Post-Translational Control of TET Function in Lymphoma

淋巴瘤 TET 功能的翻译后控制

• 批准号: 10251482
• 负责人: Ricardo C Aguiar
• 金额: --
• 依托单位: SOUTH TEXAS VETERANS HEALTH CARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10251482
• 关键词: Acetyl Coenzyme A; Acetylation; Area; B-Cell Lymphomas; Balkans; Binding; Biology; Blood Cells; Cell Line; Chemical Exposure; DNA; DNA Methylation; Data; Development; Diagnosis; Distal; Early Diagnosis; Enhancers; Enzymes; Epigenetic Process; Exercise; Gene Expression; Gene Expression Profile; Generations; Genes; Genetic; Genetic Transcription; Genomics; Glioma; Growth; Hexosamines; Histones; Human; Hyperactivity; In Vitro; Incidence; Infectious Agent; Link; Location; Lymphoma; Lymphomagenesis; Malignant Neoplasms; Maps; Mediating; Metabolic; Metabolism; Methylation; Military Personnel; Mitochondria; Mixed Function Oxygenases; Modeling; Mus; Nature; Nuclear; O-GlcNAc transferase; Oncogenic; Organelles; Outcome; Output; Oxidoreductase; Pathology; Pathway interactions; Physiology; Play; Population; Post-Translational Protein Processing; Process; Reporter; Reporting; Research; Resolution; Risk; Role; S-Adenosylmethionine; Signal Transduction; Stem Cell Development; Testing; Tetanus Helper Peptide; Therapeutic; Tumor Suppressor Proteins; Veterans; Vietnam; Western World; Work; alpha ketoglutarate; base; cancer type; chromatin immunoprecipitation; defined contribution; demethylation; in vitro Model; in vivo; large cell Diffuse non-Hodgkin' s lymphoma; mitochondrial metabolism; mouse model; myeloid leukemia cell; novel; novel marker; oxidation; programs; promoter; stem cells; transcription factor; tumor

TET DNA hydroxylases are alpha-ketoglutarate (αKG)-dependent enzymes that catalyze the oxidation of 5mC to 5-hydroxymethylcytosine (5hmC), thus promoting DNA demethylation. Mapping of 5hmC marks at single base resolution demonstrated that the main role of TET enzymes is to maintain gene enhancers hypomethylated and active. Enhancers are genomic areas to which transcription factors bind to modulate gene expression programs. Hyperactive clusters of enhancers that are densely occupied by transcriptional factors are termed super- enhancers and are typically found in cancer. Like promoters, enhancers/super-enhancers are regulated by their DNA methylation status, a process that often goes awry in cancer. Thus, given that active enhancers and super- enhancers are oncogenic in nature, and that TET enzymes maintain them hypomethylated and active, we postulate that increased TET activity may itself be oncogenic. Mitochondria function as signaling organelles by generating substrates that fuel epigenetic changes, including for example acetylation and methylation of DNA and histones, respectively. Recently, we and others described a subtler interplay between mitochondria and epigenetics, wherein the levels of the intermediate metabolites αKG and 2-hydroxyglutarate were found to modulate the activity of TET enzymes, thus controlling DNA methylation. These findings led us to hypothesize that intermediary metabolism plays as an important role in the control of DNA methylation. Specifically, we posited that the mitochondrial enzymes D-2- and L-2-hydroxyglutarate dehydrogenase (D2HGDH and L2HGDH), which catalyze the interconversion of 2-HG to αKG, are integral to the cross talk between mitochondrial metabolism, TET function and super-enhancer demethylation/activation. To expand on this initial concept, we sought to identify upstream signals that regulate D2HGDH and L2HGDH expression and, consequently, influence TET function and enhancer methylation/activity. Using reporter and ChIP assays, inducible cell lines and mouse models, we recently reported that MYC transcriptionally activates D2HGDH and L2HGDH and, in a D2HGDH/L2HGDH/αKG-dependent manner, induces TET function leading to DNA demethylation in vitro and in vivo. Remarkably, we discovered that the MYC/D2-L2HGDH/αKG axis also promotes the nuclear accumulation of TET1, TET2 and TET3, in association with enhanced O-GlcNAcylation, a post-translational modification executed by another mitochondrial enzyme, O-GlcNAc transferase (OGT). Further, we preliminarily showed that in in diffuse large B cell lymphoma (DLBCL), MYC levels associated with enhancer methylation and target gene expression. Together, these data uncovered a novel mitochondrial signaling axis which includes MYC at the proximal point, D2/L2HGDH and OGT at the center, and, distally, TET activity and subcellular location. In this proposal, we will use human B cell lymphoma models in vitro and in vivo, to test the overarching hypothesis that intermediary metabolism, in part due to MYC activity, induces TET function, maintains oncogenic enhancers/super-enhancers hypomethylated and active and promote cancer. Our specific aims are: AIM 1) Determine the mechanistic basis for the increased O-GlcNAcylation mediated by the MYC-D2/L2HGDH-αKG axis and its role in promoting TET nuclear localization and enhancer activation. AIM 2) Define the contribution of the TET activation to MYC-driven lymphomagenesis AIM 3) Characterize the MYC- driven map of 5hmC marks and super-enhancer activation in B cell lymphoma. The proposed study is significant because it will define, and mechanistically elucidate, a novel role for MYC in cancer, i.e., activation of oncogenic enhancers/super-enhancers. Downstream to MYC, the contribution of D2HGDH-L2HGDH (via αKG generation) and O-GlucNAcylation will impart a post-translational control of TET function, which challenges the current dogma that these enzymes function exclusively as tumor suppressors.

