Figure 4.
NMDA receptor activation potentiates D1R-induced Cdk5 phosphorylation in mutant STHdhQ111 cells. A, Representative Western blot showing levels of p-Cdk5, Cdk5, and α-tubulin as a loading control from wild-type (ST7/7Q) and mutant (ST111/111Q) striatal cells. B, Representative Western blot showing levels of p-Cdk5, Cdk5, and GFP and α-tubulin as a loading control from wild-type striatal cells transfected with different constructs encoding for enhanced fluorescent protein-tagged exon-1 mutant huntingtin protein with 23 (Q23), 72 (Q72), or 103 (Q103) CAG repeats. C–E, Representative Western blot showing levels of p-Cdk5, Cdk5, and α-tubulin as a loading control from wild-type (ST7/7Q) and mutant (ST111/111Q) cell extracts obtained after treatment with NMDA 500 μm (C), SKF38393 100 μm (D), or a pretreatment with NMDA before SKF38393 exposure (E). Total cell extracts were obtained at different time periods (5, 15, 30, and 60 min) after treatment. The histograms represent the relative p-Cdk5/Cdk5 ratio expressed as fold increase versus control (vehicle-treated) cells. Values are given as mean ± SD of five independent experiments. A full statistical analysis by the two-way ANOVA is described in the text. **p < 0.01, ***p < 0.001 treated versus vehicle-treated wild-type cells; +p < 0.05, ++p < 0.01, +++p < 0.001 treated versus vehicle-treated mutant cells; #p < 0.05, ##p < 0.01, ###p < 0.001 treated mutant cells versus treated wild-type cells (Bonferroni's multiple comparison test).