The NRF2-FBP1 crossregulatory loop and the control of healthy and diseased liver metabolism

NRF2-FBP1 交叉调节环路以及健康和患病肝脏代谢的控制

• 批准号: 10670920
• 负责人: Michael Karin
• 金额: $ 68.44万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2027-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10670920
• 关键词: AKT inhibition; Ablation; Aldolase B; Antioxidants; Autocrine Communication; Binding; Biochemical; Biological; Cancer Etiology; Carbohydrates; Cells; Child; Chronic; Collagen; Collagen Fiber; DDR1 gene; Defect; Dependence; Desmoplastic; Development; Down-Regulation; EGF gene; Energy Metabolism; Enzymes; Erythroid; Exhibits; Fasting; Fatty Liver; Fiber; Fructose; Gene Activation; Gene Expression; Generations; Genes; Genetic Transcription; Gluconeogenesis; Glucose; Glycogen Storage Disease; Growth; Hepatic; Hepatocyte; Hepatomegaly; Homeostasis; Human; Hypertriglyceridemia; Hypoglycemia; Individual; Inflammation; Insulin; Isoenzymes; Knockout Mice; Liver; Liver diseases; MAPK1 gene; MAPK3 gene; Malignant Neoplasms; Malignant neoplasm of liver; Malignant neoplasm of pancreas; Mediating; Messenger RNA; Metabolic; Metabolic stress; Metabolism; Molecular; Mus; Nuclear; Nuclear Translocation; Oncogenes; Oncogenic; Oncoproteins; Overdose; Pathology; Phenotype; Phosphoric Monoester Hydrolases; Phosphorylation; Physiology; Platelet-Derived Growth Factor; Post-Translational Protein Processing; Predisposition; Primary carcinoma of the liver cells; Protein Isoforms; Proteins; Proteolysis; Proteomics; Proto-Oncogene Proteins c-akt; Resistance; Role; Serine; Signal Transduction; Sorting; Stress; Technology; Testing; Tumor Suppressor Proteins; Ubiquitin; Ubiquitination; Up-Regulation; chronic liver injury; defense response; gene induction; glucose metabolism; glycogen metabolism; hypoxia inducible factor 1; inhibitor; innovation; lipid biosynthesis; lipid metabolism; liver injury; liver metabolism; metabolic phenotype; mouse model; nonalcoholic steatohepatitis; novel; overexpression; receptor; recruit; response; transcription factor; transcriptomics; treatment response; tumor growth; tumor metabolism; tumorigenesis

Project Summary/Abstract Fructose bisphosphate phosphatase (FBP1) is the rate-limiting enzyme in gluconeogenesis (GNG), whereas nuclear factor erythroid-related factor 2 encoded by the NFE2L2 gene (NRF2) is a transcription factor, previously identified as the master activator of the antioxidant defense response. NRF2 also activates the transcription of many metabolic genes, especially in liver. We found that Nrf2Act-HEP mice, in which NRF2 was selectively activated in hepatocytes, and fasted Fbp1ΔHEP mice, in which FBP1 was conditionally deleted in hepatocytes, exhibit similar metabolic phenotypes, including hypoglycemia, hepatomegaly, hepatosteatosis and hypertriglyceridemia, which are also manifested by insulin overdosed individuals and glucose- or carbohydrate-deprived FBP1-deficient children. Given these similarities, we asked whether NRF2 and FBP1 engage in biochemical crosstalk. Surprisingly, we found that hepatic activation of NRF2 induces FBP1 degradation, mediated by NRF2 induced EGF and PDGF expression, which through an autocrine signaling mechanism led to activation of ERK1/2 MAP kinases that phosphorylated FBP1 at serine 271 and triggered its ubiquitination and proteasomal degradation. Even more surprising was the finding that FBP1 expression led to inhibition of AKT, thereby relieving inhibitory phosphorylation of GSK3 isozymes, which phosphorylate a degron embedded within the NRF2 molecule and thereby induce its ubiquitin-dependent proteolysis. These findings led us to hypothesize that the NRF2-FBP1 crossregulatory loop is a key regulator of liver metabolism and homeostasis, whose aberrant function can promote liver damage and cancer. We plan to test this hypothesis through three specific aims: 1). Investigate the hypothesis that FBP1 induces NRF2 degradation in periportal hepatocytes by activating GSK3 or enhancing its recruitment to NRF2; 2). Determine whether NRF2 activation alters liver zonation and contributes to the metabolic defects caused by FBP1 ablation; 3). Investigate whether NRF2-induced FBP1 degradation or NRF2 upregulation control the progression from chronic metabolic stress to hepatocellular carcinoma. Pursuing these aims via new mouse models, cell biological studies and highly innovative Seq-Scope technology, which we had developed for high-content spatial transcriptomic and proteomic profiling of single liver cells, will answer several critical questions of general importance: 1). What are the non-enzymatic mechanisms through which FBP1 has a broad effect on liver metabolism beyond its well-studied involvement in GNG? 2). What is the role of NRF2 in the metabolic alterations caused by FBP1 deficiency? 3). What is the role of a previously described FBP1- aldolase B interaction in AKT inhibition and GSK3-induced NRF2 degradation? and 4). What is the role of AKT activation in the metabolic defects and increased susceptibility to oncogenic transformation exhibited by the FBP1-deficient liver?

