Investigation of differentially expressed proteins in rat gastrocnemius muscle during denervation–reinnervation

Abstract

To have a better insight into the molecular events involved in denervation-induced atrophy and reinnervation-induced regeneration of skeletal muscles, it is important to investigate the changes in expression levels of a great multitude of muscle proteins during the process of denervation-reinnervation. In this study, we employed an experimental model of rat sciatic nerve crush to examine the differentially expressed proteins in the rat gastrocnemius muscle at different time points (0, 1, 2, 3, 4 weeks) after sciatic nerve crush by using two-dimensional gel electrophoresis (2-DE) followed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF-MS), collectively referred to as the modern proteomic analysis. The results showed that 16 proteins in the rat gastrocnemius muscle exhibited two distinct types of change pattern in their relative abundance: (1) The relative expression levels of 11 proteins (including alpha actin, myosin heavy chain, etc.) were decreased either within 1 or 2 weeks post-sciatic nerve injury, followed by restoration during the ensuing days until 4 weeks. (2) The other 5 proteins (including alpha enolase, beta enolase, signal peptide peptidase-like 3, etc.) displayed an up-regulation in their relative expression levels within 1 week following sciatic nerve injury, and a subsequent gradual decrease in their relative expression levels until 4 weeks. Moreover, the significance of the changes in expression levels of the 16 proteins during denervation-reinnervation has been selectively discussed.

Proteomic changes in rat thyroarytenoid muscle induced by botulinum neurotoxin injection

“…α-actin, identified in two spot locations, was consistently found in the same spot sample as other protein species at a significant distance from its theoretical MW/pI. Abundance was significantly increased at 72 hr, 7 days and 56 days post injection, which contrasts with previous reports of decreased α-actin abundance in denervated and aged rat skeletal muscle [32,[34][35].…”

“…Upregulation of MyHC IIb for at least 56 days following BoNT/A injection in the rat TA was reported by Inagi et al, alongside concomitant upregulation of MyHC IIx and downregulation of IIL [17]. These findings suggest a general shift from superfast to fast MyHC isoform predominance following BoNT/A injection, and contrast with other reports of decreased MyHC IIb abundance following surgical denervation [35].…”

“…Previous proteomic studies have confirmed the downregulation and subsequent recovery of tropomyosin β-chain in denervated and then reinnervated rat gastrocnemius muscle [35], in addition to the downregulation of tropomyosin α-chain in aged rat gastrocnemius muscle [36]. Troponin T, which binds to tropomyosin in the thin filament regulatory complex, is reportedly downregulated in rat soleus muscle following denervation and hindlimb suspension [31][32].…”

“…Creatine kinase, a major energy transduction enzyme and consumer of ATP, had reduced spot abundance at all post-injection time points, although it is important to note that a second protein, troponin T, was also identified in the same spot sample. Creatine kinase downregulation has been identified in aged and denervated rat gastrocnemius muscle [34][35][36]; however upregulation of this protein has been reported for denervated rat TA muscle [18].…”

Proteomic analysis of muscle affected by motor neuron degeneration: The wobbler mouse model of amyotrophic lateral sclerosis

“…Insufficient loading, denervation or disuse is usually associated with slow-to-fast muscle transitions, which has been confirmed by recent MS-based proteomic studies [30][31][32][33][34][35]. The proteomic profiling of muscular atrophy has revealed an increase in key enzymes of the glycolytic pathway and a concomitant decrease in slow contractile proteins, such as the cardiac isoform of myosin heavy chain, slow troponin T and slow myosin light chain [30][31][32][33][34][35]. In analogy, the proteomic analysis of the WR mouse, which represents an animal model of disease-induced muscular atrophy, showed an increase in the abundance of key glycolytic enzymes.…”