Genetic Analysis of Autophagy in the Drosophila Nervous System

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DESCRIPTION (provided by applicant): During normal aging and in the progression of common neurodegenerative disorders such as Alzheimer's and Parkinson's disease, both intra-cellular and extra-cellular protein aggregates containing ubiquitin can accumulate in neurons and neural tissues of humans. The underlying cellular pathways that prevent or suppress this accumulation from occurring are not well understood but a growing body of evidence indicates the macroautophagy pathway (autophagy) is involved with the removal of age-related cellular damage and protein aggregates. Autophagy is a highly conserved lysosomal trafficking pathway that functions by sequestering damaged cellular components or aggregated proteins into new vesicles that are transported to the lysosome for degradation. Using Drosophila genetics, we have shown that mutations in autophagy genes result in progressive neural degeneration that is accompanied by the accumulation of ubiquitinated protein aggregates. We also demonstrate that increasing the expression levels of individual autophagy genes in the mature CNS can dramatically extend adult lifespan. In this research proposal we will we continue our phenotypic characterization of new autophagy mutant strains for reduced longevity and the development of progressive neural defects. To determine which members of the autophagic pathway are essential for neuronal maintenance we will use genetic and transgenic techniques (Gal4/UAS) to suppress (UAS- dsRNAi) or enhance (UAS-cDNA) the expression levels of autophagy genes in the adult fly brain. Adult longevity profiles, formation of neural aggregates and accumulation insoluble ubiquitinated proteins (IUP) will be used as assays to detect changes in aging patterns, response to environmental stress (oxidant exposure) and the suppression of cytotoxic phenotypes by aggregate prone proteins (PolyQ). Immunofluorescence imaging and electron microscopy studies will be used to determine the timing and location of ubiquitinated inclusion formation in the CNS and the type and severity of intracellular trafficking defects occurring in neurons. The goal of this proposal is to determine the role that individual autophagy genes and the pathway in general has on neuronal aging and the elimination of cellular damage from neurons. The implications for human health are significant since defects in autophagic trafficking are found in many neural degenerative disorders and that upregulating the pathway by rapamycin treatment is being used in clinical trials on Huntington's disease patients.Relevance: The accumulation of age-dependent damage and the formation of neural aggregates are associated with degenerative disorders affecting millions of people. Recent genetic research in fruit flies has shown a cellular pathway that removes cellular damage from nerve cells can significantly affect longevity by protecting the aging nervous system. Insight from this genetic model of neural degeneration and protection it affords the nervous system will enhance our understanding of complex processes that occur in people and will direct future research that is designed to promote human health and longevity.