Figure 7.
NRSF binds specifically to the Crh gene, and its levels are dramatically increased by augmented early-life environment. A, Schematic view of the chromatin of the Crh gene. The regulatory region of the Crh gene contains an intronic NRSE, and NRSF acts as a transcriptional repressor by binding to this element, recruiting cofactors and inducing epigenetic modification of gene expression. B, Top, Amplified Crh intron DNA immunoprecipitated with anti-NRSF, yielding ∼40 ng of DNA. This is compared with undetectable DNA products immunoprecipitated with nonimmune IgG. Bottom, As an additional control for the method, the amounts of amplified Actin intron DNA (a gene devoid of an NRSE) that immunoprecipitates with anti-NRSF or with nonimmune IgG are nil. These results indicate that NRSF specifically binds to the cognate sequence (NRSE), which is located within the Crh intron. Ab, Antibody. C, E, Representative Western blots and quantitative analyses of NRSF protein expression in the PVN of P9 controls and augmented-experience rats. In concurrently run samples from both groups, NRSF levels were strikingly (5-fold) increased in augmented-experience rats compared with controls. D, E, Western blots and quantitative analysis of NRSF protein expression in the PVN of P45 controls and augmented-experience rats. The increase in NRSF levels observed on P9 was persistent, as evident from the 12-fold increase in NRSF levels on P45. F, NRSF levels were not altered by the augmented experience in the thalamus, indicating that the effect of augmented early-life experience on NRSF expression was specific to the PVN. Data are represented as mean ± SEM. *p < 0.05.