Effects of PEDF on Signal Pathways in Mammalian Retinal Neurons

Abstract

Abstract: : Purpose: Pigment Epithelium Derived Factor (PEDF) is a potent anti-angiogenesis factor which we have shown to have neuroprotective effects on photoreceptor cells in vivo and in primary cultures. In this study we sought to identify the molecular components which participate in the neuroprotective effects of PEDF on cultured retinal neurons. Methods: Using mammalian expression vectors, we generated recombinant PEDF molecules and used rat retina primary cell cultures to evaluate their ability to protect retinal neurons from H₂O₂-induced apoptosis. Rabbit antibodies were used to detect PEDF and to monitor the purification of the recombinant PEDF. RNA was isolated from 10 day old control and PEDF- treated cultures and subjected to microarray analysis using Clontech Arrays to identify genes which are up- or down- regulated by PEDF. Total cellular proteins were analyzed using 2-D gels and MALDI-TOF proteomic analysis of samples obtained following the addition of PEDF to the cultures. The enzymatic activity of a key component in neuron rescue, PI3Kinase, was determined by a direct assay of control and experimental cultures. Results: The tagged recombinant PEDF was shown to retain the neuroprotective activity of native PEDF; to modulate (up and down) the mRNA and protein products of a number of genes important to signal transduction; and to transiently increase PI3Kinase activity. Conclusion: PEDF exerts its neuroprotective effects through interaction with retinal proteins and specifically activates PI3K activity. This experimental strategy should lead to the identification of the mechanisms by which PEDF protects cone and rod photoreceptor cells from apoptotic death-inducing events which occur in retinal diseases such as macular degeneration and retinitis pigmentosa. CR: None. Support: National Institutes of Health -EY13050; Research to Prevent Blindness, Inc., New York, NY; Presbyterian Health Foundation, Oklahoma City, OK.

Keywords: retinal culture • neuroprotection • photoreceptors