Mechanisms of muscular atrophy and gravisensing after simulated microgravity in Caenorhabditis elegans: Parallel control to spaceflight research in C. elegans

At present, the molecular mechanism underlying microgravity-induced muscular atrophy is still unknown, and gravisensing is the key point in this process. In order to answer these questions a research project of Caenorhabditis elegans (C. elegans) in spaceflight was carried out, which had been reported in this journal before. An environment of simulated microgravity on ground was established, and its major effects on body-wall muscles of C. elegans in the structures and functions were examined, which further confirmed the results from spaceflight studies, and comparing between these two different treatments was benefit for valuing the validity of simulated microgravity. Firstly, the survival rate and movement ability of C. elegans were observed, and five important muscle-related genes and three proteins were measured after 14 days 19.5 h rotation. The animals displayed reduced rates of movement with a lower ratio (height/width) in crawl trace wave in simulated microgravity, indicating a functional defect. In morphological observation deceased muscle fiber size in myosin immunofluorescence and duller dense-body staining were found in microgravity group, suggesting muscular atrophy had happened in C. elegans. Meantime the result of Western blotting showed the quantity of myosin A decreased significantly in simulated microgravity group, further confirming muscular atrophy. In genes transcription, it was noted that dys-1 increased significantly in body-wall muscles, while hlh-1, unc-54, myo-3 and egl-19 mRNA levels declined after rotation. This study provided evidence that dys-1 are involved in the transduction of mechanical information in skeletal muscle, potentially play a vital role in gravisensing. Genes of hlh-1, unc-54, myo-3 and egl-19 induced the muscular atrophy in simulated microgravity from the structures and functions ways respectively. Data of this study consolidated the results in our spaceflight researches. On the other hand, it is implied that simulated microgravity is an effective ways for improving the quality of space studies.