Bilirubin and amyloid-β peptide induce cytochrome c release through mitochondrial membrane permeabilization
Bilirubin and amyloid-β peptide induce cytochrome c release through mitochondrial membrane permeabilization
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DOI：
10.1007/bf03401828
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发表时间：
2000-11-01
影响因子：
5.7
通讯作者：
Brites, D
中科院分区：
文献类型：
--
作者：
Rodrigues, CMP;Solá, S;Brites, D
背景资料：胆红素脑病和阿尔茨海默病的发病机制似乎分别由未结合胆红素（UCB）和淀粉样β（A β）肽的积累引起，这可能导致细胞凋亡。线粒体膜的透化，伴随膜间蛋白的释放，与细胞死亡密切相关。抑制线粒体通透性是熊去氧胆酸盐（UDC）和牛磺熊去氧胆酸盐（TUDC）保护肝细胞和非肝细胞免于凋亡的途径之一。在这项研究中，我们进一步描述了UCB和A β诱导的神经细胞毒性，并研究了分离的线粒体与这两种药物孵育过程中的膜扰动。此外，我们评估是否抗凋亡药物UDC和TUDC防止任何变化的发生。材料和方法：原代大鼠神经元和星形胶质细胞培养物与UCB或A β肽，单独或在UDC的存在下孵育。通过DNA片段化和细胞核形态学改变来评估细胞凋亡。分离的线粒体单独或与UDC、TUDC或环孢霉素A联合使用每种毒性药物处理。结果：UCB和A β均能诱导神经细胞凋亡（P <0.01），但UCB和A β均能诱导神经细胞凋亡（P < 0.01）。与UDC共孵育使细胞凋亡减少>50%（p < 0.05）。两种毒素均引起分离的线粒体膜透化（p < 0.001）;而用UDC预处理具有保护作用（p < 0.05）。TUDC在防止A介导的基质肿胀方面甚至更有效（p < 0.01）。UDC和TUDC分别显著降低UCB和A诱导的线粒体通透性相关的细胞色素c释放（p < 0.05）。结论：UCB和A β肽可激活神经细胞凋亡机制。毒性通过一种依赖于药物的途径发生，该途径部分涉及渗透性转换孔的打开。此外，细胞色素c从线粒体释放需要膜透化，并且可以通过UDC或TUDC来防止。这些数据表明，线粒体是非结合型高胆红素血症和神经退行性疾病中细胞保护的药理学靶点，UDC或TUDC可能是潜在的治疗药物。
Background: The pathogenesis of bilirubin encephalopathy and Alzheimer's disease appears to result from accumulation of unconjugated bilirubin (UCB) and amyloid-beta (A beta) peptide, respectively, which may cause apoptosis. Permeabilization of the mitochondrial membrane, with release of intermembrane proteins, has been strongly implicated in cell death. Inhibition of the mitochondrial permeability is one pathway by which ursodeoxycholate (UDC) and tauroursodeoxycholate (TUDC) protect against apoptosis in hepatic and nonhepatic cells. In this study, we further characterize UCB- and A beta -induced cytotoxicty in isolated neural cells, and investigate membrane perturbation during incubation of isolated mitochondria with both agents. In addition, we evaluate whether the anti-apoptotic drugs UDC and TUDC prevent any changes from occurring.Materials and Methods: Primary rat neuron and astrocyte cultures were incubated with UCB or A beta peptide, either alone or in the presence of UDC. Apoptosis was assessed by DNA fragmentation and nuclear morphological changes. Isolated mitochondria were treated with each toxic, either alone or in combination with UDC, TUDC, or cyclosporine A. Mitochondrial swelling was measured spectrophotometrically and cytochrome c protein levels determined by Western blot.Results: Incubation of neural cells with both UCB and A beta induced apoptosis (p < 0.01). Coincubation with UDC reduced apoptosis by >50% (p < 0.05). Both toxins caused membrane permeabilization in isolated mitochondria (p < 0.001); whereas, pretreatment with UDC was protective (p < 0.05). TUDC was even more effective at preventing matrix swelling mediated by A (p < 0.01). UDC and TUDC markedly reduced cytochrome c release associated with mitochondrial permeabilization induced by UCB and A, respectively (p < 0.05). Moreover, cyclosporine A significantly inhibited mitochondrial swelling and cytochrome c efflux mediated by UCB (p < 0.05).Conclusion: UCB and A beta peptide activate the apoptotic machinery in neural cells. Toxicity occurs through a mitochondrial-dependent pathway which in part involves opening of the permeability transition pore. Furthermore, membrane permeabilization is required for cytochrome c release from mitochondria and can be prevented by UDC or TUDC. These data suggest that the mitochondria is a pharmacological target for cytoprotection during unconjugated hyperbilirubinemia and neurodegenerative disorders, and that UDC or TUDC may be potential therapeutic agents.