Tgf 2-2 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。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久性原发性玻璃体增生的人类眼病。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。我的总体目标之一是阐明驱动这个重要基因表达的基本机制。现有的教条认为，Arf作为“癌基因传感器”，在携带癌基因激活的异常或过度增殖信号的细胞中诱导其表达。单个细胞区分致癌刺激和同样强烈的正常增殖信号（如发育过程中发生的信号）的机制，目前还完全不清楚。然而，最近，我和我的实验室成员有了一个令人惊讶的发现，挑战了当前的范式。具体来说，在探索p19Arf阻止发育中的小鼠原发性玻璃体增生的机制时，我们发现其启动子在小鼠发育过程中以一种精细控制的模式被激活。这一发现使我可以有把握地得出结论，Arf控制必须超出由癌基因激活提供的细胞内在信号。根据我们的新发现，Tgf22 -/-部分表型类似于缺乏Arf时的表型，我已经确定转化生长因子2-2 （Tgf22）是p19Arf的重要调节因子，后者是Tgf22在体内和体外抗有丝分裂作用所必需的。在本提案中，我将利用现有的小鼠和细胞培养模型来填补我知识中的三个关键空白：Tgf2是否直接控制眼睛发育过程中p19Arf的表达？从Tgf22发出的基本细胞内信号是什么？Arf启动子的基本机制是什么？研究从Tgf22到p19Arf的这条通路将加深我们对这两种蛋白在发育中的眼睛中如何运作的理解，并更好地定义可能导致以玻璃体增生为特征的人类疾病的遗传异常。然而，从更广泛的角度来看，这可能会揭示癌细胞中如何控制Arf以及Tgf2s在发育过程中如何发挥其他功能。

DESCRIPTION (provided by applicant): Although Arf is broadly known as a tumor suppressor gene, it also is essential for mouse eye development. Mice lacking Arf are born blind with a severe developmental eye disease, mimicking a human eye disease known as Persistent Hyperplastic Primary Vitreous. Very little is known about basic mechanisms that control Arf transcription or the expression of its gene product, p19Arf. One of my overall goals is to use elucidate the fundamental mechanisms driving the expression of this important gene. The existing dogma holds that Arf functions as an "oncogene sensor" such that its expression is induced in cells carrying abnormal or excessive proliferation signals from oncogene activation. Mechanisms by which an individual cell can discriminate between an oncogenic stimulus and an equally intense, normal proliferation signal - such as that occurring during development - are not at all clear. Recently, though, members of my laboratory and I made a surprising discovering challenging the current paradigm. Specifically, while exploring mechanisms by which p19Arf prevented primary vitreous hyperplasia in the developing mouse, we showed that its promoter is activated in an exquisitely controlled pattern during mouse development. This finding allows me to safely conclude that Arf control must extend beyond the cell intrinsic signals provided by oncogene activation. Working from our new findings that part of the Tgf22 -/- phenotype resembles that in the absence of Arf, I have established the Transforming Growth Factor 2-2 (Tgf22) as an essential regulator of p19Arf and that the latter is required for the anti-mitogenic effects of Tgf22 in vivo and in vitro. In this proposal, I will take advantage of existing mouse and cell culture models to close three critical gaps in my knowledge: Does Tgf2 directly control p19Arf expression during eye development? What are the essential intracellular signals emanating from Tgf22? What are the fundamental mechanisms acting at the Arf promoter? Studying this pathway from Tgf22 to p19Arf will deepen our understanding of how the two proteins operate in the developing eye, and better define the genetic abnormalities that can contribute to human diseases characterized by hyperplasia in the vitreous. From a broader perspective, though, this potentially sheds new light on how Arf may be controlled in cancer cells and how Tgf2s may carry out other functions during development. PUBLIC HEALTH RELEVANCE: The Arf gene plays an essential role to prevent primary vitreous hyperplasia and hyaloid vascular regression, processes that are critical for normal vision. We have previously defined its temporally- and spatially-restricted expression in the developing eye, but the mechanisms underlying this expression pattern are totally unknown. My Preliminary Studies in this proposal provide the first insight: Tgf22 plays a key role in the process. Experiments in this proposal define will define the cellular and molecular mechanisms by which Tgf22 accomplishes this.