The Effects Of RhoA Activity On Bone Marrow Mesenchymal Stem Cells Under Simulated Microgravity

The purpose of the study is to investigate the effects of simulated microgravity(SMG)on cell morphology,cytoskeleton,cell adhesion,MAPK/ERK pathway,PI3K/AKT pathway,mTOR pathway on bone marrow mesenchymal stem cells(BMSC).To study the relationship between the activity of RhoA and the effects of simulated microgravity on BMSC,BMSC were cultured under the simulated microgravity condition,the RhoA activity was maintained by GST-CNF?,detected by G-LISA RhoA activity assay kit.The microfilament structure,LaminA and Vinculin,were detected via immunofluorescence staining.Western blot was used to detect RhoA protein expression,Vinculin,CycinB1,p-ERK,p-AKT,p-mTOR,eIF4 E expression.The results showed that the simulated microgravity could decrease the RhoA activity,reduce total RhoA protein expression and change the cell morphology,microfilament structure,cell adhesion.The results also showed MAPK/ERK pathway,PI3K/AKT pathway and mTOR pathway were inhibited by the simulated microgravity.CNF? could maintain the activity of RhoA.The cell changes could be reversed by CNF? in a certain extent,suggesting that simulated microgravity may affect cytoskeleton,cell adhension by inhibiting RhoA activity.The decrease of RhoA activity which linked to cytoskeleton damage further affected the signal transduction of MAPK/ERK pathway,PI3K/AKT pathway and mTOR pathways,which may explain the microgravity damage cytoskeleton,causing the effects on proliferation inhibition and other effect.