System-wide and mechanistic deconvolution of autophagy in cellular aging

Cornell University, Ithaca NY

Investigators

Abstract

Project Summary/Abstract Cellular aging is a complex physiological process defined by progressive loss of function over time, and constitutes a major risk factor for age-associated diseases. The budding yeast, Saccharomyces cerevisiae, is a foundational model for our understanding of cellular aging. We have established a new genetic system, the “daughter extinction program” (DEP), scalable for system-wide profiling of replicative aging. Enabled by the DEP, we have generated a first genome- wide quantitative aging map of a eukaryotic cell. Autophagy is a universal modifier of aging at the center of cellular aging and a promising target for therapeutic intervention in aging and age-associated disease. However, autophagy involves complex combinations of non-selective (bulk) and selective forms of autophagy for the regulated degradation of an unparalleled scope of substrates. The goal of this project is to systematically dissect the individual and combinatorial contributions of the different genes, forms and functions of autophagy to cellular aging. We have identified not only differential functions of autophagy for cellular aging, but also two new paradigms of extending replicative lifespan (RLS) by modifying specific aspects of autophagy. Our goals are to gain mechanistic understanding of how tuning autophagy towards selective forms or inhibiting a specific form of selective autophagy of mitochondria (mitophagy), which we show regulates mitochondrial size, significantly prolongs RLS. To achieve our research goals, we propose the following three aims: (1) Deconvolve the differential functions of autophagy for replicative aging. We will systematically dissect how autophagy governs cellular aging at single and combinatorial gene resolution, study how limiting or enhancing bulk and/or selective forms of autophagy determine RLS at basal level and in different genetic and chemical models of elevated autophagy, and characterize key regulators of autophagy and all selective autophagy receptors (SARs) for their potential as bone fide aging modifiers. (2) Determine the genetic landscape of Atg32-dependent replicative aging. The conserved mitophagy-receptor Atg32/BCL2L13 as a novel bone fide aging modifier. We have generated a genome-wide aging map of an Atg32-deficient cell to define the genetic requirements for Atg32-dependent RLS regulation. We will characterize the functional interactions of Atg32 with the autophagy machinery and focus on understanding how two different mitophagy receptors cause opposing effects on cellular aging. (3) Define the molecular mechanisms of Atg32/BCL2L13-mediated mitophagic scaling in replicative aging. To interrogate the function of Atg32 as an aging modifier, we aim at understanding how molecular mechanisms of mitophagic scaling interface with cellular aging utilizing multidisciplinary approaches. In sum, these studies will lead to a comprehensive model for the regulation of cellular aging by autophagy, foundational to the promise of rationale tuning of autophagy for improved human aging and age-associated disease.