TI - Exercise-induced alterations in extracellular signal-regulated kinase 1/2 and mammalian target of rapamycin ( mTOR ) signalling to regulatory mechanisms of mRNA translation in mouse muscle . AB - The present study examined the effects of an acute bout of treadmill exercise on signalling through the extracellular signal-regulated kinase ( ERK ) 1/2 and mammalian target of rapamycin ( mTOR ) pathways to regulatory mechanisms involved in mRNA translation in mouse gastrocnemius muscle . Briefly , C57BL/6 male mice were run at 26 m min ( -1 ) on a treadmill for periods of 10 , 20 or 30 min , then the gastrocnemius was rapidly removed and analysed for phosphorylation and/or association of protein components of signalling pathways and mRNA translation regulatory mechanisms . Repression of global mRNA translation was suggested by disaggregation of polysomes into free ribosomes , which occurred by 10 min and was sustained throughout the time course . Exercise repressed the mTOR signalling pathway , as shown by dephosphorylation of the eukaryotic initiation factor ( eIF ) 4E-binding protein-1 ( 4E-BP1 ) , enhanced association of the regulatory-associated protein of mTOR with mTOR , and increased assembly of the tuberin-hamartin complex . In contrast , exercise caused no change in phosphorylation of either Akt/PKB or tuberin . Upstream of mTOR , exercise was associated with an increase in cAMP , protein kinase A activity , and AMP -activated protein kinase phosphorylation . Simultaneously , exercise caused a rapid and sustained activation of the MEK1/2-ERK1/2-p90RSK pathway , resulting in increased phosphorylation of downstream targets including eIF4E and the ribosomal protein ( rp ) S6 on S235/S236 . Overall , the data are consistent with exercise-induced repression of mTOR signalling and global rates of mRNA translation , accompanied perhaps by up-regulated translation of selected mRNAs through regulatory mechanisms such as eIF4E and rpS6 phosphorylation , mediated by activation of the ERK1/2 pathway .