TET DNA羟化酶是α-酮戊二酸（αkg）依赖性酶，可催化5MC的氧化 到5-羟基甲基胞嘧啶（5HMC），从而促进DNA脱甲基化。在单个底座上的5hmc标记映射 解决方案表明，TET酶的主要作用是维持基因增强剂降甲基化和 积极的。增强子是转录因子与调节基因表达程序结​​合的基因组领域。 不被转录因子占据的增强子的多动激动簇称为超级 增强剂，通常在癌症中发现。像发起人一样，增强剂/超级增强剂受其监管 DNA甲基化状态，这种过程通常会在癌症中出现问题。鉴于积极的增强剂和超级 增强剂本质上是致癌的，TET酶将其保持降压和活性，我们 假设增加的TET活性本身可能是致癌的。线粒体作为信号细胞器的功能 产生助力表观遗传变化的底物，包括乙酰化和DNA的甲基化 和Histones。最近，我们和其他人描述了线粒体和线粒体之间的微妙相互作用 表观遗传学，其中中间代谢物αkg和2-羟基戊二酸水平被发现为 调节TET酶的活性，从而控制DNA甲基化。这些发现使我们假设 这种中间代谢在控制DNA甲基化中起着重要作用。具体来说，我们 认为线粒体酶D-2-2-和L-2-羟基戊二酸脱氢酶（D2HGDH和 L2HGDH）催化2-Hg至αkg的互转换是不可或缺的 线粒体代谢，TET功能和超增强剂脱甲基化/激活。扩展此初始 概念，我们感觉到识别调节D2HGDH和L2HGDH表达的上游信号，以及 因此，影响TET功能和增强子甲基化/活性。使用记者和芯片分析， 诱导的细胞系和小鼠模型，我们最近报道了MYC转录激活D2HGDH和 L2HGDH，并以D2HGDH/L2HGDH/αkg依赖性方式诱导TET函数导致DNA 体外和体内脱甲基化。值得注意的是，我们发现MYC/D2-L2HGDH/αkg轴也 促进TET1，TET2和TET3的核积累，与O-Glcnacylation增强（A） 通过另一种线粒体酶O-GLCNAC转移酶（OGT）执行的翻译后修饰。 此外，我们初步表明，在扩散的大B细胞淋巴瘤（DLBCL）中，MYC水平与 增强子甲基化和靶基因表达。这些数据一起发现了一种新型的线粒体 信号轴，其中包括近端的MYC，中心的D2/L2HGDH和OGT，然后分开，TET 活动和亚细胞位置。在此提案中，我们将在体外和体内使用人类B细胞淋巴瘤模型 为了测试中间代谢的总体假设，部分是由于MYC活性引起的 功能，维持致癌增强剂/超增强剂低甲基化并活跃并促进癌症。我们的 具体目的是：目标1）确定由O-Glcnacylation增加的机械基础 MYC-D2/L2HGDH-αkg轴及其在促进TET核定位和增强子激活中的作用。目标2） 定义TET激活对MYC驱动的淋巴作用的贡献3） B细胞淋巴瘤中5HMC标记和超增强剂激活的驱动图。拟议的研究很重要 因为它将定义并机械阐明MYC在癌症中的新作用，即致癌性激活 增强剂/超级增强剂。下游对MYC，D2HGDH-L2HGDH的贡献（通过αkg产生） O-Glucnacylation将赋予TET功能的翻译后控制，这挑战了当前 这些酶仅充当肿瘤补充剂的教条。