Mechanism of retinal pericyte migration through Angiopoietin/Tie-2 signaling pathway on diabetic rats.

AIM: To investigate the mechanism of pericyte migration through Angiopoietin-2 (Ang-2)/Tie-2 signaling pathway.

METHODS: We divided the rats into 5 groups. Each diabetic rat model groups injected with Tie-2 inhibitor, ERK1/2 inhibitor, Akt/PKB inhibitor, and DMSO intravitreal. Retinal digest preparation was done to examine the retinal vasculature including pericyte: endothelial ratio, and morphology of pericyte migration. Tie-2, ERK1/2 and Akt/PKB phosporylation were analyzed by confocal laser scanning microscopy.

RESULTS: There was a correlation between pericyte migration with increasing Ang-2 ( P <0.05). Pericyte number reduced by 40% (1:2.4) after 5wk diabetes on diabetic rats. The pericyte: endothelial ratio on group with Tie-2 inhibitor were 1:1.8. The same result shows on group with Akt/PKB inhibition. ERK1/2 inhibitor group shows the best results of pericyte: endothelial ratio (1:1.7). Inhibition on Tie-2 receptor decreased the phosphorylation activity of Tie-2, ERK1/2 and Akt/PKB pathway. ERK1/2 inhibition also decreasing the phosphorylation of Tie-2 and Akt/PKB. But on Akt/PKB inhibition, the phosphorylation of Tie-2 and ERK1/2 were relative the same.

CONCLUSION: Ang-2 has a role for pericyte migration on diabetic rats through Tie-2 receptor, ERK1/2 and Akt/PKB pathways. ERK1/2 is a dominant pathway based on the ability to supress another pathway activity and decreasing pericyte migration on diabetic rats.