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分子事件，预防原发性玻璃体增生，并指导眼睛发育过程中玻璃体血管系统(HVS)的消退。我将具体研究重要的哺乳动物肿瘤抑制基因arf和血小板衍生生长因子受体2(Pdgfr2)在多种发育、生理和病理过程中的作用。为了确保正常发育，哺乳动物细胞具有抑制细胞增殖刺激和保持细胞周期停滞的机制。当出现错误时，过多的有丝分裂信号会导致发育缺陷和各种各样的病理过程。Arf基因产物p19Arf最初被发现在控制过多的有丝分裂原和防止肿瘤形成方面发挥关键作用。这个R01的第一个周期所支持的工作挑战了这个简单的范例，因为我已经证明了p19Arf在小鼠眼睛发育过程中发挥着重要的功能。如果没有它，过多的血管周围细胞将玻璃体中的玻璃体血管包裹起来，阻止它们在眼睛发育的后期正常退化。缺乏ARF的小鼠由于一种与严重的持续性初级玻璃体增生症(PHPV)惊人地相似的病理过程而失明。我们已经确定了一条新的生化和遗传途径，其中Arf基因产物阻断来自Pdgfr2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。在目前的提案中，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品之间的功能关系的理解。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p19Arf依赖的Pdgfr2调控如何影响眼睛发育；(2)揭示Pdgfr2与Pdgfr2共同作用促进玻璃体增生的机制；以及(3)阐明Arf抑制Pdgfr2表达的机制。深入了解在没有Arf的情况下，Pdgfr2如何在眼睛病理中起作用，以及p19Arf如何控制依赖Pdgfr2的信号将解决眼睛发育的基本方面；让我处于理想的位置来解决这一新“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；并开始调查Pdgfr2信号的药理干扰是否可以改善疾病。公共卫生相关性：这项建议的主要目标是了解分子事件，预防原发性玻璃体增生，并指导眼睛发育过程中玻璃体血管系统(HVS)的消退。我已经发现了一种新的生化和遗传途径，在这种途径中，Arf基因产物p19Arf可以阻断来自血小板衍生生长因子受体2(Pdgfr2)的信号，以防止原发性玻璃体增生，这可能是通过抑制受体的表达来实现的。我将使用基于细胞培养和小鼠的模型来揭示在没有Arf的情况下Pdgfr2如何在眼睛病理中起作用，以及p19Arf如何控制依赖于Pdgfr2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.