Tgf Beta 2 controls p19Arf During Eye Development

描述（由申请人提供）：虽然Arf被广泛认为是一种肿瘤抑制基因，但它也是小鼠眼睛发育所必需的。我的实验室的研究表明，缺乏Arf的小鼠天生失明，患有一种严重的发育性眼病，类似于一种被称为持续性增殖性原发性玻璃体（PHPV）的人类眼病。这种眼病是由于向发育中的眼睛提供营养的玻璃状血管衰竭所致。我的总体目标之一是阐明在正常眼睛发育过程中，Arf基因产物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，在过去的两年半里，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”的增殖信号控制。相反，我们发现一种重要的信号蛋白-转化生长因子ß-2 (Tgfß2) -在眼睛发育过程中控制着Arf的表达。同样重要的是，Arf对于Tgfß2引导正常眼睛发育是绝对必要的。通过这两个发现，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至关重要。基于我们过去两年半的发现，我打算弥补我对Tgfß2如何诱导Arf表达的理解中的三个关键空白：当Tgfß2刺激时，Arf基因侧面增强其表达的DNA元件是什么？Tgfß如何在Arf启动子处参与RNA聚合酶II ?一旦聚合酶处于平衡状态，该聚合酶是如何控制的？Tgfß依赖性增强子和反式激活因子如何与转录机制交叉以增加Arf表达？研究从Tgfß2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中如何运作的理解。它还将使我们了解Tgfß和p19Arf在血管周围细胞中可能发挥的更广泛的作用，这些细胞显然具有稳定或破坏潜在血管的能力。最后，充分描述这些分子过程——包括确定基因中的关键调控元素和必要的辅助因子——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，这些知识也可能说明在癌症中如何控制Arf，以及Tgfßs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.