PROJECT SUMMARY COBRE - 1P20GM144265-01 Parent award goal: The parent award goal is the COBRE Center for the Regulation of Cellular Behavior in Response to Extracellular Cues. This COBRE grant supports 5 junior project leaders from University of Maine (UMaine) and Mount Desert Island Biological Laboratory (MDIBL). The parent award builds organizational structure to run essential research programs and help grow the research community around cohesive common research themes. Research projects funded through the COBRE center for the Regulation of Cellular Behavior in Response to Extracellular Cues will significantly develop our understanding and knowledge regarding the physiological and pathophysiological roles of external stimuli (such as cell-cell communication, signaling pathway, or viral infection) during development, regeneration, health or diseases. Supplement award goal: Title: Proteostasis, atrophy and degeneration in the context of muscle aging Sarcopenia is a multifactorial disease characterized by the loss of muscle mass, strength and function. Associated with aging and age-related diseases, it is a major issue negatively affecting quality of life and the rising cost of health care. The problem with sarcopenia is two-fold: there is a loss of proteostatic maintenance leading to degeneration of muscle fibers as well as a lack of ability to regenerate healthy tissue. During aging, muscle wasting is associated with increased expression of the striated muscle-specific protein turnover factor Atrogin-1. The Madelaine lab found that overexpression of this factor in zebrafish leads to rapid degeneration of muscle fibers, atrophic muscle tissue and locomotor dysfunctions. Surprinsigly, the expression of this factor is also increased under dietary restriction (DR) involving fasting. DR is the most robust aging intervention to increase healthy lifespan and preserve long-term muscle maintenance. As metabolic parameters are reset to match dietary limitations, adaptation to DR temporarily induces muscle catabolism associated with increased atrogin- 1. Interestingly, the Atrogin-1 protein appears to have a central role in proteostasis and muscle homeostatis in the context of both health and disease. Understanding how Atrogin-1 and associated factors regulate muscle proteostasis in different contexts may help in the development of therapeutic approaches to limit muscle atrophy and ameliorate muscle wasting. However, use of vertebrate systems like mice for investigating skeletal muscle wasting in the context of natural aging require several years and comes at great cost. Use of a alternative vertebrate model organisms would allow genetic and environmental interventions at a reduced cost and within a relatively short period of time. The zebrafish is a well established powerful organism for genetic manipulations and modeling of human diseases, while Nothobranchius furzeri (N. furzeri) has recently emerged as a model for investigating both aging and regeneration. N. furzeri is the shortest-lived vertebrate bred in captivity, living only a few months. We propose to use these fish models to investigate muscle maintenance associated with changes in proteostasis and regenerative capacity during aging and/or DR. The Madelaine lab has established a new genetic model of accelerated muscle aging in zebrafish that we will use to leverage modifications associated with increase muscle degeneration and atrophy. The Rogers lab has developed a model of dietary restriction (DR) involving intermittent fasting in N. furzeri that works to increase healthy lifespan in male and female animals. This provides an intervention strategy to mitigate loss of proteostasis and regenerative capacity that occur with age. These different experimental conditions also allows for comparison of the positive role of Atrogin-1 in adaptation to DR with its pathological role in sarcopenia. In order to generate data required to better understand cellular changes associated with muscle aging and to support future grant applications, we want to establish a substantive collaborative effort on the part of our labs. We propose to carry out the following research goals: 1) Test locomotion and swimming performance to determine muscle function in fish models of accelerated muscle aging and after fasting. 2) Assess muscle structural integrity using tissue-clearing and light-sheet imaging in a genetic model of sarcopenia, during aging and under DR. 3) Use a single cell multiomics approach to characterize changes in muscle proteostatic maintenance associated with expression of Atrogin-1, aging and under DR. This supplement award project fits in the scope of the parent award with the objective to identify molecular effectors of muscle aging and cellular changes within the muscle tissue associated with genetic and dietary interventions. The collaborative effort from two labs with complementary technical skills and expertise (accelerated muscle aging and lifespan/healthspan intervention) will strengthen the outcome of this research project.

Over the last century, progress in medicine and biomedical research has significantly increased the human lifespan. Unfortunately, the number of people suffering from age-related diseases has also increased drama=cally. A serious impediment to quality of life is age-associated degenera=ve loss of muscle leading to muscular atrophy, or sarcopenia. The overall goal of this proposal is to leverage gene=c and dietary interven=ons to iden=fy molecular and cellular mechanisms underlying dysregula=on of proteostasis and onset of muscle atrophy during aging.