Deciphering the crosstalk between methionine metabolism and methyltransferases in health and disease

项目摘要/摘要 蛋氨酸代谢是蛋白质合成、线粒体功能、 抗氧化防御和其他关键的细胞过程。通过严格控制蛋氨酸流量 蛋氨酸代谢途径对细胞的健康功能至关重要。不足为奇的是，不平衡 在这一基本的代谢途径中，已被归因于许多疾病。然而，分子 蛋氨酸可获得性改变与下游细胞过程失调之间的联系 仍然鲜为人知。甲硫氨酸和三磷酸腺苷是生产甲基供体S的唯一前体- 腺苷蛋氨酸(SAM)，甲基转移酶(MTS)的主要和限速甲基供体， 它通过将甲基转移到不同的 底物。尽管已观察到蛋氨酸代谢的重新编程与不同的 病理条件下，尚不清楚哪些下游MTS将蛋氨酸代谢与 这些病理情况的发展以及是什么中介了这种相互作用的特异性， 这代表着巨大的知识鸿沟。我假设特定的MTS的识别将 揭示蛋氨酸代谢调节基本细胞过程的新机制。这个 我们研究的目标是从机械上了解蛋氨酸的改变是如何转化为 生物效应。为了实现这一目标，我的实验室将建立和支持三个研究项目。 通过初步筛选，我们确定了几种促进抗饥饿性或 氧化应激类似于对蛋氨酸代谢途径的操纵。我将测试几个 模型来确定蛋氨酸代谢下游的MTS功能，并完成 剩余MTS的屏幕(项目1)。其次，我将测试组织特异性表达是否 选定的MTS有助于解释全球蛋氨酸水平变化如何影响特定MTS的特异性 使用我们最近开发的一种新型组织特异性蛋氨酸降解系统(项目2)。 最后，我们将使用开放式蛋白质组学方法来确定预期的下游靶点 确定的MT并测试这些MT如何影响对压力的功能反应(项目3)。这些 平台相互交叉，但也独立工作，注意到我们已经确定了几个MT 提高了对不同压力的抵抗力，因此项目2和3可以独立于 项目1.我们将采用创新的方法，结合新的遗传工具，使我们能够 操纵特定组织中的蛋氨酸水平，并使用最先进的方法来量化 蛋氨酸在体内的命运。这项拟议的研究具有重要意义，因为它将揭示一个中央 代谢途径(蛋氨酸)控制着许多基本的细胞过程。这项基础研究很可能会 进一步确定与多种人类病理相关的可用药靶点 重新编程的蛋氨酸代谢，包括癌症、肥胖、神经变性和衰老。

PROJECT SUMMARY/ABSTRACT Methionine metabolism is a central regulator of protein synthesis, mitochondrial function, antioxidant defense, and other critical cellular processes. Tightly regulating methionine flux via the methionine metabolism pathway is essential for healthy cellular function. Not surprisingly, an imbalance in this fundamental metabolic pathway has been attributed to numerous diseases. Yet, the molecular link between alterations in methionine availability and dysregulation of downstream cellular processes remains obscure. Methionine and ATP are the sole precursors for the production of the methyl donor S- adenosylmethionine (SAM), the principal and rate-limiting methyl donor for methyltransferases (MTs), which catalyze a variety of methylation reactions via the transfer of methyl groups onto different substrates. Although reprogramming of methionine metabolism has been observed with different pathological conditions, it is not known which downstream MTs link methionine metabolism to the development of these pathological conditions and what mediates the specificity of this interaction, representing a significant knowledge gap. I hypothesize that the identification of specific MTs will reveal novel mechanisms by which methionine metabolism regulates essential cellular processes. The goal of our research is to mechanistically understand how alterations in methionine are transduced into biological effects. To accomplish this goal, my laboratory will build and sustain three research projects. Through a preliminary screen, we identified several MTs that promote resistance to starvation or oxidative stress similar to manipulations of the methionine metabolism pathway. I will test several models to determine which MTs function downstream to methionine metabolism and complete the screen of the remaining MTs (Project 1). Secondly, I will test whether the tissue-specific expression of selected MTs help explain the specificity of how global changes in methionine levels affect specific MTs using a novel tissue-specific methionine degradation system that we recently developed (Project 2). Finally, we will use an open-ended proteomics approach to identify prospective downstream targets of the identified MTs and test how these MTs affect functional responses to stress (Project 3). These platforms interdigitate but also work independently, noting that we have already identified several MTs that promote resistance to different stresses, so Projects 2 and 3 can be performed independently of Project 1. We will employ innovative approaches by combining novel genetic tools that allow us to manipulate methionine levels within specific tissues and using a state-of-the-art approach to quantify methionine fate in vivo. The proposed research is significant because it will uncover how a central metabolic pathway (methionine) controls many basic cellular processes. This basic research is likely to further identify “druggable” targets relevant to multiple human pathologies associated with reprogrammed methionine metabolism including cancer, obesity, neurodegeneration, and aging.