Lysosomes in Drosophila melanogaster: Characterization of key components and analysis of their impact for neuronal development.

点击翻译按钮获取中文摘要

The overall goal of the project is to make use of Drosophila as a genetic model system for the investigation of the function and the influence of lysosomal transport in neuronal development. About 40 lysosomal inherited storage disorders in humans are known resulting from the deficiency of single or multiple lysosomal hydrolases. Besides the disturbed lysosomal function most prominent phenotypic features are neurodegenerative defects, progressive cognitive decline and mental retardation. However, lysosomes are hardly studied in neuronal cells. During the last years pathological changes were found in the endosomal/lysosomal system of neuronal cells from Alzheimer¿s disease patients. The development of neurons is well characterized in Drosophila melanogaster which is used therefore as a model organism for the investigation of neurodegenerative disorders (Alzheimer¿s, Huntington¿s and Parkinson¿s-diseases), however lysosomal components have not been characterized in the fly. We have cloned and expressed the Drosophila orthologs of the mammalian lysosomal key components in mammalian and Drosophila cells: the lysosomal enzyme receptor protein ¿LERP¿, a GGA-adaptor protein, the lysosomal proteinases cathepsin D, B und L and lysosomal membrane proteins (sun and lamp). The roles of the sorting LERP and individual components will be analyzed by RNAi techniques. The characterization of LERP binding domain will be done by expression of mutants that contain deletions in its luminal domain. Substrate specificity and activity of the cathepsins will be characterized. This basic biochemical work will be used to characterize the lysosomal compartment in Drosophila. The expression of these lysosomal components during the development of the fly will be studied with a focus on the neuronal development. We will also analyze the role of individual cathepsins in the long term memory formation regulated by their specific inhibitor CER.