Protein phosphorylation in fast and slow chicken skeletal muscles: Effect of denervation

Abstract

We have identified proteins in adult chicken skeletal muscle whose phosphorylation can be used as markers for the mature fast and slow muscle phenotype. These include phosphorylase, phosphorylase kinase, and a cyclic adenosine 3′,5′‐monophosphate (cAMP)‐stimulated, calmodulin‐inhibited 28‐kDa band (markers for fast muscle), a calmodulin‐stimulated 50‐kDa band, and two cAMP‐stimulated bands at 44 and 46 kDa (markers for slow muscle), and the relative concentrations of the regulatory subunits of cAMP‐dependent protein kinase (RI and RII). After denervation the pattern of phosphorylation in fast muscle changed to resemble that of slow muscle: phosphorylation of the fast phenotype markers decreased; the slow phenotype markers, barely detectable in normal fast muscle, appeared as significant phosphoproteins; and the concentration of RII increased with no change in RI. This is consistent with denervation‐induced changes observed using other phenotypic markers and indicates the potential for using these phosphoprotein markers in studies of muscle development and pathophysiology. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:504–513, 1998.

Neurectomy preserves fast fibers when combined with tenotomy of infraspinatus muscle via upregulation of myogenesis

“…The CaMKII isoforms are possible mediators of the calcium‐regulated fiber type transformations . In particular, δ CaMKII isoforms are associated with the regulation of gene expression and demonstrate muscle‐type specific expression, which is modified by denervation in chickens and mice . The δCaMKII protein was the most abundant CaMKII isoform in the present study (Fig.…”

“…Thus, muscular adjustments after TEN or NEU involve sarcolemma‐associated factors, such as laminin‐2/merosin, which influence muscle activity‐dependent remodeling of the fiber architecture . In addition, TEN or NEU may affect molecular aspects of muscle degeneration and regeneration, such as calcium/calmodulin‐dependent kinase II (CaMKII) and tenascin‐C . These proteins are important for neurogenic reactions, such as the increase in fast‐type muscle fibers …”

“…We also hypothesized that the exaggerated atrophy in tenotomized infraspinatus muscle is associated with the ablation of neuronal drive. We assessed the protein expression levels of factors associated with myogenesis in slow and fast‐type muscle fibers (myogenin and myogenic differentiation factor [myoD]), sarcolemmal reactions (laminin‐2), fat differentiation (isoforms 1 and 2 of transcription factor peroxisome proliferator‐activated receptor gamma [PPARG]), and denervation‐induced muscle regeneration (tenascin‐C and CaMKII) …”