Microarray analysis of the astrocyte transcriptome in the ageing brain: relationship to Alzheimer's pathology and ApoE genotype

Astrocyte dysfunction impacts their normal function, including neuronal support, thereby contributing to neurodegenerative pathologies including Alzheimer's disease (AD). Therefore to understand the role of astrocytes in the pathogenesis of age-related disorders we analysed the gene expression profile of astrocytes with respect to Alzheimer-type pathology. The aim of the present study was to combine immuno-LCM and microarray analysis to characterise the astrocyte transcriptome at different Braak stages, and with respect to ApoE genotype, in post-mortem human temporal cortex sampled dervied from the Medical Research Council Cognitive Function and Ageing Study (MRC-CFAS). GFAP-positive astrocytes were isolated from age, sex and brain pH-matched cases derived from the MRC-CFAS cohort, using immuno laser capture microdissection. The extracted RNA was amplified and applied to HGU133 Plus 2.0 Affymetrix gene arrays. Genes were considered differentially expressed if they showed a minimum 1.5 fold change at p<0.02 in all 6 individual cases in each stage of pathology [18 cases in total: 6 cases Braak stages I-II (3 cases carried at least one ApoE epsilon4 allele and 3 were ApoEe4 negative); 6 cases Braak stages III-IV (3 ApoEe4 positive and 3 ApoEe4 negative; 6 cases Braak stages V-VI (3 ApoEe4 positive and 3 ApoEe4 negative)]. keywords: human GFAP-positive astrocytes