Proteomes of aging and omega-3 supplementation in rat soleus skeletal muscle

Aging is a pan-organ process with an intricate and multimodal nature. Deciphering the aging phenomenon is complex, yet recent attention is analyzing the potential benefits of non-invasive life adjustments to achieve healthy aging. Omega-3 polyunsaturated fatty acids (FA) have emerged as promising nutraceuticals for a plethora of different medical conditions. In the current study we conducted an in-depth, bottom-up, global, shotgun proteomic study (LC-MS/MS) investigating both the effects of aging on skeletal muscle and the potential alterations due to omega-3 FA. Sprague Dawley rats were fed different diets and divided into four groups (n = 5 per group): adult controls (7-8 months, ADCTL); aged controls (22 months, AGCTL); and adult (AD omega 3) and aged (AG omega 3) rats fed an omega-3 supplemented diet. Among the identified 30,000 soleus proteins, our proteomic analysis identified 149 proteins differentially expressed in aging; 207 proteins with aging, but fed omega-3 FA; and 105 and 26 proteins, respectively, when aged and adult rats were fed omega-3 FA. Aging alone (ADCTL/AGCTL) affects many processes: carbohydrate and lipid metabolisms, proteostasis, mRNA processing and sarcomeric proteins. With FA supplementation and aging (AD omega 3/AG omega 3) similar processes were affected, but increased chromatin-related protein abundances (methylation or histone deacetylation) were observed in AG omega 3; while proteins involved in OXPHOS and mitochondrial homeostasis, including mTOR, were more represented in AD omega 3 rats. Supplementation with FA had a greater effect in aged rats (AGCTL/AG omega 3) than in adult ones (ADCTL/AD omega 3). In the ADCTL/AD omega 3 comparison, modest changes were seen, whereas in the AGCTL/AG omega 3 comparisons DNA damage repair increased and protein synthesis and degradation were observed. Further, a potential link to enhancement of myogenesis is also evident. The data presented in this work suggest potential beneficial and protective effects of omega 3 FA supplementation in the soleus muscle, as well as some potential molecular mechanisms of action.