Submitted on May 21, 2008
Revised on August 20, 2008
Accepted on August 27, 2008
Carbonic Anhydrase III and Four-and-a-Half LIM Protein 1 are preferentially oxidized with muscle unloading
Chiao-nan Chen1, Deborah A. Ferrington1, and LaDora V. Thompson1*
1 University of Minnesota
* To whom correspondence should be addressed. E-mail: thomp067{at}umn.edu.
The identities of proteins that show disuse-related changes in the content of oxidative modification are unknown. Furthermore, it is unknown whether the global accumulation of oxidized proteins is greater in the aged animals with muscle disuse. The purposes of this study are (a) to identify the exact proteins that show disuse-related changes in the oxidation levels, and (b) to test the hypothesis that the global accumulation of oxidized proteins with muscle disuse would be greater in the aged animals. Adult and old rats were randomized into 4 groups: weight bearing, 3 days, 7 days and 14 days of hindlimb unloading (HU). Soleus muscles were harvested to investigate the protein oxidation with unloading. Slot blot, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and Western blot were used to detect the accumulation of 4-hydroxy-2-nonenol (HNE) and nitrotyrosine (NT) modified proteins. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) and MS/MS were used to identify modified proteins. We found the global HNE- and NT-modified proteins accumulate significantly with aging but not with muscle unloading. Two HNE- and NT- target proteins, four-and-a-half LIM protein 1 (FHL1) and carbonic anhydrase III (CAIII), show changes in the oxidation levels with muscle unloading. The changes in the oxidation levels happen to adult rats but not old rats. However, old rats had higher baseline levels of HNE-modified FHL1. In summary, the data suggest that the muscle unloading-related changes of protein oxidation are more significant in specific proteins and the changes are age-related.
