Yan Dong, Tao Min Hui, Wu Xiao Man, Zhang Jie, Li Ming, Chang Ming Xian
State Key Laboratory of Breeding Biotechnology and Sustainable Aquaculture, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China.
PLoS Pathog. 2025 Sep 8;21(9):e1013491. doi: 10.1371/journal.ppat.1013491. eCollection 2025 Sep.
Hepatocyte nuclear factor 4 alpha (Hnf4α), a conserved nuclear receptor central to vertebrate liver development and metabolic regulation, emerges here as a pivotal immune regulator in teleosts against complex infectious threats. While its metabolic roles are well-established, Hnf4α's function in bacterial infection, viral infection, and bacterial-viral coinfection-major challenges in global aquaculture-remained uncharacterized. This study reveals that teleost Hnf4α acts as a dual-functional immune checkpoint, essential for combating Aeromonas salmonicida, grass carp reovirus (GCRV), and their coinfection. In in vivo zebrafish models, hnf4α-deficient larvae showed profound susceptibility, with survival rates reduced by 13.33-40% during infections, whereas gcHnf4α overexpression enhanced larval survival by 17.78-23.33% in single or coinfection scenarios. In vitro analyses in CIK cells demonstrated that gcHnf4α restricts A. salmonicida proliferation and GCRV replication through activation of a mitochondrial apoptotic program. Mechanistically, gcHnf4α forms a nuclear signaling complex with apoptosis-inducing factor (AIF) and caspases 3/9, driving a dual-dependent apoptotic pathway: (1) AIF-mediated caspase-independent nuclear apoptotic processes and (2) caspase 3/9-dependent cytoplasmic apoptotic execution. Confocal microscopy and co-immunoprecipitation validated direct interactions between gcHnf4α and these apoptotic effectors. Pharmacological inhibition of caspases 3/9 or AIF silencing abrogated gcHnf4α's protective effects, while ectopic caspase expression rescued survival deficits in hnf4α-deficient larvae. These findings establish Hnf4α as a conserved molecular nexus linking nuclear receptor signaling to apoptotic immunity, offering a novel strategy for aquacultural disease control. By targeting the AIF-caspase axis, Hnf4α enables efficient pathogen elimination, delineating it as a promising target for developing dual-action immunomodulators.
肝细胞核因子4α（Hnf4α）是一种保守的核受体，对脊椎动物肝脏发育和代谢调节至关重要，在硬骨鱼对抗复杂感染威胁中作为关键免疫调节因子出现。虽然其代谢作用已得到充分证实，但Hnf4α在细菌感染、病毒感染以及细菌 - 病毒混合感染（全球水产养殖中的主要挑战）中的功能仍未明确。本研究表明，硬骨鱼Hnf4α作为一种双功能免疫检查点，对于抵抗杀鲑气单胞菌、草鱼呼肠孤病毒（GCRV）及其混合感染至关重要。在体内斑马鱼模型中，缺乏hnf4α的幼虫表现出高度易感性，感染期间存活率降低13.33 - 40%，而在单感染或混合感染情况下，gcHnf4α过表达使幼虫存活率提高17.78 - 23.33%。在CIK细胞中的体外分析表明，gcHnf4α通过激活线粒体凋亡程序来限制杀鲑气单胞菌的增殖和GCRV的复制。从机制上讲，gcHnf4α与凋亡诱导因子（AIF）和半胱天冬酶3/9形成核信号复合物，驱动双依赖凋亡途径：（1）AIF介导的不依赖半胱天冬酶的核凋亡过程和（2）半胱天冬酶3/9依赖的细胞质凋亡执行。共聚焦显微镜和免疫共沉淀验证了gcHnf4α与这些凋亡效应器之间的直接相互作用。半胱天冬酶3/9的药理学抑制或AIF沉默消除了gcHnf4α的保护作用，而异位半胱天冬酶表达挽救了hnf4α缺陷幼虫的存活缺陷。这些发现确立了Hnf4α作为连接核受体信号与凋亡免疫的保守分子枢纽，为水产养殖疾病控制提供了一种新策略。通过靶向AIF - 半胱天冬酶轴，Hnf4α能够有效消除病原体，将其描绘为开发双作用免疫调节剂的有希望的靶点。
