Regulation of retinal angiogenesis and vascular integrity by the oxygen sensing mechanism

通过氧传感机制调节视网膜血管生成和血管完整性

• 批准号: 8964228
• 负责人: Guo-Hua Fong
• 金额: $ 48.71万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8964228
• 关键词: Adult; Affect; Angiogenic Factor; Animals; Astrocytes; Attention; Binding Sites; Birth; Blood Circulation; Blood Vessels; Communication; Consensus; Development; Diabetes Mellitus; Diabetic Retinopathy; Disease; Down-Regulation; Endothelial Cells; Environment; Family; Feedback; Figs - dietary; Genes; Genetic Transcription; Growth; Homologous Gene; Hydroxylation; Hyperoxia; Hypoxia; Hypoxia Inducible Factor; In Vitro; Injury; Knockout Mice; Lead; Ligands; Maintenance; Methods; Modeling; Morphogenesis; Mus; Mutation; Neonatal; Nuclear Orphan Receptor; Optic Disk; Oxygen; Pathway interactions; Polyubiquitination; Population; Procollagen-Proline Dioxygenase; Proteins; Regulation; Research Design; Response Elements; Retina; Retinal; Retinal Diseases; Retinopathy of Prematurity; Signal Transduction; Source; Stem cells; Tertiary Protein Structure; Testing; Therapeutic; Tissues; Vascular Endothelial Cell; angiogenesis; astrocyte progenitor; design; extracellular; in vivo; insight; leukemia inhibitory factor; novel; novel therapeutics; prevent; progenitor; public health relevance; retina blood vessel structure; retinal angiogenesis; theories; therapeutic target; transcription factor

 DESCRIPTION (provided by applicant): Angiogenesis has been mostly studied by examining stimulation (or inhibition) of endothelial cells (ECs) by extracellular ligands, with much less attention being paid to communications between ECs and their surrounding tissue environment. In this project we will focus on how the oxygen sensing mechanism coordinates astrocytic and vascular communication during retinal vascular morphogenesis and explore its therapeutic potentials in protecting retinal microvascular integrity in two models including oxygen induced retinopathy (OIR) and diabetic retinopathy. In preliminary studies we obtained concrete evidence that nascent retinal blood vessels drive retinal astrocytic progenitors (APCs) to differentiate into mature astrocytes (mASCs) and form an astrocytic network. Specifically, we hypothesize that leukemia inhibitory factor (LIF) from retinal vascular ECs and oxygen from the circulation may act on APCs to upregulate the expression and activity of prolyl hydroxylase domain protein 2 (PHD2), which in turn catalyzes prolyl hydroxylation of HIF-a proteins, tagging them for polyubiquitination and proteasomal degradation. Furthermore, we propose that HIF-2a and Tlx (a transcription factor in the orphan nuclear receptor family) may form a positive feedback loop wherein Tlx suppresses polyubiquitination and degradation of hydroxylated HIF-2a whereas HIF-2a promotes the transcription of the Tlx gene. Thus, downregulation of HIF-2a protein abundance by PHD2 might trigger a downward spiral of both HIF-2a and Tlx levels, leading to astrocyte maturation from their progenitors. On the other hand, our studies indicate that loss of PHD2 may be targeted to help preserve retinal vascular integrity in OIR or diabetes models, likely by stabilizing HIF-2a. We will investigate these issues in three specific aims. Aim 1. Determine if LIF regulates astrocyte and vascular development through oxygen sensing mechanisms. We will evaluate in vivo if LIF upregulates Phd2 expression, promotes the differentiation of APCs (proangiogenic) to mASCs (nonangiogenic), thus suppressing retinal angiogenesis. Aim 2. Investigate if a positive feedback loop between HIF-2a and Tlx promotes APC status and retinal angiogenesis. Aim 3. Explore therapeutic potentials of the oxygen sensing pathway in mouse OIR and diabetic retinopathy models. We will determine if mASC specific PHD2 deficiency, global or EC specific LIF deficiency, or LIF antagonist protects retinal microvessels from hyperoxia or diabetes-induced injuries. In summary, these studies are designed to provide mechanistic insights into vascular and astrocyte communication and reveal novel therapeutic opportunities to treat retinopathy of the prematurity and diabetic retinopathy.

 描述（由申请人提供）：血管生成主要是通过检查细胞外配体对内皮细胞（EC）的刺激（或抑制）来研究的，而很少关注 EC 与其周围组织环境之间的通信。在这个项目中，我们将重点研究氧传感机制如何在视网膜血管形态发生过程中协调星形胶质细胞和血管通讯，并探索其在氧诱导视网膜病变（OIR）和糖尿病视网膜病变两种模型中保护视网膜微血管完整性的治疗潜力。在初步研究中，我们获得了具体证据，表明新生视网膜血管驱动视网膜星形胶质细胞祖细胞（APC）分化为成熟星形胶质细胞（mASC）并形成星形胶质细胞网络。具体来说，我们假设来自视网膜血管EC的白血病抑制因子（LIF）和来自循环的氧气可能作用于APC，上调脯氨酰羟化酶结构域蛋白2（PHD2）的表达和活性，进而催化HIF-a蛋白的脯氨酰羟化，标记它们进行多泛素化和蛋白酶体降解。此外，我们提出HIF-2a和Tlx（孤儿核受体家族中的转录因子）可能形成正反馈环，其中Tlx抑制多泛素化和羟基化HIF-2a的降解，而HIF-2a促进Tlx基因的转录。因此，PHD2 下调 HIF-2a 蛋白丰度可能会引发 HIF-2a 和 Tlx 水平螺旋式下降，导致星形胶质细胞从其祖细胞成熟。另一方面，我们的研究表明，PHD2 的缺失可能有助于保持 OIR 或糖尿病模型中的视网膜血管完整性，可能是通过稳定 HIF-2a 来实现的。我们将从三个具体目标来研究这些问题。目标 1. 确定 LIF 是否通过氧传感机制调节星形胶质细胞和血管发育。我们将在体内评估 LIF 是否上调 Phd2 表达，促进 APC（促血管生成）分化为 mASC（非血管生成），从而抑制视网膜血管生成。目标 2. 研究 HIF-2a 和 Tlx 之间的正反馈回路是否促进 APC 状态和视网膜血管生成。目标 3. 探索氧传感通路在小鼠 OIR 和糖尿病视网膜病变模型中的治疗潜力。我们将确定 mASC 特异性 PHD2 缺陷、整体或 EC 特异性 LIF 缺陷或 LIF 拮抗剂是否可以保护视网膜微血管免受高氧或糖尿病引起的损伤。总之，这些研究旨在提供对血管和星形胶质细胞通讯的机制见解，并揭示治疗早产儿视网膜病变和糖尿病视网膜病变的新治疗机会。