To examine the effect of retinal branch vein occlusion (BRVO) on protein tyrosine phosphorylation, production of angiogenic growth factors, and activation of signal proteins in the tyrosine kinase pathways in the retina, BRVO was induced in cat retina by coagulation of retinal veins with diathermy. At 2 days, 1, 3, and 6 weeks after induction of BRVO, the retina was divided into 3 parts; a part within the distribution of the occluded vein [BRVO(IN)] or a part outside the distribution of the occluded vein [BRVO(OUT)], an prepared for western blot analysis. Overall, tyrosine-phosphorylated proteins were increased after BRVO, especially in BRVO(IN) at 2 days and 1 week. The vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were also increased in BRVO(IN) at 1 week and 2 days, respectively. The phospholipase Cgamma(PLCgamma) and mitogen-activated protein kinase (MAPK) were activated at these points. In this study, we concluded that the BRVO increased overall protein tyrosine phosphorylation in the cat retina in association with the increase of angiogenic growth factors (VEGF, bFGF) and activation of 2 signal proteins (PLCgamma and MAPK)in the tyrosine kinase pathways. These results suggest that the protein tyrosine phosphorylation may in part play an important role in mitogenesis of vascular endothelial cells and other retinal responses after BRVO.
Animals ; Blotting, Western ; Cats* ; Diathermy ; Endothelial Cells ; Fibroblast Growth Factor 2 ; Intercellular Signaling Peptides and Proteins ; Phospholipases ; Phosphorylation ; Protein Kinases ; Protein-Tyrosine Kinases* ; Retina ; Retinal Vein ; Retinaldehyde ; Tyrosine ; Vascular Endothelial Growth Factor A ; Veins