State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, China.
State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, China.
Fish Shellfish Immunol. 2024 Oct;153:109805. doi: 10.1016/j.fsi.2024.109805. Epub 2024 Aug 3.
The production of type I interferon is tightly regulated to prevent excessive immune activation. However, the role of selective autophagy receptor SQSTM1 in this regulation in teleost remains unknown. In this study, we cloned the triploid fish SQSTM1 (3nSQSTM1), which comprises 1371 nucleotides, encoding 457 amino acids. qRT-PCR data revealed that the transcript levels of SQSTM1 in triploid fish were increased both in vivo and in vitro following spring viraemia of carp virus (SVCV) infection. Immunofluorescence analysis confirmed that 3nSQSTM1 was mainly distributed in the cytoplasm. Luciferase reporter assay results showed that 3nSQSTM1 significantly blocked the activation of interferon promoters induced by 3nMDA5, 3nMAVS, 3nTBK1, and 3nIRF7. Co-immunoprecipitation assays further confirmed that 3nSQSTM1 could interact with both 3nTBK1 and 3nIRF7. Moreover, upon co-transfection, 3nSQSTM1 significantly inhibited the antiviral activity mediated by TBK1 and IRF7. Mechanistically, 3nSQSTM1 decreased the TBK1 phosphorylation and its interaction with 3nIRF7, thereby suppressing the subsequent antiviral response. Notably, we discovered that 3nSQSTM1 also interacted with SVCV N and P proteins, and these viral proteins may exploit 3nSQSTM1 to further limit the host's antiviral innate immune responses. In conclusion, our study demonstrates that 3nSQSTM1 plays a pivotal role in negatively regulating the interferon signaling pathway by targeting 3nTBK1 and 3nIRF7.
I 型干扰素的产生受到严格调控，以防止过度的免疫激活。然而，选择性自噬受体 SQSTM1 在硬骨鱼类中的这种调控作用尚不清楚。在本研究中，我们克隆了三倍体鱼 SQSTM1（3nSQSTM1），其包含 1371 个核苷酸，编码 457 个氨基酸。qRT-PCR 数据显示，在体内和体外，3nSQSTM1 的转录水平在感染鲤春病毒血症病毒（SVCV）后均升高。免疫荧光分析证实 3nSQSTM1 主要分布在细胞质中。荧光素酶报告基因检测结果表明，3nSQSTM1 显著阻断了 3nMDA5、3nMAVS、3nTBK1 和 3nIRF7 诱导的干扰素启动子的激活。共免疫沉淀实验进一步证实 3nSQSTM1 可以与 3nTBK1 和 3nIRF7 相互作用。此外，共转染时，3nSQSTM1 显著抑制了 TBK1 和 IRF7 介导的抗病毒活性。在机制上，3nSQSTM1 降低了 TBK1 的磷酸化及其与 3nIRF7 的相互作用，从而抑制了随后的抗病毒反应。值得注意的是，我们发现 3nSQSTM1 还与 SVCV N 和 P 蛋白相互作用，这些病毒蛋白可能利用 3nSQSTM1 进一步限制宿主的抗病毒先天免疫反应。总之，我们的研究表明，3nSQSTM1 通过靶向 3nTBK1 和 3nIRF7 在负调控干扰素信号通路中发挥关键作用。
