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Cathepsin D-mediated processing of Bid at Phe24, Trp48, and Phe183
Linköping University, Department of Clinical and Experimental Medicine, Experimental Pathology . Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Experimental Pathology . Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Experimental Pathology . Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Experimental Pathology . Linköping University, Faculty of Health Sciences.
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2008 (English)In: International Journal of Experimental PathologyArticle in journal (Refereed) Submitted
Place, publisher, year, edition, pages
2008.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-13202OAI: oai:DiVA.org:liu-13202DiVA: diva2:18027
Available from: 2008-04-17 Created: 2008-04-17 Last updated: 2017-08-30
In thesis
1. Lysosomal Membrane Permeabilization: A Cellular Suicide Stragegy
Open this publication in new window or tab >>Lysosomal Membrane Permeabilization: A Cellular Suicide Stragegy
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the last decade, a tremendous gain in knowledge concerning the molecular events of apoptosis signaling and execution has been achieved.

The aim of this thesis was to clarify the role of lysosomal membrane permeabilization and lysosomal proteases, cathepsins, in signaling for apoptosis. We identified cathepsin D as an important factor in staurosporine-induced human fibroblast cell death. After release to the cytosol, cathepsin D promoted mitochondrial release of cytochrome c by proteolytic activation of Bid. Cathepsin D-mediated cleavage of Bid generated two fragments with the apparent molecular mass of 15 and 19 kDa. By sequence analysis, three cathepsin D-specific cleavage sites, Phe24, Trp48, and Phe183, were identified. Moreover, we investigated the mechanism by which cathepsins escape the lysosomal compartment, and found that Bax is translocated from the cytosol to lysosomes upon staurosporine treatment. In agreement with these data, recombinant Bax triggered release of cathepsins from isolated rat liver lysosomes. Conceivably, the Bcl-2 family of proteins may govern release of pro-apoptotic factors from both lysosomes and mitochondria. The importance of lysosomal cathepsins in apoptosis signaling was studied also in oral squamous cell carcinoma cells following exposure to the redox-cycling drug naphthazarin or agonistic anti-Fas antibodies. In this experimental system, cathepsins were released to the cytosol, however, inhibition of neither cathepsin D, nor cysteine cathepsin activity suppressed cell death. Interestingly, cysteine cathepsins still appeared to be involved in activation of the caspase cascade. Cathepsins are often overexpressed and secreted by cancer cells, and it has been reported that extracellular cathepsins promote tumor growth and metastasis. Here, we propose that cathepsin B secreted from cancer cells may suppress cancer cell death by shedding of the Fas death receptor.

Defects in the regulation of apoptosis contribute to a wide variety of diseases, such as cancer, neurodegeneration and autoimmunity. Increased knowledge of the molecular details of apoptosis could lead to novel, more effective, treatments for these illnesses. This thesis emphasizes the importance of the lysosomal death pathway, which is a promising target for future therapeutic intervention.

Abstract [en]

In the last decade, a tremendous gain in knowledge concerning the molecular events of apoptosis signaling and execution has been achieved.

The aim of this thesis was to clarify the role of lysosomal membrane permeabilization and lysosomal proteases, cathepsins, in signaling for apoptosis. We identified cathepsin D as an important factor in staurosporine-induced human fibroblast cell death. After release to the cytosol, cathepsin D promoted mitochondrial release of cytochrome c by proteolytic activation of Bid. Cathepsin D-mediated cleavage of Bid generated two fragments with the apparent molecular mass of 15 and 19 kDa. By sequence analysis, three cathepsin D-specific cleavage sites, Phe24, Trp48, and Phe183, were identified. Moreover, we investigated the mechanism by which cathepsins escape the lysosomal compartment, and found that Bax is translocated from the cytosol to lysosomes upon staurosporine treatment. In agreement with these data, recombinant Bax triggered release of cathepsins from isolated rat liver lysosomes. Conceivably, the Bcl-2 family of proteins may govern release of pro-apoptotic factors from both lysosomes and mitochondria. The importance of lysosomal cathepsins in apoptosis signaling was studied also in oral squamous cell carcinoma cells following exposure to the redox-cycling drug naphthazarin or agonistic anti-Fas antibodies. In this experimental system, cathepsins were released to the cytosol, however, inhibition of neither cathepsin D, nor cysteine cathepsin activity suppressed cell death. Interestingly, cysteine cathepsins still appeared to be involved in activation of the caspase cascade. Cathepsins are often overexpressed and secreted by cancer cells, and it has been reported that extracellular cathepsins promote tumor growth and metastasis. Here, we propose that cathepsin B secreted from cancer cells may suppress cancer cell death by shedding of the Fas death receptor.

Defects in the regulation of apoptosis contribute to a wide variety of diseases, such as cancer, neurodegeneration and autoimmunity. Increased knowledge of the molecular details of apoptosis could lead to novel, more effective, treatments for these illnesses. This thesis emphasizes the importance of the lysosomal death pathway, which is a promising target for future therapeutic intervention.

Place, publisher, year, edition, pages
Linköping University Electronic Press, 2008. 105 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1055
Keyword
apoptosis, lysosomes, lysosomal membrane permeabilization, cathepsins, Bax, Bid, mitochondria, caspases
National Category
Dentistry
Identifiers
urn:nbn:se:liu:diva-11614 (URN)978-91-7393-940-9 (ISBN)
Public defence
2008-05-15, Linden, Campus US, Linköpings universitet, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2008-04-17 Created: 2008-04-17 Last updated: 2017-08-30

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Johansson, Ann-CharlotteMild, HannaJohansson, UnoNilsson, CathrineKågedal, KatarinaÖllinger, Karin

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Johansson, Ann-CharlotteMild, HannaJohansson, UnoNilsson, CathrineKågedal, KatarinaÖllinger, Karin
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Experimental Pathology Faculty of Health SciencesDepartment of Clinical Pathology and Clinical Genetics
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