Ghafourifar P, Klein S D, Schucht O, Schenk U, Pruschy M, Rocha S, Richter C
Laboratory of Biochemistry I, Swiss Federal Institute of Technology, Universitatsstrasse 16, CH-8092 Zurich, Switzerland.
J Biol Chem. 1999 Mar 5;274(10):6080-4. doi: 10.1074/jbc.274.10.6080.
In the present study we show that N-acetylsphingosine (C2-ceramide), N-hexanoylsphingosine (C6-ceramide), and, to a much lesser extent, C2-dihydroceramide induce cytochrome c (cyto c) release from isolated rat liver mitochondria. Ceramide-induced cyto c release is prevented by preincubation of mitochondria with a low concentration (40 nM) of Bcl-2. The release takes place when cyto c is oxidized but not when it is reduced. Upon cyto c loss, mitochondrial oxygen consumption, mitochondrial transmembrane potential (Delta Psi), and Ca2+ retention are diminished. Incubation with Bcl-2 prevents, and addition of cyto c reverses the alteration of these mitochondrial functions. In ATP-energized mitochondria, ceramides do not alter Delta Psi, neither when cyto c is oxidized nor when it is reduced, ruling out a nonspecific disturbance by ceramides of mitochondrial membrane integrity. Furthermore, ceramides decrease the reducibility of cyto c. We conclude that the apoptogenic properties of ceramides are in part mediated via their interaction with mitochondrial cyto c followed by its release and that the redox state of cyto c influences its detachment by ceramide from the inner mitochondrial membrane.
在本研究中，我们发现N-乙酰鞘氨醇（C2-神经酰胺）、N-己酰鞘氨醇（C6-神经酰胺）以及程度小得多的C2-二氢神经酰胺可诱导细胞色素c（细胞色素c）从分离的大鼠肝线粒体中释放。用低浓度（40 nM）的Bcl-2预孵育线粒体可防止神经酰胺诱导的细胞色素c释放。当细胞色素c被氧化时会发生释放，而当它被还原时则不会。细胞色素c丢失后，线粒体氧消耗、线粒体跨膜电位（ΔΨ）和Ca2+保留都会减少。用Bcl-2孵育可防止这种情况，添加细胞色素c可逆转这些线粒体功能的改变。在ATP供能的线粒体中，无论细胞色素c被氧化还是被还原，神经酰胺都不会改变ΔΨ，排除了神经酰胺对线粒体膜完整性的非特异性干扰。此外，神经酰胺会降低细胞色素c的可还原性。我们得出结论，神经酰胺的凋亡特性部分是通过它们与线粒体细胞色素c的相互作用，随后细胞色素c释放来介导的，并且细胞色素c的氧化还原状态影响其被神经酰胺从线粒体内膜上分离。
