Proteomic analysis of rat laryngeal muscle following denervation and reinnervation

Abstract Problem: Laryngeal muscle atrophy induced by nerve injury is a major factor contributing to the disabling symptoms associated with laryngeal paralysis. Although changes in myosin-heavy chain components have been described in denervated laryngeal muscle, little is known about alterations occurring in the general population of muscle proteins. Alteration of proteins in rat laryngeal muscle following denervation and reinnervation was therefore studied using proteomic techniques. Methods: Adult Sprague-Dawley rats were divided into normal control, denervation (RLN divided and ligated), and reinnervation (RLN divided and suture repaired) groups. The thyroarytenoid (TA) muscle was excised 60 days after surgery. Protein separation and identification were performed using 2-dimensional electrophoresis, MALDI-TOF mass spectrometry, and MASS/MASS with database search. Results: Forty-five proteins and their modified isoforms were found to have significant alteration in expression level after denervation. The majority of these proteins (60%), associated with energy metabolism, cellular proliferation and differentiation, signal transduction, and stress reaction, were found to have decreased levels of expression in denervated TA muscle. The remaining 40% of proteins, involved with degradation of cellular proteins, immunoreactivity and injury repair, regulation of muscle contraction and microtubular formation, were found to have increased levels of expression. Multiple spot patterns due to site modification by phosphorylation were detected in 16% of identified proteins. In the reinnervated group, only 8 protein spots identified were significantly different from normal controls. Changes in expression levels were similar to denervated muscle although to a lesser degree. Conclusion: Significant changes in protein expression occur in denervated laryngeal muscle. Fewer changes are observed in reinnervated muscle. Significance: Modulation of these protein shifts by trophic factors may provide potential therapeutic strategies for the treatment of laryngeal paralysis. Support: None reported.