Figure 3. Expression of ΔFosB and phosphorylation of histone H3 at the fosB gene promoter is reduced in mitogen- and stress-activated kinase 1 knock out (MSK1 KO) mice.

Wild-type and MSK1 KO mice received unilateral striatal injections of 6-hydroxydopamine (Les) while the contralateral striatum remained intact (Unles). ΔFosB was determined by immunofluorescence 24 hr after the last drug administration. A, Representative confocal micrographs showing ΔFosB immunoreactivity in the striata of a wild-type and a MSK1 KO mice. Scale bar = 40 μm. B, Quantification of ΔFosB positive-neurons. Data are shown as means ± SEM. ** p < 0.01 and *** p < 0.001 vs. unlesioned hemisphere of the same genotype; ^○○ p < 0.01 vs. wild-type lesioned hemisphere. C, Wild-type and MSK1 KO mice with unilateral injections of 6-hydroxydopamine were treated with L-DOPA, killed after 60 min and striatal tissue was subjected to chromatin immunoprecipitation using an antibody against phospho-Ser10-H3 histone (H3S10p) (left) or control IgG (right). Epitope enrichment on chromatin was assessed by quantitative PCR using primers for the fosB promoter region and normalized to levels of histone H3 (see Materials and Methods). Data are shown as means ± SEM. * p < 0.05 and *** p < 0.001 vs. unlesioned hemisphere of the same genotype; ^○○○ p < 0.001 vs. wild-type lesioned hemisphere.