Inhibition of translation initiation by volatile anesthetics involves nutrient-sensitive GCN-independent and -dependent processes in yeast
Inhibition of translation initiation by volatile anesthetics involves nutrient-sensitive GCN-independent and -dependent processes in yeast
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DOI：
10.1091/mbc.e05-02-0127
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发表时间：
2005-08-01
影响因子：
3.3
通讯作者：
Keil, RL
中科院分区：
文献类型：
--
作者：
Palmer, LK;Shoemaker, JL;Keil, RL
挥发性麻醉剂，包括异氟烷影响所有的细胞检查，但其作用机制仍然未知。为了研究麻醉剂作用的细胞基础，我们正在研究酿酒酵母突变体对麻醉剂反应的改变。zzz 3 -1突变使酵母对异氟烷具有耐药性，并且是GCN 3的等位基因。Gcn 3 p在进化上保守的一般氨基酸控制（GCN）途径中起作用，该途径通过真核起始因子2（eIF 2 α）的α亚基的磷酸化来调节蛋白质合成和基因表达以响应营养物质的可用性。eIF 2 α的过度磷酸化在氨基酸饥饿期间抑制翻译起始。异氟烷快速（< 15分钟）抑制酵母细胞分裂和氨基酸摄取。出乎意料的是，eIF 2 α的磷酸化在初始暴露后显著降低，尽管随后发生了过度磷酸化。即使eIF 2 α磷酸化降低，异氟烷也可抑制翻译起始，且这种抑制作用不依赖于GCN。抑制的维持需要eIF 2 α的GCN依赖性过度磷酸化。因此，显示独特功能的两个营养敏感阶段促进异氟烷诱导的翻译起始抑制。快速阶段是GCN独立的，显然以前没有被认识到。维持期是GCN依赖性的，需要抑制增强的eIF 2 α磷酸化引起的一般翻译。令人惊讶的是，如图所示，转录激活因子Gcn 4p不影响麻醉反应。
Volatile anesthetics including isoflurane affect all cells examined, but their mechanisms of action remain unknown. To investigate the cellular basis of anesthetic action, we are studying Saccharomyces cerevisiae mutants altered in their response to anesthetics. The zzz3-1 mutation renders yeast isoflurane resistant and is an allele of GCN3. Gcn3p functions in the evolutionarily conserved general amino acid control (GCN) pathway that regulates protein synthesis and gene expression in response to nutrient availability through phosphorylation of the a subunit of eukaryotic initiation factor 2 (eIF2 alpha. Hyperphosphorylation of eIF2 alpha inhibits translation initiation during amino acid starvation. Isoflurane rapidly (in < 15 min) inhibits yeast cell division and amino acid uptake. Unexpectedly, phosphorylation of eIF2 alpha decreased dramatically upon initial exposure although hyperphosphorylation occurred later. Translation initiation was inhibited by isoflurane even when eIF2 alpha phosphorylation decreased and this inhibition was GCN-independent. Maintenance of inhibition required GCN-dependent hyperphosphorylation of eIF2 alpha. Thus, two nutrient-sensitive stages displaying unique features promote isoflurane-induced inhibition of translation initiation. The rapid phase is GCN-independent and apparently has not been recognized previously. The maintenance phase is GCN-dependent and requires inhibition of general translation imparted by enhanced eIF2 alpha phosphorylation. Surprisingly, as shown here, the transcription activator Gcn4p does not affect anesthetic response.