Department of Geriatrics, Jiangsu Provincial Key Laboratory of Geriatrics, the First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China.
Department of Anesthesiology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China.
Cell Death Differ. 2020 Sep;27(9):2651-2667. doi: 10.1038/s41418-020-0536-x. Epub 2020 Apr 24.
Liver dysfunction is strongly associated with poor survival of sepsis patients. Cytosolic lipopolysaccharide (LPS) sensing by Caspase-4/5/11 for pyroptosis activation is a major driver of the development of sepsis. Studies in macrophages and endothelial cells have demonstrated that LPS is inactivated by acyloxyacyl hydrolase (AOAH) and leading to desensitizing Caspase-4/5/11 to LPS. However, little is known about the cytosolic LPS-induced pyroptosis in hepatocytes during sepsis. Heat shock protein 12A (HSPA12A) is a novel member of the HSP70 family. Here, we report that LPS increased HSPA12A nuclear translocation in hepatocytes, while knockout of HSPA12A (Hspa12a) in mice promoted LPS-induced acute liver injury. We also noticed that the LPS-induced Caspase-11 activation and its cleavage of gasdermin D (GSDMD) to produce the membrane pore-forming GSDMD (markers of pyroptosis) were greater in livers of Hspa12a mice compared with its wild type controls. Loss- and gain-of-function studies showed that HSPA12A deficiency promoted, whereas HSPA12A overexpression inhibited, cytosolic LPS accumulation, Caspase-11 activation and GSDMD generation in primary hepatocytes following LPS incubation. Notably, LPS-induced AOAH expression was suppressed by HSPA12A deficiency, whereas AOAH overexpression reversed the HSPA12A deficiency-induced promotion of LPS-evoked and Caspase-11-mediated pyroptosis of hepatocytes. In-depth molecular analysis showed that HSPA12A interacted directly with peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and increased its nuclear translocation, thereby inducing AOAH expression for cytosolic LPS inactivation, which ultimately leading to inhibition of the Caspase-11 mediated pyroptosis of hepatocytes. Taken together, these findings revealed HSPA12A as a novel player against LPS-induced liver injury by inhibiting cytosolic LPS-induced hepatocyte pyroptosis via PGC-1α-mediated AOAH expression. Therefore, targeting hepatocyte HSPA12A represents a viable strategy for the management of liver injury in sepsis patients.
肝功能障碍与脓毒症患者的生存预后密切相关。细胞质中内毒素（LPS）被胱天蛋白酶-4/5/11 识别，从而激活细胞焦亡，这是脓毒症发展的主要驱动因素。在巨噬细胞和内皮细胞中的研究表明，LPS 被酰氧基酰基水解酶（AOAH）失活，从而使 Caspase-4/5/11 对 LPS 脱敏。然而，对于脓毒症期间肝细胞中细胞质 LPS 诱导的细胞焦亡知之甚少。热休克蛋白 12A（HSPA12A）是 HSP70 家族的一个新成员。在这里，我们报告 LPS 增加了肝细胞中 HSPA12A 的核易位，而在小鼠中敲除 HSPA12A（Hspa12a）则促进了 LPS 诱导的急性肝损伤。我们还注意到，与野生型对照相比，Hspa12a 小鼠肝脏中 LPS 诱导的 Caspase-11 激活及其对 Gasdermin D（GSDMD）的切割产生的膜孔形成 GSDMD（细胞焦亡的标志物）更大。缺失和功能获得研究表明，HSPA12A 缺乏促进，而 HSPA12A 过表达抑制，LPS 孵育后原代肝细胞中细胞质 LPS 积累、Caspase-11 激活和 GSDMD 生成。值得注意的是，LPS 诱导的 AOAH 表达受 HSPA12A 缺乏抑制，而过表达 AOAH 逆转了 HSPA12A 缺乏诱导的 LPS 诱导和 Caspase-11 介导的肝细胞焦亡。深入的分子分析表明，HSPA12A 直接与过氧化物酶体增殖物激活受体 γ 共激活因子 1α（PGC-1α）相互作用，增加其核易位，从而诱导 AOAH 表达，使细胞质 LPS 失活，最终抑制 Caspase-11 介导的肝细胞焦亡。总之，这些发现表明 HSPA12A 通过 PGC-1α 介导的 AOAH 表达抑制 LPS 诱导的肝细胞焦亡，从而成为一种新的对抗 LPS 诱导肝损伤的因子。因此，靶向肝细胞 HSPA12A 可能成为脓毒症患者肝损伤管理的一种可行策略。
