Ho Philip Wing-Lok, Chan David Yiu-Leung, Kwok Ken Hon-Hung, Chu Andrew Chi-Yuen, Ho Jessica Wing-Man, Kung Michelle Hiu-Wai, Ramsden David Boyer, Ho Shu-Leong
Division of Neurology, University Department of Medicine, University of Hong Kong, Hong Kong, People's Republic of China.
J Neurosci Res. 2005 Jul 15;81(2):261-8. doi: 10.1002/jnr.20569.
Methyl-4-phenylpyridinium ion (MPP(+)), a specific dopaminergic neurotoxin, inhibits mitochondrial complex I activity, generates reactive oxygen species (ROS), reduces ATP production, and induces cell death. We explored changes in expression of uncoupling proteins (UCPs 2, 4, and 5) following MPP(+)-induced toxicity in SK-N-SH cells over 72 hr at the transcriptional (quantification of mRNA by real-time RT-PCR) and translational (Western analysis) levels. UCP5 mRNA and protein were markedly up-regulated (1 mM MPP(+) at 72 hr caused a twofold increase, P < 0.01), as was UCP4 mRNA, albeit to a much lesser extent. Surprisingly, UCP2 mRNA levels decreased at 24 hr (P < 0.05) but thereafter significantly increased to greater than control levels at 72 hr (P < 0.05), although UCP2 protein levels were decreased throughout (1 mM MPP(+) at 72 hr caused a reduction of 50%, P < 0.01). The increase in ROS production may be attenuated by UCP4 and UCP5 up-regulation. The consequence of decreased UCP2 levels is unclear, although this may represent an adaptive response to declines in ATP levels, the subsequent increase in mRNA being a response to further increases in oxidative stress.
甲基-4-苯基吡啶离子（MPP(+)）是一种特异性多巴胺能神经毒素，它会抑制线粒体复合物I的活性，产生活性氧（ROS），减少ATP生成，并诱导细胞死亡。我们在转录水平（通过实时逆转录PCR对mRNA进行定量）和翻译水平（蛋白质印迹分析）上，探究了SK-N-SH细胞在MPP(+)诱导的毒性作用72小时后解偶联蛋白（UCP2、UCP4和UCP5）表达的变化。UCP5的mRNA和蛋白显著上调（72小时时1 mM MPP(+)导致其增加两倍，P < 0.01），UCP4的mRNA也是如此，尽管程度要小得多。令人惊讶的是，UCP2的mRNA水平在24小时时下降（P < 0.05），但随后在72小时时显著增加至高于对照水平（P < 0.05），尽管UCP2蛋白水平在整个过程中都下降（72小时时1 mM MPP(+)导致其减少50%，P < 0.01）。UCP4和UCP5的上调可能会减弱ROS生成的增加。UCP2水平降低的后果尚不清楚，尽管这可能代表对ATP水平下降的一种适应性反应，随后mRNA的增加是对氧化应激进一步增加的一种反应。
