The Laryngoscope · 2025
Smad2/3 Signaling Mediates the Atrophic Response in Vocal Fold Myoblasts In Vitro.
СтатьяПоддержка NIH: внешняя программаНазвание и аннотация: Перевод в очереди
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Yoshimatsu Masayoshi, Nakamura Ryosuke, Bing Renjie, Gartling Gary J, Branski Ryan C
Аннотация
BACKGROUND/OBJECTIVES: Vocal fold (VF) muscle atrophy, often associated with neuromuscular disorders and aging, can lead to voice-related disability. Myostatin is well-known to mediate skeletal muscle atrophy via Smad2/3 signaling, whereas TGF-β1, a potent inducer of Smad2/3 signaling, is upregulated following VF injury. However, the impact of Smad2/3 signaling on laryngeal muscles remains unclear. This study provides foundational insight regarding Smad2/3-dependent atrophic responses of VF skeletal muscle cells, to ultimately develop novel therapeutic strategies for VF muscle atrophy.
STUDY DESIGN: In vitro.
METHODS: Myoblasts isolated from the rat thyroarytenoid muscle were differentiated into myotubes in myogenic differentiation medium ±500 ng/mL myostatin or 10 ng/mL TGF-β1, in the presence or absence of an ALK4/5 inhibitor or siRNA targeting Smad2 and Smad3. Myotube formation and activation of Smad2/3 (nuclear localization of Smad2/3) were assessed via immunofluorescence. Transcription related to myotube differentiation and Smad2/3 signaling was quantified by qRT-PCR.
RESULTS: Both myostatin and TGF-β1 suppressed myogenic differentiation, increased Smad2/3 nuclear intensity, downregulated Myh2, and upregulated downstream targets of Smad2/3 (Ccn2 and Serpine1) and Fbox32, an atrophy-related gene. These effects were more pronounced with TGF-β1 than with myostatin and were reversed by inhibition of ALK4/5. Furthermore, Smad2/3 knockdown via siRNA promoted myogenic differentiation, further supporting the role of Smad2/3 signaling in the atrophic response in VF myoblasts.
CONCLUSIONS: Smad2/3 signaling mediates differentiation of VF myoblasts and TGF-β1, a potent mediator of fibrosis, elicited a more pronounced atrophic response than myostatin. Smad2/3 may be an attractive therapeutic target for VF muscle atrophy.
LEVEL OF EVIDENCE: NA.
STUDY DESIGN: In vitro.
METHODS: Myoblasts isolated from the rat thyroarytenoid muscle were differentiated into myotubes in myogenic differentiation medium ±500 ng/mL myostatin or 10 ng/mL TGF-β1, in the presence or absence of an ALK4/5 inhibitor or siRNA targeting Smad2 and Smad3. Myotube formation and activation of Smad2/3 (nuclear localization of Smad2/3) were assessed via immunofluorescence. Transcription related to myotube differentiation and Smad2/3 signaling was quantified by qRT-PCR.
RESULTS: Both myostatin and TGF-β1 suppressed myogenic differentiation, increased Smad2/3 nuclear intensity, downregulated Myh2, and upregulated downstream targets of Smad2/3 (Ccn2 and Serpine1) and Fbox32, an atrophy-related gene. These effects were more pronounced with TGF-β1 than with myostatin and were reversed by inhibition of ALK4/5. Furthermore, Smad2/3 knockdown via siRNA promoted myogenic differentiation, further supporting the role of Smad2/3 signaling in the atrophic response in VF myoblasts.
CONCLUSIONS: Smad2/3 signaling mediates differentiation of VF myoblasts and TGF-β1, a potent mediator of fibrosis, elicited a more pronounced atrophic response than myostatin. Smad2/3 may be an attractive therapeutic target for VF muscle atrophy.
LEVEL OF EVIDENCE: NA.