Ceramide generated by acidic sphingomyelinase contributes to tumor necrosis factor-alpha-mediated apoptosis in human colon HT-29 cells through glycosphingolipids formation. Possible role of ganglioside GD3.
In the present study we assessed the contribution of acidic sphingomyelinase (ASMase), a ceramide generating enzyme, in tumor necrosis factor (TNF)-mediated apoptosis in human colon HT-29 cells. TNF induced apoptosis in HT-29 cells in a time- and dose-dependent fashion. Downregulation of the active endogenous ASMase form prevented TNF-stimulated ASMase activity and apoptosis. Furthermore, inhibition of glucosylceramide synthase, which blunted TNF-stimulated GD3 levels, abolished TNF-mediated cell death. Immunocytochemical staining revealed the co-localization of GD3 with mitochondria induced by TNF. The knockdown of targeted GD3 synthase by antisense expression vector protected HT-29 cells against TNF-induced cell death. Thus, ASMase plays a key role in TNF-induced cell death in human colon epithelial cells possibly through GD3 generation.
Liver Unit, Instituto de Malalties Digestives, Hospital Clinic i Provincial, Instituto Investigaciones Biomedicas August Pi Suñer, C/Villarroel 170, Barcelona 08036, Spain.
Anna
A
Colell
Albert
A
Morales
José C
JC
Fernández-Checa
Carmen
C
García-Ruiz
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002518:Ceramides / Q000378:metabolism*; D003110:Colonic Neoplasms; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006028:Glycosphingolipids / Q000378:metabolism*; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D013108:Sphingomyelin Phosphodiesterase / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002518:Ceramides; D006028:Glycosphingolipids; D014409:Tumor Necrosis Factor-alpha; D013108:Sphingomyelin Phosphodiesterase