Neurodegeneration in the Retina: Effect of the Glial Pigment Epithelium-Derived Factor (PEDF)

糖尿病患者的视网膜经历血管和神经系统的慢性退行性变化，这可能最终导致不可逆的视力丧失。该项目强调色素上皮衍生因子（PEDF）的调节和作用，PEDF主要发生在视网膜中，因为它由视网膜胶质（Müller）细胞产生。PEDF作为抗血管生成因子和神经营养/保护因子发挥重要作用。考虑到这些活性，PEDF是预防视网膜中的新血管形成和神经元变性的合适的候选分子。为了提高我们对这些特定PEDF固有功能的理解，将产生转基因动物，其允许操纵Müller细胞衍生的PEDF表达朝向过表达。在迄今为止进行的工作过程中，我们已经开发了实现这一目标所需的适当结构。我们预计，涉及这些动物的拟议实验将阐明代谢应激暴露的神经元（和内皮细胞）的生存是如何通过神经胶质PEDF的产生来调节的。我们已经产生了体外数据，表明缺氧条件下Müller细胞的PEDF释放增加，PEDF上调受HIF-1和VEGF控制。我们发现PEDF支持视网膜神经节细胞存活（在缺氧条件下显著减弱）;此外，其活性抑制缺氧诱导的Müller细胞产生VEGF。最后，我们的研究确定了一种新的结合分子作为视网膜微血管内皮细胞上的假定PEDF受体，这表明PEDF可能干扰PlGF和VEGF与这些细胞的结合，为其抗血管生成活性提供了新的解释。在这里，我们建议在我们的项目中通过进一步的工作来调查短暂缺氧，然后再充氧，是否会导致Müller-cell衍生的PEDF产量增加。最后，进一步的实验工作将旨在阐明我们鉴定的新型PEDF结合分子是否参与刺激视网膜内皮细胞中发生的信号传导机制。

The retina of diabetic patients undergoes chronic degenerative changes in both the vascular and the neuronal system, which may ultimately lead to irreversible loss of vision. This project places emphasis on the regulation and effects of pigment epithelium-derived factor (PEDF), which mainly occurs in the retina due to its production by retinal glial (Müller) cells. PEDF plays important roles as an anti-angiogenic as well as a neurotrophic/ -protective factor. Given these activities, PEDF is an appropriate candidate molecule to prevent both neovascularization and neuronal degeneration in the retina. To improve our understanding of these particular PEDF-inherent functions, transgenic animals are to be generated which allow to manipulate Müller-cell derived PEDF expression towards an overexpression. In the course of hitherto performed work we have developed appropriate constructs required to accomplish this goal. We anticipate that the proposed experiments involving these animals will shed light on how survival of metabolic stress-exposed neurons (and endothelial cells) is modulated by glial PEDF production. We have generated in vitro data indicating an increased PEDF release from Müller cells under hypoxia, with a PEDF upregulation that was controlled by HIF-1 und VEGF. PEDF was shown by us to support retinal ganglion cell survival (which was markedly attenuated under hypoxia); furthermore, its activity inhibited the hypoxia-induced VEGF production by Müller cells. Finally, our studies identified a new binding molecule as a putative PEDF receptor on retinal microvascular endothelial cells which suggests that PEDF may interfere with PlGF and VEGF binding to these cells, providing a new explanation for its anti-angiogenic activity. Here we propose to investigate by further work in our project whether transient hypoxia, followed by re-oxygenation, causes an increase of Müller-cell derived PEDF production. Finally, further experimental work will be aimed at elucidating whether the novel PEDF binding molecule identified by us, is involved in signaling mechanisms occurring in stimulated retinal endothelial cells.