Invited review: Neural control of phenotypic expression in mammalian muscle fibers

Abstract

In this review, the present knowledge about the mechanisms involved in the control of the phenotypic expression of mammalian muscle fibers is summarized. There is a discussion as to how the activity imposed on the muscle fibers by the motoneuron finally induces in the muscle cells the expression of those genes that define its particular phenotype. The functional and molecular heterogeneity of skeletal muscle is thus defined by the existence of motor units with varied function, while the homogeneity of muscle fibers belonging to the same motor unit is yet another indication of the importance of activity in the control of gene expression of the mammalian muscle fiber.

Changes in muscle mass and phenotype and the expression of autocrine and systemic growth factors by muscle in response to stretch and overload

“…The interconvertibility of fibre types was demonstrated by cross-innervation and by chronic stimulation and has been reviewed (Pette & Vrbova, 1986). It became generally accepted that the frequency of stimulation was the important factor in determining fibre type transition.…”

Novel murine clonal cell lines either express slow or mixed (fast and slow) muscle markers following differentiation in vitro

“…Muscle inactivity results in a transition from slow-oxidative toward a fast-glycolytic phenotype (Bigard et al, 1998;Hourde et al, 2005;Stevens et al, 1990), that affects both MHC and enzymes involved in metabolism. Conversely, controlled stimulation of a rapid-glycolytic muscle induces changes toward a slow-oxidative phenotype (Pette and Vrbova, 1985). However, good models to investigate muscle plasticity in vitro are lacking.…”

Changes in myosin mRNA and protein expression in denervated rat soleus and tibialis anterior

“…In both the soleus and TA, denervation significantly shifted the MHC mRNA profile as early as 4 days following denervation without any corresponding changes at the protein level. Significant mRNA changes without large changes in MHC protein composition continued throughout the denervation period suggesting that the muscle may be prevented from premature functional transitions by mechanisms such as decreased mRNA stability, translational block, or increased turnover of newly synthesized proteins.Keywords : myosin heavy chain ; denervation; ribonuclease-protection assay; adaptation.The importance of the nerve in the determination and maintenance of myosin heavy chain (MHC) isoforms has been studied using experimental models including cross-reinnervation, electrical stimulation, and denervation [1]. In contrast to cross-reinnervation or electrical stimulation, denervation provides a model in which the muscle is deprived of both electrical activity and trophic factors.…”

“…The importance of the nerve in the determination and maintenance of myosin heavy chain (MHC) isoforms has been studied using experimental models including cross-reinnervation, electrical stimulation, and denervation [1]. In contrast to cross-reinnervation or electrical stimulation, denervation provides a model in which the muscle is deprived of both electrical activity and trophic factors.…”