The Experimental Study Of Effect And Mechanism Of Rho Kinase Inhibitor On Dexamethasone-Induced Ocular Hypertension

Objective: The purpose of this study was to investigate the intraocular pressure(IOP)-lowering effect of Rho-associated protein kinase(ROCK)inhibitor in a dexamethasone(DEX)-induced ocular hypertension rabbit model and to explore the underlying mechanism in cultured human trabecular meshwork(HTM)cells.Here,we explore how DEX and ROCK inhibitor modulates the Yes-associated protein(YAP)/transcriptional coactivator with PDZ-binding domain(TAZ)pathway and extracellular matrix genes,and how this may be play a role in the onset and progression of glaucoma.Methods: In this study,IOP-lowering effects were evaluated in ocular normotensive rabbits and ocular hypertensive model with treatment of Y-39983.Primary HTM cells were cultured with DEX and/or Y-39983,the cell viability was assessed by CCK-8,RT-PCR was used to determine the impact of DEX and Y-39983 on the expression of mechanotransducers,YAP/TAZ related genes.In addition,the expression of YAP as well as its phosphorylation status in HTM cells was determined by Western blotting,and immunofluorescence was used to determine YAP protein localization.Results: Topical administration of Y-39983 provides statistically significant IOP–lowering effects in ocular normotensive rabbits and dexamethasone-induced ocular hypertensive rabbits.In vitro,DEX stimulation increased the dephosphorylation of YAP,and Y-39983 treatment can reversed these effects.Similarly,DEX stimulation resulted in markedly elevated nuclear localization of YAP,while Y-39983 treatment decreased nuclear localization.YAP/TAZ and YAP/TAZ-dependent target genes,including CTGF and CYR61 were up-regulated in DEX-treated HTM cells in comparison to the untreated and vehicle samples.Treatment with Y-39983 resulted in a dramatic down-regulation of YAP but not TAZ.Conclusion: These results demonstrate the importance of YAP/TAZ,the major downstream effectors of the Hippo pathway,in the HTM and suggest their role in glaucoma.DEX alters YAP/TAZ expression in HTM cells,while then modulate the expression of extracellular matrix proteins which may influence the progression of glaucoma.We hypothesize that YAP activation by DEX and inactivation by ROCK inhibitor may be related to stiffness of trabecular meshwork and resistance of aqueous humor outflow.As contractility of TM tissues is associated with IOP,ROCK inhibitor may more accurately target the alterations in glaucoma and reduce IOP.