Couteaudier Mathilde, Nivard Mona, Cochard Jade, Mammano Fabrizio, Roingeard Philippe, de Rocquigny Hugues, Chouteau Philippe
INSERM U1259 MAVIVHe, Faculté de Médecine, Université de Tours and CHRU de Tours, 10 Boulevard Tonnellé - BP 3223, 37032, Tours Cedex 1, France.
Plate-Forme IBiSA Des Microscopies, PPF ASB, Université de Tours and CHRU de Tours, 10 Boulevard Tonnellé - BP 3223, 37032, Tours Cedex 1, France.
Cell Mol Life Sci. 2025 Jun 19;82(1):241. doi: 10.1007/s00018-025-05739-0.
We recently developed an original HCV-permissive cell culture model based on both partial differentiation and physiological oxygen pressure (Hypo-Diff cells) that produces highly infectious lipid-rich and native-like HCV-lipoviroparticles (LVPs). Here, we explored the precise role of physiological hypoxia and related specific transcription factors, hypoxia-inducible factors 1α and 2α (HIF-1α and HIF-2α) to better understand the mechanism governing viral morphogenesis. Knocking-down HIF-2α specifically reduced both the number and size of neutral lipid-rich droplets in Huh7.5 Hypo-Diff cells, suggesting a central role for HIF-2 in controlling lipid metabolism under physiological hypoxia. In HCV-infected siHIF-2α Hypo-Diff cells, both HCV replication and the specific infectious viral efficacy of progeny viruses were significantly impaired. Interestingly, the ectopic expression of a mutated form of the HIF-2α protein, stabilized in normoxia, both increased the number and size of neutral lipid-rich droplets and restored the production of highly infectious HCV viruses in the absence of cell differentiation. Finally, by iodixanol fractionation of supernatants to determine the mean buoyant density of infectious HCV LVPs, we established that HIF-2α is exclusively responsible for producing highly lipidated and broadly infectious HCV-LVPs by Hypo-Diff cells. These findings thus clearly establish the central role of physiological hypoxia, and notably HIF-2, in the production of highly infectious lipid-rich native-like HCV particles. Since physiological hypoxia is a shared characteristic in mammalian tissues, we propose to reconsider the role of natural oxygen tension and especially the role of HIF-2 in the life cycle of other lipid-associated viruses, whether hepatotropic or not.
我们最近基于部分分化和生理氧压开发了一种原始的丙型肝炎病毒（HCV）允许性细胞培养模型（低分化细胞），该模型可产生具有高度传染性的富含脂质且类似天然的HCV脂质病毒颗粒（LVPs）。在此，我们探究了生理缺氧及相关特异性转录因子——缺氧诱导因子1α和2α（HIF-1α和HIF-2α）的精确作用，以更好地理解控制病毒形态发生的机制。特异性敲低HIF-2α可使Huh7.5低分化细胞中富含中性脂质的脂滴数量和大小均减少，这表明HIF-2在生理缺氧条件下控制脂质代谢中起核心作用。在HCV感染的siHIF-2α低分化细胞中，HCV复制及子代病毒的特异性感染效力均显著受损。有趣的是，在常氧条件下稳定的HIF-2α蛋白突变体的异位表达，既增加了富含中性脂质的脂滴数量和大小，又在无细胞分化的情况下恢复了高传染性HCV病毒的产生。最后，通过对上清液进行碘克沙醇分级分离以确定感染性HCV LVPs的平均浮力密度，我们确定HIF-2α专门负责由低分化细胞产生高度脂化且具有广泛感染性的HCV-LVPs。因此，这些发现清楚地确立了生理缺氧，尤其是HIF-2，在产生高度传染性的富含脂质的类似天然HCV颗粒中的核心作用。由于生理缺氧是哺乳动物组织的一个共同特征，我们建议重新考虑自然氧张力的作用，尤其是HIF-2在其他脂质相关病毒（无论是否为嗜肝病毒）生命周期中的作用。
