Abstract
Skeletal muscle is a vital organ for a healthy life, but its mass and function decline with aging, resulting in a condition termed sarcopenia. The etiology of sarcopenia remains unclear. We recently demonstrated that interstitial mesenchymal progenitors are essential for homeostatic muscle maintenance, and a diminished expression of the mesenchymal-specific gene Bmp3b is associated with sarcopenia. Here, we assessed the protective function of Bmp3b against sarcopenia by generating conditional transgenic (Tg) mice that enable a forced expression of Bmp3b specifically in mesenchymal progenitors. The mice were grown until they reached the geriatric stage, and the age-related muscle phenotypes were examined. The Tg mice had significantly heavier muscles compared to control mice, and the type IIB myofiber cross-sectional areas were preserved in Tg mice. The composition of the myofiber types did not differ between the genotypes. The Tg mice showed a decreasing trend of fibrosis, but the degree of fat infiltration was as low as that in the control mice. Finally, we observed the preservation of innervated neuromuscular junctions (NMJs) in the Tg muscle in contrast to the control muscle, where the NMJ degeneration was conspicuous. Thus, our results indicate that the transgenic expression of Bmp3b in mesenchymal progenitors alleviates age-related muscle deterioration. Collectively, this study strengthens the beneficial role of mesenchymal Bmp3b against sarcopenia and suggests that preserving the youthfulness of mesenchymal progenitors may be an effective means of combating sarcopenia.
Highlights
The skeletal muscle is the largest organ in the human body
Bmp3b is expressed in mesenchymal progenitors, but its expression level is significantly decreased by aging [13]
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Summary
The skeletal muscle is the largest organ in the human body. The skeletal muscle is an essential component of the musculoskeletal system and is essential for exercise and physical activity. The skeletal muscle has a significant impact on the whole-body metabolism. It is the largest target organ of insulin and serves as a major reservoir of amino acids. The skeletal muscle is vital for a healthy life. Skeletal muscle mass and function gradually decline with age, eventually leading to a pathological condition termed sarcopenia. Sarcopenia reduces physical activity and deteriorates the general health and is one of the major determinants of a healthy life expectancy. Since the population is rapidly aging globally, preventing sarcopenia is an important task for public health
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