Alic Nazif, Higgins Vincent J, Pichova Alena, Breitenbach Michael, Dawes Ian W
Ramaciotti Centre for Gene Function Analysis, School of Biotechnology and Biomolecular Sciences, University of New South Wales, 2052 New South Wales, Australia.
J Biol Chem. 2003 Oct 24;278(43):41849-55. doi: 10.1074/jbc.M307760200. Epub 2003 Aug 11.
Saccharomyces cerevisiae is capable of responding to oxidants, including lipid peroxidation products. We investigate here the role of the mitogen-activated protein kinase Mpk1p in protection against linoleic acid hydroperoxide (LoaOOH), a product of radical attack on an unsaturated lipid. MPK1 was found to be required for resistance to LoaOOH. Furthermore, Mpk1p was rapidly and transiently phosphorylated in response to LoaOOH. This phosphorylation was dose-dependent and stimulated by sublethal concentrations as low as 1 mum in the external medium. Such low doses have been shown to result in resistance to subsequent challenge with a higher dose through the process of adaptation. However MPK1 was not essential for this adaptive response. MPK1 was also not involved in cell cycle modulation and acted independently of the cell cycle-regulating Oca1p. Transcriptional profiling of the mpk1Delta cells during LoaOOH stress indicated that Mpk1p may be important in effecting changes to the cell surface and metabolism during LoaOOH exposure. Furthermore, it revealed that Mpk1p is required for the regulation of 97 LoaOOH-responsive transcripts. Evidence is presented that the activation of Mpk1p may be caused by the activation of protein kinase C by LoaOOH.
酿酒酵母能够对包括脂质过氧化产物在内的氧化剂作出反应。我们在此研究丝裂原活化蛋白激酶Mpk1p在抵御亚油酸氢过氧化物（LoaOOH）中的作用，LoaOOH是自由基攻击不饱和脂质的产物。发现MPK1是抵抗LoaOOH所必需的。此外，Mpk1p会因LoaOOH而迅速且短暂地磷酸化。这种磷酸化呈剂量依赖性，并且在外部培养基中低至1 μmol的亚致死浓度即可刺激其发生。已表明如此低的剂量可通过适应性过程导致对随后更高剂量攻击的抗性。然而，MPK1对于这种适应性反应并非必不可少。MPK1也不参与细胞周期调节，并且独立于细胞周期调节蛋白Oca1p发挥作用。在LoaOOH胁迫期间对mpk1Δ细胞进行转录谱分析表明，Mpk1p在LoaOOH暴露期间对细胞表面和代谢产生变化方面可能很重要。此外，研究表明Mpk1p是调控97个LoaOOH反应性转录本所必需的。有证据表明，Mpk1p的激活可能是由LoaOOH激活蛋白激酶C所致。
