Caspase cleavage product lacking amino-terminus of IκBα sensitizes resistant cells to TNF-α and TRAIL-induced apoptosis
Caspase cleavage product lacking amino-terminus of IκBα sensitizes resistant cells to TNF-α and TRAIL-induced apoptosis
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DOI：
10.1002/jcb.10139
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发表时间：
2002-01-01
影响因子：
4
通讯作者：
Jung, YK
中科院分区：
文献类型：
--
作者：
Kim, KW;Kim, BJ;Jung, YK
响应于多种信号，IkappaB α被蛋白酶体靶向磷酸化依赖性降解，从而激活NF-κ B。在这里，我们证明了IkappaB α的裂解产物在各种死亡信号中的作用。在分别暴露于肿瘤坏死因子（TNF）相关凋亡诱导配体（TRAIL）、Fas、血清剥夺或TNF-α的NIH 3 T3、Jurkat、Rat-1和L929细胞凋亡过程中，IkappaB α以半胱天冬酶依赖性方式裂解。在体外和体内裂解试验和定点诱变表明，caspase-3切割IkappaB α之间的Asp 31和Ser 32。缺乏氨基末端（1-31）的切割产物Δ I κ B α的表达使否则具有抗性的NIH 3 T3成纤维细胞对TNF-α或TRAIL诱导的细胞凋亡敏感，并且使HeLa肿瘤细胞对TNF-α敏感。DeltaIkappaB α与野生型或抗裂解（D31 E）IkappaB α突变体相比更促凋亡，并且在NIH 3 T3细胞中，DeltaIkappaB α引起的敏化与显性负突变体（S32，36 A）IkappaB α引起的敏化一样有效。DeltaIkappaB α抑制TNF-α或TRAIL诱导的NF-κ B的反式激活，这反映在转录酶报告活性上。相反，NF-κ B的p65亚基的表达抑制TNF-α、TRAIL和血清剥夺诱导的细胞死亡。相反，DeltaIkappaB α在增加已经对死亡信号（包括TRAIL、依托泊苷或紫杉醇）敏感的HeLa细胞的死亡率方面效果较差。这些结果表明，由各种死亡信号产生的Δ I κ B α通过抑制NF-κ B活性使细胞对凋亡敏感。J.细胞。85：334-345，2002. (C)2002 Wiley-Liss，Inc.
In response to a diverse array of signals, IkappaBalpha is targeted for phosphorylation-dependent degradation by the proteasome, thereby activating NF-kappaB. Here we demonstrate a role of the cleavage product of IkappaBalpha in various death signals. During apoptosis of NIH3T3, Jurkat, Rat-1, and L929 cells exposed to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), Fas, serum deprivation, or TNF-alpha, respectively, IkappaBalpha was cleaved in a caspase-dependent manner. In vitro and in vivo cleavage assays and site-directed mutagenesis showed that caspase-3 cleaved IkappaBalpha between Asp31 and Ser32. Expression of the cleavage product lacking amino-terminus (1-31), DeltaIkappaBalpha, sensitized otherwise resistant NIH3T3 fibroblast cells to apoptosis induced by TNF-alpha or TRAIL, and HeLa tumor cells to TNF-alpha. DeltaIkappaBalpha was more pro-apoptotic compared to wild type or cleavage-resistant (D31E)IkappaBalpha mutant and the sensitization elicited by DeltaIkappaBalpha was as effective as that by the dominant negative mutant, (S32,36A)IkappaBalpha, in NIH3T3 cells. DeltaIkappaBalpha suppressed the transactivation of NF-kappaB induced by TNF-alpha or TRAIL, as reflected by luciferase-reporter activity. Conversely, expression of the p65 subunit of NF-kappaB suppressed TNF-alpha, TRAIL-, and serum deprivation-induced cell death. On the contrary, DeltaIkappaBalpha was less effective at increasing the death rate of HeLa cells that were already sensitive to death signals including TRAIL, etoposide, or taxol. These results suggest that DeltaIkappaBalpha generated by various death signals sensitizes cells to apoptosis by suppressing NF-kappaB activity. J. Cell. Biochem. 85: 334-345, 2002. (C) 2002 Wiley-Liss, Inc.