Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea.
J Biol Chem. 2011 Mar 4;286(9):7248-56. doi: 10.1074/jbc.M110.189183. Epub 2010 Dec 24.
To investigate the biochemical mechanism underlying the effect of sterol deprivation on longevity in Caenorhabditis elegans, we treated parent worms (P0) with 25-azacoprostane (Aza), which inhibits sitosterol-to-cholesterol conversion, and measured mean lifespan (MLS) in F2 worms. At 25 μM (∼EC(50)), Aza reduced total body sterol by 82.5%, confirming sterol depletion. Aza (25 μM) treatment of wild-type (N2) C. elegans grown in sitosterol (5 μg/ml) reduced MLS by 35%. Similar results were obtained for the stress-related mutants daf-16(mu86) and gas-1(fc21). Unexpectedly, Aza had essentially no effect on MLS in the stress-resistant daf-2(e1370) or mitochondrial complex II mutant mev-1(kn1) strains, indicating that Aza may target both insulin/IGF-1 signaling (IIS) and mitochondrial complex II. Aza increased reactive oxygen species (ROS) levels 2.7-fold in N2 worms, but did not affect ROS production by mev-1(kn1), suggesting a direct link between Aza treatment and mitochondrial ROS production. Moreover, expression of the stress-response transcription factor SKN-1 was decreased in amphid neurons by Aza and that of DAF-28 was increased when DAF-6 was involved, contributing to lifespan reduction.
为了研究甾醇剥夺对秀丽隐杆线虫寿命延长的生化机制，我们用 25-氮杂胆固醇（Aza）处理亲代线虫（P0），Aza 可以抑制植物固醇向胆固醇的转化，并在 F2 代线虫中测量平均寿命（MLS）。在 25 μM（约 EC50）时，Aza 将总身体甾醇降低了 82.5%，证实了甾醇耗竭。在含有 5μg/ml 植物固醇的条件下，用 25μM 的 Aza 处理野生型（N2）秀丽隐杆线虫，将其平均寿命降低了 35%。应激相关突变体 daf-16(mu86) 和 gas-1(fc21) 也得到了类似的结果。出乎意料的是，Aza 对应激抗性较强的 daf-2(e1370) 或线粒体复合物 II 突变体 mev-1(kn1) 菌株的平均寿命几乎没有影响，这表明 Aza 可能同时靶向胰岛素/IGF-1 信号通路（IIS）和线粒体复合物 II。Aza 使 N2 线虫中的活性氧（ROS）水平增加了 2.7 倍，但对 mev-1(kn1) 的 ROS 产生没有影响，这表明 Aza 处理与线粒体 ROS 产生之间存在直接联系。此外，Aza 降低了线虫触角神经元中应激反应转录因子 SKN-1 的表达，当 DAF-6 参与时，DAF-28 的表达增加，这导致了寿命的缩短。
