Cells require a continuous supply of nutrients and energy for growth, metabolism, and survival, and employ dedicated mechanisms to adjust to changes in nutrient availability. Autophagy is a key evolutionarily conserved degradation pathway, by which cellular components are recycled. Autophagy is induced in response to extracellular or intracellular stress by signals that include limited nutrients, growth factor deprivation, ER stress, and/or pathogen infection. Thus, autophagy has to be regulated by signaling pathways that integrate environmental conditions, with developmental progression. A great deal of progress has been made in identifying essential components of the autophagy pathway such as (ATG genes) and their biochemical functions, whereas the mechanisms that regulate autophagy remain poorly understood. We propose here (1) to capitalize on the powerful features of C. elegans genetics to investigate critical protein functions required for autophagy cellular and developmental processes in vivo and, (2) to extend our analysis to mammalian cells. Our preliminary data, and that of others, indicate that autophagy is inappropriately activated in rab-10 mutants, as would be expected if TOR activity depends on RAB-10. Loss of RAB-10 extends lifespan in C. elegans, and the longevity of rab-10 mutants is autophagy dependent. Yet, a mechanism for how RAB-10 regulates TOR, autophagy, and autophagy dependent processes such as germline proliferation or longevity, is not known. We will (i) define the role of RAB-10 in the regulation of TOR, and autophagy, during nutrient replete conditions, dietary restriction, and reduced insulin signaling and (ii) elucidate the role of RAB-10 in two developmental processes: germline proliferation and aging. The C. elegans germline is a valuable model to study the genetic, developmental, and environmental control of germ cell proliferation. These studies are significant because they will advance our understanding of the mechanisms by which autophagy is regulated during development of a multicellular organism, and for control of cell proliferation. They will be informative in regard to both the tissues that require autophagy in development and the proteins involved in the autophagy pathway. Our laboratory is uniquely positioned to pursue this project with our expertise in C. elegans genetics and the study of autophagy.
(3 lines, lay person): This study aims to explore the mechanisms by which RAB-10 mediates the regulation of TOR, autophagy, germline proliferation and longevity. We will examine the interaction between RAB-10 and the exocyst in autophagosome biogenesis and autophagosome fusion with the lysosome.
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