Molecular architecture of the DED chains at the DISC: regulation of procaspase-8 activation by short DED proteins c-FLIP and procaspase-8 prodomain
Molecular architecture of the DED chains at the DISC: regulation of procaspase-8 activation by short DED proteins c-FLIP and procaspase-8 prodomain
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DOI：
10.1038/cdd.2015.137
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发表时间：
2016-04-01
影响因子：
12.4
通讯作者：
Lavrik, I. N.
中科院分区：
文献类型：
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作者：
Schleich, K.;Buchbinder, J. H.;Lavrik, I. N.
CD95/Fas/APO-1 死亡诱导信号复合物 (DISC) 由 CD95、FADD、procaspase-8、procaspase-10 和 c-FLIP 组成，在细胞凋亡诱导中发挥关键作用。最近，研究表明 procaspase-8 的激活是由 DISC 的死亡效应域 (DED) 链驱动的。在这里，我们分析了链的分子结构以及短 DED 蛋白在链模型中调节 procaspase-8 激活中的作用。我们证明 DED 链主要由 procaspase-8 裂解产物，特别是其前结构域组成。 DED 链还包含 c-FLIP 和 procaspase-10，其含量比 procaspase-8 低 10 倍。我们发现，短的 c-FLIP 异构体可以通过与 procaspase-8 形成无活性的异二聚体来抑制过表达时 CD95 诱导的细胞死亡。此外，我们还使用实验和数学建模方法解决了链伸长终止的机制。我们发现 c-FLIP 和 procaspase-8 结构域前体都不终止 DED 链，而是 procaspase-8 的解离/缔合速率决定了链的稳定性，从而决定了其长度。此外，我们提供的证据表明 DISC 生成的 procaspase-8 前结构域构成了 procaspase-8 激活中的负反馈环。总的来说，这些发现为 DED 链中 caspase-8 的激活和细胞凋亡的启动提供了新的见解。
The CD95/Fas/APO-1 death-inducing signaling complex (DISC), comprising CD95, FADD, procaspase-8, procaspase-10, and c-FLIP, has a key role in apoptosis induction. Recently, it was demonstrated that procaspase-8 activation is driven by death effector domain (DED) chains at the DISC. Here, we analyzed the molecular architecture of the chains and the role of the short DED proteins in regulating procaspase-8 activation in the chain model. We demonstrate that the DED chains are largely composed of procaspase-8 cleavage products and, in particular, of its prodomain. The DED chain also comprises c-FLIP and procaspase-10 that are present in 10 times lower amounts compared with procaspase-8. We show that short c-FLIP isoforms can inhibit CD95-induced cell death upon overexpression, likely by forming inactive heterodimers with procaspase-8. Furthermore, we have addressed mechanisms of the termination of chain elongation using experimental and mathematical modeling approaches. We show that neither c-FLIP nor procaspase-8 prodomain terminates the DED chain, but rather the dissociation/association rates of procaspase-8 define the stability of the chain and thereby its length. In addition, we provide evidence that procaspase-8 prodomain generated at the DISC constitutes a negative feedback loop in procaspase-8 activation. Overall, these findings provide new insights into caspase-8 activation in DED chains and apoptosis initiation.