Jab1-P53-HIF-1α复合物对VEGF分泌的调节在低氧诱导的视网膜新生血管中的作用

VEGF secretion, which mediated by HIF-1α, is an important cause of pathological retinal neovascularization (RNV) under hypoxia condition. However, its specific mechanism is still unclear. It is reported that JAB1 promotes VEGF secretion by binding with HIF-1α. Besides, Jab1 integrates with P53 to promote its degradation. Furthermore, HIF-1α degradation is induced by P53. Our preliminary results showed that in retinal microvascular endothelial cells (RMECs), Jab1 could form ternary complex with P53 and HIF-1α to reduce VEGF secretion and inhibit proliferation, migration of RMECs. In this study, we firstly explored whether Jab1, P53 and HIF-1α could form a ternary complex in hypoxia-induced RMECs. Then we analyzed the formation of ternary complex, the changes of corresponding inflammatory cytokines and angiogenesis of RMECs after Jab1 expression was being suppressed. Finally, the effects of the ternary complex in VEGF secretion and RNV in oxygen-induced retinopathy (OIR) mice were clarified. This study is expected to provide a new molecular target for the prevention and treatment of RNV associated with ophthalmopathy.

低氧条件下HIF-1α介导的VEGF分泌是视网膜病理性新生血管（RNV）发生的重要原因，但其具体调控机制仍未明确。文献报道Jab1绑定HIF-1α，促进其转录生成VEGF；Jab1绑定P53，促进其出核降解；P53可诱导HIF-1α降解。我们预实验结果发现低氧诱导的视网膜血管内皮细胞（RMECs）中Jab1能与P53和HIF-1α形成三元复合物，并调节RMECs增殖、迁移、内皮管腔形成和VEGF分泌。本研究拟首先在低氧诱导的RMECs中证明Jab1、P53和HIF-1α可形成三元复合物；接着分析干预RMECs中Jab1的表达，对于三元复合物的形成及RMECs增殖、迁移、炎症因子分泌、内皮管腔形成的影响；最后在氧诱导的视网膜病变（OIR）动物模型中干预Jab1表达，阐明对三元复合物形成、VEGF分泌及RNV生成的影响。该研究有望为RNV相关性眼病的防治提供立论依据和新的分子靶点。

缺氧诱导因子1α（HIF-1α）是缺氧介导新生血管生成的关键调节因子，在视网膜病理性新生血管形成（RNV）中起重要作用。既往研究发现c-Jun 激活区域-连接蛋白1（Jab1）与HIF-1α存在相互作用，能够减少HIF-1α泛素化降解并增强其稳定性。本研究聚焦于Jab1-HIF-1α，构建多种缺氧内皮细胞模型和眼底新生血管动物模型，通过体内外干预Jab1表达，研究Jab1对于HIF-1α-血管内皮生长因子（VEGF）信号通路的调控以及对眼底新生血管的影响。本项目的主要研究结果包括：（1）敲低Jab1减弱人脐静脉内皮细胞（HUVEC）增殖、迁移和内皮管腔形成能力；（2）敲除小鼠内皮细胞中的Jab1影响视网膜正常血管发育，并抑制眼底新生血管动物模型中的视网膜和脉络膜新生血管；（3）过表达Jab1增强HUVEC增殖、迁移和内皮管腔形成能力，使用Nedd化修饰激动剂可以减弱Jab1过表达的影响；（4）Jab1抑制HIF-1α与Nedd8结合，减少HIF-1α泛素化，导致HIF-1α细胞内积累，HIF-1α入核增加并促进VEGF表达。本研究明确了Jab1对HIF-1α具体调控机制，有望为治疗新生血管性眼病提供新的理论依据和干预靶点。