Decreased RNA Polymerase II Occupancy at Promoters and Coding Regions of Genes Down-Regulated in SCA7 Mice

(A–F) ChIP assays were performed using formaldehyde-fixed chromatin extracts of retina from 2-mo-old control (WT or R7N; dark grey) and R7E (light grey) mice. Specific regions within the different genes were analyzed, as depicted; within theRho gene, each amplified regions were separated by 1.5 kb at least. Each bar represents the mean value ± SEM (n = 4–6). RNA polymerase II occupancy, and thus transcriptional activity, was assessed using an antibody directed against the heptapeptide repeat of its C-terminal domain (Pol II CTD). All genes down-regulated at the mRNA level in R7E retina(Rho, Pde6b, Rbp3, Nrl, andCrx) showed marked decrease in Pol II occupancy at their promoters.