Defining an acetyl-CoA sensing mechanism as a form of inter-organelle communication in cancer

项目总结 癌细胞受制于多变的、往往严重营养有限的微环境，在这种微环境中，癌细胞 必须适应才能生存。此外，有效的癌症新陈代谢靶向治疗需要 了解代谢灵活性的代偿网络和机制 代谢酶被抑制。为了让细胞激活补偿机制，它们必须首先能够 来检测代谢缺陷。AMP激活的蛋白激酶(AMPK)就是一个例子，它感觉到一种 AMP/ATP比值升高，介导信号转导效应，降低ATP消耗，增强ATP 制作。现在大量的证据表明，乙酰辅酶A也是一种关键的代谢物 由细胞监测，并在其可获得性有限时启用自适应机制。此外， 正在进行的临床试验表明，存在靶向乙酰辅酶A产生酶的治疗窗口。 ATP-柠檬酸裂解酶(ACLY)，至少在肝脏中。我们之前报道过，在对ACLY抑制或 乙酰辅酶A合成酶短链家族成员2(ACSS2)是一种基因缺失 从乙酸乙酯生成乙酰辅酶A，上调，支持细胞存活和增殖。此外， 醋酸盐通常对细胞来说是不必要的，但在没有ACLY的情况下，它成为生存所必需的。 然而，细胞感知乙酰辅酶A缺乏并实现这一适应性的机制 反应仍不得而知。 在这项赠款申请中，以已公布的和初步的数据为基础，并利用我们的 实验室和我们长期合作伙伴的代谢组学和蛋白质组学专业知识，我们提出了一种方法 解决细胞如何感知乙酰辅酶A的根本问题。我们假设乙酰辅酶A感应 需要线粒体、胞浆、内质网和线粒体之间紧密的细胞器内通讯 原子核。我们将：1)确定乙酰辅酶A产生促进的亚细胞位置 ACSS2上调；2)定义乙酰辅酶A不足的感觉机制 ACSS2上调；以及3)鉴定核胞质乙酰辅酶A对生存至关重要的功能。 这项研究的发现将定义营养传感的基本机制，并提供最佳信息 靶向乙酰辅酶A代谢的治疗方法。

PROJECT SUMMARY Cancer cells are subjected to variable and often severely nutrient-limited microenvironments to which they must adapt in order to survive. In addition, effective therapeutic targeting of cancer metabolism requires an understanding of the compensatory networks and mechanisms of metabolic flexibility that are engaged when a metabolic enzyme is inhibited. In order for cells to activate compensatory mechanisms, they must first be able to detect a metabolic deficiency. This is exemplified by AMP-activated protein kinase (AMPK), which senses a rise in the AMP/ATP ratio and mediates signaling effects to reduce ATP consumption and enhance ATP production. Abundant evidence now indicates that acetyl-CoA is also a key metabolite that is closely monitored by cells and that adaptive mechanisms are engaged when its availability is limited. Moreover, ongoing clinical trials indicate that a therapeutic window exists for targeting the acetyl-CoA producing enzyme ATP-citrate lyase (ACLY), at least in the liver. We previously reported that in response to ACLY inhibition or Acly genetic deletion, the enzyme acyl-CoA synthetase short-chain family member 2 (ACSS2), which generates acetyl-CoA from acetate, is upregulated and supports cell viability and proliferation. Moreover, acetate, which is normally dispensable for cells, becomes essential for survival in the absence of ACLY. However, the mechanisms through which cells sense a deficiency in acetyl-CoA and implement this adaptive response remain unknown. In this grant application, building on published and preliminary data and leveraging reagents generated in our lab and the metabolomics and proteomics expertise of our long-time collaborators, we propose an approach to address the fundamental question of how cells sense acetyl-CoA. We hypothesize that acetyl-CoA sensing requires close intraorganelle communication between the mitochondria, cytosol, endoplasmic reticulum, and nucleus. We will: 1) determine the subcellular location at which acetyl-CoA production is sensed to promote ACSS2 upregulation; 2) define the mechanisms through which acetyl-CoA insufficiency is sensed to induce ACSS2 upregulation; and 3) identify the functions of nuclear-cytosolic acetyl-CoA that are essential for viability. Findings from this study will both define fundamental mechanisms of nutrient sensing and inform optimal approaches for targeting acetyl-CoA metabolism therapeutically.