Using C. elegans to Investigate the Effects of Polyunsaturated Fatty Acids and Their Metabolites on Lifespan and Healthspan

Abstract

Aging is a burdensome process that increases one's susceptibility to disease and disability. Many environmental factors, including diet, have been shown to influence aging outcomes. Specific omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) have been shown to have protective effects against aging-related conditions such as cardiovascular disease, inflammation, and Alzheimer's Disease. However, it is unclear which unsaturated fatty acids are required in the diet and how these molecules and their metabolites affect different health and disease states. This study aims to investigate the physiological roles of individual unsaturated fatty acids in the aging process. Our data will grant us the preliminary knowledge for making dietary and treatment suggestions to ameliorate aging-related conditions and promote healthy aging. This study will utilize the model organism C. elegans because of its short lifespan, its genetic pliability, and its ability to reliably function as a model for human health and disease. Single and multiple genetic knockouts of fatty acid desaturase enzymes will be used to assess the in vivo effects of unsaturated fatty acids on the aging process because these mutants contain different PUFA compositions in vivo. This investigation will lead to the creation of one dataset that includes lifespan and healthspan data for every available desaturase enzyme genetic knockout in the worm. Lifespan assays were used to quantify changes in the lifespans of different genetic knockouts, and thrashing assays were used to assess their physical fitness throughout the aging process, an indicator of healthspan. Additionally, gas chromatography/mass spectrometry fatty acid methyl esters analysis (GC/MS FAME) was used to assess the lipidome of key strains. We hypothesized that certain PUFAs play more important physiological roles than others due to their corresponding downstream metabolites’ role in lipid signaling. Our data confirm this hypothesis and demonstrate that the different desaturase enzyme knockouts vary in lifespan, fitness, and their lipid profile throughout the aging process. All mutants that have genetic disruption of PUFA biosynthesis were observed to have decreased median lifespan. Interestingly, our results from several mutants are different from the published data which involve the use of FuDR, a chemical that prevents the production of progeny. These mutants additionally have poor physical fitness across the first five days of adulthood. Notably, lipidomic analysis of day 1 adult fat-3 knockout worms, which cannot endogenously synthesize long chain PUFAs, revealed that these in vivo observations are associated with an increase in linoleic acid and alpha-linolenic acid and a decrease in other upstream and downstream metabolites. Taken together, our data suggest that altering endogenous levels of PUFAs decreases lifespan and healthspan. Investigating this metabolic pathway may elucidate novel pharmacological drug targets and reveal affordable dietary supplements that could revolutionize chronic disease treatment and prevention.