Caspase proteolysis of desmin produces a dominant-negative inhibitor of intermediate filaments and promotes apoptosis
Caspase proteolysis of desmin produces a dominant-negative inhibitor of intermediate filaments and promotes apoptosis
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DOI：
10.1074/jbc.m212021200
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发表时间：
2003-02-28
影响因子：
4.8
通讯作者：
Cryns, VL
中科院分区：
文献类型：
--
作者：
Chen, F;Chang, R;Cryns, VL
半胱天冬酶对关键细胞骨架蛋白（包括几种中间丝蛋白）的裂解会引发细胞骨架的剧烈分解，这是细胞凋亡的特征。在这里，我们将肌肉特异性中间丝蛋白结蛋白描述为一种新型半胱天冬酶底物。在体外和正在经历凋亡的肌原性细胞中，结蛋白在其 L1-L2 连接结构域（VEMD 向下箭头 M-264）中的保守 Asp 残基处被 caspase-6 选择性切割。我们证明，半胱天冬酶在 Asp 263 处对结蛋白进行切割具有重要的功能后果，包括产生氨基末端切割产物 N-结蛋白，该产物无法组装成中间丝，而是形成大的细胞内聚集体。此外，对于结蛋白和结构相关的中间丝蛋白波形蛋白而言，N-结蛋白均充当丝组装的显性失活抑制剂。我们还表明，抗 caspase 裂解的 desmin D263E 突变体的稳定表达可部分保护细胞免受肿瘤坏死因子-α 诱导的细胞凋亡。综上所述，这些结果表明，Caspase 对 Asp(263) 处的 desmin 进行蛋白水解，产生中间丝的显性失活抑制剂，并积极参与细胞凋亡的执行。此外，这些发现提供了进一步的证据，表明中间丝细胞骨架在细胞凋亡过程中已被系统地靶向降解。
Caspase cleavage of key cytoskeletal proteins, including several intermediate filament proteins, triggers the dramatic disassembly of the cytoskeleton that characterizes apoptosis. Here we describe the muscle-specific intermediate filament protein desmin as a novel caspase substrate. Desmin is cleaved selectively at a conserved Asp residue in its L1-L2 linker domain (VEMD down arrow M-264) by caspase-6 in vitro and in myogenic cells undergoing apoptosis. We demonstrate that caspase cleavage of desmin at Asp 263 has important functional consequences, including the production of an amino-terminal cleavage product, N-desmin, which is unable to assemble into intermediate filaments, instead forming large intracellular aggregates. Moreover, N-desmin functions as a dominant-negative inhibitor of filament assembly, both for desmin and the structurally related intermediate filament protein vimentin. We also show that stable expression of a caspase cleavage-resistant desmin D263E mutant partially protects cells from tumor necrosis factor-alpha-induced apoptosis. Taken together, these results indicate that caspase proteolysis of desmin at Asp(263) produces a dominant-negative inhibitor of intermediate filaments and actively participates in the execution of apoptosis. In addition, these findings provide further evidence that the intermediate filament cytoskeleton has been targeted systematically for degradation during apoptosis.