicating that the fragments generated are functionally active. Moreover, apoptosis was associated with cytosolic acidification, thereby providing a more favorable environment for the cathepsin D-mediated cleavage of Bid. Our study suggests that cytosolic cathepsin D triggers Bax-mediated cytochrome c release by proteolytic activation of Bid.
authors.affiliation: Experimental Pathology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linkoping University, Sweden. hanna.appelqvist@liu.se
authors.forename: Hanna
authors.initials: H
authors.lastname: Appelqvist
authors.forename: Ann-Charlotte
authors.initials: AC
authors.lastname: Johansson
authors.forename: Emma
authors.initials: E
authors.lastname: Linderoth
authors.forename: Uno
authors.initials: U
authors.lastname: Johansson
authors.forename: Bruno
authors.initials: B
authors.lastname: Antonsson
authors.forename: Robert
authors.initials: R
authors.lastname: Steinfeld
authors.forename: Katarina
authors.initials: K
authors.lastname: Kågedal
authors.forename: Karin
authors.initials: K
authors.lastname: Ollinger
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism*; D002402:Cathepsin D / Q000378:metabolism*; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010539:Permeability / Q000187:drug effects; D010649:Phenylalanine / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D019311:Staurosporine / Q000494:pharmacology; D013379:Substrate Specificity / Q000187:drug effects; D014364:Tryptophan / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D051023:BH3 Interacting Domain Death Agonist Protein; D051028:bcl-2-Associated X Protein; D010649:Phenylalanine; D014364:Tryptophan; D002402:Cathepsin D; D019311:Staurosporine