The role of heme in retinal vascular development and disease

项目摘要 视网膜血管疾病是美国和世界各地视力丧失的主要原因。为了更好地 治疗这些疾病，我们需要了解控制细胞生长和完整性的信号通路 视网膜血管。我们最近的出版物和初步数据详细描述了一种新的血管生成信号系统 以血红素为中心，它是氧气运输、新陈代谢和基因转录的关键辅助因素。我们发现 这种血红素通过调节顶端/柄的选择来促进视网膜中的血管生成生长，并减少了血红素 生产或进口导致视网膜血管形成减少和组织缺氧，与其他视网膜相似 血管病变包括早产儿视网膜病变、脉络膜新生血管以及罕见但重要的 渗出性玻璃体视网膜病变。此外，我们还发现，血管内皮生长因子抑制去甲肾上腺素，而去甲肾上腺素促进血管生成。 专性内皮血红素进口体Flvcr2的表达。根据这些数据，我们假设 血红素参与视网膜血管生成和视网膜血管病变。这项建议的具体目的是 (1)确定血红素如何与Notch信号相交以控制血管生成尖端/茎的选择，(2)确定 诱导Flvcr2/heme信号通路是否充分和必要逆转血管缺陷和 在渗出性玻璃体视网膜病变小鼠模型中观察到的下游视力变化，以及(3)表征 Flvcr2/heme在血管内皮生长因子诱导的血管生成和新生血管形成中的作用要实现这些目标 目的，我们开发了新的工具来直接操作培养的视网膜内皮细胞中的血红素并评估血红素。 体外转运和细胞内转运。我们还产生了新的条件性敲入和敲除等位基因 在体内操纵内皮细胞的血红素转运。我们的研究将从根本上影响我们对 如何控制内皮血红素水平，以及血红素在视网膜血管生成和血管疾病中的作用。

PROJECT ABSTRACT Retinal vascular diseases are major causes of vision loss in the United States and around the world. To better treat these disorders, we need to understand the signaling pathways that control the growth and integrity of retinal blood vessels. Our recent publications and preliminary data detail a novel angiogenic signaling system centered around heme, a co-factor critical for oxygen transport, metabolism, and gene transcription. We found that heme promotes angiogenic growth in the retina by regulating tip/stalk selection, and that reduced heme production or import leads to reduced retinal vascularization and tissue hypoxia, similar to other retinal vasculopathies including retinopathy of prematurity, choroidal neovascularization, and the rare but important exudative vitreoretinopathies. Furthermore, we found that VEGF suppresses, while Norrin-bCatenin promotes, the expression of the obligate endothelial heme importer, Flvcr2. Based on these data, we hypothesize that heme, is involved in retinal angiogenesis and retinal vasculopathies. The Specific Aims of this proposal are to (1) determine how heme intersects with Notch signaling to control angiogenic tip/stalk selection, (2) determine whether induction of Flvcr2/heme signaling is sufficient and necessary to reverse the vascular defects and downstream vision changes observed in mouse models of exudative vitreoretinopathy, and (3) characterize the role for Flvcr2/heme in VEGF-induced angiogenic proliferation and neo-vascularization. To accomplish these aims, we developed new tools to directly manipulate heme in cultured retinal endothelial cells and assess heme transport and intracellular trafficking in vitro. We also generated new conditional knock-in and knock-out alleles to manipulate endothelial heme transport in vivo. Our studies will fundamentally impact our understanding of how endothelial heme levels are controlled, and the role of heme in retinal angiogenesis and vascular disease.