Space Flight Induces Reduction of Paramyosin and Troponin T: Proteomic Analysis of Space-Flown Caenorhabditis elegans

Muscle atrophy is a serious concern during space flight and has been observed in vertebrates in previous space flight experiments. In the present study, proteomic analysis was performed to assess changes in protein expression due to space flight in the model species Caenorhabditis elegans. Approximately 100 proteins were identified by MALDI-TOF mass spectrometry following two-dimensional gel electrophoresis, revealing that the expression of muscle-related proteins was significantly altered in space-flown worms. In particular, the protein expression level of paramyosin, which is a core component of invertebrate thick filaments, was significantly reduced in space-flown worms. In contrast, the expression of troponin T, which binds tropomyosin and tethers the troponin complex to the thin filament, was reduced; however, phosphorylation of troponin T was increased during space flight. These proteins play important roles in the maintenance of muscle structure and function, suggesting that changes in their expression and post-translational modification may be involved in the locomotion of the worms during space flight. Furthermore, we observed that the expression level of aconitase was reduced during space flight, possibility affecting ATP generation in C. elegans muscle.