Defective TNF-α-mediated hepatocellular apoptosis and liver damage in acidic sphingomyelinase knockout mice
Defective TNF-α-mediated hepatocellular apoptosis and liver damage in acidic sphingomyelinase knockout mice
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DOI：
10.1172/jci200316010
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发表时间：
2003-01-01
影响因子：
15.9
通讯作者：
Fernández-Checa, JC
中科院分区：
文献类型：
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作者：
García-Ruiz, C;Colell, A;Fernández-Checa, JC
本研究探讨了酸性鞘磷脂酶 (ASMase) 在 TNF-α 介导的肝细胞凋亡中的作用。耗尽线粒体谷胱甘肽 (mGSH) 的培养肝细胞对 TNF-α 变得敏感，在线粒体膜去极化、细胞色素 c 释放和 caspase 激活之前经历时间依赖性细胞凋亡。环孢素 A 治疗可将 mGSH 耗尽的肝细胞从 TNF-α 诱导的细胞死亡中拯救出来。相比之下，缺乏 ASMase 的 mGSH 耗尽的肝细胞能够抵抗 TNF-α 介导的细胞死亡，但对外源 ASMase 敏感。此外，虽然对半乳糖胺预处理的ASMase(+/+)小鼠体内给予TNF-α或LPS引起肝损伤，但ASMase(-/-)小鼠表现出最小的肝细胞损伤。为了分析 ASMase 的需求，我们评估了葡萄糖神经酰胺合成酶抑制对 TNF-α 介导的细胞凋亡的影响。这种方法减弱了 TNF-α 产生的鞘糖脂，保护了 mGSH 耗尽的 ASMase(+/+) 肝细胞免受 TNF-α 的影响，尽管 TNF-α 刺激的神经酰胺形成有所增强。为了进一步测试鞘糖脂的参与，我们重点关注神经节苷脂 GD3 (GD3)，因为它通过与线粒体相互作用在细胞凋亡中发挥新的作用。通过激光扫描共聚焦显微镜对 GD3 的细胞重新分布进行分析，揭示了 GD3 靶向 ASMase(+/+) 肝细胞中的线粒体，而不是 ASMase(-/-) 肝细胞中的线粒体。然而，用外源 ASMase 处理 ASMase(-/-) 肝细胞会诱导 GD3 和线粒体共定位。因此，ASMase 通过促进鞘糖脂的线粒体靶向来促进 TNF-α 诱导的肝细胞凋亡。
This study addressed the contribution of acidic sphingomyelinase (ASMase) in TNF-alpha-mediated hepatocellular apoptosis. Cultured hepatocytes depleted of mitochondrial glutathione (mGSH) became sensitive to TNF-alpha, undergoing a time-dependent apoptotic cell death preceded by mitochondrial membrane depolarization, cytochrome c release, and caspase activation. Cyclosporin A treatment rescued mGSH-depleted hepatocytes from TNF-alpha-induced cell death. In contrast, mGSH-depleted hepatocytes deficient in ASMase were resistant to TNF-alpha-mediated cell death but sensitive to exogenous ASMase. Furthermore, although in vivo administration of TNF-alpha or LPS to galactosamine-pretreated ASMase(+/+) mice caused liver damage, ASMase(-/-) mice exhibited minimal hepatocellular injury. To analyze the requirement of ASMase, we assessed the effect of glucosylceramide synthetase inhibition on TNF-alpha-mediated apoptosis. This approach, which blunted glycosphingolipid generation by TNF-alpha, protected mGSH-depleted ASMase(+/+) hepatocytes from TNF-alpha despite enhancement of TNF-alpha-stimulated ceramide formation. To further test the involvement of glycosphingolipids, we focused on ganglioside GD3 (GD3) because of its emerging role in apoptosis through interaction with mitochondria. Analysis of the cellular redistribution of GD3 by laser scanning confocal microscopy revealed the targeting of GD3 to mitochondria in ASMase(+/+) but not in ASMase(-/-) hepatocytes. However, treatment of ASMase(-/-) hepatocytes with exogenous ASMase induced the colocalization of GD3 and mitochondria. Thus, ASMase contributes to TNF-alpha-induced hepatocellular apoptosis by promoting the mitochondrial targeting of glycosphingolipids.