Expression of Nlrp1b Inflammasome Components in Human Fibroblasts Confers Susceptibility to Anthrax Lethal Toxin
Expression of Nlrp1b Inflammasome Components in Human Fibroblasts Confers Susceptibility to Anthrax Lethal Toxin
复制标题
DOI：
10.1128/iai.00276-09
复制
发表时间：
2009-10-01
影响因子：
3.1
通讯作者：
Mogridge, Jeremy
中科院分区：
文献类型：
--
作者：
Liao, Kuo-Chieh;Mogridge, Jeremy
炭疽致命毒素导致巨噬细胞和树突状细胞从一些小鼠品系进行半胱天冬酶-1依赖性细胞死亡。这一过程的核心是NOD样受体Nlrp 1b（Nalp 1b），它检测到中毒，然后自我缔合形成一种复合物，称为炎性小体，能够激活半胱氨酸天冬氨酸蛋白酶-1酶原。由Nlrp 1b直接检测到的信号的性质尚不清楚，并且对炎性小体组装的机制知之甚少。在这里，我们证明，转染人成纤维细胞与质粒编码鼠Nlrp 1b和半胱天冬酶原-1是足以赋予易感性致死毒素介导的细胞死亡。正如在小鼠巨噬细胞中观察到的，致死毒素和蛋白酶体的酶活性都是Nlrp 1b炎性体激活所必需的，并且这种激活导致白细胞介素-1 β前体加工。白细胞介素-1 β从细胞中的释放不依赖于细胞裂解，因为其分泌不受阻止培养基中乳酸脱氢酶出现的细胞保护剂的影响。我们产生了组成型活性突变体的Nlrp 1b的氨基末端缺失的蛋白质，并观察到，激活procaspase-1的能力是依赖于CARD结构域，结合procaspase-1，和一个区域相邻的CARD结构域，促进自我关联。我们的研究结果表明，致命毒素可以激活Nlrp 1b在非髓系细胞系，并与工作，表明激活诱导接近的半胱氨酸天冬氨酸蛋白酶原-1。
Anthrax lethal toxin causes macrophages and dendritic cells from some mouse strains to undergo caspase-1-dependent cell death. Central to this process is the NOD-like receptor Nlrp1b (Nalp1b), which detects intoxication and then self-associates to form a complex, termed an inflammasome, that is capable of activating the procaspase-1 zymogen. The nature of the signal detected directly by Nlrp1b is not known, and the mechanisms of inflammasome assembly are poorly understood. Here, we demonstrate that transfection of human fibroblasts with plasmids encoding murine Nlrp1b and procaspase-1 was sufficient to confer susceptibility to lethal toxin-mediated death on the cells. As has been observed in murine macrophages, the enzymatic activities of lethal toxin and the proteasome were both required for activation of the Nlrp1b inflammasome and this activation led to prointerleukin-1 beta processing. Release of interleukin-1 beta from cells was not dependent on cell lysis, as its secretion was not affected by an osmoprotectant that prevented the appearance of lactate dehydrogenase in the culture medium. We generated constitutively active mutants of Nlrp1b by making amino-terminal deletions to the protein and observed that the ability to activate procaspase-1 was dependent on the CARD domain, which bound procaspase-1, and a region adjacent to the CARD domain that promoted self-association. Our results demonstrate that lethal toxin can activate Nlrp1b in a nonmyeloid cell line and are consistent with work that suggests that activation induces proximity of procaspase-1.