Description
Sarcopenia is prevalent among people over 60 years of age and is characterized as involuntary aging-related muscle atrophy that influences skeletal muscle strength and performance. In elucidating the underlying cause of sarcopenia, a previous study distinguished specific sites of superoxide-induced post-translational modifications (PTMs) to human skeletal muscle myosin, a protein that is integral to muscle contraction. This thesis identifies the roles of specific residues of the myosin molecular motor and rod domains that are post-translationally modified during aging to further characterize mechanisms of the disease etiology that might serve as a target for treatment. It was hypothesized that myosin’s biochemical properties are affected by aging-related post-translational modifications that may disorder myofibril structure and reduce muscle contraction. Mimics of human myosin heavy chain PTMs in skeletal muscle (N81T, R908E, and N1186D) were used to assess their involvement in muscle deterioration in Drosophila. Assays evaluating muscle function in vivo along with myosin function and proteostasis in vitro demonstrated aging-related effects of the mimic mutations, substantiating further investigation for treatment. It was hypothesized that overexpression of the FOXO proteostasis regulator would recover muscle function by removing damaged myosins in post-translationally modified mimic heterozygotes experiencing sarcopenia. Improvements in muscle function occurred only in controls with potential leaky FOXO overexpression rather than in flies with strong overexpression levels. This combination of data demonstrated how PTM alterations of myosin worsen muscle structure and function during aging and yielded insights into methods for ameliorating this deterioration, such as slight FOXO overexpression.
