[Change and Significance of RhoA/ROCK signaling pathway in the model with natural degeneration of the rat endplate chondrocytes]

Abstract

Objective: To explore the change and Significance of RhoA/ROCK signaling pathway in the model with natural degeneration of the rat endplate chondrocytes.

Methods: Endplate chondrocytes were selected by enzyme digestion and cultured in vitro to divided into control (P2 cells), naturally passaged (P5 cells) groups and treatment group (P5+ROCK Inhibitor Y27632). The phenotype of endplate chondrocytes were identified by toluidine blue stains and F-actin stains. Type II collagen, aggrecan and SOX9 genes were examed by Real-time RT-PCR to verify the degeneration model. The RhoA/ROCK signaling pathway related gene ROCK-1, ROCK-2 were detected by RT-PCR and Western blot. The actived RhoA was examed by active-RhoA detection and Western blot.

Results: With the passaging,endplate chondrocytes completely lost the original cell morphology, the levels of type II collagen (P5/P2=0.248, P<0.001), aggrecan (P5/P2=0.172, P<0.001) and SOX9 (P5/P2 =0.499, P<0.001) significantly reduced. There is also a certain reduction of ROCK-1 (P5/P2=0.652, P<0.001), but ROCK-2 (P5/P2=2.527, P<0.001) expression increased significantly. And the active-RhoA were Significant increased too.ROCK-1 AND ROCK-2 were down-regulated in the treatment group. And type II collagen, aggrecan, SOX9 significantly increased.

Conclusion: The degeneration of endplate chondrocytes with decreased ROCK-1 expression but increased active-RhoA and ROCK-2 expression suggest that RhoA/ROCK signaling pathway play an important role in the in vitro degeneration of endplate chondrocytes.Modulating the expression of RhoA/ROCK signaling pathway may be a new method of solving the problem of the degeneration of intervertebral disc.