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Myostatin suppression of Akirin1 mediates glucocorticoid-induced satellite cell dysfunction
Yanjun Dong1, Jenny S Pan, Liping Zhang
1Department of Medicine, Nephrology Division, Baylor College of Medicine, Houston, Texas, United States of America.
Abstract:
Glucocorticoids production is increased in many pathological conditions that are associated with muscle loss, but their role in causing muscle wasting is not fully understood. We have demonstrated a new mechanism of glucocorticoid-induced muscle atrophy: Dexamethasone (Dex) suppresses satellite cell function contributing to the development of muscle atrophy. Specifically, we found that Dex decreases satellite cell proliferation and differentiation in vitro and in vivo. The mechanism involved Dex-induced upregulation of myostatin and suppression of Akirin1, a promyogenic gene. When myostatin was inhibited in Dex-treated mice, Akirin1 expression increased as did satellite cell activity, muscle regeneration and muscle growth. In addition, silencing myostatin in myoblasts or satellite cells prevented Dex from suppressing Akirin1 expression and cellular proliferation and differentiation. Finally, overexpression of Akirin1 in myoblasts increased their expression of MyoD and myogenin and improved cellular proliferation and differentiation, theses improvements were no longer suppressed by Dex. We conclude that glucocorticoids stimulate myostatin which inhibits Akirin1 expression and the reparative functions of satellite cells. These responses attribute to muscle atrophy. Thus, inhibition of myostatin or increasing Akirin1 expression could lead to therapeutic strategies for improving satellite cell activation and enhancing muscle growth in diseases associated with increased glucocorticoid production.
Insights
Glucocorticoids like Dexamethasone cause muscle atrophy by suppressing satellite cell function. Inhibiting myostatin or boosting Akirin1 can restore satellite cell activity and muscle growth.
Area of Science:
- Muscle physiology and molecular biology
- Endocrinology and metabolic diseases
Background:
- Glucocorticoids are linked to muscle loss in various diseases, but the precise mechanisms remain unclear.
- Understanding how glucocorticoids induce muscle atrophy is crucial for developing targeted therapies.
Purpose of the Study:
- To elucidate the molecular mechanisms by which glucocorticoids, specifically Dexamethasone, induce muscle atrophy.
- To investigate the roles of myostatin and Akirin1 in glucocorticoid-mediated suppression of satellite cell function.
Main Methods:
- In vitro and in vivo experiments using Dexamethasone treatment in mice and cell cultures (myoblasts and satellite cells).
- Analysis of gene expression (myostatin, Akirin1, MyoD, myogenin) and satellite cell activity (proliferation, differentiation).
- Genetic manipulation including myostatin inhibition/silencing and Akirin1 overexpression.
Main Results:
- Dexamethasone suppressed satellite cell proliferation and differentiation by upregulating myostatin and downregulating Akirin1.
- Inhibition of myostatin in Dexamethasone-treated mice reversed these effects, increasing Akirin1, satellite cell activity, and muscle regeneration.
- Overexpression of Akirin1 in myoblasts enhanced myogenic gene expression and proliferation, counteracting Dexamethasone's suppressive effects.
Conclusions:
- Glucocorticoids induce muscle atrophy via a pathway involving increased myostatin, which suppresses Akirin1 expression and impairs satellite cell repair functions.
- Targeting the myostatin/Akirin1 axis presents a potential therapeutic strategy for muscle wasting conditions associated with elevated glucocorticoid levels.
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