Purchase this article with an account.
E.C. Johnson, L. Jia, W.O. Cepurna, S.L. Barber, J.C. Morrison; Altered Gene Expression In The Aged Retina: Analysis By Microarray And Real–time RT–PCR . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2171.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Aging is an important risk factor for glaucoma and other degenerative retinal diseases. The purpose of this study is to identify altered gene expression in the aged rat retina that may increase the susceptibility of retinal cells, particularly retinal ganglion cells (RGC), to injury. Methods: Retinal mRNA was prepared from aged (31 months) and mature adult (8 months) Brown Norway rats (10 animals per group). A portion of each mRNA sample was pooled (3 retinas/pool) and gene expression in aged retinas was compared to that in adult retinas using spotted cDNA microarrays. Three separate array comparisons were made, each consisting of 4 technical replicates. Gene expression data from each comparison was normalized using Robust Linear Regression (Speed), combined and analyzed using Significance Analysis of Microarrays (SAM). Reserved mRNA from each retina was quantitated by real–time RT–PCR to verify array results and examine genes not included in the arrays. Results: We detected retinal expression for approximately 80% of the 8273 array genes. Genes significantly altered by both array and RT–PCR included a 2–fold upregulation of cyclin D2 (cell cycle entry) and downregulation of UDP–glucose dehydrogenase (UTPGDH, glycosaminoglycan synthesis), EIF4E (translation initiation factor), and beta–tubulin 15. Additional, altered genes identified by RT–PCR in aged retinas were: GFAP (135% of adult retinal values, p<0.02), neurofilament H (80%, p<0.05), Thy–1 (72%, p<0.01), p53(80%, p<0.02) and BAX (77%, p<0.05). BRN3b, the specific RGC marker, was unchanged (100%, p=0.99), as were neurotrophins BDNF and NT4/5 and receptors p75NTR, TrkB, TrkB– and TrkC. Five genes found unaltered by both methods were GAPDH, cyclophilin A, cJun, TrkB and t–alpha–1 tubulin. Conclusions:Aged Brown Norway rats exhibit changes in retinal gene expression levels as compared to mature adults. The upregulation of GFAP may indicate retinal glial cell activation. Increased mRNA levels for some key regulatory proteins (cyclin D2) and decreased levels for others (EIF4E and UTPGDH) suggests broad alterations in the capacity of retinal cells to respond to elevated intraocular pressure or other insults. BRN3b mRNA remains unchanged, supporting previous evidence of no significant RGC loss in the aged retina. However, specific decreases in mRNAs for proteins primarily associated with RGC axons (Thy–1, beta–tubulin and neurofilament H) suggest that the RGC in aged animals have a reduced ability to maintain axonal integrity. This also suggests that axons of aged RGCs may be less resistant to injury due to elevated intraocular pressure.
This PDF is available to Subscribers Only