Ferulic Acid Induces Mammalian Target of Rapamycin Inactivation in Cultured Mammalian Cells
Ferulic Acid Induces Mammalian Target of Rapamycin Inactivation in Cultured Mammalian Cells
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DOI：
10.1248/bpb.b12-00695
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发表时间：
2013-01-01
影响因子：
2
通讯作者：
Ueno, Takashi
中科院分区：
文献类型：
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作者：
Bian, Zehua;Furuya, Norihiko;Ueno, Takashi
阿魏酸(FA)是一种天然存在的多酚，大量存在于蔬菜和米糠中，已知具有强大的抗氧化活性，从而保护细胞免受氧化应激的伤害。在本研究中，我们发现阿魏酸除了具有已知的抗氧化活性外，还对雷帕霉素靶标(MTOR)信号通路发挥重要的抑制作用。在HeLa细胞和用常规营养丰富的培养液培养的小鼠原代肝细胞中，阿魏酸(1 MM)可诱导S6激酶及其底物核糖体S6的去磷酸化。阿魏酸的脱磷活性几乎与mTOR抑制剂雷帕霉素(TORC1)相当。接下来，我们研究了阿魏酸对自噬的影响，自噬是细胞的一个主要降解过程，对维持细胞内环境平衡有重要作用。用传统的绿色荧光蛋白-微管相关蛋白IA/IB轻链3(GFP-LC3)斑点分析评价自噬通量，我们发现在富含血清的条件下，阿魏酸能显著增加HeLa细胞中GFP-LC3点的数量。阿魏酸对自噬通量的增强作用与雷帕霉素相当。此外，阿魏酸显著促进C-14-亮氨酸标记的长寿命蛋白在营养丰富的培养小鼠肝细胞中的自噬降解，而不是在营养缺乏的条件下。这些结果表明，阿魏酸在抑制mTOR(TORC1)方面几乎与雷帕霉素相当，这使其成为基础自噬的有效激活剂。
Ferulic acid (FA), a naturally occurring polyphenol abundant in vegetables and rice bran, is known to possess a potent antioxidant activity, thereby protecting cells from oxidative stress. In the present study, we show that in addition to its known anti-oxidant activity, ferulic acid exerts substantial inhibitory activity on cellular mammalian target of rapamycin (mTor)-signaling pathways. In HeLa cells and mouse primary hepatocytes cultured with conventional nutrient-rich media, ferulic acid (1 mM) elicited dephosphorylation of S6 kinase and its substrate ribosomal S6. The dephosphorylating activity of ferulic acid was almost comparable to that of rapamycin, an established mTor inhibitor (TORC1). We next investigated the effect of ferulic acid on autophagy, a major cellular degradative process, which significantly contributes to the maintenance of cell homeostasis. Using a conventional green fluorescent protein-microtubule-associated protein IA/IB light chain 3 (GFP-LC3) dot assay to evaluate autophagy flux, we showed that ferulic acid caused a significant increase in GFP-LC3 dots under serum-rich conditions in HeLa cells. The enhancement of autophagic flux by ferulic acid was almost equivalent to that of rapamycin. Furthermore, ferulic acid significantly enhanced autophagic degradation of C-14-leucine-labeled long-lived proteins of cultured mouse hepatocytes under nutrient-rich conditions, but not nutrient-deprived conditions. These results indicate that ferulic acid is almost the equivalent of rapamycin in the ability to inhibit mTor (TORC1), which makes it a potent activator of basal autophagy.