Oxidative pentose phosphate pathway regulates AMPK homeostasis by balancing opposing LKB1 and PP2A

氧化戊糖磷酸途径通过平衡 LKB1 和 PP2A 来调节 AMPK 稳态

• 批准号: 10738318
• 负责人: Jing Chen
• 金额: $ 1.55万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-15 至 2025-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10738318
• 关键词: 6-phosphogluconate; A549; Acetylation; Acute; Acute Myelocytic Leukemia; Affect; Anabolism; Antioxidants; Binding; Cell Proliferation; Cells; Cellular Metabolic Process; Colorectal Cancer; Combined Modality Therapy; Complex; Enzymes; Focal Adhesion Kinase 1; Foundations; Gene Expression; Glucose-6-Phosphate; Glucosephosphate Dehydrogenase; Glycolysis; H1299; HCT116 Cells; HT29 Cells; Homeostasis; Human; Hydrolysis; In Vitro; K-562; Link; Lysine; Malignant neoplasm of lung; Metabolic; Metabolic Pathway; Mitochondria; Molecular; NADP; Nucleotide Biosynthesis; Oncogenic; Oxidation-Reduction; Pathway interactions; Patients; Pentosephosphate Pathway; Phosphogluconate Dehydrogenase; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Physiological; Play; Post-Translational Protein Processing; Probability; Proliferating; Property; Protein Phosphatase 2A Regulatory Subunit PR53; Proteins; Reactive Oxygen Species; Regulation; Reporting; Role; SOD2 gene; STK11 gene; Series; Signal Pathway; Signal Transduction; Signaling Molecule; Testing; acute myeloid leukemia cell; attenuation; cancer cell; in vivo; inhibitor; knock-down; leukemia; lipid biosynthesis; lung cancer cell; macromolecule; mouse model; novel; patient derived xenograft model; programs; recruit; response; ribulose 5-phosphate; tumor growth

Project Summary/Abstract: The interplay between metabolic pathways and cell signaling networks that contribute to the “metabolic reprogramming” in cancer cells remains largely unknown. The oxidative pentose phosphate pathway (oxiPPP) plays a crucial role in the metabolic coordination of glycolysis, biosynthesis and redox homeostasis in cells by producing precursors for nucleotide and lipid biosynthesis, as well as antioxidant NADPH that quenches the reactive oxygen species (ROS) produced during rapid proliferation of cancer cells. There are three key enzymes along the oxiPPP. The first enzyme glucose-6-phosphate dehydrogenase (G6PD) converts glycolytic intermediate glucose-6-phosphate (G6P) to 6-phosphogluconolactone (6PGL) and produces NADPH. The second enzyme 6-phosphogluconolactonase (PGLS) converts 6PGL to 6-phosphogluconate (6PG). The third enzyme 6-phosphogluconate dehydrogenase (6PGD) converts 6PG to ribulose-5-phosphate (Ru-5-P) and also produces NADPH. We recently reported that 6PGD is commonly activated by lysine acetylation in cancer cells and activates lipogenesis through controlling its product Ru-5-P, which inhibits the LKB1-AMPK pathway by disrupting the active LKB1 complex (Shan et al., 2014 Mol Cell; Lin et al., 2015, Nat Cell Biol.). Interestingly, we found that knockdown of G6PD did not alter AMPK activation despite decreased Ru-5-P and subsequent LKB1 activation, due to enhanced activity of PP2A, the upstream phosphatase of AMPK. In contrast, knockdown of 6PGD or PGLS reduced PP2A activity. Mechanistically, knockdown of G6PD or PGLS decreased or increased 6PGL level, respectively, which enhanced the inhibitory phosphorylation of PP2A by Src. There are two forms of 6PGL, γ-6-phosphogluconolactone (γ-6PGL) is an oxiPPP byproduct with unknown function that is generated through intramolecular rearrangement of δ-6-phosphogluconolactone (δ-6GL), while δ-6PGL is the only substrate of PGLS and can undergo quick spontaneous hydrolysis. Thus, γ-6PGL is relatively stable compared to δ-6GL but does not participate in oxiPPP. Further studies revealed that γ-6PGL, but not δ-6GL, promotes Src-PP2A association, probably by binding to Src but not PP2A and enhancing PP2A recruitment. Thus, we hypothesize that G6PD, PGLS and 6PGD play differential roles in regulation of AMPK homeostasis by balancing the opposing LKB1 and PP2A, through the oxiPPP intermediate Ru-5-P and an oxiPPP “byproduct” γ-6PGL, respectively; and γ-6PGL, previously considered as a “dead end” byproduct of the oxiPPP with unknown physiological function, functions as a signaling molecule that links the metabolic oxiPPP with the Src-PP2A-AMPK signaling pathway. The specific aims are proposed: (1) To elucidate the molecular and signaling basis underlying γ-6PGL-dependent contribution to AMPK activation through inhibition of PP2A by Src; (2) To determine the differential effects of G6PD and PGLS on AMPK activation, redox homeostasis and tumor growth; and (3) To evaluate combined therapy with oxiPPP inhibitors and AMPK activator in the treatment of human leukemia and lung cancer cells in vitro and in vivo.

