ABSTRACT
<p><b>OBJECTIVE</b>To investigate the relationship between c-fos gene and filamentous actin (F-actin) in MG-63 osteoblasts under cyclic tensile stress.</p><p><b>METHODS</b>MG-63 osteoblasts were subjected to cyclic tensile stress (0.5 Hz, 2 000 microstrain) for 3, 6, and 12 h. The changes of c-fos gene were investigated by fluorescent quantitation polymerase chain reaction. Then the best loading time group was screened as the experimental group compared with 0 h group. The changes of F-actin and c-fos were investigated with or without cytochalasin D treatment.</p><p><b>RESULTS</b>Cyclic tensile stress induced high expression of c-fos mRNA, and peaked at 3 h. After loading, F-actin had a structure reorganization, but had no change in expression. After cytochalasin D treatment, the formation of stress fibers and the fluorescence intensity of F-actin cytoskeleton significantly reduced, meanwhile the c-fos mRNA expression was inhibited.</p><p><b>CONCLUSION</b>After loading, there is only structure reorganization for F-actin, and the expression has not any change. That means the remodeling F-actin is the existing one. F-actin reorganization is an important part in c-fos gene expression induced by stress.</p>