State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.
Autophagy. 2010 Jan;6(1):61-6. doi: 10.4161/auto.6.1.10326. Epub 2010 Jan 13.
Autophagy functions as an important catabolic mechanism by mediating the turnover of intracellular organelles and protein complexes. Although the induction of autophagy by starvation has been extensively studied, we still understand very little about how autophagy is regulated under normal nutritional conditions. Here we describe a study using a small molecule autophagy inducer, fluspirilene, as a tool to explore the mechanism of autophagy induction in normal living cells. We confirm the activity of fluspirilene in inhibiting Ca(2+) flux. Furthermore, we show that reducing intracellular Ca(2+) prevents the cleavage of ATG5, which in turn increases the levels of full-length ATG5 and ATG12-ATG5 conjugate. Using siRNA mediated gene silencing, we demonstrate that inhibiting calpain1 is sufficient to induce autophagy in living cells. We conclude that calpain1 plays an important role in controlling the levels of autophagy in normal living cells by regulating the levels of a key signaling molecule, ATG12-ATG5 conjugate.
自噬作为一种重要的分解代谢机制，通过介导细胞内细胞器和蛋白质复合物的周转来发挥作用。尽管饥饿诱导自噬的作用已经得到了广泛的研究，但我们对自噬在正常营养条件下是如何被调控的仍然知之甚少。在这里，我们使用小分子自噬诱导剂氟哌噻吨作为一种工具来研究正常活细胞中自噬诱导的机制。我们证实氟哌噻吨能够抑制 Ca(2+) 流。此外，我们表明降低细胞内 Ca(2+) 可以阻止 ATG5 的切割，从而增加全长 ATG5 和 ATG12-ATG5 缀合物的水平。通过 siRNA 介导的基因沉默，我们证明抑制钙蛋白酶 1 足以诱导活细胞中的自噬。我们的结论是，钙蛋白酶 1 通过调节关键信号分子 ATG12-ATG5 缀合物的水平，在正常活细胞中控制自噬水平方面发挥着重要作用。
