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.

坏死性凋亡是由坏死体复合物的形成引起的一种受调节的细胞死亡形式。然而，调节这一过程的因素和坏死性凋亡的全身病理生理效应尚待了解。在这里，我们发现 Beclin 1 在用 TNFα、Smac 模拟物和泛半胱天冬酶抑制剂治疗后被募集到坏死体复合物中并通过抑制 MLKL 寡聚化，从而防止质膜的破坏，从而起到抗坏死性凋亡因子的作用。Beclin 1 被消融或敲除的细胞以不依赖自噬的方式对坏死性凋亡敏感，而不会影响坏死体形成本身。有趣的是，将 Beclin 1 募集到坏死体复合物取决于 MLKL 的激活和磷酸化。生化上，Beclin 1 的卷曲螺旋结构域 (CCD) 与 MLKL 的 CCD 结合，从而抑制了磷酸化 MLKL 的寡聚化。最后，发现 Beclin 1 耗竭可促进白血病细胞的坏死性凋亡，并在用 Smac 模拟物和半胱天冬酶抑制剂治疗后增强异种移植肿瘤的消退。这些结果表明，Beclin 1 通过抑制 MLKL 寡聚化在坏死性凋亡的执行中起负调节作用。