Abstract
Purpose: :
Plasma prorenin levels are associated with the severity of diabetes retinopathy (DR). However, the mechanism(s) of action of prorenin remains elusive. A (pro)renin receptor (PRR) recently described might be instrumental in the role played by prorenin. In this study, we aimed at investigating and characterizing the expression and function of PRR in human RPE cells.
Methods: :
Expression of PRR was examined in isolated human RPE and in cultured human RPE cells, by using RT-PCR. Regulation of PRR by its ligand prorenin was evaluated by semi-quantitative RT-PCR. Confluent cultures of human RPE cells were incubated with different concentrations of prorenin for either 10 minutes or 24 hours. Thereafter, cells and supernatant were collected and protein content determined. Extracellular matrix molecules and pErk/Erk were analyzed by Western blot, while MMP-2 activity was evaluated by zymography.
Results: :
Human RPE cells express the PRR. Prorenin has the ability of regulating the expression level of its own receptor, decreasing the transcriptional level of PRR after incubation for 24 h. Phosphorylation of Erk is elicited after stimulation of RPE cells with prorenin for 10 minutes, showing that PRR is functionally active in this cell type. In addition, prorenin induces an increase in collagen type I protein content. However, prorenin does not affect MMP-2 activity.
Keywords: diabetic retinopathy • retinal pigment epithelium • receptors: pharmacology/physiology