title: Concentrations of signal transduction proteins exercise and insulin responses in rat extensor digitorum longus and soleus muscles.
abstract: Differences in the concentrations of signal transduction proteins often alter cellular function and phenotype, as is evident from numerous, heterozygous knockout mouse models for signal transduction proteins. Here, we measured signal transduction proteins involved in the adaptation to exercise and insulin signalling in fast rat extensor digitorum longus (EDL; 3% type I fibres) and the slow soleus muscles (84% type I fibres). The EDL and soleus were excised from four rats, the proteins extracted and subjected to Western blots for various signal transduction proteins. Our results show major differences in signal transduction protein concentrations between EDL and soleus. The EDL to soleus concentration ratios were: Calcineurin: 1.43 +/- 0.10; ERK1: 0.38 +/- 0.18; ERK2: 0.61 +/- 0.16; p38alpha, beta: 1.36 +/- 0.15; p38gamma/ERK6: 0.95 +/- 0.11; PKB/AKT: 1.44 +/- 0.08; p70S6k: 6.86 +/- 3.58; GSK3beta: 0.69 +/- 0.03; myostatin: 1.95 +/- 0.43; NF-kappaB: 0.32 +/- 0.10 (values >1 indicate higher expression in the EDL, and values < 1 indicate higher expression in the soleus). With the exception of p38gamma/ERK6, the concentration of each signal transduction protein was uniformly higher in one muscle than in the other in all four animals. These experiments show that signal transduction protein concentrations vary between fast and slow muscles, presumably reflecting a concentration difference on a fibre level. Proteins that promote particular functions such as growth or slow phenotype are not necessarily higher in muscles with that particular trait (e.g. higher in larger fibres or slow muscle). Interindividual differences in fibre composition might explain variable responses to training and insulin.
authors.affiliation: Department of Biological Sciences, University of Central Lancashire, Preston, PR1 2HE, England, UK.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Atherton
authors.forename: James M
authors.initials: JM
authors.lastname: Higginson
authors.forename: Jaipaul
authors.initials: J
authors.lastname: Singh
authors.forename: Henning
authors.initials: H
authors.lastname: Wackerhage
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000032:analysis / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D018482:Muscle, Skeletal / Q000276:immunology / Q000378:metabolism*; D055435:Myostatin; D016328:NF-kappa B / Q000032:analysis / Q000378:metabolism; D010805:Physical Conditioning, Animal; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000378:metabolism
chemical_list: D007328:Insulin; C525912:Mstn protein, mouse; C525913:Mstn protein, rat; D055435:Myostatin; D016328:NF-kappa B; D011506:Proteins; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D019703:Calcineurin