|Heat map of the 25 most differentially expressed proteins during the hibernation cycle; EA, early arousal; LT, late torpor; PR, post-reproduction
Mammalian hibernation is a complex process involving large-scale reorganization of metabolic and other pathways. In this study, the researchers constructed a database of more than 3,000 liver proteins from arctic ground squirrels (Urocitellus parryii) and then used label-free shotgun proteomics to analyze changes in protein expression throughout the torpor/arousal hibernation cycle. Consistent with previous studies measuring mRNA changes, proteins involved in glycolysis and fatty-acid synthesis were significantly underexpressed in both late-torpid and early-aroused squirrels compared with nonhibernating animals, while proteins involved in fatty acid catabolism were significantly overexpressed. However, in other cases, the protein and mRNA data did not entirely mesh; for example, proteins involved in translation, protein degradation, mRNA processing and oxidative phosphorylation were overexpressed in early-aroused animals compared with late-torpid animals, whereas no significant changes in mRNA levels between those stages had been observed. The discrepancies suggest substantial post-transcriptional regulation of proteins occurs during hibernation.
Shotgun Proteomic Analysis of Hibernating Arctic Ground Squirrels
Chunxuan Shao, Yuting Liu, Hongqiang Ruan, Ying Li, Haifang Wang, Franziska Kohl, Anna V. Goropashnaya, Vadim B. Fedorov, Rong Zeng, Brian M. Barnes and Jun Yan
Mol. Cell. Proteomics, published online Nov. 20, 2009
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