Characterization of a novel autophagy pathway

新型自噬途径的表征

• 批准号: 9021671
• 负责人: Eric H Baehrecke
• 金额: $ 31.83万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9021671
• 关键词: Animals; Apoptosis; Autoimmunity; Autophagocytosis; Autophagosome; Binding; Binding Proteins; Caspase; Cell Death; Cell Size; Cells; Cellular Morphology; Data; Defect; Development; Disease; Drosophila genus; Enzymes; Genes; Genetic Programming; Goals; Homeostasis; Human; Intestines; Malignant Neoplasms; Mammals; Mediating; Midgut; Mitochondria; Modeling; Molecular; Nerve Degeneration; Neurodegenerative Disorders; Organism; Pathway interactions; Peptide Hydrolases; Phenotype; Play; Process; Recruitment Activity; Regulation; Role; Starvation; Steroids; Tissues; UBA Domain; Ubiquitin; Ubiquitin Like Proteins; Ubiquitination; Yeasts; fly; in vivo; interest; mutant; novel; parkin gene/protein; programs; public health relevance; receptor; ubiquitin-protein ligase

 DESCRIPTION (provided by applicant): Programmed cell death plays an important role during animal development, and defects in this process result in a variety of human disorders including cancer, neurodegeneration and autoimmunity. Apoptosis and autophagic cell death are the two most prominent morphological forms of programmed cell death that occur during development. The regulation of apoptosis is relatively well understood, but little is known about the mechanisms that mediate autophagic programmed cell death. We are studying steroid-activated autophagic cell death in Drosophila, and are using the midgut of the larval intestine as a model. An increase in steroid triggers a genetic program that activates midgut cell death. These developmentally-regulated cell deaths do not depend on apoptosis genes, including caspase proteases, and they possess the morphology of cells that die by autophagic cell death. Significantly, autophagy (Atg) genes are required for midgut degradation where they regulate programmed cell size reduction. While much is known about the function and regulation of macro-autophagy (autophagy) in yeast, less is known about the mechanisms that regulate this process in animal cells in vivo, and little is known about the function of autophagy during cell death. It has been assumed that the mechanisms controlling autophagy are identical between yeast and humans. Our hypothesis is that the cell-specific use of autophagy in multicellular organisms involves previously unrecognized regulatory mechanisms that integrate with core autophagy pathways. In support of this hypothesis, we have discovered that the conserved E1 and E2 enzymes encoded by Atg7and Atg3 are not required for autophagy and degradation of the fly midgut, while these genes are required for starvation-triggered autophagy in flies. By contrast, autophagy in midgut cells depends on Uba1, the E1 used for ubiquitination. These and other data indicate that we have discovered a novel mechanism by which ubiquitin regulates Atg7 and Atg3-independent autophagy, and our goal is to characterize molecular mechanisms that control autophagy during midgut cell death. Here we propose to: (1) investigate the role of Atg8 in midgut autophagy and cell size reduction, (2) determine the role of ubiquitin-binding proteins and Parkin substrates in autophagy, and (3) characterize new genes that are required for clearance of mitochondria and autophagy. The recent association of autophagy with neurodegenerative disorders and cancer indicates the importance of investigating the understudied role of autophagy during programmed cell death.

 描述（由申请人提供）：程序性细胞死亡在动物发育过程中起着重要作用，该过程中的缺陷导致多种人类疾病，包括癌症、神经变性和自身免疫。细胞凋亡和自噬性细胞死亡是发生在发育过程中的两种最突出的细胞程序性死亡形态。细胞凋亡的调控是相对较好的理解，但很少有人知道介导自噬性程序性细胞死亡的机制。我们正在研究果蝇类固醇激活的自噬细胞死亡，并使用幼虫肠的中肠作为模型。类固醇的增加触发了一个激活中肠细胞死亡的遗传程序。这些发育调节的细胞死亡不依赖于凋亡基因，包括半胱天冬酶蛋白酶，并且它们具有通过自噬细胞死亡而死亡的细胞的形态。值得注意的是，自噬（Atg）基因是中肠降解所必需的，它们调节程序性细胞大小减小。虽然对酵母中的宏自噬（自噬）的功能和调节了解很多，但对动物细胞体内调节该过程的机制知之甚少，并且对细胞死亡期间自噬的功能知之甚少。据推测，控制自噬的机制在酵母和人类之间是相同的。我们的假设是，在多细胞生物体中，细胞特异性使用自噬涉及以前未被认识到的与核心自噬途径整合的调控机制。为了支持这一假设，我们发现由Atg7和Atg3编码的保守的E1和E2酶对于苍蝇中肠的自噬和降解是不需要的，而这些基因对于饥饿触发的苍蝇自噬是需要的。相比之下，中肠细胞中的自噬依赖于Uba1，用于泛素化的E1。这些和其他数据表明，我们已经发现了一种新的机制，泛素调节Atg7和Atg3独立的自噬，我们的目标是表征分子机制，控制自噬在中肠细胞死亡。在此，我们建议：（1）研究Atg8在中肠自噬和细胞大小减小中的作用，（2）确定泛素结合蛋白和帕金底物在自噬中的作用，以及（3）表征线粒体和自噬清除所需的新基因。最近自噬与神经退行性疾病和癌症的关联表明了研究自噬在程序性细胞死亡中未充分研究的作用的重要性。