Regulation of autophagy and mitochondrial permeability by target of rapamycin complex 2

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Autophagy is a conserved process by which all eukaryotic cells eliminate defective organelles and molecules, and is generally regarded as a health- and longevity-promoting process. Mutations in the autophagy machinery contribute to human conditions such as autoimmune, metabolic, inflammatory, neoplastic, and neurodegenerative diseases, and prompt changes consistent with premature aging. Conversely, nearly all genetic and environmental manipulations that extend lifespan do so in a manner dependent upon autophagy. However, we have determined that autophagy has negative consequences on health when it occurs in the setting of increased mitochondrial permeability. The net consequence of autophagy in the setting of increased mitochondrial permeability is shortened lifespan and increased susceptibility to ischemia/reperfusion injury. There is a critical need to understand the cellular and molecular mechanisms by which mitochondrial permeability is regulated in order to develop the next generation of interventions to reduce negative impacts of autophagy in aging and disease. The long-term goal of this project is to determine how mitochondrial permeability is regulated and to define the consequences of increased mitochondrial permeability on cellular and organismal dysfunction in aging. Our objective in this particular application is to define how upstream signaling pathways involved in promoting longevity and reducing disease suppress mitochondrial permeability, and the consequences this has on autophagy, mitochondrial function, and lifespan. This project will meet this objective by studying the detailed mechanisms by which mitochondrial permeability is regulated and the consequences of this regulation. We have determined that defects in signaling in the mTOR complex 2 pathway lead to increases in mitochondrial permeability and autophagy, shortening lifespan and increasing ischemia/reperfusion injury. The central hypothesis of this proposal is that low mitochondrial permeability is a central determinant of the effects of autophagy on lifespan and aging-associated diseases. The rationale for this proposal is that fuller understanding of the regulation of mitochondrial permeability will permit us to target permeability to promote healthy aging in humans. Guided by preliminary data, we will test our hypothesis in three specific aims. In Aim 1, we will define the mechanisms by which mitochondrial permeability is decreased by prolongevity pathways. In Aim 2 we will define the mechanisms by which mitochondrial permeability and defects in mTOR complex 2 signaling drive autophagy. Aim 3 will determine the mechanism by which the union of mitochondrial permeability and autophagy shorten lifespan. At the conclusion of these studies, we will have identified the major mechanisms by which mitochondrial permeability disrupts cellular function and shortens lifespan. The proposed research is significant because it will have broad implications for rational design of the next generation of interventions that promote healthy aging through manipulation of autophagy and mitochondrial permeability.