Different effects of 3-week disuse on the phenotype and gene expression of the calf and thigh muscles

Disuse, like several other pathological conditions, has specific effects on various skeletal muscles. The mechanisms underlying these responses remain unclear. Three-week bed rest resulted in a greater decrease in lean mass, endurance, and more pronounced changes in the proteome and transcriptome of the calf muscles than the thigh muscles. A greater decrease in calf muscle mass was related to suppression of translation regulators. Meanwhile, a decrease in endurance of the calf muscles was associated with mitochondrial dysregulation. Most large-scale changes in the transcriptome did not translate into changes in the proteome. However, changes in the RNA levels played a dominant role in regulating expression of specific proteins, such as mitochondrial biogenesis regulators, whereas for others (proteins of ribosome and exosome, etc.) this factor played little or no role. Our findings provide a foundation for developing targeted approaches to counteract the negative effects of disuse on different muscles.