Caspase-mediated inhibition of sphingomyelin synthesis is involved in FasL-triggered cell death.
Cell Death Differ
; 17(4): 642-54, 2010 Apr.
Article
de En
| MEDLINE
| ID: mdl-19779494
ABSTRACT
Ceramide can be converted into sphingomyelin by sphingomyelin synthases (SMS) 1 and 2. In this study, we show that in human leukemia Jurkat cells, which express mainly SMS1, Fas ligand (FasL) treatment inhibited SMS activity in a dose- and time-dependent manner before nuclear fragmentation. The SMS inhibition elicited by FasL (1) was abrogated by benzyloxycarbonyl valyl-alanyl-aspartyl-(O-methyl)-fluoromethylketone (zVAD-fmk), a broad-spectrum caspase inhibitor; (2) did not occur in caspase-8-deficient cells and (3) was not affected in caspase-9-deficient cells. Western blot experiments showed SMS1 cleavage in a caspase-dependent manner upon FasL treatment. In a cell-free system, caspase-2, -7, -8 and -9, but not caspase-3 and -10, cleaved SMS1. In HeLa cells, SMS1 was Golgi localized and relocated throughout the cytoplasm in cells exhibiting an early apoptotic phenotype on FasL treatment. zVAD-fmk prevented FasL-induced SMS1 relocation. Thus, FasL-mediated SMS1 inhibition and relocation depend on caspase activation and likely represent proximal events in Fas signaling. FasL-induced ceramide production and cell death were enhanced in cells stably expressing an siRNA against SMS1. Conversely, in cells stably overexpressing SMS1, FasL neither increased ceramide generation nor efficiently induced cell death. Altogether, our data show that SMS1 is a novel caspase target that is functionally involved in the regulation of FasL-induced apoptosis.
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Sphingomyéline
/
Leucémies
/
Apoptose
/
Transferases (other substituted phosphate groups)
/
Caspases
/
Ligand de Fas
/
Protéines membranaires
/
Protéines de tissu nerveux
Limites:
Humans
Langue:
En
Journal:
Cell Death Differ
Année:
2010
Type de document:
Article
Pays d'affiliation:
France