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

糖尿病患者的视网膜会经历血管和神经系统的慢性退行性改变，最终可能导致不可逆转的视力丧失。本项目重点研究色素上皮衍生因子（PEDF）的调控和作用，PEDF主要由视网膜胶质细胞（m<s:1> ller）产生，存在于视网膜中。PEDF作为抗血管生成因子和神经营养/保护因子具有重要作用。鉴于这些活性，PEDF是一个合适的候选分子，以防止视网膜新生血管和神经元变性。为了提高我们对这些特定的PEDF固有功能的理解，将产生转基因动物，使其能够操纵<s:1>勒细胞衍生的PEDF表达向过表达方向表达。在迄今为止的工作过程中，我们发展了实现这一目标所需的适当结构。我们预计，这些动物的实验将揭示代谢应激暴露的神经元（和内皮细胞）的存活是如何被神经胶质PEDF的产生所调节的。我们获得的体外数据表明，缺氧条件下，<s:1> ller细胞的PEDF释放增加，PEDF上调由HIF-1和VEGF控制。PEDF支持视网膜神经节细胞存活（在缺氧情况下明显减弱）；此外，其活性抑制缺氧诱导的<s:1> ller细胞产生VEGF。最后，我们的研究发现了一种新的结合分子作为视网膜微血管内皮细胞上的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研究短暂的缺氧，然后再氧合，是否会导致<s:1>勒细胞来源的PEDF产生的增加。最后，进一步的实验工作将旨在阐明我们发现的新的PEDF结合分子是否参与刺激视网膜内皮细胞发生的信号机制。

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.