The roles of Frizzled-4 and Sox17 in retinal vascular development and maintenance

描述（由申请人提供）：项目概述：遗传性和获得性视网膜血管疾病是美国失明的主要原因。约翰霍普金斯医学院的Jeremy Nathans博士的实验室已经定义并表征了调节脊椎动物视网膜血管发育的中央信号系统之一-通过Muller胶质衍生配体Norrin的旁分泌作用激活内皮细胞受体Frizzled 4（Fz 4）和辅助受体Lrp 5-并描述了这一途径的扰动如何导致人类一系列遗传性视网膜血管疾病。我们实验室最近的研究结果表明，Fz 4是一种泛内皮受体，继续在成年小鼠的成熟视网膜血管中表达，这表明Fz 4的功能可能是维持成熟血管或它们如何应对缺血性视网膜病变所必需的。此外，我们已经确定了一个转录因子，Sox 17，这似乎是一个下游效应的Norrin/Fz 4信号在发展中的视网膜血管。该培训奖学金由两个目标组成，第一个目标是使用条件Fz 4小鼠来表征Fz 4在成熟视网膜血管中的体内功能，所述条件Fz 4小鼠允许仅在成人血管丛完全发育后操纵Fz 4信号。使用这些小鼠，我们还将研究Fz 4在缺血性视网膜病变中的功能，通过表征激光诱导的视网膜动脉和静脉阻塞引起的新血管生长的模式和时间过程。第二个目标提出了在视网膜血管发育中使用条件靶向的Sox 17小鼠，允许基因失活，通过Cre介导的重组，特别是在内皮细胞中的Sox 17的体内功能的特征。为了帮助促进这些研究，我们正在产生小鼠品系，这将使我们能够荧光标记肌动蛋白细胞骨架和视网膜内皮细胞的特定亚群。总之，这些目标将为Norrin/Fz 4信号通路在血管健康中的功能提供重要的见解，长期目标是为先天性和获得性视网膜血管疾病开发创新的医学治疗方法。

DESCRIPTION (provided by applicant): Project Summary: Inherited and acquired retinal vascular disorders are a leading cause of blindness in the United States. The laboratory of Dr. Jeremy Nathans at Johns Hopkins Medical School has defined and characterized one of the central signaling systems that regulates vascular development in the vertebrate retina-the activation of the endothelial cell receptor Frizzled4 (Fz4) and coreceptor Lrp5 by the paracrine action of the Muller glia-derived ligand Norrin-and described how perturbations in this pathway cause a series of inherited retinal vascular disorders in humans. Recent findings from our lab now indicate that Fz4 is a pan-endothelial receptor that continues to be expressed in the mature retinal blood vessels of adult mice, suggesting that Fz4 functions may be required for the maintenance of mature blood vessels or how they respond to ischemic retinopathy. Also, we have identified a transcription factor, Sox17, which appears to be a downstream effector of Norrin/Fz4 signaling in the developing retinal vasculature. This training fellowship consists of two aims, the first of which proposes to characterize the in vivo functions of Fz4 in mature retinal blood vessels using conditional Fz4 mice that permit the manipulation of Fz4 signaling only after the adult vascular plexus has fully developed. Using these mice, we will also investigate the functions of Fz4 in ischemic retinopathy by characterizing the pattern and time course of new blood vessel growth in response to laser-induced retinal artery and vein occlusion. The second aim proposes to characterize the in vivo functions of Sox17 in retinal vascular development using conditionally targeted Sox17 mice that permit gene inactivation, via Cre-mediated recombination, specifically in endothelial cells. To help facilitate these studies, we are generating mouse lines that will enable us to fluorescently label the actin cytoskeleton and specific subpopulations of retinal endothelial cells. Together, these aims will provide important insight into the functions of the Norrin/Fz4 signaling pathway in vascular health, with the long term goals of developing innovative medical treatments for congenital and acquired retinal vascular disorders.