Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
School of Pharmacy, Jiangxi University of Traditional Chinese Medicine, Nanchang, Jiangxi 330006, China.
Proc Natl Acad Sci U S A. 2017 Sep 5;114(36):E7450-E7459. doi: 10.1073/pnas.1707531114. Epub 2017 Aug 21.
Mixed-lineage kinase domain-like protein (MLKL) is essential for TNF-α-induced necroptosis. How MLKL promotes cell death is still under debate. Here we report that MLKL forms SDS-resistant, disulfide bond-dependent polymers during necroptosis in both human and mouse cells. MLKL polymers are independent of receptor-interacting protein kinase 1 and 3 (RIPK1/RIPK3) fibers. Large MLKL polymers are more than 2 million Da and are resistant to proteinase K digestion. MLKL polymers are fibers 5 nm in diameter under electron microscopy. Furthermore, the recombinant N-terminal domain of MLKL forms amyloid-like fibers and binds Congo red dye. MLKL mutants that cannot form polymers also fail to induce necroptosis efficiently. Finally, the compound necrosulfonamide conjugates cysteine 86 of human MLKL and blocks MLKL polymer formation and subsequent cell death. These results demonstrate that disulfide bond-dependent, amyloid-like MLKL polymers are necessary and sufficient to induce necroptosis.
混合谱系激酶结构域样蛋白（MLKL）对于 TNF-α 诱导的细胞坏死性死亡是必需的。然而，MLKL 如何促进细胞死亡仍存在争议。在此，我们报道在人和鼠细胞的坏死性死亡过程中，MLKL 形成不溶于 SDS、依赖二硫键的聚合物。MLKL 聚合物的形成并不依赖于受体相互作用蛋白激酶 1 和 3（RIPK1/RIPK3）纤维。在分子量上，大的 MLKL 聚合物超过 200 万道尔顿，且对蛋白酶 K 具有抗性。电子显微镜下，MLKL 聚合物呈现 5nm 直径的纤维状。此外，MLKL 的重组 N 端结构域形成淀粉样纤维并结合刚果红染料。不能形成聚合物的 MLKL 突变体也不能有效地诱导细胞坏死性死亡。最后，化合物 necrosulfonamide 与人类 MLKL 的半胱氨酸 86 结合并阻止 MLKL 聚合物的形成和随后的细胞死亡。这些结果表明，依赖二硫键、类似淀粉样的 MLKL 聚合物是诱导细胞坏死性死亡所必需的和充分的。
