Aug 2026· Free Radical Biology & Medicine· Vol 255, pp. 930-945· 0 citations· 21 references
Medicine
TL;DR
UCP3-associated redox homeostasis is identifies UCP3-associated redox homeostasis as an important downstream mechanism linking HDAC6 inhibition to protection against dexamethasone-induced muscle atrophy.
Abstract
Objective
Long-term use of glucocorticoids, such as dexamethasone, often leads to glucocorticoid-induced muscle atrophy (GIMA), a condition associated with mitochondrial oxidative stress and abnormal activation of protein degradation pathways. Histone deacetylase 6 (HDAC6) is involved in cellular stress regulation, but its role in GIMA remains unclear. We investigated the protective effects of HDAC6 inhibition/loss-of-function against dexamethasone-induced muscle atrophy and its potential molecular mechanisms.
Methods
Using Hdac6 knockout (KO) mice and C2C12 myotube models, combined with the HDAC6-selective inhibitor ACY-1215, we evaluated the phenotype of dexamethasone-induced muscle atrophy. We performed transcriptomic sequencing, Western blotting, immunofluorescence assays, and measured oxidative stress markers including reactive oxygen species (ROS), malondialdehyde (MDA), and the reduced glutathione to oxidized glutathione disulfide ratio (GSH/GSSG). Mitochondria-specific parameters, including mitochondrial superoxide (MitoSOX), mitochondrial membrane potential (MT-1 and JC-1), mitochondrial biogenesis markers (PGC-1α and TFAM), and antioxidant enzymes (SOD2, GPx1, and GPx4), were assessed. To investigate the regulatory mechanism, we assessed Ucp3 mRNA abundance and UCP3 protein stability. We also performed UCP3 knockdown and overexpression experiments in C2C12 myotubes to determine the functional contribution of UCP3 to the protective effects of HDAC6 loss or inhibition.
Results
Hdac6 knockout or HDAC6 inhibition significantly attenuated dexamethasone-induced muscle atrophy, as evidenced by increased grip strength, restored muscle mass, enlarged muscle fiber diameter, and downregulated MuRF1/Atrogin-1 expression in mice. RNA-seq analysis identified DEX-responsive changes in redox-related pathways in Hdac6-deficient skeletal muscle, with Ucp3 among the DEX-responsive genes. Mechanistically, HDAC6 knockdown increased Ucp3 mRNA abundance without detectably altering UCP3 protein stability. This was accompanied by reduced mitochondrial superoxide, restored mitochondrial membrane potential, and increased expression of mitochondrial biogenesis markers and antioxidant enzymes. Importantly, UCP3 overexpression in C2C12 myotubes, without HDAC6 manipulation, was sufficient to attenuate dexamethasone-induced myotube atrophy. Functional rescue experiments showed that UCP3 knockdown reversed the antioxidant and anti-atrophic effects of HDAC6 knockdown. ACY-1215 attenuated dexamethasone-induced muscle atrophy in both mice and C2C12 myotubes. In C2C12 myotubes, UCP3 knockdown abolished the antioxidant and anti-atrophic effects of ACY-1215, demonstrating UCP3 dependence in the in vitro model.
Conclusion
This study identifies UCP3-associated redox homeostasis as an important downstream mechanism linking HDAC6 inhibition to protection against dexamethasone-induced muscle atrophy. In C2C12 myotubes, UCP3 was required for the protective effects of HDAC6 knockdown and ACY-1215, whereas UCP3 overexpression was sufficient to attenuate dexamethasone-induced myotube atrophy. ACY-1215 also alleviated dexamethasone-induced muscle atrophy in mice, although the UCP3 dependence of this in vivo effect remains to be determined.
Prolonged glucocorticoid (GC) exposure is a clinically relevant cause of skeletal muscle atrophy through activation of glucocorticoid receptor (GR)-dependent catabolic transcriptional programs, including those mediated by Krüppel-like factor 15 (KLF15). However, the post-translational regulatory mechanisms that modulate the magnitude of GC-driven catabolic signaling in skeletal muscle remain incompletely understood. In this study, we investigated the role of SUMOylation as a stress-responsive post-translational regulatory mechanism in GC-induced muscle toxicity. Pharmacological modulation of SUMOylation was examined using the SUMOylation activator N106 in differentiated C2C12 myotubes and in a DEX-treated mouse model, both subjected to dexamethasone (DEX) treatment. Morphological, transcriptional, and functional parameters were assessed in vitro and in vivo, and the requirement for SUMO conjugation was interrogated using the SUMO E1 inhibitor TAK981. DEX exposure was associated with reduced SUMO-conjugated protein levels and induced a robust GR-KLF15-dependent catabolic transcriptional response in skeletal muscle cells and tissues. Enhancement of SUMOylation by N106 attenuated DEX-induced reductions in myotube diameter and muscle fiber cross-sectional area and suppressed the induction of muscle atrogenes (Fbxo32, Trim63) and metabolic enzymes (Pdk4, Bcat2). In vivo, N106 mitigated DEX-associated impairments in muscle function, including grip strength and treadmill endurance. In contrast, pharmacological inhibition of SUMOylation by TAK981 enhanced GC-induced catabolic gene expression, supporting an important role for SUMO conjugation in regulating skeletal muscle stress responses. Collectively, these findings identify SUMOylation as a post-translational regulatory layer that constrains GR-mediated catabolic transcription under GC stress. Chemical modulation of the SUMOylation pathway influences the severity of GC-induced muscle atrophy, highlighting SUMOylation as an important determinant of skeletal muscle susceptibility to GC-induced toxicity.
