Role of Caveolin-1 in the Maintenance of Blood-retinal Barrier Integrity

描述（由申请人提供）：血视网膜屏障（BRB）选择性地、紧密地调节神经视网膜的局部环境。BRB完整性丧失是三种主要致盲原因的常见病理：糖尿病视网膜病变；年龄相关性黄斑变性；以及早产儿视网膜病变。最近的证据表明，caveolin-1 （Cav- 1）是一种特殊的脂质微域称为caveolae的完整蛋白质成分，对正常的视网膜功能至关重要。视网膜电图（ERG）显示，Cav-1缺失小鼠的视网膜功能下降，提示存在光感受器缺陷。然而，这种光感受器功能的降低不能用对光导的直接影响来解释，因为在分离的Cav-1空棒的记录中反应是正常的。这表明Cav-1缺失视网膜的功能缺陷是由光感受器周围异常的局部环境引起的。为了支持这一假设，令人信服的证据表明，Cav-1缺失小鼠具有高渗透性BRB。通透性的增加与紧密连接的改变、Na/ k - atp酶活性的改变和视网膜外水肿有关。Cav-1缺失小鼠提供了令人信服的数据，显示视网膜色素上皮和血管屏障功能明显丧失。这种增加的渗透性改变了正常的光感受器环境，这与在这些小鼠中观察到的视网膜功能下降和与年龄相关的视网膜变性是一致的。此外，当受到应激范式（氧诱导视网膜病变）时，Cav-1缺失小鼠表现出严重的视网膜下和视网膜内出血。这些发现清楚地表明，Cav-1的表达/功能对于维持强健的BRB至关重要，但这种调节的机制尚不清楚。第一个目的是确定Cav-1在使用细胞特异性、可诱导的基因缺失特异性调节视网膜色素上皮内屏障活性中的作用。第二个目标是测试Cav-1在上皮细胞-细胞接触和根尖过程中脂质和蛋白质结构组织中的作用。最终目的将集中在Na/ k - atp酶失调的作用以及Cav-1如何调节atp酶活性。

DESCRIPTION (provided by applicant): The blood-retinal barrier (BRB) selectively and tightly regulates the local environment of the neural retina. Loss of BRB integrity is a common pathology in three major causes of blindness: diabetic retinopathy; age- related macular degeneration; and retinopathy of prematurity. Recent evidence indicates that caveolin-1 (Cav- 1), an integral protein component of specialized lipid micro-domains called caveolae, is essential for normal retinal function. Cav-1 null mice display reduced retinal function in Cav-1 null mice as indicated by electroretinography (ERG) that suggested at a photoreceptor defect. However, this reduced photoreceptor function could not be explained by a direct effect on phototransduction as responses were normal in recordings from isolated Cav-1 null rods. This suggests that the functional deficit in Cav-1 null retinas results from an abnormal local environment surrounding photoreceptors. In support of this hypothesis, compelling evidence indicates that Cav-1 null mice have a hyper-permeable BRB. The increased permeability correlates with alterations in tight junctions, changes in Na/K-ATPase activity, and outer retinal edema. Cav-1 null mice provide compelling data showing a clear loss of retinal pigment epithelial and vascular barrier functions. This increased permeability alters the normal photoreceptor environment which is consistent with reduced retinal function and age-related retinal degeneration observed in these mice. Furthermore, when subjected to a stress paradigm (oxygen-induced retinopathy), Cav-1 null mice display severe sub-retinal and intra-retinal hemorrhaging. These findings clearly indicate that Cav-1 expression/function is essential for the maintenance of a robust BRB but the mechanism(s) of this regulation is unknown. The first aim is designed to determine the role of Cav-1 in regulating barrier activity specifically within the retinal pigment epithelium using cell-specific, inducible genetic deletion. The second aim will test the role of Cav-1 in the structural organization of lipids and proteins in epithelial cell-cell contacts and apical process. The final aim will focus on the role that dysregulation of the Na/K-ATPase plays and how Cav-1 regulates ATPase activity. PUBLIC HEALTH RELEVANCE: Loss of blood-retinal barrier integrity is a common pathology in three major causes of blindness: diabetic retinopathy; age-related macular degeneration; and retinopathy of prematurity. This project is designed to study mechanisms that regulate blood-retinal barrier integrity to define novel potential therapeutic strategies to ameliorate pathological blood-retinal barrier permeability.