Short-Term Striatal Gene Expression Responses to Brain-Derived Neurotrophic Factor Are Dependent on MEK and ERK Activation
Figure 7
BDNF-induced activation of ELK and CREB is MEK-dependent.
(A,B) Stimulation of E16 rat ganglionic eminence cultures with BDNF (50 ng/ml) for 15 min, results in increased phosphorylation of ELK1 at Ser 383 and CREB at Ser133. 30 min pretreatment with the specific MEK1/2 inhibitor PD98059 blocked BDNF-induced phosphorylation. Phosphorylation of ELK and CREB is shown by representative immunoblots, with quantitation summarized in the bar graphs. Error bars represent SEM for n = 3–4. *p<0.05 compared to other conditions (Student's t-test). Representative immunoblot images are shown below the bar graphs. (C) A SRE-luciferase promoter reporter assay for Elk1/TCF-mediated transcriptional activity (see Materials and Methods) showed increased SRE-dependent transcriptional activity after BDNF treatment (50 ng/ml for 90 min). SRE-dependent gene expression was blocked by 30 min pretreatment with the specific MEK1/2 inhibitor PD98059 (50 µM). Y axis represents percentage luminescence ratio of SRE signal to normalization control PGK promoter signal; Error bars represent SEM for n = 3–4. *p<0.05 compared to other conditions (Student's t-test). (D) A CRE-luciferase promoter reporter assay for CREB activation (see Experimental Procedures) also showed increased CRE-dependent transcriptional activity after BDNF treatment (50 ng/ml for 90 min). CRE-dependent gene expression was blocked by 30 min pretreatment with the specific MEK1/2 inhibitor PD98059 (50 µM). Y axis represents relative luminescence units (RLU); Error bars represent SEM for n = 5. *p<0.05 compared to other conditions (Student's t-test).