Landar Aimee, Shiva Sruti, Levonen Anna-Liisa, Oh Joo-Yeun, Zaragoza Corinne, Johnson Michelle S, Darley-Usmar Victor M
Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Biochem J. 2006 Feb 15;394(Pt 1):185-95. doi: 10.1042/BJ20051259.
The electrophilic lipid 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) is known to allow adaptation to oxidative stress in cells at low concentrations and apoptosis at high levels. The mechanisms leading to adaptation involve the covalent modification of regulatory proteins, such as Keap1, and augmentation of antioxidant defences in the cell. The targets leading to apoptosis are less well defined, but mitochondria have been indirectly implicated in the mechanisms of cell death mediated by electrophilic lipids. To determine the potential of electrophilic cyclopentenones to induce pro-apoptotic effects in the mitochondrion, we used isolated liver mitochondria and demonstrated that 15d-PGJ2 promotes Ca2+-induced mitochondrial swelling and cytochrome c release. The mechanisms involved are consistent with direct modification of protein thiols in the mitochondrion, rather than secondary formation of reactive oxygen species or lipid peroxidation. Using proteomic analysis in combination with biotinylated 15d-PGJ2, we were able to identify 17 potential targets of the electrophile-responsive proteome in isolated liver mitochondria. Taken together, these results suggest that electrophilic lipid oxidation products can target a sub-proteome in mitochondria, and this in turn results in the transduction of the electrophilic stimulus to the cell through cytochrome c release.
亲电子脂质15-脱氧-Δ12,14-前列腺素J2（15d-PGJ2）已知在低浓度时可使细胞适应氧化应激，而在高浓度时可诱导细胞凋亡。导致适应的机制包括调节蛋白（如Keap1）的共价修饰以及细胞内抗氧化防御的增强。导致细胞凋亡的靶点尚不太明确，但线粒体已间接参与亲电子脂质介导的细胞死亡机制。为了确定亲电子环戊烯酮在线粒体中诱导促凋亡作用的潜力，我们使用分离的肝线粒体，并证明15d-PGJ2可促进Ca2+诱导的线粒体肿胀和细胞色素c释放。所涉及的机制与线粒体中蛋白质硫醇的直接修饰一致，而不是活性氧的二次形成或脂质过氧化。通过蛋白质组学分析结合生物素化的15d-PGJ2，我们能够在分离的肝线粒体中鉴定出亲电子反应性蛋白质组的17个潜在靶点。综上所述，这些结果表明亲电子脂质氧化产物可靶向线粒体中的一个亚蛋白质组，进而通过细胞色素c释放将亲电子刺激转导至细胞。
