Department of Biochemistry, College of Life science and Biotechnology, Yonsei University, Seoul, Korea.
Environmental Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Korea.
Cell Death Differ. 2020 Nov;27(11):3065-3081. doi: 10.1038/s41418-020-0561-9. Epub 2020 May 26.
Necroptosis is a form of regulated cell death caused by formation of the necrosome complex. However, the factors modulating this process and the systemic pathophysiological effects of necroptosis are yet to be understood. Here, we identified that Beclin 1 functions as an anti-necroptosis factor by being recruited into the necrosome complex upon treatment with TNFα, Smac mimetic, and pan-caspase inhibitor and by repressing MLKL oligomerisation, thus preventing the disruption of the plasma membrane. Cells ablated or knocked-out for Beclin 1 become sensitised to necroptosis in an autophagy-independent manner without affecting the necrosome formation itself. Interestingly, the recruitment of Beclin 1 into the necrosome complex is dependent on the activation and phosphorylation of MLKL. Biochemically, the coiled-coil domain (CCD) of Beclin 1 binds to the CCD of MLKL, which restrains the oligomerisation of phosphorylated MLKL. Finally, Beclin 1 depletion was found to promote necroptosis in leukaemia cells and enhance regression of xenografted-tumour upon treatment with Smac mimetics and caspase inhibitors. These results suggest that Beclin 1 functions as a negative regulator in the execution of necroptosis by suppressing MLKL oligomerisation.
细胞坏死是一种由坏死体复合物形成引起的受调控的细胞死亡形式。然而，调节这一过程的因素以及细胞坏死的系统病理生理学效应仍有待了解。在这里，我们发现 Beclin 1 作为一种抗细胞坏死因子，通过在 TNFα、Smac 模拟物和泛半胱天冬酶抑制剂处理时被招募到坏死体复合物中，并通过抑制 MLKL 寡聚化，从而防止质膜破裂，从而发挥作用。细胞中 Beclin 1 的缺失或敲除会导致其在不影响坏死体形成本身的情况下，以一种非自噬依赖性的方式对细胞坏死变得敏感。有趣的是，Beclin 1 被招募到坏死体复合物中依赖于 MLKL 的激活和磷酸化。从生化角度来看，Beclin 1 的卷曲螺旋结构域（CCD）与 MLKL 的 CCD 结合，从而抑制磷酸化 MLKL 的寡聚化。最后，发现 Beclin 1 的缺失会促进白血病细胞中的细胞坏死，并增强 Smac 模拟物和半胱天冬酶抑制剂治疗时异种移植肿瘤的消退。这些结果表明，Beclin 1 通过抑制 MLKL 寡聚化，作为细胞坏死执行的负调控因子发挥作用。
