Characterization of a novel autophagy pathway

新型自噬途径的表征

基本信息

批准号：
8886827
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
项目类别：
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

项目摘要

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（由适用提供）：程序性细胞死亡在动物发育过程中起着重要作用，并且在此过程中的缺陷导致各种人类疾病，包括癌症，神经变性和自身免疫性。凋亡和自噬细胞死亡是发育过程中发生的编程细胞死亡的两种最突出的形态形式。凋亡的调节相对较充分地理解，但是对介导自噬编程细胞死亡的机制知之甚少。我们正在研究果蝇中类固醇激活的自噬细胞死亡，并将幼虫肠中的中肠作为模型。类固醇的增加触发了一种激活中腹细胞死亡的遗传程序。这些受发育调节的细胞死亡并不依赖于包括caspase蛋白酶在内的凋亡基因，并且具有因自噬细胞死亡而死亡的细胞的形态。值得注意的是，中肠降解需要自噬（ATG）基因调节编程细胞尺寸的减少。尽管对酵母中宏观噬菌体（自噬）的功能和调节知之甚少，但对调节体内动物细胞中这一过程的机制知之甚少，对细胞死亡过程中自噬的功能知之甚少。已经假定控制自噬的机制在酵母和人之间是相同的。我们的假设是，自噬在多细胞生物中的细胞特异性使用涉及与核心自噬途径相结合的先前未识别的调节机制。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酶是自噬和苍蝇中肠的降解所必需的，而这些基因是需要在果蝇中饥饿触发的自噬所必需的。相比之下，中肠细胞中的自噬取决于UBA1，这是用于泛素化的E1。这些和其他数据表明，我们发现了一种新型机制，泛素可以调节ATG7和ATG3无依赖性自噬，我们的目标是表征在中肠细胞死亡过程中控制自噬的分子机制。在这里，我们建议：（1）研究ATG8在中肠自噬和细胞大小降低中的作用，（2）确定泛素结合蛋白和帕克蛋白底物在自噬中的作用，（3）（3）特征是清除线粒体和自动噬菌所需的新基因。自噬与神经退行性疾病和癌症的最新关联表明，研究自噬在程序性细胞死亡中的作用的重要性。