Tgf Beta 2 controls p19Arf During Eye Development

描述(申请人提供)：虽然Arf基因被广泛认为是一种肿瘤抑制基因，但它对小鼠眼睛的发育也是必不可少的。我的实验室的工作表明，缺乏ARF的小鼠出生时就会失明，患有一种严重的发育性眼病，类似于一种名为持续性初级玻璃体增生症(PHPV)的人类眼病。这种眼病是由于为发育中的眼睛提供营养的玻璃体血管退化失败所致。我的总体目标之一是阐明Arf基因产物在正常眼睛发育过程中引导这些关键血管变化的基本机制。人们对控制Arf转录或其基因产物p19Arf表达的基本机制知之甚少。但是，在过去的21年半里，我的实验室团队的发现提供了新的信息，挑战了现有的教条，即ARF主要由“异常”或“过度”的扩散信号控制。相反，我们发现了一种重要的信号蛋白-转化生长因子-2(转化生长因子2)-在眼睛发育过程中控制Arf的表达。同样重要的是，Arf对转化生长因子2引导正常眼睛发育是绝对必要的。有了这两个发现，我们建立了一个新的生化和遗传途径，这对正常的眼睛发育和视力是必不可少的。根据我们过去两年半的发现，我打算填补我对转化生长因子2如何诱导Arf表达的理解中的三个关键空白：当转化生长因子2刺激时，哪些DNA元件位于arf基因两侧以增强其表达？转化生长因子如何与Arf启动子上的RNA聚合酶II接合，一旦该聚合酶稳定，又是如何控制的？依赖于转化生长因子的增强子和反式激活因子如何与转录机制相交以增加Arf的表达？研究从转化生长因子2到p19Arf的这一途径将加深我们对这两种蛋白质在发育中的眼睛如何运作的理解。它还将使我们了解转化生长因子和p19Arf在血管周围细胞中可能扮演的更广泛的角色，这些细胞显然具有稳定或破坏潜在血管稳定的能力。最终，充分描述这些分子过程--包括确定基因中的关键调控元件和基本辅助因子--将使我能够更有效地对PHPV或类似眼病患者进行遗传学研究。然而，从更广泛的角度来看，这一知识也可能说明ARF如何在癌症中受到控制，以及转化生长因子-S如何在发育和疾病中发挥其他功能。

DESCRIPTION (provided by applicant): Although Arf is broadly known as a tumor suppressor gene, it also is essential for mouse eye development. Work from my laboratory has demonstrated that mice lacking Arf are born blind with a severe developmental eye disease, mimicking a human eye disease known as Persistent Hyperplastic Primary Vitreous (PHPV). This eye disease is due to failed involution of the hyaloid vasculature that provides nutrients to the developing eye. One of my overall goals is to elucidate the fundamental mechanisms by which the Arf gene product guides these critical vascular changes during normal eye development. Very little is known about basic mechanisms that control Arf transcription or the expression of its gene product, p19Arf. But, discoveries from my laboratory team over the last 21/2 years have provided new information challenging the existing dogma that Arf is primarily controlled by "abnormal" or "excessive" proliferation signals. Instead, we showed that an important signaling protein - Transforming Growth Factor ß-2 (Tgfß2) - controls Arf expression during eye development. As importantly, Arf is absolutely essential for Tgfß2 to guide normal eye development. With these two findings, we established a new biochemical and genetic pathway that is essential for normal eye development and vision. Building naturally from our findings over the last 2 1/2 years, I intend to close three critical gaps in my understanding of how Tgfß2 can induce Arf expression: What are the DNA elements that flank the Arf gene to enhance its expression when stimulated by Tgfß2? How does Tgfß engage RNA polymerase II at the Arf promoter and how is this polymerase controlled once it is poised? How do the Tgfß dependent enhancers and trans-activating factors intersect with the transcriptional machinery to increase Arf expression? Studying this pathway from Tgfß2 to p19Arf will deepen our understanding of how the two proteins operate in the developing eye. It will also inform our knowledge of the broader role that Tgfß and p19Arf may play in perivascular cells that obviously have the capacity to either stabilize or destabilize underlying blood vessels. In the end, fully characterizing these molecular processes - including identifying the key regulatory elements in the gene and essential cofactors - will allow me to more effectively carry out genetics studies of patients with PHPV or similar eye diseases. From a broader perspective, though, the knowledge may also illustrate how Arf might be controlled in cancer and how Tgfßs may carry out other functions in development and disease.