Bcl‐xL interrupts oxidative activation of neutral sphingomyelinase

FEBS Letters

Obeid, Lina M¹  Hannun, Yusuf A²  Okamoto, Yasuo² 

[1]Ralph H. Johnson Veterans Affairs Medical Center and Department of Medicine, Medical University of South Carolina, Charleston, 173 Ashley Ave., Charleston, SC 29425, USA

[2]Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, 173 Ashley Ave., Charleston, SC 29425, USA

关键词: Bcl-xL;    Neutral sphingomyelinase;    Glutathione;    Ceramide;    A-SMase;    acid sphingomyelinase;    N-SMase;    neutral sphingomyelinase;    SM;    sphingomyelin;    GSH;    glutathione;    TNFα;    tumor necrosis factor-α;    bSMase;    bacterial sphingomyelinase;    GSSG;    oxidized GSH;    NAC;    N-acetylcysteine;    FBS;    fetal bovine serum;    PBS;    phosphate-buffered saline;   

DOI  :  10.1016/S0014-5793(02)03435-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Recent studies demonstrate a role for intracellular oxidation in the regulation of neutral sphingomyelinase (N-SMase). Glutathione (GSH) has been shown to regulate N-SMase in vitro and in cells. However, it has not been established whether the effects of GSH in cells are due to direct action on N-SMase. In this study, treatment of human mammary carcinoma MCF-7 cells with diamide, a thiol-depleting agent, caused a decrease in intracellular GSH and degradation of sphingomyelin (SM) to ceramide. The SM pool hydrolyzed in response to diamide belonged to the bacterial SMase-resistant pool of SM. Importantly, pretreatment of MCF-7 cells with GSH, N-acetylcysteine, an antioxidant, or GW69A, a specific N-SMase inhibitor, prevented diamide-induced degradation of SM to ceramide, suggesting that intracellular levels of GSH regulate the extent to which SM is degraded to ceramide and that this probably involves a GW69A-sensitive N-SMase. Unexpectedly, expression of Bcl-xL prevented tumor necrosis factor-α-induced SM hydrolysis and ceramide accumulation but not the decrease in intracellular GSH. Furthermore, Bcl-xL inhibited diamide-induced SM hydrolysis and ceramide accumulation but not the decrease in intracellular GSH. These results suggest that the site of action of Bcl-xL is downstream of GSH depletion and upstream of ceramide accumulation, and that GSH probably does not exert direct physiologic effects on N-SMase.

【 授权许可】

Unknown