Li X, Commane M, Jiang Z, Stark G R
Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Proc Natl Acad Sci U S A. 2001 Apr 10;98(8):4461-5. doi: 10.1073/pnas.071054198. Epub 2001 Apr 3.
Mutant I1A cells, lacking IL-1 receptor-associated kinase (IRAK) mRNA and protein, have been used to study the involvement of IRAK in NFkappaB and c-Jun N-terminal kinase (JNK) activation. A series of IRAK deletion constructs were expressed in I1A cells, which were then tested for their ability to respond to IL-1. Both the N-terminal death domain and the C-terminal region of IRAK are required for IL-1-induced NFkappaB and JNK activation, whereas the N-proximal undetermined domain is required for the activation of NFkappaB but not JNK. The phosphorylation and ubiquitination of IRAK deletion mutants correlate tightly with their ability to activate NFkappaB in response to IL-1, but IRAK can mediate IL-1-induced JNK activation without being phosphorylated. These studies reveal that the IL-1-induced signaling pathways leading to NFkappaB and JNK activation diverge either at IRAK or at a point nearer to the receptor.
缺乏白细胞介素-1受体相关激酶(IRAK)mRNA和蛋白质的突变I1A细胞已被用于研究IRAK在核因子κB(NFκB)和c-Jun氨基末端激酶(JNK)激活中的作用。一系列IRAK缺失构建体在I1A细胞中表达,然后测试它们对白细胞介素-1作出反应的能力。IRAK的N末端死亡结构域和C末端区域对于白细胞介素-1诱导的NFκB和JNK激活都是必需的,而靠近N端的未确定结构域对于NFκB的激活是必需的,但对JNK的激活不是必需的。IRAK缺失突变体的磷酸化和泛素化与其响应白细胞介素-1激活NFκB的能力紧密相关,但IRAK可以在不被磷酸化的情况下介导白细胞介素-1诱导的JNK激活。这些研究表明,导致NFκB和JNK激活的白细胞介素-1诱导信号通路在IRAK处或在更靠近受体的点处出现分歧。