LONDRAVILLE, R. L.*; NIEWIAROWSKI, Peter/H; KAVETI, Suma; KINTER, Michael; University of Akron; University of Akron; Cleveland Clinic Foundation; Cleveland Clinic Foundation: Proteomic Analyses reveal that Components of the Cytoskeletal Network are Up-Regulated before Hibernation in Fence Lizards
We are undertaking long-term studies aimed at understanding the mechanistic basis of differences in life-history strategies among populations of the fence lizard Sceloporus undulatus. One aspect of these studies employs proteomics. Because the liver is metabolically �central�, we examined differences in the liver proteome from seasonally acclimatized lizards (Nebraska population, collected 7/04 & 9/04). Proteins were extracted from whole livers of individual animals (n=6 for 7/04 and 5 for 9/04) and separated by 2-dimensional gel electrophoresis. Homologous bands were compared across gels and seasons to assess relative differences in protein expression. Bands of interest were excised and submitted to mass spectrometry analyses for identification (trypsin digestion, ESI-LC-Ms/MS(ITD), CID, MALDI-TOF). To date, >50 proteins have been analyzed. Among these are 6 bands up-regulated ~2-14 fold in the fall; all of these bands (except one that remains unidentified) are components of the cytoskeletal network (tropomyosins, cytokeratin, actin). We hypothesize that the cytoskeletal network becomes more active in the fall when metabolic fuel is moved through the cell for storage (e.g. in fat bodies). In the spring, components of intermediary metabolism (cytochrome C oxidase, short-chain dehydrogenase) are up-regulated. We hypothesize that these changes support high activity and growth in the spring. In addition, overall diversity of protein expressed is different between seasons, with a mean of 591 bands resolved in the fall, and 800 in the Spring (p<0.01). We contend that liver cells may reduce protein diversity during sub-acute stress (hibernation), and we have seen similar responses in other organisms (fish) with other stressors (parasitism and high-calorie diet).
