Acute-phase response proteins are increased after a short-term combination of endurance exercise and Tat-Beclin1 in muscle of old male mice

Introduction: Regular exercise training is the front-line therapy for sarcopenia. However, even with exercise, sarcopenia still progresses, suggesting that successful treatment will likely require a combination of therapeutic approaches.Pharmacological agents tested with exercise have shown frustrating outcomes on aged muscles, likely due to our limited understanding of the molecular mechanisms causing sarcopenia. Since autophagy is required to preserve muscle mass and function, we integrated endurance exercise training with Tat-Beclin1, a specific autophagic activator, to identify new molecular signatures regulating the benefits of endurance exercise and Tat-Beclin1. We hypothesize that optimizing autophagy by combining Tat-Beclin1 and endurance exercise will highlight proteins associated with improved muscle health in old male mice. Methods: Male C57BL/6J mice (23 months old) were divided into four groups: Control (N=3), Tat-Beclin1 (TB, N=4), Exercise (Exe, N=4), and TB+Exe (N=4). Endurance exercise and Tat-Beclin1 administration were intercalated to avoid overactivation of autophagy-induced muscle dysfunction. Exercising animals ran on a treadmill every Monday, Wednesday, and Friday for 30 – 60 minutes, while Tat-Beclin1 injections (15 mg/kg, IP) were performed every Tuesday and Thursday. Forelimb grip strength, muscle mass, autophagic proteins by western blotting, and proteome in the gastrocnemius (GAST) muscle were assessed. Results: Body weight and muscle mass (p>0.05) did not differ among groups among groups. All treatment conditions (TB, Exe, and TB+Exe; p<0.05) increased grip strength compared to control. There was a trend to increase grip strength in the TB+Exe group compared to the TB and Exe groups. Compared to other groups, there was a significant decrease in the Sequestosome1/p62 protein expression in the GAST muscle from the TB+Exe group. Although LC3B-II, a marker of autophagosome formation, was lower in the TB+Exe group, it did not reach statistical significance. Overall, the proteomics analysis in the GAST muscle tended to decrease proteins known to induce muscle deterioration, including milk fat globule epidermal growth factor 8 (MFG-E8), which is reported to contribute to sarcopenia through neuromuscular junction dysfunction and angiopoietin-related protein 7 (Angpl7), a myokine postulated to promote sarcopenia. Specifically, comparing TB+Exe vs. Exe groups, TB+Exe increased acute-phase proteins, including orosomuscoid1 and haptoglobin. Orosomucoid1 prevents muscle fatigue while increasing endurance and glycogen content in muscles. In addition, haptoglobin deletion is sufficient to induce muscle atrophy. Conclusion: Our combinatory therapeutic strategy elicits molecular reprogramming that favors the increase of proteins that support healthier muscle metabolism. Future studies will include an in-depth understanding of highly expressed proteins in sarcopenia development and the inclusion of female mice, which is crucial to improving our findings’ translational value. Funding: Camden Research Health Initiative. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.