Project 5

项目总结(见说明)： 糖尿病视网膜病变(DR)传统上被认为是糖尿病视网膜的一种微血管并发症。 然而，越来越多的人和动物认识到，视网膜神经元功能和活性的丧失发生在糖尿病人和动物的视网膜微血管异常发生之前。糖尿病会导致光感受器退化。视锥细胞变性尤其具有破坏性，因为视锥细胞感光细胞负责明亮和颜色的视觉。目前，糖尿病诱导的光感受器退化的机制在很大程度上尚不清楚。最近的研究表明，血管内皮生长因子(VEGF)是一种主要的血管生成因子，在低氧和糖尿病条件下表达上调，可能是包括光感受器在内的视网膜神经元的生存因子。然而，血管内皮生长因子是糖尿病视网膜血管并发症的治疗靶点，抗血管内皮生长因子药物已被用于开发治疗糖尿病视网膜病变的药物，其中血管内皮生长因子受体-2(VEGFR2)和神经黏附蛋白-1(Nrp1)的表达最多。 在神经细胞中大量表达VEGFR2和Nrp1受体样蛋白，明确VEGFR2和Nrp1在视网膜神经元中的作用和机制对于长期抗VEGF治疗DR的安全性至关重要。为了验证我们的中心假设，即通过VEGFR2和Nrp1传递的VEGFR2和Nrp1信号在维持DR的光感受器功能和生存能力方面起着至关重要的作用，我们将使用这两种方法 体外和体内模型，以确定VEGFR2和Nrp1信号在光感受器中的功能和机制。在目标1中，我们将研究VEGFA/EGFR2信号激活通路，VEGFR2活性的调节，以及Nrp1在血管内皮生长因子信号级联中的作用。在目标2中，我们将通过检测视锥细胞密度、视网膜形态和视锥细胞特异性VEGFR2基因敲除小鼠的光感受器功能，来确定VEGFR2的缺失是否会加剧缺血或糖尿病诱导的光感受器功能障碍。在目标3中，我们将建立杆状或锥体特异性的Nrp1基因敲除小鼠，并在缺血或糖尿病条件下表征这些条件性Nrp1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.