Epigenetic regulation of cancer metabolism by G9A

描述(申请人提供)：癌细胞重新编程它们的新陈代谢，以迎接生长和增殖的生物合成挑战。癌症新陈代谢是如何在癌细胞中启动和维持的，是癌症研究的中心问题。最近的研究表明，丝氨酸-甘氨酸合成途径的激活增加是癌症代谢的组成部分，丝氨酸-甘氨酸合成途径产生许多生物合成前体和代谢物，是产生蛋白质、脂膜和核酸所必需的。我们最近发现了组蛋白H3赖氨酸9(H3K9)甲基转移酶G9a在这一生物合成途径的表观遗传激活中的重要作用。G9a在催化H3K9单甲基化和二甲基化(H3K9me1和H3K9me2)中起主要作用，其中H3K9me1是活性标记，H3K9me2是抑制标记。G9a在许多类型的人类癌症中都有过表达。我们发现，G9a通过增加途径基因启动子上的H3K9me1来转录激活丝氨酸-甘氨酸的合成。拟议的研究旨在确定1)鉴于G9a没有序列特异的DNA结合域，G9a如何特异性地针对途径基因，以及2)鉴于G9a可以催化H3K9me1和H3K9me2，G9a如何用H3K9me1特异性标记这些基因。在目标1中，我们将研究序列特异性DNA结合转录因子ATF4作为靶向G9a丝氨酸途径基因启动子的机制。我们将确定G9a是否需要ATF4与这些启动子结合，调节它们的H3K9甲基化状态，并增加丝氨酸-甘氨酸合成的糖酵素通量。我们还将研究G9a-ATF4相互作用的分子基础。在目标2中，我们将研究转录因子MYCN作为靶向G9a丝氨酸途径基因的替代机制，特别是在G9a过表达的癌细胞中。我们将确定G9a是否需要MYCN与这些基因启动子结合，调节它们的H3K9甲基化状态，并增加丝氨酸-甘氨酸合成的糖酵素通量。我们还将研究G9a-MYCN相互作用的分子基础。在目标3中，我们将检验这样的假设，即专门去除H3K9me2和H3K9me3的H3K9去甲基酶KDM4C与G9a合作，在这些基因启动子上保持高水平的H3K9me1。我们将确定G9a和KDM4C是否同时与这些基因启动子结合，以及G9a是否需要KDM4C在这些启动子上保持高水平的H3K9me1以进行转录激活。我们还将研究G9a-KDM4C合作的分子基础。这项拟议的研究有望确定一种控制丝氨酸-甘氨酸合成的新调节机制，并引入一种新的靶向癌症代谢的治疗途径。此外，功能分析还包括

DESCRIPTION (provided by applicant): Cancer cells reprogram their metabolism to meet the biosynthetic challenge of growth and proliferation. How cancer metabolism is initiated and maintained in cancer cells is a central question of cancer research. Recent studies demonstrate that increased activation of the serine-glycine synthesis pathway, which generates many biosynthetic precursors and metabolites essential for the production of proteins, lipid membranes and nucleic acids, is an integral part of cancer metabolism. We recently uncovered an essential role of the histone H3 lysine 9 (H3K9) methyltransferase G9A in epigenetic activation of this biosynthesis pathway. G9A has a primary role in catalyzing H3K9 monomethylation and dimethylation (H3K9me1 and H3K9me2), with H3K9me1 being an active mark and H3K9me2 being a repressive mark. G9A overexpression has been observed in many types of human cancers. We found that G9A transcriptionally activates serine-glycine synthesis by increasing H3K9me1 at the promoters of the pathway genes. The proposed research is to determine 1) how G9A is specifically targeted to the pathway genes, given that G9A has no sequence-specific DNA-binding domain, and 2) how G9A specifically marks these genes with H3K9me1, given that G9A can catalyze both H3K9me1 and H3K9me2. In Aim 1, we will investigate the sequence-specific DNA-binding transcription factor ATF4 as a mechanism for targeting G9A to the promoters of the serine pathway genes. We will determine whether ATF4 is required for G9A to bind to these promoters, to modulate their H3K9 methylation states, and to increase glycolic flux for serine-glycine synthesis. We will also investigate the molecular basis o the G9A-ATF4 interaction. In Aim 2, we will investigate the transcription factor MYCN as an alternative mechanism for targeting G9A to the serine pathway genes, particularly in cancer cells with G9A overexpression. We will determine whether MYCN is required for G9A to bind to these gene promoters, to modulate their H3K9 methylation states, and to increase glycolic flux for serine-glycine synthesis. We will also investigate the molecular basis of the G9A-MYCN interaction. In Aim 3, we will test the hypothesis that the H3K9 demethylase KDM4C, which specifically removes H3K9me2 and H3K9me3, cooperates with G9A to maintain high levels of H3K9me1 at these gene promoters. We will determine whether G9A and KDM4C bind simultaneously to these gene promoters and whether G9A requires KDM4C to maintain high-level H3K9me1 at these promoters for transcriptional activation. We will also investigate the molecular basis of the G9A-KDM4C cooperation. The proposed investigation is anticipated to identify a new regulatory mechanism for the control of serine-glycine synthesis and to introduce a new avenue to target cancer metabolism for therapy. Additionally, functional assays of