ELONGIN C: FUNCTION AND ROLE IN VHL DISEASE

多项证据表明，作为长素转录因子的调控亚基，长素C在von Hippel-Landau蛋白（VHL）的肿瘤抑制功能中起着与转录无关的重要作用。本提案的总体目标是确定伸长蛋白C的生物学功能及其在VHL肿瘤抑制中的作用。我们已经确定了伸长蛋白C的酵母同源物。我们的基本原理是伸长蛋白C的功能将在哺乳动物细胞中保守。我们的初步数据表明，酵母伸长蛋白C与4种酵母蛋白Snf4、Yap4、Yap6和Mdj1有强烈的特异性相互作用。值得注意的是，这些长链蛋白C结合伙伴都有哺乳动物同源物，可以与特定的应激反应相关联。因此，我们的假设是长链蛋白C是应激反应的关键蛋白。这一假设将在以下具体目标中进行检验。具体目标研究酵母伸长蛋白C在应激反应中的特性。初步研究表明，酵母伸长蛋白C基因是非必需的，在正常细胞生长过程中表达水平较低，该蛋白存在于细胞核和细胞质中。实验描述了评估缺氧，营养和氧化应激对长素c零菌株的影响。具体目标2。研究长链蛋白C与Snf4、Yap4、Yap6和Mdj1相互作用的性质和意义。Snf4是哺乳动物amp活化蛋白激酶(AMPK) γ亚基的同源物。我们将评估长链蛋白C与Snf4结合对激酶活性的影响。Yap4和Yap6是推测的转录因子，Mdj1是线粒体伴侣。这些蛋白与伸长蛋白C之间的相互作用将确定可能与伸长蛋白C平行或冗余的其他因素。本文描述了一种合成致死筛选方法，以确定可能补偿伸长蛋白C缺失的VHL肿瘤抑制的其他因素，阐明伸长蛋白C的功能可能导致确定治疗VHL疾病的新治疗靶点。

Several lines of evidence indicate that Elongin C, a regulatory subunit of the Elongin transcription factor, plays an essential role, unrelated to transcription, in the tumor suppression function of the von Hippel-Landau protein (VHL). The overall objective of this proposal is to determine the biological function(s) of Elongin C and its role in VHL tumor suppression. We have identified the yeast homologue of Elongin C. Our rationale is that Elongin C function will be conserved in mammalian cells. Our preliminary data indicate that yeast Elongin C interacts strongly and specifically with 4 yeast proteins: Snf4, Yap4, Yap6 and Mdj1. Notably each of these Elongin C binding partners has a mammalian homologue and can be linked to specific stress responses. Thus our hypothesis is that Elongin C is a key protein in the stress response. This hypothesis will be examined as described in the following specific aims. Specific Aim 1. To characterize yeast Elongin C during the stress response. Preliminary studies indicate that the yeast Elongin C gene is non-essential, expressed at low levels during normal cell growth and that the protein is present in both the nucleus and in the cytoplasm. Experiments are described to assess the effects of hypoxic, nutrient, and oxidant stress in Elongin c null strains. Specific Aim 2. To examine the nature and significance of the Elongin C interactions with Snf4, Yap4, Yap6 and Mdj1. Snf4 is the homologue of the gamma subunit of mammalian AMP-activated protein kinase (AMPK). The affect of binding of Elongin C to Snf4 on the kinase activity will be assessed. Yap4 and Yap6 are putative transcription factors and Mdj1 is a mitochondrial chaperone. The interaction between these proteins and Elongin C will identify other factors that may operate in parallel or be redundant with Elongin C. A synthetic lethal screen is described to identify other factors that may compensate for absence of Elongin C VHL tumor suppression, the elucidation of the function(s) of Elongin C may lead to the identification of new therapeutic targets for treatment of VHL disease.