Mitogen-activated protein kinase signal transduction in skeletal muscle: effects of exercise and muscle contraction

Exercise has numerous growth and metabolic effects in skeletal muscle, incl uding changes in glycogen metabolism, glucose and amino acid uptake, protei n synthesis and gene transcription. However, the mechanism(s) by which exer cise regulates intracellular signal transduction to the transcriptional mac hinery in the nucleus, thus modulating gene expression, is largely unknown. This review will provide insight on potential intracellular signalling mec hanisms by which muscle contraction/exercise leads to changes in gene expre ssion. Mitogen-activated protein kinase (MAPK) cascades are associated with increased transcriptional activity. The MAPK family members can be separat ed into distinct parallel pathways including the extracellular signal-regul ated kinase (ERK) 1/2, the stress-activated protein kinase cascades (SAPK1/ JNK and SAPK2/p38) and the extracellular signal-regulated kinase 5 (ERK5). Acute exercise elicits signal transduction via MAPK cascades in direct resp onse to muscle contraction. Thus, MAPK pathways appear to be potential phys iological mechanisms involved in the exercise-induced regulation of gene ex pression in skeletal muscle.