Post Translational Regulation of TET2 Function by Glucose Signaling

 描述（申请人提供）：胞嘧啶5位（5 mC）的DNA甲基化是一种关键的表观遗传修饰，在各种生物学和病理过程中发挥着关键作用。双加氧酶的10 - 11易位（泰特）家族主要催化5 mC转化为5-羟甲基胞嘧啶（5 hmC）。最近的几项研究表明，泰特活性和由此产生的5 hmC水平作为表观遗传屏障，用于维持ES细胞多能性，控制器官发育和预防癌症进展。特别是，当泰特基因表达或活性受损时，癌细胞已显示出更具侵袭性。这些研究表明，5 hmC和泰特家族蛋白作为癌细胞生长的检查点发挥作用。出于这些原因，研究泰特蛋白和5 hmC水平是如何调节的是必要的，以充分了解泰特和5 hmC如何有助于正常和病理稳态。基于可靠的初步数据和癌细胞中葡萄糖摄取的既定失调，我们假设TET 2功能是由独特的翻译后修饰（PTM）进行后调节的，这可以通过葡萄糖信号转导来调节。我们进一步提出，癌细胞中5 hmC肿瘤抑制通路的丧失部分归因于葡萄糖摄取增加和葡萄糖信号转导失调。本研究的主要目的是了解TET 2水平和活性如何通过独特的PTM调节，这反过来又影响TET 2控制的DNA甲基化/羟甲基化。此外，该提议将揭示蛋白质修饰酶如何响应葡萄糖信号的变化而差异调节TET 2 PTM。具体来说，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，鉴定由TET 2响应异常葡萄糖信号传导而失调引起的羟甲基化/甲基化组的癌症促进变化。在目标2&3中，我们将鉴定和表征在TET 2上观察到的两种类型的葡萄糖依赖性PTM（糖基化和磷酸化），其由OGT和AMPK进行。总之，该提案将表征一种新的调节回路，该回路通过TET 2的翻译后修饰响应于葡萄糖信号传导来维持5 hmC水平。如果成功的话，这一提议将大大推进我们对在表观遗传水平上促进癌症相关变化的分子机制的理解，以响应代谢失调。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，识别由环境线索控制的可以打开/关闭癌症中5 hmC抗肿瘤生长屏障的分子开关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.