Atypical fast SERCA1a protein expression in slow myofibers and differential S-nitrosylation prevented by exercise during long term bed rest.
We monitored changes in SERCA isoform specific expression and S-nitrosylation in myofibers of lower limb soleus (SOL) and vastus lateralis (VL) muscle biopsies before and after 60 days of voluntary long term bed rest (BR) without (BR-CTRL group, n = 8) and with exercise countermeasure (BR-EX group, n = 8). Before BR, a typical myofiber type-specific distribution of fast and slow SERCA1/2a isoforms was seen. After BR, a subpopulation (approx. 15%) of slow myofibers in BR-CTRL additionally expressed the fast SERCA1a isoform which was not seen in BR-EX. After BR, SERCA1a S-nitrosylation patterns analyzed by the biotin-switch assay decreased in disused SOL only but increased in both muscles following exercise. Differential SERCA1a S-nitrosylation and SERCA1a/2a co-expression in subsets of slow myofibers should be considered as signs of an altered cytosolic Ca(2+) homeostasis following chronic muscle disuse. Exercise preserved myofiber type-specific SERCA1a expression and S-nitrosylation in VL and SOL in a different way, suggesting muscle-specific responses to the countermeasure protocol applied during bed rest.
Salanova
Michele
M
Department of Vegetative Anatomy, Center of Space Medicine Berlin, Neuromuscular Group, Charité Universitätsmedizin Berlin, Campus Benjamin Franklin, Arnimallee 22, Berlin 14195, Germany. michele.salanova@charite.de
Schiffl
Gudrun
G
Blottner
Dieter
D
D001510:Bed Rest / Q000009:adverse effects; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D035002:Lower Extremity; D018657:Muscle Fibers, Slow-Twitch / Q000201:enzymology*; D020966:Muscular Disorders, Atrophic / Q000201:enzymology* / Q000473:pathology / Q000517:prevention & control; D009210:Myofibrils / Q000201:enzymology*; D020033:Protein Isoforms / Q000378:metabolism; D052097:Quadriceps Muscle / Q000201:enzymology; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism*
D020033:Protein Isoforms; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506943:ATP2A1 protein, human; C506946:ATP2A2 protein, human