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: 8689154
• 负责人: MONDIRA KUNDU
• 金额: $ 42.88万
• 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/8689154
• 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.

描述（由申请人提供）：该项目的长期目标是破译调节自噬所涉及的分子途径，以便可以更精确地操纵该过程以治疗造血疾病和恶性肿瘤。自噬是细胞中的主要回收途径，主要负责细胞器（包括线粒体）和长寿或错误折叠的蛋白质。细胞对各种代谢或蛋白质毒性应激响应响应适当水平的自噬的能力使细胞能够生存并适应环境挑战。实际上，许多肿瘤依靠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，ULK1蛋白（一种自噬的关键调节剂）的稳定与预后不良有关 - 也许是由于增强了使自噬机械能力响应压力的能力而导致的。因此，了解调节自噬所涉及的信号传导途径不仅可以洞悉自噬在维持健康细胞和疾病中的作用，而且还应揭示出在癌症治疗中操纵自噬的新目标。 ULK1和ULK2是普遍表达的ATG1的哺乳动物同源物，ATG1是一种良好的丝氨酸 - 苏氨酸激酶，可调节酵母中选择性和非选择性自噬。 ULK1是氨基酸饥饿在培养细胞中诱导的自噬所必需的，并清除红细胞和肝细胞中的线粒体，并在去极化损伤之后。 ULK2与自噬有关。但是，尚未报告ULK2基因敲除动物的特定缺陷。相反，缺乏ULK1和ULK2的小鼠表现出与缺乏核心非冗余基因（如MATG5或MATG7）相似的围产期致死性，这表明ULK1和ULK2在调节自噬时具有一些重叠的功能。鉴于核心自噬基因缺乏对生物有害，因此确定和表征ULK1和ULK2调节的差异可能会揭示出独特的机会，以选择性地靶向一种或另一种蛋白质，并且更精确地操纵癌症治疗的自噬。最近的研究表明，虽然ULK1和ULK2都是能量激酶AMPK的底物，但单独使用ULK1（非ULK2）是HSP90-CDC37伴侣复合体的客户，其激活和稳定性对HSP90功能的改变敏感。尽管AMPK和HSP90-CDC37在激活ULK1功能和维持细胞稳态方面都很重要，但这些参与者合作以整合自噬和线粒体周转的调节的方式与细胞的不断变化的能源需求相结合。 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基于细胞和体内模型。