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Sphingomyelin Hydrolysis to Ceramide during the Execution Phase of Apoptosis Results from Phospholipid Scrambling and Alters Cell-Surface Morphology

Apoptosis is generally accompanied by a late phase of ceramide (Cer) production, the significance of which is unknown. This study describes a previously unrecognized link between Cer accumulation and phosphatidylserine (PS) exposure at the cell surface, a characteristic of the execution phase of apo...

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Autores principales: Tepper, Annemiek D., Ruurs, Paula, Wiedmer, Therese, Sims, Peter J., Borst, Jannie, van Blitterswijk, Wim J.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2000
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2185573/
https://www.ncbi.nlm.nih.gov/pubmed/10893264
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author Tepper, Annemiek D.
Ruurs, Paula
Wiedmer, Therese
Sims, Peter J.
Borst, Jannie
van Blitterswijk, Wim J.
author_facet Tepper, Annemiek D.
Ruurs, Paula
Wiedmer, Therese
Sims, Peter J.
Borst, Jannie
van Blitterswijk, Wim J.
author_sort Tepper, Annemiek D.
collection PubMed
description Apoptosis is generally accompanied by a late phase of ceramide (Cer) production, the significance of which is unknown. This study describes a previously unrecognized link between Cer accumulation and phosphatidylserine (PS) exposure at the cell surface, a characteristic of the execution phase of apoptosis resulting from a loss of plasma membrane phospholipid asymmetry. Using a fluorescent sphingomyelin (SM) analogue, N-(N-[6-[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]caproyl]–sphingosylphosphorylcholine (C(6)-NBD-SM), we show that Cer is derived from SM, initially located in the outer leaflet of the plasma membrane, which gains access to a cytosolic SMase by flipping to the inner leaflet in a process of lipid scrambling paralleling PS externalization. Lipid scrambling is both necessary and sufficient for SM conversion: Ca(2+) ionophore induces both PS exposure and SM hydrolysis, whereas scrambling-deficient Raji cells do not show PS exposure or Cer formation. Cer is not required for mitochondrial or nuclear apoptotic features since these are still observed in Raji cells. SM hydrolysis facilitates cholesterol efflux to methyl-β-cyclodextrin, which is indicative of a loss of tight SM–cholesterol interaction in the plasma membrane. We provide evidence that these biophysical alterations in the lipid bilayer are essential for apoptotic membrane blebbing/vesiculation at the cell surface: Raji cells show aberrant apoptotic morphology, whereas replenishment of hydrolyzed SM by C(6)- NBD-SM inhibits blebbing in Jurkat cells. Thus, SM hydrolysis, during the execution phase of apoptosis, results from a loss of phospholipid asymmetry and contributes to structural changes at the plasma membrane.
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spelling pubmed-21855732008-05-01 Sphingomyelin Hydrolysis to Ceramide during the Execution Phase of Apoptosis Results from Phospholipid Scrambling and Alters Cell-Surface Morphology Tepper, Annemiek D. Ruurs, Paula Wiedmer, Therese Sims, Peter J. Borst, Jannie van Blitterswijk, Wim J. J Cell Biol Original Article Apoptosis is generally accompanied by a late phase of ceramide (Cer) production, the significance of which is unknown. This study describes a previously unrecognized link between Cer accumulation and phosphatidylserine (PS) exposure at the cell surface, a characteristic of the execution phase of apoptosis resulting from a loss of plasma membrane phospholipid asymmetry. Using a fluorescent sphingomyelin (SM) analogue, N-(N-[6-[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]caproyl]–sphingosylphosphorylcholine (C(6)-NBD-SM), we show that Cer is derived from SM, initially located in the outer leaflet of the plasma membrane, which gains access to a cytosolic SMase by flipping to the inner leaflet in a process of lipid scrambling paralleling PS externalization. Lipid scrambling is both necessary and sufficient for SM conversion: Ca(2+) ionophore induces both PS exposure and SM hydrolysis, whereas scrambling-deficient Raji cells do not show PS exposure or Cer formation. Cer is not required for mitochondrial or nuclear apoptotic features since these are still observed in Raji cells. SM hydrolysis facilitates cholesterol efflux to methyl-β-cyclodextrin, which is indicative of a loss of tight SM–cholesterol interaction in the plasma membrane. We provide evidence that these biophysical alterations in the lipid bilayer are essential for apoptotic membrane blebbing/vesiculation at the cell surface: Raji cells show aberrant apoptotic morphology, whereas replenishment of hydrolyzed SM by C(6)- NBD-SM inhibits blebbing in Jurkat cells. Thus, SM hydrolysis, during the execution phase of apoptosis, results from a loss of phospholipid asymmetry and contributes to structural changes at the plasma membrane. The Rockefeller University Press 2000-07-10 /pmc/articles/PMC2185573/ /pubmed/10893264 Text en © 2000 The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Original Article
Tepper, Annemiek D.
Ruurs, Paula
Wiedmer, Therese
Sims, Peter J.
Borst, Jannie
van Blitterswijk, Wim J.
Sphingomyelin Hydrolysis to Ceramide during the Execution Phase of Apoptosis Results from Phospholipid Scrambling and Alters Cell-Surface Morphology
title Sphingomyelin Hydrolysis to Ceramide during the Execution Phase of Apoptosis Results from Phospholipid Scrambling and Alters Cell-Surface Morphology
title_full Sphingomyelin Hydrolysis to Ceramide during the Execution Phase of Apoptosis Results from Phospholipid Scrambling and Alters Cell-Surface Morphology
title_fullStr Sphingomyelin Hydrolysis to Ceramide during the Execution Phase of Apoptosis Results from Phospholipid Scrambling and Alters Cell-Surface Morphology
title_full_unstemmed Sphingomyelin Hydrolysis to Ceramide during the Execution Phase of Apoptosis Results from Phospholipid Scrambling and Alters Cell-Surface Morphology
title_short Sphingomyelin Hydrolysis to Ceramide during the Execution Phase of Apoptosis Results from Phospholipid Scrambling and Alters Cell-Surface Morphology
title_sort sphingomyelin hydrolysis to ceramide during the execution phase of apoptosis results from phospholipid scrambling and alters cell-surface morphology
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2185573/
https://www.ncbi.nlm.nih.gov/pubmed/10893264
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