MuRF‐1 is Involved in Laryngeal Muscle Denervation Atrophy by Regulating G‐Actin Ubiquitination

Objective Muscle RING‐finger protein‐1 (MuRF‐1), an E3 ubiquitin ligase, has been reported to aggravate skeletal muscle denervated atrophy by mediating the ubiquitination degradation of multiple proteins, whereas the molecular mechanism underlying MuRF‐1‐mediated internal laryngeal muscle denervated atrophy remains unknown. Methods A rat unilateral recurrent laryngeal nerve (RLN) transection model was established to evaluate denervated muscle atrophy of the larynx. The expression of MuRF‐1, G‐ and F‐actin in thyroarytenoid muscle (TA) myocytes before and after RLN injury was analyzed by immunofluorescence and Western blotting. Coimmunoprecipitation experiments detected molecular interactions between MuRF‐1 and G‐actin. Immunoprecipitation tested MuRF‐1‐mediated ubiquitination of G‐actin in denervated and innervated TA muscle tissues. The shRNA‐MuRF‐1 AAV was used to suppress MuRF‐1 expression in denervated TA muscles in vivo. Results First, MuRF‐1 expression was significantly elevated in denervated TA muscle compared to innervated TA muscle ( p < 0.001). Second, there was a progressive increase in the G/F‐actin ratio in TA myocytes from day 3 to 14 after RLNI ( p < 0.01). Furthermore, colocalization of MuRF‐1 and G‐actin in denervated TA myocytes was observed. Moreover, the upregulation of MuRF‐1 was closely associated with the ubiquitination of G‐actin in denervated TA myocytes and muscle tissues. Knockdown of MuRF‐1 decelerated the degree of TA muscle atrophy compared with that in the Blank and NC groups ( p < 0.001) but seemed to promote the compensatory movement of the healthy side. Conclusion Collectively, we illustrate a novel molecular mechanism underlying MuRF‐1‐mediated internal laryngeal muscle denervated atrophy in that MuRF‐1 could promote disequilibrium of the G/F‐actin ratio by regulating G‐actin ubiquitination. Level of Evidence NA Laryngoscope , 134:855–864, 2024