Regulation of autophagy by AMPK, Hsp90-Cdc37 and Ulk1 in erythroid cells

AMPK、Hsp90-Cdc37 和 Ulk1 在红系细胞中对自噬的调节

• 批准号: 8345199
• 负责人: MONDIRA KUNDU
• 金额: $ 43.75万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8345199
• 关键词: AMP-activated protein kinase kinase; Accounting; Affinity; Amino Acids; Autophagocytosis; Binding; Biochemical; Biological; Cells; Client; Complex; Cultured Cells; Defect; Diabetes Mellitus; Disease; Eating; Erythrocytes; Erythroid; Erythroid Cells; Genes; Goals; Hematopoietic; Hepatocyte; Homeostasis; Homologous Gene; Life; Maintenance; Malignant Neoplasms; Mediating; Metabolic; Mitochondria; Modeling; Molecular; Molecular Chaperones; Mus; N-terminal; Nerve Degeneration; Organelles; Organism; Pathogenesis; Pathway interactions; Perinatal; Phenotype; Phosphorylation; Phosphotransferases; Physiological; Process; Proline-Rich Domain; Protein-Serine-Threonine Kinases; Proteins; Recycling; Regulation; Reporting; Role; Serine; Signal Pathway; Staging; Starvation; Stress; Testing; Therapeutic; Yeasts; base; cancer therapy; cancer type; in vivo; in vivo Model; insight; knockout animal; mitochondrial autophagy; mutant; outcome forecast; protein misfolding; response; stressor; tumor

DESCRIPTION (provided by applicant): The long-term goal of this project is to decipher the molecular pathways involved in regulating autophagy so that the process can be more precisely manipulated for the treatment of hematopoietic disorders and malignancies. Autophagy, the primary recycling pathway in cells, is largely responsible for the turnover of organelles, includin mitochondria, and long-lived or misfolded proteins. The ability of cells to induce appropriate levels of autophagy in response to various metabolic or proteotoxic stressors allows cells to survive and adapt to environmental challenges. Indeed, many tumors rely on autophagy for survival under adverse conditions. A recent study indicates that stabilization of Ulk1 protein (a key regulator of autophagy) in certain types of cancer is associated with a poor prognosis-perhaps as a consequence of enhanced ability to engage the autophagy machinery in response to stress. Thus, understanding the signaling pathways involved in regulating autophagy will not only provide insight into the role of autophagy in the maintenance of healthy cells and in disease, but should also reveal new targets for manipulating autophagy in the treatment of cancer. Ulk1 and Ulk2 are ubiquitously expressed mammalian homologues of Atg1, a well-characterized serine- threonine kinase that regulates both selective and non-selective autophagy in yeast. Ulk1 is required for amino acid starvation induced autophagy in cultured cells and for clearance of mitochondria in red blood cells and hepatocytes, and following depolarizing damage. Ulk2 has been implicated in autophagy; however, specific defects in Ulk2 knockout animals have not been reported. Rather, mice lacking both Ulk1 and Ulk2 show perinatal lethality similar to those lacking core non-redundant genes such as mAtg5 or mAtg7, suggesting that Ulk1 and Ulk2 share some overlapping functions in the regulation of autophagy. Given that deficiency of core autophagy genes is detrimental to organisms, identifying and characterizing differences in the regulation of Ulk1 and Ulk2 may reveal unique opportunities to selectively target one or the other protein, and more precisely manipulate autophagy in the treatment of cancer. Recent studies have demonstrated that while both Ulk1 and Ulk2 are substrates of the energy-sensing kinase AMPK, Ulk1 alone (not Ulk2) is a client of the Hsp90-Cdc37 chaperone complex whose activation and stability is sensitive to alterations in Hsp90 function. Despite the importance of both AMPK and Hsp90-Cdc37 in activating Ulk1 function and in maintaining cellular homeostasis, the way in which these players cooperate to integrate regulation of autophagy and mitochondrial turnover with the changing energy demands of the cell remains unclear. Since the primary phenotype associated with Ulk1-deficiency in vivo is a defect in the clearance of mitochondria during the terminal stages of erythroid maturation, we propose to examine the molecular basis and physiologic relevance of Ulk1 regulation by AMPK and Hsp90-Cdc37 in the context of erythroid maturation through a combination of biochemical, structural and cell biological approaches using both cell-based and in vivo models. PUBLIC HEALTH RELEVANCE: This proposal is focused on understanding the regulation of autophagy ("self-eating"), a cellular response to stress and starvation, which has been implicated in the pathogenesis of diseases, including neurodegeneration, diabetes, and cancer.

描述（由申请人提供）：该项目的长期目标是破译参与调节自噬的分子途径，以便可以更精确地操纵该过程以治疗造血系统疾病和恶性肿瘤。自噬是细胞内主要的再循环途径，在很大程度上负责细胞器的周转，包括线粒体和长寿命或错误折叠的蛋白质。细胞响应于各种代谢或蛋白毒性应激源诱导适当水平的自噬的能力允许细胞存活并适应环境挑战。事实上，许多肿瘤依赖于自噬在不利条件下生存。最近的一项研究表明，在某些类型的癌症中，Ulk 1蛋白（自噬的关键调节因子）的稳定与不良的增殖有关，这可能是由于自噬机制对压力的反应能力增强。因此，了解参与调节自噬的信号通路不仅可以深入了解自噬在维持健康细胞和疾病中的作用，还可以揭示在癌症治疗中操纵自噬的新靶点。Ulk 1和Ulk 2是Atg 1的普遍表达的哺乳动物同源物，Atg 1是一种充分表征的丝氨酸-苏氨酸激酶，其调节酵母中的选择性和非选择性自噬。Ulk 1是培养细胞中氨基酸饥饿诱导的自噬和红细胞和肝细胞中线粒体的清除以及去极化损伤所必需的。Ulk 2与自噬有关;然而，Ulk 2敲除动物中的特定缺陷尚未报道。相反，缺乏Ulk 1和Ulk 2的小鼠显示出与缺乏核心非冗余基因（如mAtg 5或mAtg 7）的小鼠相似的围产期致死率，这表明Ulk 1和Ulk 2在自噬调控中具有一些重叠的功能。鉴于核心自噬基因的缺乏对生物体是有害的，识别和表征Ulk 1和Ulk 2调节的差异可能揭示选择性靶向一种或另一种蛋白质的独特机会，并在癌症治疗中更精确地操纵自噬。最近的研究表明，虽然Ulk 1和Ulk 2都是能量敏感激酶AMPK的底物，但Ulk 1单独（而不是Ulk 2）是Hsp 90-Cdc 37伴侣复合物的客户端，其激活和稳定性对Hsp 90功能的改变敏感。尽管AMPK和Hsp 90-Cdc 37在激活Ulk 1功能和维持细胞内稳态方面都很重要，但这些参与者合作整合自噬和线粒体周转调节与细胞不断变化的能量需求的方式仍不清楚。由于与体内Ulk 1缺陷相关的主要表型是在红系成熟的终末阶段线粒体的清除中的缺陷，我们建议通过生物化学，结构和细胞生物学方法的组合，使用基于细胞的模型和体内模型，在红系成熟的背景下，研究AMPK和Hsp 90-Cdc 37对Ulk 1调节的分子基础和生理相关性。 公共卫生关系：该提案的重点是了解自噬（“自食”）的调节，自噬是对压力和饥饿的细胞反应，与神经变性、糖尿病和癌症等疾病的发病机制有关。