Liu Xing, Cai Xiaolian, Hu Bo, Mei Zhichao, Zhang Dawei, Ouyang Gang, Wang Jing, Zhang Wei, Xiao Wuhan
From the Key Laboratory of Aquatic Biodiversity and Conservation and.
From the Key Laboratory of Aquatic Biodiversity and Conservation and
J Biol Chem. 2016 Dec 2;291(49):25692-25705. doi: 10.1074/jbc.M116.745471. Epub 2016 Oct 24.
FOXO3a, a member of the forkhead homeobox type O (FOXO) family of transcriptional factors, regulates cell survival in response to DNA damage, caloric restriction, and oxidative stress. The von Hippel-Lindau (VHL) tumor suppressor gene encodes a component of the E3 ubiquitin ligase complex that mediates hypoxia-inducible factor α degradation under aerobic conditions, thus acting as one of the key regulators of hypoxia signaling. However, whether FOXO3a impacts cellular hypoxia stress remains unknown. Here we show that FOXO3a directly binds to the VHL promoter and up-regulates VHL expression. Using a zebrafish model, we confirmed the up-regulation of vhl by foxo3b, an ortholog of mammalian FOXO3a Furthermore, by employing the clustered regularly interspaced short palindromic repeats (CRISPR)-associated RNA-guided endonuclease Cas9 (CRISPR/Cas9) technology, we deleted foxo3b in zebrafish and determined that expression of hypoxia-inducible genes was affected under hypoxia. Moreover, foxo3b-null zebrafish exhibited impaired acute hypoxic tolerance, resulting in death. In conclusion, our findings suggest that, by modulating hypoxia-inducible factor activity via up-regulation of VHL, FOXO3a (foxo3b) plays an important role in survival in response to hypoxic stress.
叉头框O型（FOXO）转录因子家族成员FOXO3a可响应DNA损伤、热量限制和氧化应激来调节细胞存活。冯·希佩尔-林道（VHL）肿瘤抑制基因编码E3泛素连接酶复合物的一个组分，该复合物在有氧条件下介导缺氧诱导因子α的降解，因此是缺氧信号传导的关键调节因子之一。然而，FOXO3a是否影响细胞缺氧应激仍不清楚。在此我们表明，FOXO3a直接结合至VHL启动子并上调VHL表达。利用斑马鱼模型，我们证实了哺乳动物FOXO3a的直系同源基因foxo3b可上调vhl的表达。此外，通过应用成簇规律间隔短回文重复序列（CRISPR）相关的RNA引导的核酸内切酶Cas9（CRISPR/Cas9）技术，我们在斑马鱼中敲除了foxo3b，并确定在缺氧条件下缺氧诱导基因的表达受到影响。此外，foxo3b基因敲除的斑马鱼表现出急性缺氧耐受性受损，最终导致死亡。总之，我们的研究结果表明，FOXO3a（foxo3b）通过上调VHL来调节缺氧诱导因子的活性，在应对缺氧应激的细胞存活中发挥重要作用。
