Abstract
Purpose: :
Müller cells play a critical role in the retina by serving as the primary glial cell. Neurodegeneration is a pathological feature of diabetic retinopathy. One key element of neurodegeneration is a reduction in the number of synapses between neurons. The aim of this study was to test the hypothesis that diabetes alters the expression of specific synaptic and structural proteins in the rat retina.
Methods: :
The Müller cell line TR–MUL5 was maintained in culture medium containing 5 mM glucose. On the day of the study, cells were incubated in medium containing either 25mM glucose or mannitol for 3 or 12 hours and RNA was isolated from the cells. RNA was subjected to whole genome microarray analysis using Codelink arrays. Statistical and ontological analysis was performed on the array data to determine processes and pathways affected by elevated glucose. Genes identified as regulated by microarray analysis were then confirmed by quantitative PCR using TaqMan fluorescent probes and real–time detection.
Results: :
Of the 33911 probes on the array, 21168 were present at a detectable level. 78 genes were found to be significantly different between glucose and mannitol conditions at 3 hours and 186 were found to be altered at 12 hours. Of these changes a significant increased abundance of vesicle and cytoskeletal genes were found at the 12 hour timepoint. Quantitative PCR analysis confirmed significantly higher expression of the NGFI–A, NGFI–B, Fos, and VEGFA mRNAs, and significantly lower expression of Igfbp2. In addition, elevated expression of Jundp2 and reduced expression of KIFC2 were confirmed at 12 hours.
Conclusions: :
Elevated concentrations of glucose cause a number of significant changes in gene expression in cultures of Müller cells within hours of treatment. Further experiments must be performed to examine these changes in Müller cells within the retina.
Keywords: diabetic retinopathy • Muller cells • gene microarray