Epigenetic regulation of cancer metabolism by G9A

描述（由申请人提供）：癌细胞重新编程其代谢，以满足生长和增殖的生物合成挑战。癌症代谢如何在癌细胞中启动和维持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，其产生许多生物合成前体和代谢物，这些前体和代谢物对于蛋白质、脂质膜和核酸的产生是必不可少的，是癌症代谢的组成部分。我们最近发现了组蛋白H3赖氨酸9（H3 K9）甲基转移酶G9 A在该生物合成途径的表观遗传激活中的重要作用。G9 A在催化H3 K9单甲基化和二甲基化（H3 K9 me 1和H3 K9 me 2）中具有主要作用，其中H3 K9 me 1是活性标记，H3 K9 me 2是抑制性标记。在许多类型的人类癌症中已经观察到G9 A过表达。我们发现，G9 A转录激活丝氨酸-甘氨酸合成增加H3 K9 me 1的途径基因的启动子。这项研究的目的是确定1）G9 A如何特异性地靶向通路基因，因为G9 A没有序列特异性DNA结合结构域，以及2）G9 A如何特异性地用H3 K9 me 1标记这些基因，因为G9 A可以催化H3 K9 me 1和H3 K9 me 2。在目的1中，我们将研究序列特异性DNA结合转录因子ATF 4作为靶向G9 A的丝氨酸途径基因的启动子的机制。我们将确定G9 A是否需要ATF 4来结合这些启动子，调节它们的H3 K9甲基化状态，并增加丝氨酸-甘氨酸合成的乙醇酸通量。我们还将研究G9 A-ATF 4相互作用的分子基础。在目标2中，我们将研究转录因子MYCN作为将G9 A靶向丝氨酸途径基因的替代机制，特别是在G9 A过表达的癌细胞中。我们将确定MYCN是否是G9 A结合这些基因启动子所必需的，以调节它们的H3 K9甲基化状态，并增加丝氨酸-甘氨酸合成的乙醇酸通量。我们还将研究G9 A-MYCN相互作用的分子基础。在目的3中，我们将测试以下假设：特异性去除H3 K9 me 2和H3 K9 me 3的H3 K9去甲基化酶KDM 4C与G9 A合作以在这些基因启动子处维持高水平的H3 K9 me 1。我们将确定G9 A和KDM 4C是否同时结合这些基因启动子，以及G9 A是否需要KDM 4C在这些启动子处维持高水平的H3 K9 me 1以进行转录激活。我们还将研究G9 A-KDM 4C合作的分子基础。预计拟议的研究将确定一种新的调节机制，用于控制丝氨酸-甘氨酸合成，并引入一种新的途径，以靶向癌症代谢的治疗。此外，功能测定

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