COBRE: PI 3-KINASE & ITS DOWNSTREAM TARGET BCL-XL IN RPE

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。我的实验室对磷脂酰肌醇（PI）循环中产生的脂质第二信使在光导、视网膜变性和保护视网膜细胞免于凋亡中的作用感兴趣。PI-3激酶（PI3K）产生的信使pi -3,4,5- p3在细胞保护、细胞增殖、葡萄糖稳态、膜运输和细胞骨架重排中发挥重要作用。在神经元细胞中，PI3K的激活已被证明可以保护细胞免受应激诱导的凋亡。然而，PI3K在视觉系统中的功能尚不清楚。视网膜色素上皮细胞（RPE）是有丝分裂后的细胞，提供“血液-视网膜屏障”，并控制视网膜和血液之间的营养物质和废物的流动。这些细胞的死亡导致视杆细胞和视锥细胞的死亡，RPE功能的损害可能是年龄相关性黄斑变性的一个因素。由于PI3K的下游靶点Bcl-x在细胞毒性应激下的RPE细胞中高表达，因此PI3K可能在RPE细胞存活中发挥重要作用。我们假设PI3K和BOI-xL是RPE的主要存活因子。为了验证这一假设，我们将采用遗传方法破坏RPE中的PI3K和Bcl-x (BCl-xL)，并将突变小鼠的功能、生化和结构表型与野生型小鼠进行比较。由于传统的PI3K（p85odp110o_）和Bcl-x敲除小鼠是新生儿或胚胎致死的，因此将使用Cre/Iox系统以RPE特异性的方式生成PI3K和Bcl-x零突变的小鼠模型。因此，我提出：1)制备并表征RPE65启动子驱动的表达rpe特异性Cre的转基因小鼠；2)生成RPE特异性PI3K和/或Bcl-x缺失小鼠，验证PI3K和/或BCl-xL参与RPE细胞存活的假设；3)使用本研究生成的RPE特异性PI3K或Bcl-x缺失小鼠和ABCR缺失（RPE变性）小鼠，验证受损的RPE细胞可能加剧PI3K和/或Bcl-x缺失突变的光受体细胞死亡的假设。在COBRE项目的背景下，这个项目的一个主要目标是建立小鼠模型，可以在未来的研究中用于阐明固有视网膜变性的机制。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. My laboratory is interested in the roles of lipid second messengers generated in the phosphatidylinositol (PI) cycle in phototransduction, retinal degeneration, and protection of retinal cells from apoptosis. One messenger, PI-3,4,5-P3, generated by the PI-3 kinase (PI3K), plays an important role in cell protection, cell proliferation, glucose homeostasis, membrane trafficking and cytoskeletal rearrangement. In neuronal cells, activation of PI3K has been shown to protect the cells from stress-induced apoptosis. However, the functions of PI3K in visual systems are not well understood. Retinal pigment epithelial (RPE) cells are post-mitotic cells that provide the "blood-retinal barrier", and control the flow of nutrients and waste products between the retina and the blood. Death of these cells leads to death of rod and cone photoreceptor cells, and compromise in RPE function may be a contributing factor in age-related macular degeneration. Since Bcl-x,, a downstream target of PI3K is highly expressed in RPE cells under cytotoxic stress, it is likely that PI3K plays an important role in RPE cell survival. We hypothesize that PI3K and BOI-xL are major survivor factors in RPE. To test this hypothesis, we will use a genetic approach to disrupt PI3K and Bcl-x (BCl-xL) in RPE, and compare the functional, biochemical, and structural phenotypes of the mutant mice with those of wild type mice. Since the conventional PI3K(p85odp110o_) and Bcl-x knockout mice are neonatal or embryonic lethal, mouse models of PI3K and Bcl-x null mutation will be generated in a RPE specific fashion, using the Cre/Iox system. Therefore, I propose 1) to generate and characterize transgenic mice expressing RPE-specific Cre driven by RPE65 promoter; 2) to generate RPE-specific PI3K and/or Bcl-x null mice and test the hypothesis that PI3K and BCl-xL are involved in RPE cell survival, 3) to test the hypothesis that compromised RPE cells may exacerbate the death of photoreceptor cells with PI3K and/or Bcl-x null mutations using the RPE-specific PI3K, or Bcl-x null mice generated in this study and the ABCR null (RPE degeneration) mice. A major goal of this project in the context of the COBRE program is to establish mouse models that can be used in future studies to elucidate the mechanisms of inherent retinal degeneration.