Saw Swee Hock School of Public Health, National University of Singapore, Singapore.
Biochem Biophys Res Commun. 2012 Oct 12;427(1):11-7. doi: 10.1016/j.bbrc.2012.08.117. Epub 2012 Aug 30.
At present the role of autophagy in cell death and cell survival remains controversial, partly owning to the contradictory results from the immortalized mouse embryonic fibroblasts (MEFs) with knockout of different autophagy-related genes (Atg). Here we aimed to reexamine the role of autophagy in cell death under starvation and other stress conditions. First, different clones of Atg5 knockout MEFs had different susceptibility to stress-mediated cell death, indicating that it is the clonal variation, rather than the deficiency of Atg5 or autophagy per se that determines the susceptibility. Next, we tested two cell lines with inducible Atg5 deletion or expression and demonstrated that cells without Atg5 expression were more sensitive to starvation-induced apoptosis. Finally, we found that chloroquine was only effective in sensitizing starvation-induced cell death in Atg5-expressing cells, but not in Atg5-deficient cells. Such observations thus provide unequivocal evidence supporting the pro-survival function of autophagy under starvation. Moreover, our data demonstrate the usefulness of cells with inducible deletion or expression of Atg in the study of autophagy in cell death and cell survival.
目前，自噬在细胞死亡和细胞存活中的作用仍然存在争议，部分原因是由于具有不同自噬相关基因（Atg）缺失的永生化小鼠胚胎成纤维细胞（MEFs）的结果相互矛盾。在这里，我们旨在重新研究自噬在饥饿和其他应激条件下细胞死亡中的作用。首先，Atg5 敲除 MEF 的不同克隆对应激介导的细胞死亡具有不同的敏感性，这表明决定敏感性的是克隆变异，而不是 Atg5 或自噬本身的缺乏。接下来，我们测试了两种具有诱导型 Atg5 缺失或表达的细胞系，并证明没有 Atg5 表达的细胞对饥饿诱导的细胞凋亡更为敏感。最后，我们发现氯喹仅能有效敏化 Atg5 表达细胞的饥饿诱导细胞死亡，但不能敏化 Atg5 缺失细胞。这些观察结果因此提供了明确的证据，支持自噬在饥饿条件下的生存功能。此外，我们的数据证明了具有诱导型 Atg 缺失或表达的细胞在研究细胞死亡和细胞存活中的自噬的有用性。
