RNA epigenetic regulation of cancer metabolism

这项研究旨在探讨一种新的表观遗传学机制， 在癌细胞中重新编程。假尿苷酸化是人类mRNA的常见表观遗传修饰， 由假尿苷脱氨酶（PUS）家族催化，所述假尿苷脱氨酶（PUS）通过碱- 特异性异构化mRNA假尿苷化的分子和功能后果是很差的， 明白一个主要的障碍是缺乏合适的和可靠的实验模型来研究功能和 mRNA假尿苷酸化的调节。我们通过关注PUS家族来解决这个问题， 癌症中的酶我们的初步研究表明，其中一种酶PUS 7的表达是 转录上调的癌基因MYC和MYCN，这是通常激活的各种 人类癌症的类型。PUS 7的表达增加促进癌细胞增殖和肿瘤发生。 PUS 7的一个关键下游靶点是ATF 4，它是应激反应和细胞代谢的主要调节因子， MYCN在重编程细胞代谢以维持癌细胞增殖中也以其为靶点。 PUS 7催化ATF 4 mRNA中特定位点的假尿苷化并上调ATF 4表达。基于 基于这些发现，我们假设PUS 7是MYC/MYCN在癌症代谢中的效应子， 通过ATF 4 mRNA假尿苷酸化增强ATF 4表达来重编程。我们进一步 假设这个PUS 7-ATF 4轴在控制应激诱导的代谢中具有关键作用， 重新编程拟议的研究将检验这些假设。目标1研究将侧重于 应激模型系统中PUS 7依赖性ATF 4 mRNA假尿苷化的生物学相关性 应答我们将明确PUS 7依赖性ATF 4 mRNA表达的分子机制。 假尿苷化增加ATF 4表达（目的1.1）。我们将确定PUS 7依赖性ATF 4 mRNA 假尿苷化受应激信号调节，并且是ATF 4的应激诱导所需的（Aim 1.2）。我们将 确定PUS 7是否通过调节ATF 4表达来控制应激诱导的代谢重编程（Aim 1.3）。 目的2研究将集中于PUS 7依赖性ATF 4 mRNA假尿苷酸化的癌症相关性 使用MYC/MYCN癌细胞系和肿瘤模型。我们将确定PUS 7是否是MYC/MYCN的效应子， 代谢重编程（目标2.1）。我们将确定PUS 7介导的ATF 4 mRNA 假尿苷化受MYC/MYCN调节，是MYC驱动的肿瘤过程中的表观遗传事件 发展（目标2.2）。我们将研究PUS 7敲低是否会在细胞中产生代谢脆弱性。 MYC/MYCN驱动的肿瘤可用于癌症治疗（目标2.3）。成功完成本 该项目将揭示PUS 7依赖性mRNA的生物学功能和癌症相关性 假尿苷化，这可能被用于更好的癌症治疗。

The proposed research is to investigate a new epigenetic mechanism for the control of metabolic reprogramming in cancer cells. Pseudouridylation is a common epigenetic modification of human mRNA, which is catalyzed by the family of pseudouridine synthases (PUS) that convert uridine to pseudouridine via base- specific isomerization. The molecular and functional consequences of mRNA pseudouridylation are poorly understood. A major barrier is the lack of suitable and robust experimental models to study the function and regulation of mRNA pseudouridylation. We approached this problem by focusing on the PUS family of enzymes in cancer. Our preliminary studies revealed that the expression of one of the enzymes, PUS7, is transcriptionally upregulated by the oncogenes MYC and MYCN, which are commonly activated in various types of human cancers. Increased expression of PUS7 promotes cancer cell proliferation and tumorigenesis. A key downstream target of PUS7 is ATF4, a master regulator of stress responses and cellular metabolism, which is also targeted by MYCN in reprogramming cellular metabolism to sustain cancer cell proliferation. PUS7 catalyzes pseudouridylation at specific sites in ATF4 mRNA and upregulates ATF4 expression. Based on these findings, we hypothesize that PUS7 is an effector of MYC/MYCN in cancer metabolic reprogramming by boosting ATF4 expression via ATF4 mRNA pseudouridylation. We further hypothesize that this PUS7-ATF4 axis has a key role in the control of stress-induced metabolic reprogramming. The proposed research will test these hypotheses. Aim 1 studies will be focused on the biological relevance of PUS7-dependent ATF4 mRNA pseudouridylation in the model system of stress responses. We will define the molecular mechanism by which PUS7-dependent ATF4 mRNA pseudouridylation increases ATF4 expression (Aim 1.1). We will determine if PUS7-dependent ATF4 mRNA pseudouridylation is regulated by stress signals and is required for stress induction of ATF4 (Aim 1.2). We will determine if PUS7 controls stress-induced metabolic reprogramming by regulating ATF4 expression (Aim 1.3). Aim 2 studies will be focused on the cancer relevance of PUS7-dependent ATF4 mRNA pseudouridylation using MYC/MYCN cancer cell lines and tumor models. We will determine if PUS7 is an effector of MYC/MYCN in metabolic reprogramming (Aim 2.1). We will determine whether PUS7-mediated ATF4 mRNA pseudouridylation is regulated by MYC/MYCN and is an epigenetic event during MYC-driven tumor development (Aim 2.2). We will investigate if PUS7 knockdown creates a metabolic vulnerability in MYC/MYCN-driven tumors that could be exploited for cancer therapy (Aim 2.3). Successful completion of this project will shed light on the biological function and cancer relevance of PUS7-dependent mRNA pseudouridylation, which might be exploited for better cancer treatment.