Proteolytic Control of Iron Metabolism by the E3 Ubiquitin Ligase FBXL5

E3 泛素连接酶 FBXL5 对铁代谢的蛋白水解控制

• 批准号: 9145231
• 负责人: James Akira Wohlschlegel
• 金额: $ 30.04万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9145231
• 关键词: Alanine; Amino Acids; Anemia; Autophagocytosis; Binding; Biogenesis; Biological Process; Cell Respiration; Cell physiology; Cells; Communication; Complex; Coupling; DNA Repair; DNA biosynthesis; Data; Defect; Disease; Ensure; Enzymes; Eukaryotic Cell; Ferritin; Foundations; Gap Junctions; Gene Expression; Gene Expression Regulation; Goals; Grant; Health; Hemochromatosis; Homeostasis; Investigation; Ions; Iron; Iron Regulatory Protein 1; Iron-Regulatory Proteins; Laboratories; Link; Lipids; Malignant Neoplasms; Mediating; Mediator of activation protein; Messenger RNA; Metabolic Pathway; Metabolism; Modeling; Molecular; N-terminal; NCOA4 gene; Nucleotides; Oxidative Stress; Pathogenesis; Pathway interactions; Phosphotransferases; Physiological; Play; Proline; Protein S; Proteins; Proteomics; RNA-Binding Proteins; Regulation; Research; Role; Signal Pathway; Signal Transduction; System; Testing; Toxic effect; Trace metal; Ubiquitin; Work; base; design; insight; iron deficiency; iron metabolism; mRNA Expression; multicatalytic endopeptidase complex; novel; prevent; protein complex; protein expression; response; ubiquitin ligase; ubiquitin-protein ligase

 DESCRIPTION (provided by applicant): Intracellular iron homeostasis is a critical cellular process that ensures intracellular iron concentrations are sufficient to perform essential iron-dependent functions in aerobic respiration, DNA replication and repair, and multiple biosynthetic pathways (amino acid, nucleotide, and lipid) while avoiding the toxicity associated with excess iron. We previously identified the E3 ubiquitin ligase FBXL5 as a master regulator of iron homeostasis that was responsible for "sensing" intracellular iron levels through an N-terminal iron-binding domain and coupling changes in iron concentration to its ability to degrade Iron Regulatory Proteins (IRPs) - RNA binding proteins that the post-transcriptional expression of genes involved iron utilization, transport, and storage. In the proposed work, we will examine the hypothesis that FBLX5 is a key signaling hub that coordinates IRP- mediated gene regulation with variety of other iron metabolic pathways in order to generate an integrated cellular response to iron deficiency. Specific aim 1 will explore the role of the Fe-S cluster assembly pathways in regulating iron homeostasis by characterizing a novel interaction identified in our laboratory between FBXL5 and the CIA targeting complex, a protein complex required for Fe-S protein biogenesis. In specific aim 2, we will elucidate the cellular mechanism by which FBXL5 is degraded in iron-depleted cells by defining the roles of the E3 ubiquitin ligase HERC2 and the kinase SPAK in this proteolytic pathway. Finally, specific aim 3 will focus on examining a role for FBXL5 in regulating ferritin degradation via its association with the autophagy adaptor NCOA4. Investigation of these three aims will uncover the molecular mechanisms that govern how FBXL5 integrates and interprets signals transduced through multiple iron-regulated signaling pathways in order to dictate the multi-faceted cellular response to iron availability.

 描述（由申请人提供）：细胞内铁稳态是一个关键的细胞过程，可确保细胞内铁浓度足以在有氧呼吸、DNA复制和修复以及多种生物合成途径（氨基酸、核苷酸和脂质）中执行基本的铁依赖性功能，同时避免与过量铁相关的毒性。我们以前确定E3泛素连接酶FBXL 5作为铁稳态的主要调节因子，负责通过N-末端铁结合结构域“感知”细胞内铁水平，并将铁浓度的变化与其降解铁调节蛋白（IRP）- RNA结合蛋白的能力偶联，该蛋白是基因转录后表达涉及铁的利用、转运和储存。在所提出的工作中，我们将检验以下假设：FBLX 5是一个关键的信号传导枢纽，它协调IRP介导的基因调控与各种其他铁代谢途径，以产生对铁缺乏的综合细胞反应。具体目标1将探索Fe-S簇组装途径在调节铁稳态中的作用，通过表征在我们实验室中确定的FBXL 5和CIA靶向复合物（Fe-S蛋白生物合成所需的蛋白质复合物）之间的新型相互作用。在具体目标2中，我们将通过定义E3泛素连接酶HERC 2和激酶SPAK在该蛋白水解途径中的作用来阐明FBXL 5在铁耗尽细胞中降解的细胞机制。最后，具体目标3将侧重于审查 FBXL 5通过其与自噬衔接子NC 0A 4的关联调节铁蛋白降解。对这三个目标的研究将揭示FBXL 5如何整合和解释通过多种铁调节信号通路转导的信号的分子机制，以决定对铁可用性的多方面细胞反应。