Ahyoung Lee, Y. Jeong, Hayeong Kwon et al.· Scientific Reports· 0 citations
Cisplatin is a widely used chemotherapeutic agent whose clinical utility is limited by various adverse effects. Although skeletal muscle loss during chemotherapy is often attributed to cachexia or generalized wasting, accumulating evidence indicates that cisplatin directly induces skeletal muscle atrophy. However, the underlying cellular stress responses and signaling pathways remain unclear. In this study, we investigated the involvement of endoplasmic reticulum (ER) stress and translational regulation in cisplatin-induced skeletal muscle atrophy, focusing on DNA damage-inducible transcript 4/Regulated in development and DNA damage response-1 (Ddit4/REDD1), a stress-responsive inhibitor of mammalian target of rapamycin complex 1 (mTORC1). Using a mouse model and differentiated C2C12 myotubes, we examined ER stress signaling, protein synthesis, and mTORC1 activity following cisplatin treatment, and evaluated the effects of tauroursodeoxycholic acid (TUDCA), an ER stress-suppressing chemical chaperone. Cisplatin induced skeletal muscle atrophy accompanied by ER stress activation and suppression of protein synthesis in mice. TUDCA significantly attenuated muscle mass and strength loss without affecting body weight reduction. Cisplatin upregulated ER stress-responsive genes and decreased phosphorylation of p70 S6 kinase, whereas these changes were suppressed by TUDCA. Pharmacological ER stress induction increased Ddit4/REDD1 expression, and PERK inhibition reduced cisplatin-induced Ddit4/REDD1 upregulation in C2C12 myotubes. Furthermore, Ddit4/REDD1 knockdown partially restored protein synthesis and mTORC1 signaling. These findings indicate that cisplatin induces skeletal muscle atrophy via ER stress-associated translational suppression, at least partly through Ddit4/REDD1-mediated inhibition of mTORC1.
Ketosis is a common metabolic disorder in periparturient dairy cows and is characterized by elevated circulating BHBA concentrations. Although the effects of ketosis on hepatic metabolism have been extensively studied, its impact on skeletal muscle remains poorly understood. This study investigated the effects of BHBA on bovine muscle satellite cells (BMSCs) and the role of mitochondrial quality control in BHBA-induced cellular injury. BHBA treatment significantly inhibited BMSC proliferation, promoted apoptosis, increased intracellular and mitochondrial ROS accumulation, reduced antioxidant enzyme activities, and impaired mitochondrial membrane potential in a dose-dependent manner. BHBA also disrupted mitochondrial ultrastructure, altered the expression of mitochondrial respiratory chain genes, promoted mitochondrial fission, and suppressed mitophagy. Similar effects were observed in C
2
C
12
myoblasts, indicating that the detrimental effects of BHBA on myogenic cells are conserved across different cellular models. Notably, activation of mitophagy alleviated BHBA-induced oxidative stress, reduced ROS accumulation, improved antioxidant capacity, and enhanced ketone body metabolism, whereas inhibition of mitophagy exacerbated these alterations. These findings demonstrate that BHBA directly induces oxidative damage and mitochondrial dysfunction in myogenic cells. Impaired mitophagy contributes to the progression of cellular injury, whereas enhancement of mitochondrial quality control confers protection. This study provides new insights into the cellular mechanisms underlying skeletal muscle metabolic dysfunction during bovine ketosis and identifies mitophagy as a potential therapeutic target.
