Abstract
Purpose: :
The goal of this study was to investigate the cellular signaling involved in beta-adrenergic receptor regulation of apoptosis in serum-starved human microvascular retinal endothelial cells (HMREC).
Methods: :
Cells were grown in high glucose until 80% confluency was reached. Cells were serum starved for 18-24 hours, followed by treatment with a beta-1-adrenergic receptor agonist, xamoterol (10uM), and cell culture lysates were collected at 15, 30, and 45 minutes, along with not-treated controls. Immunoblotting was performed for apoptotic proteins, as well as a caspase-3 and -8 ELISA.
Results: :
Treatment of HMREC with xamoterol significantly decreased levels of pro-apoptotic Fas ligand at the 15 and 30 minutes. Fas receptor was also significantly reduced at all time points investigated. The ratio of phosphorylated FADD to total FADD was significantly decreased following beta-1-adrenergic receptor stimulation at the 30 minute time point. Cleaved caspase-8 levels decreased significantly in cells treated with xamoterol at all time points. Levels of cleaved caspase-3 were significantly decreased at the 45 minute time point after xamoterol stimulation.
Keywords: apoptosis/cell death • retinal culture • diabetes