ARF Controls Vascular Regression During Eye Development

描述（由申请人提供）：本提案的主要目标是了解在眼睛发育过程中预防原发性玻璃体增生并指导玻璃体血管系统（HVS）消退的分子事件。我将专门研究的作用Arf，一个重要的哺乳动物肿瘤抑制基因，和血小板衍生生长因子受体2（Pdgfr 2），这有助于各种发育，生理和病理过程。为了确保正常发育，哺乳动物细胞具有检查细胞增殖刺激和保持细胞周期停滞的机制。当出错时，过量的促有丝分裂信号导致发育缺陷和各种各样的病理过程。最初发现Arf基因产物p19 Arf作为“融合物”发挥关键作用，以控制过量的有丝分裂原并防止肿瘤形成。R 01的第一个周期支持的工作挑战了这个简单的范例，因为我已经证明了p19 Arf在小鼠眼睛发育过程中起着重要的作用。没有它，过多的血管周围细胞包裹玻璃体中的玻璃体血管，阻止它们在眼睛发育的后期正常退化。缺乏Arf的小鼠由于与严重的持续性增生性原始玻璃体（PHPV）惊人相似的病理过程而失明。我们已经确定了一种新的生化和遗传途径，其中Arf基因产物阻断来自Pdgfr 2的信号，以防止原发性玻璃体增生，可能是通过抑制受体的表达。在目前的建议中，我将解决一些关键问题，这些问题仍然困扰着我们对这两种基因产物之间功能关系的理解。我将利用现有的细胞培养系统和小鼠模型，其中之一将在本提案中开发，以（1）确定Pdgfr 2的p19 Arf依赖性控制如何影响眼发育;（2）揭示Pdgfr 2促进玻璃体增生而不需要Arf的机制;（3）阐明Arf抑制Pdgfr 2表达的机制。深入了解Pdgfr 2如何在缺乏Arf的情况下促进眼部病理学，以及p19 Arf如何控制Pdgfr 2依赖性信号，将解决眼部发育的基本问题;使我能够理想地解决这一新“途径”中的遗传异常是否有助于PHPV或其他玻璃体视网膜病变的发病机制;并开始研究药物干扰Pdgfr 2信号传导是否可以改善疾病。公共卫生相关性：这项建议的主要目标是了解分子事件，防止原发性玻璃体增生和指导退化的玻璃体血管系统（HVS）在眼睛的发展。我已经确定了一种新的生化和遗传途径，其中Arf基因产物p19 Arf阻断源自血小板衍生生长因子受体2（Pdgfr 2）的信号，以防止原发性玻璃体增生，可能是通过抑制受体的表达。我将使用基于细胞培养的小鼠模型来揭示Pdgfr 2如何在缺乏Arf的情况下对眼部病理学做出贡献，以及p19 Arf如何控制Pdgfr 2依赖的信号。

DESCRIPTION (provided by applicant): The major goal of this proposal is to understand molecular events preventing primary vitreous hyperplasia and guiding the regression of the hyaloid vascular system (HVS) during eye development. I will specifically investigate the roles of Arf, an important mammalian tumor suppressor gene, and Platelet-derived growth factor receptor 2 (Pdgfr2), which contributes to a variety of developmental, physiological, and pathological processes. To assure normal development, mammalian cells have mechanisms to check cell proliferation stimuli and preserve cell cycle arrest. When gone awry, excess mitogenic signals lead to developmental defects and a wide variety of pathological processes. The Arf gene product, p19Arf, was initially discovered to play a key role as a "fuse" to control excess mitogens and prevent tumor formation. Work supported by the first cycle of this R01 has challenged this simple paradigm as I have shown p19Arf plays an essential function during mouse eye development. Without it, excess numbers of perivascular cells envelop the hyaloid vasculature in the vitreous, preventing their normal involution during the later stages of eye development. Mice lacking Arf are blind due to a pathological process strikingly similar to severe persistent hyperplastic primary vitreous (PHPV). We have identified a new biochemical and genetic pathway in which the Arf gene product blocks signals stemming from Pdgfr2 to prevent primary vitreous hyperplasia, likely by repressing the expression of the receptor. In the current proposal, I will tackle the critical questions that still cloud our understanding of the functional relationship between the two gene products. I will take advantage of existing cell culture system and mouse models one of which will be developed in this proposal to (1) identify how p19Arf- dependent control of Pdgfr2 influences eye development; (2) uncover mechanisms by with Pdgfr2 fosters vitreous hyperplasia without Arf; and (3) elucidate mechanisms by which Arf represses Pdgfr2 expression. Insight into how Pdgfr2 contributes to the eye pathology in the absence of Arf and how p19Arf controls Pdgfr2-dependent signals will address fundamental aspects of eye development; leave me ideally positioned to address whether genetic abnormalities in this new "pathway" contribute to the pathogenesis of PHPV or other vitreoretinopathies; and begin to investigate whether pharmacological disruption of Pdgfr2 signaling can ameliorate the disease. PUBLIC HEALTH RELEVANCE: The major goal of this proposal is to understand molecular events preventing primary vitreous hyperplasia and guiding the regression of the hyaloid vascular system (HVS) during eye development. I have identified a new biochemical and genetic pathway in which the Arf gene product, p19Arf, blocks signals stemming from Platelet-derived growth factor receptor 2 (Pdgfr2) to prevent primary vitreous hyperplasia, likely by repressing the expression of the receptor. I will use cell culture-based and mouse models to uncover how Pdgfr2 contributes to the eye pathology in the absence of Arf and how p19Arf controls Pdgfr2-dependent signals.