Department of Biochemistry and Molecular Biology and the Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
J Biol Chem. 2013 Apr 19;288(16):11378-83. doi: 10.1074/jbc.M112.448795. Epub 2013 Mar 11.
Human pyrin with gain-of-function mutations in its B30.2/SPRY domain causes the autoinflammatory disease familial Mediterranean fever by assembling an ASC-dependent inflammasome that activates caspase-1. Wild-type human pyrin can also form an inflammasome complex with ASC after engagement by autoinflammatory PSTPIP1 mutants. How the pyrin inflammasome is activated in the absence of disease-associated mutations is not yet known. We report here that ribotoxic stress triggers the assembly of the human pyrin inflammasome, leading to ASC oligomerization and caspase-1 activation in THP-1 macrophages and in a 293T cell line stably reconstituted with components of the pyrin inflammasome. Knockdown of pyrin and selective inhibition of p38 MAPK greatly attenuated caspase-1 activation by ribotoxic stress, whereas expression of the conditional mutant ΔMEKK3:ER* allowed the activation of caspase-1 without ribotoxic stress. Disruption of microtubules by colchicine also inhibited pyrin inflammasome activation by ribotoxic stress. Together, our results indicate that ribotoxic stress activates the human pyrin inflammasome through a mechanism that requires p38 MAPK signaling and microtubule stability.
人源 pyrin 的 B30.2/SPRY 结构域发生功能获得性突变会导致家族性地中海热这一自身炎症性疾病，其机制是形成 ASC 依赖性的炎性小体，从而激活半胱天冬酶-1。野生型人源 pyrin 在与自身炎症性 PSTPIP1 突变体结合后，也可以与 ASC 形成炎性小体复合物。目前尚不清楚在没有与疾病相关的突变时，pyrin 炎性小体是如何被激活的。我们在此报告，核糖体应激会触发人源 pyrin 炎性小体的组装，导致 THP-1 巨噬细胞和稳定重建了 pyrin 炎性小体成分的 293T 细胞系中 ASC 寡聚化和半胱天冬酶-1 的激活。pyrin 的敲低和 p38 MAPK 的选择性抑制极大地减弱了核糖体应激诱导的半胱天冬酶-1 的激活，而条件性突变体 ΔMEKK3:ER* 的表达则允许在没有核糖体应激的情况下激活半胱天冬酶-1。秋水仙碱破坏微管也会抑制核糖体应激诱导的 pyrin 炎性小体的激活。综上所述，我们的研究结果表明，核糖体应激通过需要 p38 MAPK 信号和微管稳定性的机制激活人源 pyrin 炎性小体。
