CNRS IBGC UMR 5095, Bordeaux, France.
PLoS One. 2010 Jan 18;5(1):e8755. doi: 10.1371/journal.pone.0008755.
Autophagy is described to be involved in homeostasis, development and disease, both as a survival and a death process. Its involvement in cell death proceeds from interrelationships with the apoptotic pathway. We focused on survival autophagy and investigated its interplays with the apoptotic machinery. We found that while Mcl-1 remained ineffective, Bcl-2 and Bcl-xL were required for starved cells to display a fully functional autophagic pathway as shown by proteolysis activity and detection of autophagic vesicles. Such pro-autophagic functions of Bcl-2 and Bcl-xL were independent of Bax. However they appeared to operate through non redundant mechanisms as Bcl-xL wielded a tighter control than Bcl-2 over the regulation of autophagy: unlike Bcl-2, Bcl-xL and Atg7 manipulation yielded identical phenotypes suggesting they could be components of the same signalling pathway; Bcl-xL subcellular localisation was modified upon starvation, and importantly Bcl-xL acted independently of Beclin 1. Still an intact BH3-binding site was required for Bcl-xL to stimulate a fully functional autophagic pathway. This study highlights that, in addition to their well-established anti-death function during apoptosis, Bcl-2 and Bcl-xL have a broader role in cell survival. Should Bcl-2 and Bcl-xL stand at the cross-roads between pro-survival and pro-death autophagy, this study introduces the new concept that the regulation of autophagy by Bcl-2 and Bcl-xL is adjusted according to its survival or death outcome.
自噬被描述为参与体内平衡、发育和疾病,既是生存过程也是死亡过程。它在细胞死亡中的作用来源于与凋亡途径的相互关系。我们专注于存活自噬,并研究了它与凋亡机制的相互作用。我们发现,虽然 Mcl-1 仍然无效,但 Bcl-2 和 Bcl-xL 是饥饿细胞显示完全功能性自噬途径所必需的,如蛋白水解活性和自噬小体的检测所示。Bcl-2 和 Bcl-xL 的这种促进自噬的功能独立于 Bax。然而,它们似乎通过非冗余机制起作用,因为 Bcl-xL 比 Bcl-2 更严格地控制自噬的调节:与 Bcl-2 不同,Bcl-xL 和 Atg7 的操作产生相同的表型,表明它们可能是同一信号通路的组成部分;Bcl-xL 在饥饿时的亚细胞定位发生改变,重要的是 Bcl-xL 独立于 Beclin 1 起作用。仍然需要完整的 BH3 结合位点才能使 Bcl-xL 刺激完全功能性自噬途径。这项研究强调,除了在凋亡过程中它们已确立的抗死亡功能外,Bcl-2 和 Bcl-xL 在细胞存活中具有更广泛的作用。如果 Bcl-2 和 Bcl-xL 处于抗生存和促死亡自噬的十字路口,本研究提出了一个新概念,即 Bcl-2 和 Bcl-xL 对自噬的调节根据其生存或死亡结果进行调整。