Tao Tang, Jing Zhou, Xianbo Jia et al.· Frontiers in Cell and Develo...· 0 citations
Sarcopenia, characterized by progressive loss of skeletal muscle mass and function, is exacerbated by chronic glucocorticoid exposure, which activates catabolic signaling pathways and accelerates muscle protein degradation. Although Cryptotaenia japonica Hassk (Apiaceae) has been reported to possess antioxidant and anti-inflammatory properties, its role in glucocorticoid-induced muscle atrophy remains unclear. In this study, we investigated the myoprotective effects of Cryptotaenia japonica extract (CJE) using both in vitro and in vivo models. C2C12 myotubes were treated with dexamethasone (Dex, 10 μM) in the presence or absence of CJE (10–100 μg/mL), and key signaling pathways were analyzed by Western blotting and confocal microscopy. In vivo, Dex-induced muscle atrophy was established in ICR mice, followed by oral administration of CJE (200 mg/kg/day). Muscle tissues were evaluated for protein expression, histological alterations, and serum GDF-8 levels. CJE treatment attenuated Dex-induced upregulation of the E3 ubiquitin ligases MuRF-1 and FBX32 and inhibited FOXO1 nuclear translocation in C2C12 myotubes. In dexamethasone-treated mice, CJE restored mTOR phosphorylation and normalized the dexamethasone-induced dysregulation of AKT phosphorylation, while suppressing the FOXO/E3 ubiquitin ligase catabolic axis. In Dex-treated mice, CJE reduced the expression of FOXO3a, MuRF-1, and FBX32, preserved muscle fiber architecture, and increased muscle fiber cross-sectional area. Furthermore, CJE modulated circulating GDF-8 levels associated with muscle atrophy. Collectively, these findings demonstrate that CJE mitigates glucocorticoid-induced muscle atrophy by coordinately regulating the AKT/mTOR–FOXO/E3 ubiquitin ligase signaling axis. These results suggest that CJE may serve as a promising natural therapeutic candidate for the prevention of sarcopenia and muscle-wasting conditions.
D. Choi, Hui-Yi Lee, Seokhoon Heo et al.· Frontiers in Physiology· 0 citations
INTRODUCTION
Disuse muscle atrophy is strongly associated with oxidative stress, with antioxidants such as melatonin emerging as potential therapeutic agents, particularly due to their protective effects on mitochondrial function. This study aimed to investigate the effects of melatonin on redox balance, cellular morphology, and expression of atrophy-related genes, Atrogin-1 and MuRF1, in an H2O2-induced muscle atrophy model using the C2C12 cell line.
MATERIALS AND METHODS
Four experimental groups were established, namely Control, Melatonin, H2O2, and Melatonin + H2O2. Morphological alterations were evaluated by measuring myotube diameters. Redox status was assessed using the Oxidative Stress Index (OSI), calculated from Total Antioxidant Status (TAS) and Total Oxidant Status (TOS). The expression levels of Atrogin-1 and MuRF1 were analyzed using quantitative real-time PCR.
RESULTS
Significant differences in myotube diameters were observed among the groups (p < 0.05). The Melatonin + H2O2 group exhibited the lowest OSI values, indicating improved redox balance. Although the differences were not statistically significant, melatonin treatment was associated with lower expression levels of Atrogin-1 and MuRF1 compared to other groups.
DISCUSSION
The findings suggest that melatonin may alleviate oxidative stressinduced muscle atrophy by preserving myotube morphology and improving cellular redox balance. The observed trends in Atrogin-1 and MuRF1 expression indicate a potential modulatory effect of melatonin on atrophy-related pathways; however, additional time-course and protein-level analyses are needed to further clarify these mechanisms.
CONCLUSION
Melatonin demonstrated protective effects against HⁿOⁿ-induced muscle atrophy in C2C12 cells, particularly through the preservation of myotube morphology and enhancement of cellular antioxidant status. These findings support the potential role of melatonin as a therapeutic candidate for oxidative stress-related muscle atrophy.
Nazlı Karimi Ahmadi, A. B. Dinçsoy· Current molecular medicine· 0 citations
ABSTRACT Chronic glucocorticoid (GC) exposure is the leading clinical cause of skeletal muscle atrophy, steroid myopathy, and secondary sarcopenia, triggering irreversible motor function decline, disease progression, and elevated all‐cause mortality. The underlying pathological mechanisms remain unclear, and no safe and effective targeted interventions are currently available. This study identifies Lipocalin 2 (LCN2) as a pivotal driver of GC‐induced muscle atrophy. Using multi‐omics analysis, dexamethasone‐induced mouse models, primary myotube models, and gain/loss‐of‐function assays, we found that LCN2 was the most strikingly upregulated factor in atrophic muscle, and that its transcription was directly activated by glucocorticoid receptor (GR) binding to the conserved glucocorticoid response element (GRE) in its promoter. Muscle‐specific LCN2 overexpression disrupts extracellular matrix (ECM) homeostasis and triggers severe muscle atrophy and motor dysfunction, whereas LCN2 silencing markedly alleviates GC‐induced ECM injury and atrophy without impairing normal muscle homeostasis. Mechanistically, the interaction of LCN2 with matrix metalloproteinase 9 (MMP9) triggers ECM dysregulation and consequent focal adhesion kinase (FAK) signaling inactivation, which represses the PI3K‐Akt‐mTOR anabolic cascade and activates FoxO‐driven catabolic signaling, thereby leading to dysregulated muscle protein metabolism. This study reveals the core pathogenic role of the LCN2‐MMP9‐ECM‐FAK axis in GC‐induced muscle atrophy, providing a promising novel therapeutic target for steroid myopathy.
Hongwei Shi, Xiaojing Hao, Yi Yan et al.· Advancement of science· 0 citations
