Abstract
Purpose: :
Intravitreal administration of CNTF, BDNF, or FGF–2 protects photoreceptors from degeneration in several animal models. We and others have provided evidence that these factors may act indirectly, most likely through Müller cells. To identify Müller cell–derived molecules that might mediate neuroprotection activity, we have been performing transcriptional profiling of isolated individual retinal cells and of whole retinas treated with various neurotrophic factors. Here we describe microarray studies comparing gene expression profiles of mouse retina following intravitreal injection of CNTF, BDNF, or FGF–2.
Methods: :
Adult, wild type C57BL/6J mice received an intravitreal injection of either CNTF, BDNF, FGF–2 (1 µg), or the vehicle. Animals were sacrificed within 1∼2 hours post–injection for immunocytochemistry, or at 48 hours post–injection for microarray and real time PCR analysis. RNA harvesting and Affymetrix microarray analysis (MOE430_2) were performed by standard methods. Individual Müller and photoreceptor cells were isolated 48 hours post–injection, and used to generate single cell cDNA libraries as previously described.
Results: :
The microarray results identified, and real time PCR confirmed, several families of genes that were induced by individual growth factors, including acute response genes, immune response genes, extracellular matrix molecules, and transcription factors. Although each growth factor up–regulated the expression of a distinct subset of genes, their induction profiles did overlap with each other; thus, all three factors induced lipocalin 2, chitinase 3 like 1, serpin A3N, interferon–induced protein with tetratricopeptide repeats 1, P lysozyme structural, histocompatibility class II antigen Aa, and CD52 antigen. These findings are being further analyzed by in situ hybridization and immunocytochemistry.
Conclusions: :
The significant overlap in the microarray results has identified candidate molecules that may mediate a common mechanism for photoreceptor rescue by CNTF, BDNF, and FGF–2. Ongoing experiments with single cells suggest that these molecules are up–regulated preferentially in Müller cells, rather than in photoreceptors.
Keywords: retinal degenerations: cell biology • growth factors/growth factor receptors • gene microarray