George L. Sutphin - US grants

ABSTRACT The goal of the work outlined in this proposal is to understand the fundamental biology of cellular response to different forms and combinations of stress. Cells are constantly subjected to a variety of intrinsic and extrinsic stresses?oxidative, protein misfolding, osmotic?that have deleterious impact on cellular structures and function. In response, eukaryotic cells activate a range of molecular pathways to mitigate and repair damage? oxidative stress response, unfolded protein response, osmotic stress response. While substantial molecular detail is known about individual stress response pathways, and some types of intervention improve resistance to multiple forms of stress (e.g. dietary restriction, inhibition of insulin signaling), surprisingly little is known about how these responses differ when cells are challenged with multiple types of stress simultaneously. The molecular architecture underlying multi-stress response represents a critical knowledge gap in the field. This gap has broad implications for medicine. Human diseases rarely involve a single form of stress?Alzheimer's disease is characterized by neuroinflammation, increased oxidative stress, and accumulation of misfolded proteins, while cancer exhibits oxidative stress, DNA damage, and localized hypoxia. By understanding the network of molecular pathways that underlie stress response, we aim to identify specific intervention points that can be targeted to target different stress profiles. Our lab employs a novel platform for high-throughput health and survival analysis in Caenorhabditis elegans. Combining this platform with tools in systems and classical genetics, we will: (1) define the genetic network that modulates the response to multiple forms of stress in C. elegans; (2) determine which network components are activated in response to distinct combinations of stress; (3) investigate mechanisms of cross-adaptation?mild exposure to one stress imparting resistance to another form of stress?for different combinations of stressors; and (4) identify key intervention points that can be targeted to mitigate different combinations of cellular stress. Using this approach, we have identified 3- hydroxyanthranilic acid (3HAA), a metabolite in the tryptophan-kynurenine pathway, that improves survival and health in C. elegans by mitigating both oxidative stress and ER stress. These benefits are realized, at least in part, through direct antioxidant and chaperone activity by 3HAA. We are now beginning mouse studies to validate our mechanistic model for the action of 3HAA in a mammalian system. The long-term goal of our work is to answer several outstanding questions about the fundamental biology of cellular stress response: (1) How is the genetic network underlying cellular stress response organized? (2) Which elements of this stress response network are general (i.e. responsive to a wide range of types of stress) and which are specific (e.g. responsive to only specific stressors)? (3) How does the cellular response to one type of stress alter an organism's resistance to another type? (4) What are the key molecular nodes in the stress response network that can be targeted to improve health or treat specific forms of disease in humans?