Publication Date

2010

Document Type

Honors Thesis

Department

Biochemistry

Keywords

Mice-Muscles, Mice-Exercise-Physiological effect, Proteomics, Skeletal muscle, Eccentric exercise, Mouse model, Exercise

Abstract

Skeletal muscle is a plastic tissue, capable of generating large forces to move the body while maintaining the highly organized structure required for its biomechanical efficiency. Skeletal muscle also has the capacity to adapt to the increased functional demands associated with exercise. Differential proteome profiling can be used to obtain a global view of proteins that change expression following a single bout of eccentrically biased exercise, as well as the gender-specific nature of this response. In this study, exercise-naïve male and female mice ran downhill (-15°) on a treadmill at 25 m/min for 15 min and 800 μg of total biceps brachii extract was electrophoresed on pH 5.0-8.0 2-D gels. The resulting spots that changed at least +/- two-fold, and were shown to be significantly different (p < 0.05) relative to unexercised controls of the appropriate gender using PDQuest 8.0, were then analyzed by LC/MS/MS and identified using Bioworks Sequest 3.3.1. The expression change patterns were followed at 0, 24, 48, 72 and 168 hours post-exercise and evaluated relative to a pre-exercise control. Proteins changing expression in both male and female skeletal muscle postexercise are concentrated among metabolic, cytoskeletal, and stress proteins. These data indicate that exercise-naïve skeletal muscle is disrupted by the unfamiliar mechanical and energetic demands of exercise. Post-exercise protein expression patterns further suggest that structural components of the contractile apparatus and various metabolic pathways within the muscle adjust to meet these new demands. This skeletal muscle response to exercise occurs in two phases, a stochastic phase and a sustained response phase. The stochastic phase occurs immediately post-exercise. Although initial protein expression changes may seem random and disorganized, it is likely that metabolic pathways are working to establish a new homeostatic point. The stochastic phase is also often where exercise-naïve gender differences are resolved. After the initial shock of strenuous exercise has been overcome, the true exercise-induced response of different proteins is revealed during the sustained response phase. Protein expression in this phase either demonstrates similar trends in both males and females or is gender-specific. Trends observed in well-studied proteins agree satisfactorily with the literature, such as a decrease in intermediate filament protein abundance and an increase in the abundance of small stress proteins. This study verifies the dynamic nature of the mouse skeletal muscle proteome, and facilitates a deeper understanding of the underlying mechanisms of physiological adaptation and damage mitigation in muscle.

Language

English

Comments

x, 131 p. : col. ill. Honors Project-Smith College, Northampton, Mass., 2010. Includes bibliographical references (p. 121-131)

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