Project 5

项目总结（见说明）： 糖尿病视网膜病变（DR）是糖尿病视网膜的一种微血管并发症。 然而，越来越多的人认识到，在糖尿病人和动物中，视网膜神经元功能和活力的丧失发生在视网膜微血管异常发作之前。糖尿病导致感光细胞变性。视锥细胞变性是特别具有破坏性的，因为视锥细胞光感受器负责明亮和彩色视觉。目前，糖尿病诱导的光感受器变性的机制在很大程度上尚未探索。最近的研究表明，血管内皮生长因子（VEGF），一种主要的血管生成因子，在缺氧和糖尿病条件下上调，可能发挥作用，作为视网膜神经元，包括光感受器的存活因子。然而，VEGF是糖尿病诱导的视网膜血管并发症的治疗靶点，并且抗VEGF剂已用于开发DR的治疗剂。 由于VEGF受体样蛋白在神经元细胞中大量表达，因此确定VEGF信号通过VEGFR 2和NRP 1在视网膜神经元中的作用和机制对于DR的长期抗VEGF治疗的安全性至关重要。为了验证我们的中心假设，即VEGF信号通过VEGFR 2和NRP 1在DR中保护光感受器功能和活力方面起着重要作用，我们将使用这两种方法， 体外和体内模型，以确定VEGFR 2和NRP 1信号传导在光感受器中的功能和机制。在目的1中，我们将研究VEGFA/EGFR 2信号激活途径，VEGFR 2活性的调节，以及NRP 1在VEGF信号级联中的参与。在目标2中，我们将通过检查视杆细胞或视锥细胞特异性VEGFR 2敲除小鼠的视锥细胞密度、视网膜形态学和感光功能来确定VEGFR 2的缺失是否加剧缺血或糖尿病诱导的感光功能障碍。在目标3中，我们将产生视杆细胞或视锥细胞特异性NRP 1基因敲除小鼠，并在缺血或糖尿病条件下表征这些条件性NRP 1基因敲除小鼠的光感受器功能、形态和密度。

PROJECT SUMMARY (See instructions): Diabetic retinopathy (DR) is traditionally regarded as a microvascular complication in diabetic retinas. However, it is increasingly recognized that the loss of retinal neuronal function and viability occurs before the onset of retinal microvascular abnormalities in diabetic humans and animals. Diabetes induces photoreceptor degeneration. Cone degeneration is particularly devastating, as cone photoreceptors are responsible for bright and color vision. At present, the mechanisms governing diabetes-induced photoreceptor degeneration are largely unexplored. Recent studies suggest that vascular endothelial growth factor (VEGF), a major angiogenic factor that is up-regulated under hypoxic and diabetic conditions, may play a role as a survival factor for retinal neurons, including photoreceptors. However, VEGF is a therapeutic target of diabetes-induced retinal vascular complications and anti-VEGF agents have been used to develop therapeutics for DR. As VEGF receptor-2 (VEGFR2) and neuropilin-1 (NRP1) are the most abundantly expressed VEGF receptor-like proteins in neuronal cells, identifying the roles and mechanisms of VEGF signaling through VEGFR2 and NRP1 in retinal neurons is paramount to the safety of long-term anti-VEGF treatments for DR. To test our central hypothesis that VEGF signaling through VEGFR2 and NRP1 plays an essential role in preserving photoreceptor function and viability in DR, we will use both in vitro and in vivo models to determine the function and mechanisms of VEGFR2 and NRP1 signaling in photoreceptors. In Aim 1 we will examine VEGFA/EGFR2 signaling activated pathways, regulation of VEGFR2 activity, and the involvement of NRP1 in VEGF signaling cascade. In Aim 2 we will determine if the loss of VEGFR2 exacerbates ischemia- or diabetes-induced photoreceptor dysfunction by examining cone density, retinal morphology, and photoreceptor function in rod- or cone-specific VEGFR2 knockout mice. In Aim 3 we will generate rod- or cone-specific NRP1 knockout mice and characterize photoreceptor function, morphology, and density in these conditional NRP1 knockout mice under ischemic or diabetic conditions.