Objective: To investigate the role of RhoA/ROCK-1 signaling pathway and Ecadherin/P120-catenin complex in intermittent cyclic mechanical tension(ICMT)promoted endplate chondrocytes degeneration.Methods: ICMT(strain at 0.5Hz sinusoidal curve at 8%elongation)was applied to rat endplate chondrocytes for 6 days,16 hours a day.We examined the Cell viability and Cell apoptosis by the LIVE/DEAD viability/cytotoxicity kit and Flow cytometry.Histological staining was used to examine the whole lumbar spine tissue morphology and extracellular matrix after application of ICMT in vitro.RhoA/ROCK-1 pathway-specific inhibitors,Ecadherin and p120-catenin plasmid were preformed to regulate RhoA/ROCK-1signaling,E-cadherin and P120-catenin expression.Co-immunoprecipitation was employed to examine the interaction between E-cadherin and P120-catenin,P120-catenin and RhoA.Related gene expression and protein location was examined by reverse transcription-polymerase chain reaction,western blot and immunofluorescence.Results: There was no change in viability after the application of ICMT that verified by LIVE/DEAD assay and Flow cytometry.ICMT loading led to RhoA/ROCK-1 signaling activation and the loss of the chondrogenic phenotype of endplate chondrocytes in both an in intro whole rabbit lumbar spine tissue model and in vitro endplate chondrocyte ICMT system.Inhibition of RhoA/ROCK-1 signaling significantly ameliorated the reduce in ICMT induced chondrogenic gene expression.P120-catenin and E-cadherin expression were inhibited by ICMT application.ICMT reduced the interaction between P120-catenin and E-cadherin.Further more,over-expression of P120-catenin and E-cadherin can all suppressed the chondrogenic gene expression,at the same time,over-expression of P120-catenin suppressed the RhoA/ROCK-1 signaling,but over-expression of E-cadherin did not.Conclusion: P120-catenin protects endplate Chondrocytes from Intermittent Cyclic Mechanical Tension Induced degeneration by inhibits the expression of RhoA/ROCK-1signaling pathway. |