Activation of procaspase-8 in the death effector domain (DED) filaments of the death-inducing signaling complex (DISC) is a key step in apoptosis. In this study, a rationally designed cell-penetrating peptide, DEDid, was engineered to mimic the h2b helical region of procaspase-8-DED2 containing a highly conservative FL motif. Furthermore, mutations were introduced into the DEDid binding site of the procaspase-8 type I interface. Additionally, our data suggest that DEDid targets other type I DED interactions such as those of FADD. Both approaches of blocking type I DED interactions inhibited CD95L-induced DISC assembly, caspase activation and apoptosis. We showed that inhibition of procaspase-8 type I interactions by mutations not only diminished procaspase-8 recruitment to the DISC but also destabilized the FADD core of DED filaments. Taken together, this study offers insights to develop strategies to target DED proteins, which may be considered in diseases associated with cell death and inflammation.

死亡诱导信号复合物 (DISC) 死亡效应结构域 (DED) 细丝中 procaspase-8 的激活是细胞凋亡的关键步骤。在这项研究中，合理设计的细胞穿透肽 DEDid 被设计为模拟含有高度保守的 FL 基序的 procaspase-8-DED2 的h 2b 螺旋区域。此外，在 procaspase-8 I 型接口的 DEDid 结合位点中引入了突变。此外，我们的数据表明 DEDid 针对其他 I 型 DED 相互作用，例如 FADD 的相互作用。两种阻断 I 型 DED 相互作用的方法均抑制 CD95L 诱导的 DISC 组装、半胱天冬酶激活和细胞凋亡。我们发现，通过突变抑制 procaspase-8 I 型相互作用不仅减少了 procaspase-8 向 DISC 的募集，而且还破坏了 DED 丝的 FADD 核心的稳定性。总而言之，这项研究为开发针对 DED 蛋白的策略提供了见解，可以在与细胞死亡和炎症相关的疾病中考虑使用 DED 蛋白。