Cross-Organ Proteome Analysis Reveals Changes in Protein Expression Related With Glucose and Amino Acid Metabolism in Muscles and Hearts of Torpid Mice

Mammals undergoing hibernation or torpor can reduce their metabolic rate. However, the mechanisms of hypometabolism in hibernating animals remain unclear. Analysis of hibernation mechanisms, taking into account commonalities and differences among organs, is essential for a comprehensive understanding of this reduction in physiological activity. Therefore, we investigated and compared changes in protein expression in the hearts and skeletal muscles of torpid mice using quantitative proteomics. Most of the 108 proteins commonly decreased in both tissues were related to translation, and the decrease in protein expression under torpid conditions was greater in muscle than in the heart. Furthermore, glycolysis related to proteins and pyruvate dehydrogenase expression was significantly decreased only in skeletal muscle. In contrast, only three proteins had significantly increased expression in the heart and muscles, with pyruvate dehydrogenase kinase 4 being the most increased. These results suggested that glucose consumption was reduced under torpid conditions. Our results suggest that the heart and muscles respond to low nutritional levels during torpor by reducing glucose and amino acid consumption to preserve energy. Moreover, this adaptation occurs more strongly in skeletal muscle than in the heart.