Abstract
Purpose: :
To study whether phosphatases are involved in the contact inhibited proliferation and barrier function of confluent cultured bovine corneal endothelial cells.
Methods: :
Confluent cultures of bovine corneal endothelial cells were treated with different concentrations and durations of the general phosphatase inhibitor, sodium orthovanadate (SOV). Immunocytochemistry (ICC) was used to evaluate the effect of SOV on cell–cell contacts by staining for alpha–catenin, p120 and N–cadherin. Cell cycle progression was evaluated by staining for Ki67. Western blot analysis was used to evaluate the expression level of alpha–catenin, p120, N–cadherin, cyclin A, cyclin E and PCNA under different conditions. Transendothelial electric resistance (TER) was used to evaluate the cellular permeability in different groups.
Results: :
Dose and time dependent effect of SOV on cell–cell junctions was proved by IHC with alpha–catenin, p120 and N–cadherin. 50 uM/ 24 hours of SOV can cause maximal effects of SOV on cell–cell junctions without causing obvious cellular death. Although cell–cell junctions can be broken through by SOV, only limited cells reenter cell cycle. Western blot showed a generalized effect of protein tyrosine phosphorylation in cells treated with SOV. However, no obvious change of alpha–catenin, p120, N–cadherin, cyclin A, cyclin E and PCNA can be found. TER demonstrated that cells treated with 50 uM/ 24 hours of SOV can increase cell permeability.
Conclusions: :
SOV can induce a time and dose dependent release of cell–cell contacts and increase transendothelial permeability in confluent cultures of bovine corneal endothelial cells. However, such phenomenon is not enough to promoted cell cycle progression even the cell–cell contact mechanism is disrupted.
Keywords: cornea: endothelium • cell adhesions/cell junctions • proliferation