项目摘要/摘要 果糖双磷酸磷酸酶（FBP1）是糖异生（GNG）中的限速酶 NFE2L2基因（NRF2）编码的核因子红系相关因子2是转录因子，以前 被确定为抗氧化剂防御反应的主激活剂。 NRF2还激活了 许多代谢基因，尤其是在肝脏中。我们发现NRF2ACT-HEP小鼠，其中NRF2被选择性地激活 在肝细胞和禁食的FBP1ΔHEP小鼠中，其中FBP1在肝细胞中有条件地删除，暴露了相似的 代谢表型，包括低血糖症，肝toposisos和高甘油三酯血症，这些表型，这些表型 胰岛素过量的个体以及葡萄糖或碳水化的FBP1也表现出来 孩子们。鉴于这些相似之处，我们询问NRF2和FBP1是否进行生化串扰。 令人惊讶的是，我们发现NRF2的肝激活会影响FBP1降解，由NRF2介导 EGF和PDGF表达，通过自分泌信号传导机制导致ERK1/2 MAP的激活 在丝氨酸271处磷酸化FBP1并触发其泛素化和蛋白酶体降解的激酶。 更令人惊讶的是，发现FBP1表达导致AKT抑制，从而缓解了抑制 GSK3同工酶的磷酸化，该磷酸化磷酸化嵌入NRF2分子中的DEGRON和 从而诱导其泛素依赖性蛋白水解。这些发现使我们假设NRF2-FBP1 交叉调节环是肝代谢和稳态的关键调节剂，其异常功能可以 促进肝损害和癌症。我们计划通过三个特定目标来检验这一假设：1）。调查 通过激活GSK3或增强，FBP1影响外周肝细胞中NRF2降解的假设 它招募到NRF2； 2）。确定NRF2激活是否改变了肝脏分化并有助于 由FBP1消融引起的代谢缺陷； 3）。研究NRF2诱导的FBP1降解还是NRF2是 上调控制了从慢性代谢应激到肝细胞癌的发展。追求这些 通过新的鼠标模型，细胞生物学研究和高度创新的SEQ-SCOPE技术的目的，我们 为单个肝细胞的高含量空间转录组和蛋白质组学分析而开发，将回答几个 一般重要性的关键问题：1）。 FBP1的非酶机制是什么 超出其深入研究GNG的广泛影响？ 2）。 NRF2在 FBP1缺乏引起的代谢改变？ 3）。先前描述的FBP1-的作用是什么 Akt抑制和GSK3诱导的NRF2降解中的醛酶B相互作用？和4）。 AKT的角色是什么 代谢缺陷的激活以及增加对致癌转化的敏感性 FBP1缺陷肝？