项目摘要/摘要： 代谢途径和细胞信号网络之间的相互作用促成了“代谢 癌细胞中的氧化戊糖磷酸途径（oxiPPP）仍然很大程度上未知。 在细胞内糖酵解、生物合成和氧化还原稳态的代谢协调中起着至关重要的作用 产生核苷酸和脂质生物合成的前体，以及抗氧化剂 NADPH，可淬灭 癌细胞快速增殖过程中产生的活性氧（ROS）有3种关键酶。 第一个酶葡萄糖-6-磷酸脱氢酶 (G6PD) 沿 oxiPPP 转化糖酵解。 中间体葡萄糖-6-磷酸 (G6P) 转化为 6-磷酸葡萄糖酸内酯 (6PGL) 并产生 NADPH。 第二种酶 6-磷酸葡萄糖酸内酯酶 (PGLS) 将 6PGL 转化为 6-磷酸葡萄糖酸 (6PG)。 6-磷酸葡萄糖酸脱氢酶 (6PGD) 将 6PG 转化为 5-磷酸核酮糖 (Ru-5-P)，并且 我们最近报道，6PGD 通常被癌细胞中的赖氨酸乙酰化激活。 并通过控制其产物 Ru-5-P 激活脂肪生成，Ru-5-P 通过抑制 LKB1-AMPK 途径 破坏活性 LKB1 复合物（Shan 等人，2014 Mol Cell；Lin 等人，2015，Nat Cell Biol.）。 发现尽管 Ru-5-P 和随后的 LKB1 减少，但 G6PD 的敲低并没有改变 AMPK 激活 激活，由于 AMPK 上游磷酸酶 PP2A 的活性增强，相反，敲低。 6PGD 或 PGLS 降低 PP2A 活性 从机制上讲，G6PD 或 PGLS 的敲低会降低或增加。 6PGL水平分别增强了Src对PP2A的抑制性磷酸化作用，有两种形式。 6PGL，γ-6-磷酸葡萄糖酸内酯 (γ-6PGL) 是产生的功能未知的 oxiPPP 副产物 通过δ-6-磷酸葡萄糖酸内酯（δ-6GL）的分子内重排，而δ-6PGL是唯一的 γ-6PGL 是 PGLS 的底物，可以快速自发水解，因此相对稳定。 进一步的研究表明，γ-6PGL 可以促进 δ-6GL，但不参与 oxiPPP。 Src-PP2A 关联，可能是通过与 Src 结合但不与 PP2A 结合并增强 PP2A 募集。 因此，我们研究G6PD、PGLS和6PGD在AMPK的调节中发挥不同的作用 通过 oxiPPP 中间体 Ru-5-P 和一个平衡相反的 LKB1 和 PP2A 来实现稳态 oxiPPP“副产品”γ-6PGL 和 γ-6PGL，以前被认为是“死胡同”副产品 oxiPPP 生理功能未知，作为连接代谢oxiPPP 的信号分子 提出的具体目标是：（1）阐明Src-PP2A-AMPK信号通路的分子和机制。 通过 Src 抑制 PP2A，γ-6PGL 依赖性地促进 AMPK 激活的信号传导基础； (2) 确定G6PD和PGLS对AMPK激活、氧化还原稳态和肿瘤的不同影响 联合生长；以及 (3) 评估 oxiPPP 抑制剂和 AMPK 激活剂治疗 人类白血病和肺癌细胞的体外和体内。