Abstract 13750: Metabolic Labeling Reveal Novel Properties of Proteome Dynamics in Mouse Mitochondria
Mitochondrial dysfunction is associated with many human diseases. Inadequate protein quality control causes accumulation of damaged mitochondria, which further contributes to the pathogenesis. Maintenance of mitochondrial functions requires a delicate balance of its continuous protein synthesis and degradation, i.e. protein turnover. To understand mitochondrial protein dynamics and kinetics in vivo, we developed a strategy employing metabolic heavy water (2H2O) labeling at a minimum rate (<5% body water) without impacting the mouse physiology; and determined the turnover rates of individual proteins on a proteomic scale. A novel multi-parameter fitting approach computationally extracted normalized intensities of peptide mass isotopomers at initial and steady-state time points, and enabled quantitative analyses of protein half-lives exceeding that of the experimental labeling period. Briefly, 117 mice were fed with 2H2O; protein samples were collected from 9 mice each for thirteen time points spanning 0 hr to 90 days (d) post-labeling. To date, we obtained the turnover rates of 459 distinct proteins in mouse cardiac and hepatic mitochondria. The median turnover rates were 0.0402 and 0.163 1/d for cardiac and hepatic mitochondrial proteins, respectively, translating to median half-lives of 17.2 and 4.26 d, correspondingly. Mitochondria in heart and liver exhibited distinct protein dynamics with evidence of limited synchronized turnover within the functional clusters/pathways. There were considerable inter-protein differences in the turnover rates of both tissues; their protein half-lives span from a few hours short to a few months long (∼60 days). Our investigation is the first demonstration on large-scale mitochondrial protein turnover rate in vivo. It provides both a proteomics platform and a computation model to delineate protein kinetics in live mammals with promising potentials for translational research.
- © 2012 by American Heart Association, Inc.