Localization of neutral ceramidase in caveolin-enriched light membranes of murine endothelial cells.
Sphingomyelinase (SMase) and ceramidase (CDase) activities participate in sphingomyelin (SM) metabolism and have a role in the signal transduction of a variety of ligands. In this study evidence is presented that caveolin-enriched light membranes (CELMs) of murine endothelial cells, characterized by high SM, ceramide (Cer) and cholesterol content, bear acid and neutral SMase as well as neutral CDase activities. Localization of neutral CDase in CELMs was confirmed by Western analysis. Notably, cell treatment with cyclodextrin, which depleted cell cholesterol, did not affect acid or neutral SMase activities but significantly enhanced neutral CDase activity in CELMs, indicating a negative role for cholesterol in CDase regulation. These findings suggest that neutral CDase is implicated, together with SMase activities, in the control of caveolar Cer content that may be critical for caveola dynamics.
Romiti
E
E
Dipartimento di Scienze Biochimiche, Viale G.B. Morgagni 50, Florence, Italy.
Meacci
E
E
Tanzi
G
G
Becciolini
L
L
Mitsutake
S
S
Farnararo
M
M
Ito
M
M
Bruni
P
P
D000581:Amidohydrolases / Q000378:metabolism*; D000818:Animals; D022461:Caveolins / Q000378:metabolism*; D002458:Cell Fractionation; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry / Q000201:enzymology*; D002499:Centrifugation, Density Gradient; D055572:Ceramidases; D002518:Ceramides / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology*; D051379:Mice; D055576:Neutral Ceramidase; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism
D022461:Caveolins; D002518:Ceramides; D013109:Sphingomyelins; D013108:Sphingomyelin Phosphodiesterase; D000581:Amidohydrolases; C526747:Asah2 protein, mouse; D055572:Ceramidases; D055576:Neutral Ceramidase