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

项目摘要 癌细胞受到可变的并且通常严重营养有限的微环境的影响， 为了生存必须适应。此外，癌症代谢的有效治疗靶向需要 了解代偿网络和代谢灵活性的机制，参与时， 代谢酶被抑制。为了使细胞激活补偿机制，它们必须首先能够 来检测代谢缺陷这以AMP激活的蛋白激酶（AMPK）为例，AMPK感测细胞内的蛋白质。 AMP/ATP比值升高，并介导信号传导作用，以减少ATP消耗并增强ATP 生产现在有大量的证据表明，乙酰辅酶A也是一种关键的代谢产物， 由细胞监测，并且当其可用性有限时，使用自适应机制。此外，委员会认为， 正在进行的临床试验表明，存在针对乙酰辅酶A产生酶的治疗窗口 ATP-柠檬酸裂解酶（ACLY），至少在肝脏中。我们以前报道过，在对ACLY抑制或 Acly基因缺失，酰基辅酶A合成酶短链家族成员2（ACSS 2）， 从乙酸产生乙酰辅酶A，被上调并支持细胞活力和增殖。此外，委员会认为， 乙酸盐，通常是细胞的必需品，在缺乏ACLY的情况下，对细胞的存活至关重要。 然而，细胞感知乙酰辅酶A缺乏并实现这种适应性的机制， 反应仍然未知。 在这项资助申请中，基于已发表的和初步的数据，并利用我们在实验室中产生的试剂， 实验室和我们的长期合作者的代谢组学和蛋白质组学专业知识，我们提出了一种方法， 解决了细胞如何感知乙酰辅酶A的基本问题。我们假设乙酰辅酶A传感 需要线粒体、胞质溶胶、内质网和 原子核我们将：1）确定乙酰辅酶A产生的亚细胞位置， ACSS 2上调; 2）确定乙酰辅酶A不足感测到诱导ACSS 2上调的机制。 ACSS 2上调;和3）鉴定对存活力至关重要的核-胞质乙酰辅酶A的功能。 这项研究的结果将定义营养感测的基本机制，并为最佳营养感测提供信息。 治疗上靶向乙酰辅酶A代谢的方法。

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.