Abstract
Purpose: :
The Y402H single nucleotide polymorphism in the complement regulator, Complement Factor H (CFH), is associated with increased susceptibility to Age-related Macular Degeneration (AMD). The contribution of this variant of CFH to the pathology of AMD is not well characterised. To understand how Y402H contributes to AMD pathology we performed microarray analysis of the RPE/choroid in wild type (WT) and cfh-/- mice to investigate the transcriptional changes in response to the loss of this complement regulator in both young and aged mice.
Methods: :
RPE/choroid RNA was isolated from young (7-8 weeks) and old (16 months) WT and cfh-/- C57Bl/6 mice. RNA was extracted using Trizol followed by RNeasy clean up (QIAgen). DNA was removed by DNase I digestion and RNA quality was assessed using the Agilent Bioanalyser. RNA was linearly amplified (NuGEN), labelled and hybridized to Mouse Gene 1.0 ST Affymetrix chips. Four chips were used per group of which each contained cDNA from one mouse. Data underwent background adjustment, normalisation and summarisation. Differential expression was analysed using ANOVA and Benjamini-Hochberg (FDR) test was applied for multiple correction.
Results: :
In young mice loss of CFH significantly changed the transcription of 4 genes (p value < 0.05). With age this increased to 33 genes of which only 17 encoded known proteins. Three of the four genes that were altered in young mice were also significantly different in aged mice. Ageing in WT animals resulted in significant differential regulation of 657 genes compared with 543 in cfh-/- mice, with 243 of these genes being common to both WT and cfh-/-.
Conclusions: :
Previous work from our lab has shown that the loss of CFH in aged mice causes retinal abnormalities and visual dysfunction. Here we report that loss of the complement regulator, CFH, causes transcriptional changes in the RPE/choroid even in young mice. The loss of CFH has a greater effect with age. Fewer than 50% of the genes changing with age were the same for both WT and cfh-/-, suggesting that the transcriptomics of ageing are significantly different in the absence of CFH. We anticipate that some of the genes identified will have causative roles in the functional and anatomical changes observed in the aged cfh-/- retina.
Keywords: age-related macular degeneration • aging • gene microarray