Fnip1 Function in Lymphocyte Development, Activation and Metabolism

描述（由申请人提供）：项目概述相对于静息淋巴细胞，活化淋巴细胞和癌细胞都表现出细胞代谢从氧化磷酸化（有效产生能量）到有氧糖酵解（产生燃料电池分裂所需的生物前体（如脂质、氨基酸和核苷酸））的独特转变。对控制这种代谢转换（称为“瓦尔堡效应”）的因素的理解是非常重要的，因为它可能导致选择性阻断自身免疫性疾病中的淋巴细胞活化和/或抑制癌细胞存活的新策略。在本申请中，我们建议研究一种新的蛋白质，称为滤泡素相互作用蛋白-1（Fnip 1），我们的研究表明，它对维持能量应激过程中的“代谢平衡”至关重要，例如淋巴细胞活化、营养限制和癌基因活化。基于外周血中完全不存在B淋巴细胞，我们在化学诱变筛选中鉴定了一种缺乏Fnip 1的创新小鼠新品系。Fnip 1缺失小鼠在细胞通常依赖于c-Myc（一种有效驱动有氧糖酵解的致癌基因）进行大规模分裂的阶段具有前B细胞和不变的自然杀伤T（iNKT）细胞发育的阻断。值得注意的是，在伯基特B细胞淋巴瘤的小鼠模型中，Fnip 1的缺失也保护免受c-Myc诱导的前B细胞淋巴瘤。虽然Fnip 1的功能尚不清楚，但它与卵泡素（一种功能未知的蛋白质）和主代谢调节因子AMP激酶相互作用，AMP激酶是一种能量传感分子，可刺激能量产生（氧化磷酸化）以响应能量应激，并抑制由哺乳动物雷帕霉素靶蛋白（mTOR）调节的能量消耗合成代谢过程。我们的长期目标是确定Fnip 1如何控制淋巴细胞的发育、代谢和转化。本研究的具体目的是：（1）研究Fnip 1在前B细胞发育和代谢中的作用。我们将利用代谢组学、代谢流分析和转录组学方法来确定Fnip 1的缺失是否抑制“瓦尔堡效应”;（2）确定Fnip 1在B淋巴细胞中功能的分子机制。我们将使用生物化学，遗传学和质谱方法来确定是否Fnip 1是必不可少的“关闭”mTOR介导的营养消耗，并“打开”自噬（细胞器的自我消化，以产生营养），以响应营养不足;（3）确定Fnip 1在iNKT细胞发育和存活中的作用。我们将定义如何Fnip 1控制Myc依赖的发展，生存和代谢这一重要的调节性T细胞亚群。这些研究将解决我们的总体创新假设，即Fnip 1的抑制“断开”合成代谢细胞生长和有氧糖酵解之间的重要联系，通过允许活化的淋巴细胞和/或肿瘤细胞在缺乏足够能量和生物底物的情况下生长，导致“营养耗尽”和细胞死亡。

DESCRIPTION (provided by applicant): Project Summary Relative to resting lymphocytes, both activated lymphocytes and cancer cells exhibit a unique shift in cell metabolism from oxidative phosphorylation, which efficiently produces energy, to aerobic glycolysis, which generates bio-precursors (such as lipids, amino acids, and nucleotides) required to fuel cell division. An understanding of the factors that control this metabolic switch (termed "Warburg effect") is highly significant because it could lead to novel strategies to selectively block lymphocyte activation in autoimmune disease, and/or inhibit cancer cell survival. In this application, we propose to investigate a novel protein called Folliculin Interacting protein-1 (Fnip1) which our studies suggest is essential for maintaining "metabolic balance" during energy stress such as during lymphocyte activation, nutrient restriction, and oncogene activation. We identified an innovative new strain of mice lacking Fnip1 in a chemical mutagenesis screen, based on the complete absence of B lymphocytes in peripheral blood. Fnip1 null mice have blocks in pre-B cell and invariant natural killer T (iNKT) cell development at stages where the cells normally undergo massive division dependent on c- Myc, an oncogene which potently drives aerobic glycolysis. Remarkably, loss of Fnip1 also protects against pre-B cell lymphoma induced by c-Myc in a mouse model of Burkitt's B cell lymphoma. Although the functions of Fnip1 are unknown, it interacts with Folliculin (a protein of unknown function) and the master metabolic regulator AMP kinase, an energy sensing molecule that stimulates energy production (oxidative phosphorylation) in response to energy stress and inhibits energy-consuming anabolic processes regulated by mammalian target of rapamycin (mTOR). Our long-term goals are to determine how Fnip1 functions to control the development, metabolism, and transformation of lymphocytes. Our Specific Aims are: (1) To examine the roles of Fnip1 in pre-B cell development and metabolism. We will utilize metabolomic, metabolic flux analysis, and transcriptomic approaches to determine whether loss of Fnip1 inhibits the "Warburg effect"; (2) To define the molecular mechanisms of Fnip1 function in B lymphocytes. We will use biochemical, genetic, and mass spectrometry approaches to determine whether Fnip1 is essential to "turn off" mTOR mediated nutrient consumption, and "turn on" autophagy (self-digestion of organelles to generate nutrients) in response to nutrient deficit; and (3) To determine the roles of Fnip1 in iNKT cell development and survival. We will define how Fnip1 controls Myc-dependent development, survival and metabolism of this important regulatory T cell subset. These studies will address our overall innovative hypothesis that inhibition of Fnip1 "disconnects" the essential link between anabolic cell growth and aerobic glycolysis, by permitting activated lymphocytes and/or tumor cells to grow in the absence of sufficient energy and bio-substrates, resulting in "nutrient exhaustion" and cell death.