Li Shuo, Peng Weijiao, Li Jiafang, Hao Gaixiang, Geng Xuyun, Sun Jinsheng
Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Xiqing District, Tianjin 300387, China.
Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Xiqing District, Tianjin 300387, China.
Fish Shellfish Immunol. 2017 Aug;67:536-545. doi: 10.1016/j.fsi.2017.06.043. Epub 2017 Jun 16.
Caspase1 is a member of inflammatory Caspases that play important roles in the innate immune system. Although several teleost caspase1 genes have been identified, their partner proteins and implication in extracellular ATP-mediated immune signaling in fish are still very limited. Here we identified and characterized a caspase1 gene, named JfCaspase1, from Japanese flounder Paralichthys olivaceus. JfCaspase1 mRNA was constitutively expressed in all examined normal tissues with high expression in skin and gills and moderate expression in the enriched Japanese flounder head kidney macrophages (HKMs) and peripheral blood leukocytes (PBLs). JfCaspase1 was initially down-regulated but significantly up-regulated at the later stage upon LPS and poly(I:C) challenges in the HKMs. JfCaspase1 was also up-regulated in the Japanese flounder immune-related tissues including head kidney, gill and spleen by bacterial challenge with Edwardsiella tarda. JfCaspase1 protein is comprised of 384 amino acid residues with a calculated molecular mass of 43.75 kDa and is phylogenetically close to fish Caspase1 proteins. JfCaspase1 was co-immunopercipitated with Japanese flounder apoptosis-associated speck-like protein (ASC) when co-expressed in HeLa cells, suggesting that there is a potential interaction between the two proteins. In addition, we showed that extracellular ATP, a potent signaling molecule in activating innate immune response, rapidly up-regulates JfCaspase1 expression and enhances its enzymatic activity both in the HKMs and PBLs. Our findings indicated that the inflammatory JfCaspase1 interacted with ASC protein is implicated in the extracellular ATP-mediated immune signaling in fish.
半胱天冬酶1是炎症性半胱天冬酶家族的成员，在天然免疫系统中发挥重要作用。尽管已经鉴定出几种硬骨鱼的半胱天冬酶1基因，但它们的伴侣蛋白以及在鱼类细胞外ATP介导的免疫信号传导中的作用仍然非常有限。在此，我们从日本牙鲆（Paralichthys olivaceus）中鉴定并表征了一个名为JfCaspase1的半胱天冬酶1基因。JfCaspase1 mRNA在所有检测的正常组织中组成性表达，在皮肤和鳃中高表达，在富集的日本牙鲆头肾巨噬细胞（HKMs）和外周血白细胞（PBLs）中中度表达。在HKMs中，JfCaspase1最初被下调，但在LPS和聚肌苷酸:聚胞苷酸（poly(I:C)）刺激后期显著上调。迟缓爱德华氏菌（Edwardsiella tarda）细菌攻击也使日本牙鲆免疫相关组织（包括头肾、鳃和脾脏）中的JfCaspase1上调。JfCaspase1蛋白由384个氨基酸残基组成，计算分子量为43.75 kDa，在系统发育上与鱼类半胱天冬酶1蛋白相近。当在HeLa细胞中共表达时，JfCaspase1与日本牙鲆凋亡相关斑点样蛋白（ASC）共免疫沉淀，表明这两种蛋白之间存在潜在相互作用。此外，我们发现细胞外ATP是激活天然免疫反应的有效信号分子，在HKMs和PBLs中均可迅速上调JfCaspase1表达并增强其酶活性。我们的研究结果表明，与ASC蛋白相互作用的炎症性JfCaspase1参与了鱼类细胞外ATP介导的免疫信号传导。
