Oxidative stress triggers Ca-dependent lysosome trafficking and activation of acid sphingomyelinase.
Recent studies demonstrate that rapid translocation of the acid sphingomyelinase (ASM), a lysosomal hydrolase, to the outer leaflet of the cell membrane and concomitant release of ceramide constitute a common cellular signaling cascade to various stimuli including CD95 ligation, UV-irradiation, bacterial and viral infections. Reactive oxygen species (ROS) were shown to play a crucial role in regulating this signaling cascade at least for some bacterial infections and UV-irradiation. However, the precise role of ROS for regulation of ASM is unknown. Here, by confocal microscopy and flow cytometry analysis, we demonstrate that hydrogen peroxide (H(2)O(2)), a primary form of ROS in mammalian cells, induces very rapid translocation of ASM and formation of ceramide-enriched membrane platforms in the plasma membrane of Jurkat T cells. In parallel, H(2)O(2) triggers lysosome trafficking and fusion with the plasma membrane, i.e. lysosome exocytosis, as detected by exposure of a lysosome-associated protein, LAMP1. Depletion of intracellular Ca(2+) by cell permeable EGTA-AM inhibits H(2)O(2)-induced lysosome exocytosis, ASM translocation and formation of ceramide-enriched platforms. Pharmacological inhibition or genetic deficiency of ASM did not affect H(2)O(2)-induced lysosome exocytosis. These results indicate that ROS-induced membrane translocation of ASM is mediated by exocytosis of lysosomes, which is dependent on intracellular Ca(2+) release.
Department of Pharmacology & Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613 , USA.
Xiang
X
Li
Erich
E
Gulbins
Yang
Y
Zhang
D002118:Calcium / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism*; D004789:Enzyme Activation; D005089:Exocytosis; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D019169:Jurkat Cells; D051907:Lysosomal Membrane Proteins / Q000032:analysis / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D008561:Membrane Fusion; D018384:Oxidative Stress; D021381:Protein Transport; D013108:Sphingomyelin Phosphodiesterase / Q000032:analysis / Q000378:metabolism*; D052118:Lysosomal-Associated Membrane Protein 1
D002118:Calcium; D002518:Ceramides; D006861:Hydrogen Peroxide; D051907:Lysosomal Membrane Proteins; D013108:Sphingomyelin Phosphodiesterase; C489116:LAMP1 protein, human; D052118:Lysosomal-Associated Membrane Protein 1