A Sema3C Mutant Resistant to Cleavage by Furin (FR-Sema3C) Inhibits Choroidal Neovascularization

In age-related macular degeneration (AMD), abnormal sub retinal choroidal neovascularization (CNV) is a major cause of blindness. FR-sema3C is a point mutated form of semaphorin-3C that is resistant to cleavage by furin like pro-protein convertases (FPPC). We have found in previous work that FR-sema3C functions as an anti-angiogenic factor. In this study we investigated the possible use of FR-sema3C as an inhibitor of CNV. FR-sema3C inhibits VEGF as well as PDGF-BB signal transduction in endothelial cells and to less extent bFGF induced signal transduction using a mechanism that does not depend upon the binding of VEGF like the drugs that are currently the mainstay treatment for AMD. CNV was induced in eyes of C57 black mice by laser photocoagulation. Intravitreal injection of FR-Sema3C or aflibercept (VEGF-trap) was then used to inhibit CNV formation. Invading choroidal vessels were visualized a week later by injection of FITC-dextran into the circulation, followed by the measurement of the area of the invading blood vessels. Injection of 0.1 μg FR-Sema3C inhibited CNV by 55% (P在年龄相关性黄斑变性（age-related macular degeneration, AMD）中，异常视网膜下脉络膜新生血管（sub retinal choroidal neovascularization, CNV）是引发失明的主要诱因。FR-sema3C是信号素3C（semaphorin-3C）的点突变体，能够抵抗弗林蛋白酶类前蛋白转化酶（furin like pro-protein convertases, FPPC）的切割作用。我们在前期研究中证实，FR-sema3C可作为抗血管生成因子发挥生物学功能。本研究探讨了FR-sema3C作为CNV抑制剂的潜在应用价值。FR-sema3C可抑制内皮细胞内血管内皮生长因子（VEGF）与血小板衍生生长因子-BB（PDGF-BB）的信号转导，对碱性成纤维细胞生长因子（bFGF）诱导的信号转导也存在较弱的抑制作用，其作用机制与当前作为AMD一线主流治疗药物的VEGF结合类药物不同，无需依赖VEGF结合过程。本研究通过激光光凝术在C57黑色小鼠眼部诱导建立CNV模型，随后通过玻璃体内注射FR-sema3C或阿柏西普（aflibercept, VEGF-trap）以抑制CNV形成。造模一周后，向小鼠血液循环系统注射异硫氰酸荧光素-葡聚糖（FITC-dextran）以可视化侵入性脉络膜血管，并对侵入血管的面积进行定量检测。注射0.1 μg的FR-sema3C可使CNV面积降低55%（P