[Disruption of microfilament cytoskeleton induced by simulated microgravity increases the activity of COL1A1...

It is well known that cytoskeleton system is the sensor of gravity in cells. Under microgravity condition, cytoskeleton is associated with the changes of cell shape, function, signaling and so on; but the relationship between cytoskeleton and gene expression is not fully understood. In present study, we discussed the effects of cell microfilament on the activity of collagen type I alpha 1 chain gene (COL1A1) promoter under microgravity simulated by clinostat and/or cytochalasin B as microfilament depolymerizer in the established EGFP-ROS cell line using the method of fluorescence semi-quantitative analysis and the fluorescent stain of microfilament. Compared with the normal control, the microfilament of ROS17/2.8 cell tended to disassemble, marginal distribution of fiber stress, and showed reducing stress fibers after spaceflight in Photon-M1 or clinorotation simulated microgravity, which suggested that microgravity destroyed the well-order cell cytoskeleton and induced a rearrangement. Treatment with suitable concentration of cytochalasin B in normal gravity induced disruption of microfilament, increased the activity of COL1A1 promoter and resulted in a dose-dependent increase of EGFP fluorescence. Therefore, a certain extent disruption of the microfilament system was associated with increased activity of the COL1A1 promoter. All above demonstrate that microfilament cytoskeleton system takes part in the regulation of COL1A1 promoter activity and plays an important role in the signaling of microgravity.