The role of orosomucoid1 in skeletal muscle aging during an optimized autophagy activity intervention - Project Summary/Abstract The age-related loss of muscle mass and function (e.g., strength and physical performance) is known as sarcopenia. It is a muscle disorder that leads to increased physical fatigue, falls, and fractures and is highly associated with hospitalization and mortality. Despite its remarkable clinical relevance, no pharmacological agents are approved for this condition, and exercise training remains the only recommended therapy. Nevertheless, some pharmacological agents alleviate sarcopenia in mice and humans when prescribed as a single-mode therapy, but combining them with exercise has produced frustrating outcomes. Given the pressing need to identify a viable drug that enhances exercise benefits, we postulated that enhancing autophagy by administering Tat-Beclin1 would boost exercise adaptation in old mice. Our focus on autophagy is due to its requirement to preserve muscle health. Our preliminary data shows that combining Tat-Beclin1 and exercise increases autophagy status, grip strength, and endurance capacity. To determine the molecular mechanisms by which adding Tat-Beclin1 to an exercise regimen elicits functional benefits in aged muscles, we performed a proteomic analysis in the gastrocnemius (GAST) muscles. Our data revealed orosomucoid1 as one of the top proteins upregulated in the GAST muscles of old mice subjected to integrative therapy. Orosomucoid1 is an acute-phase protein shown to attenuate physical fatigue and increase endurance capacity and glycogen content in the muscles of young mice. The central hypothesis is that orosomucoid1 attenuates sarcopenia and is necessary for the improvements induced by combining Tat-Beclin1 and exercise. The hypothesis will be tested with two specific aims. Aim 1 asks whether orosomucoid1 is necessary for the improvements induced by Tat-Beclin1 and endurance exercise. We will electroporate a miRNA encoding orosomucoid1 in the hindlimb muscles of male (26 months old) and female (28 months old) mice and subject animals to exercise, Tat- Beclin1, or a combination of the two therapies for two months. A miRNA control encoding a nontargeting pre- miR hairpin sequence in the contralateral leg to serve as an experimental control. In vivo muscle function and comprehensive ex vivo assay will be performed. Aim 2 asks whether increasing orosomucoid1 levels can prevent, halt, or revert sarcopenia. We will administer exogenous purified orosomucoid1 (IP) for 30 days in 18-, 26-, and 30-month-old male and 18-, 28-, and 32-month-old female mice. Functional, biochemical, morphological, and molecular (i.e., proteomics) will be assessed. The proposal is significant because it addresses a relevant and poorly understood area of muscle biology, and it could put into development a new therapeutic approach to tackle sarcopenia.
