Post Translational Regulation of TET2 Function by Glucose Signaling

 描述(由申请人提供)：胞嘧啶(5mC)5位的DNA甲基化是一种关键的表观遗传修饰，在各种生物和病理过程中发挥关键作用。10-11双加氧酶家族主要催化5mC向5-羟甲基胞嘧啶(5HmC)的转化。最近的一些研究表明，Tet活性和由此产生的5hmC水平是维持ES细胞多能性、调控器官发育和防止癌症进展的表观遗传屏障。特别是，当Tet基因的表达或活性受到影响时，癌细胞被证明变得更具侵袭性。这些研究表明，5hmC和Tet家族蛋白对癌细胞生长起着检查点的作用。出于这些原因，研究Tet蛋白和5hmC水平是如何调节的，对于充分了解Tet和5hmC如何促进正常和病理的动态平衡是必要的。基于可靠的初步数据和癌细胞葡萄糖摄取的成熟放松调控，我们假设TET2功能是由独特的翻译后修饰(PTM)调控的，该修饰可以受到葡萄糖信号的调节。我们进一步提出，癌细胞中5hmC肿瘤抑制通路的缺失部分归因于葡萄糖摄取增加和葡萄糖信号失控。本研究的主要目的是了解不同的PTM如何调节TET2的水平和活性，进而影响TET2控制的DNA甲基组/羟甲基组。此外，这一提议将揭示蛋白质修饰酶如何根据葡萄糖信号的变化而不同地调节TET2 PTM。具体地说，在AIM 1中，我们将使用我们开发的高分辨率全基因组作图技术，识别由于TET2的解除调控而导致的羟甲基组/甲基组的癌症变化，以响应异常的葡萄糖信号。在目标2和3中，我们将鉴定和表征在TET2上观察到的两种类型的葡萄糖依赖的PTM(糖基化和磷酸化)，它们是由OGT和AMPK进行的。综上所述，这一提议将描述一种新的调节电路，它通过TET2对葡萄糖信号的翻译后修饰来维持5hmC水平。如果成功，这项提议将极大地促进我们对促进表观遗传水平的癌症相关变化的分子机制的理解，以响应代谢调节的放松。这项研究还将在代谢输入的变化与癌症表观基因组的适应之间建立牢固的机制联系。更重要的是，识别受环境信号控制的分子开关，可以打开/关闭癌症中的5hmC抗肿瘤生长屏障，将提供新的治疗药物靶向策略和治疗方法。

 DESCRIPTION (provided by applicant): DNA methylation at the 5 position of cytosine (5mC) is a critical epigenetic modification and plays key roles in various biological and pathological processes. The ten-eleven translocation (TET) families of dioxygenases primarily catalyze the conversion of 5mC to 5-hydroxymethylcytosine (5hmC). Several recent studies demonstrated that TET activities and the resultant 5hmC levels function as an epigenetic barrier for maintaining ES cell pluriopotency, governing organ development and preventing cancer progression. In particular, cancer cells have been shown to become more aggressive when TET gene expression or activity is compromised. These studies suggest that 5hmC and TET family proteins function as a checkpoint for cancer cell growth. For these reasons, investigating how TET proteins and 5hmC levels are regulated is necessary to fully understand how TET and 5hmC contribute to normal and pathological homeostasis. Based on solid preliminary data and the well-established deregulation of glucose uptake in cancer cells, we hypothesize that TET2 function is post-translationally regulated by distinctive post-translational modification (PTM), which can be modulated by glucose signaling. We further propose that the loss of the 5hmC tumor suppressor pathway in cancer cells is in part attributed to elevated glucose uptake and deregulated glucose signaling. The primary goal of this study is to understand how TET2 levels and activity are regulated by distinctive PTMs, which in turn impact on the TET2-controled DNA methylome/hydroxymethylome. Moreover, this proposal will unravel how protein-modifying enzymes differentially regulate TET2 PTMs in response to changes of glucose signaling. Specifically, in aim1 we will identify the cancer promoting changes to the hydorxymethylome/methylome that result from the deregulation of TET2 in response to aberrant glucose signaling, using the high resolution genome-wide mapping technologies we have developed. In aim 2&3, we will identify and characterize two types of glucose dependent PTMs observed on TET2, (glycosylation and phosphorylation), which are carried out by OGT and AMPK. Altogether, this proposal will characterize a novel regulatory circuit that maintains 5hmC levels through the posttranslational modifications of TET2 in response to glucose signaling. If successful, this proposal will significantly advance our understanding of the molecular mechanisms that facilitate cancer related changes at the epigenetic level in response to metabolic deregulation. This study will also establish a firm mechanistic link between changes in metabolic input to the adaption of the cancer epigenome. More importantly, identifying the molecular switch controlled by environmental cues that can turn on/off the 5hmC anti-tumor growth barrier in cancer will provide new therapeutic drug targeting strategies and treatments.