Alternative vacuolar targeting mechanisms in yeast

描述(申请人提供)：自噬的字面意思是亚细胞水平的“自噬”。就像你的身体在长时间饥饿时分解脂肪和蛋白质储备一样，细胞也会做同样的事情，将细胞质输送到溶酶体/液泡中，以降解和回收产生的大分子。自噬存在于所有真核生物中，自噬机制的蛋白质组分从酵母到哺乳动物都是保守的。这一过程的标志是形成双膜胞液小泡，即隔离细胞质的自噬小体。完成后，自噬小体与溶酶体/液泡融合，释放被分解的内部小泡，从而进入货物。自噬是一种饥饿反应，但它也在各种发育过程中发挥作用，并与一系列病理生理状况有关：自噬缺陷可导致某些类型的癌症、心脏病和神经退化，包括阿尔茨海默氏症、帕金森氏症和亨廷顿病。自噬还与先天免疫、清除入侵的致病细菌和病毒以及延长寿命有关。自噬可以是非特异性的；然而，特定类型的自噬在各种过程中发挥作用，包括去除受损或多余的细胞器，以及消除某些病原体。细胞质到空泡的靶向途径是特异性自噬的另一个例子。关于自噬还有许多问题有待回答。例如，我们想要确定环境信号是如何转化为自噬反应的，什么调控机制决定了特定类型和非特定类型的自噬之间的切换，实现货物专一性的机制，隔离小泡膜的起源，以及小泡形成的分子细节。我们正在使用酵母来研究自噬的分子机制；这是对这一复杂过程进行分子遗传和生化分析的最佳系统。然而，由于高度保守，我们从酵母中学到的信息将适用于高等真核生物。目前，我们已经鉴定了20多种自噬相关(ATG)蛋白，确定了它们在自噬过程中的位置和作用阶段。我们现在正在定义特定的相互作用区域，并为蛋白质分配一个作用的时间顺序，最终目的是了解它们的生化功能。我们还建立了体内重建系统，使我们能够确定单个ATG蛋白的功能和特征。这一知识将提供有关基本细胞生物学过程的重要信息，包括管理动态膜重排的机制，并允许具体认识维持离散细胞器所需的亚细胞组件的基本方面。对自噬的充分了解也可能允许对与一系列疾病条件有关的过程进行治疗性调节。

DESCRIPTION (provided by applicant): Autophagy literally means "self-eating" at the subcellular level. In the same way that your body breaks down fat and protein reserves if starved for a long enough time, the cell does the same thing, delivering cytoplasm to the lysosome/vacuole for degradation and recycling of the resulting macromolecules. Autophagy occurs in all eukaryotes and the protein components of the autophagic machinery are conserved from yeast to mammals. The hallmark of this process is the formation of double-membrane cytosolic vesicles, autophagosomes that sequester cytoplasm. After completion, the autophagosomes fuse with the lysosome/vacuole to release the inner vesicle that is broken down, allowing access to the cargo. Autophagy is a starvation response, but it also plays a role in various developmental processes and is associated with a range of pathophysiological conditions: Defects in autophagy can lead to some types of cancer, heart disease and neurodegeneration including Alzheimer's, Parkinson's and Huntington's diseases. Autophagy is also involved in innate immunity, in eliminating invading pathogenic bacteria and viruses and in lifespan extension. Autophagy can be non-specific; however, specific types of autophagy play a role in various processes including the removal of damaged or superfluous organelles, and the elimination of certain pathogens. The cytoplasm to vacuole targeting pathway is another example of specific autophagy. There are many questions about autophagy that remain to be answered. For example, we want to determine how environmental signals are transduced into an autophagic response, what regulatory controls determine the switch between specific and non-specific types of autophagy, the mechanism of achieving cargo specificity, the origin of the sequestering vesicle membrane and the molecular details of vesicle formation. We are using yeast to investigate the molecular mechanism of autophagy; this is the best system for a molecular genetic and biochemical analysis of this complex process. Because of the high degree of conservation, however, the information we learn from yeast will be applicable to higher eukaryotes. At present, we have characterized over twenty autophagy-related (Atg) proteins, determining their location and stage of action in the autophagy process. We are now defining specific interaction domains, and assigning a temporal order of action to the proteins with the ultimate goal of understanding their biochemical function. We have also established an in vivo reconstitution system that will allow us to define the functions and characteristics of individual Atg proteins. This knowledge will provide important information about basic cell biological processes including the mechanisms that govern dynamic membrane rearrangements, and allow specific recognition of subcellular components essential aspects required to maintain discrete organelles. A full understanding of autophagy may also allow therapeutic modulation of a process that is implicated in a range of disease conditions.