Journal: Cell
Article Title: Presenilin-dependent ErbB4 nuclear signaling regulates the timing of astrogenesis in the developing brain.
doi: 10.1016/j.cell.2006.07.037
Figure Lengend Snippet: Figure 5. NRG1-ErbB4 Nuclear Signaling Inhibits GFAP Promoter Activation and Induces E4ICD Recruitment to this Promoter (A) NRG1 blocks CNTF-induced GFAP promoter activation in a presenilin-dependent manner. NPs were cotransfected with GFAP-luciferase and TK-renilla reporters. The next day, cells were treated with NRG1, CNTF, and/or DAPT. DAPT was added 30 min prior to NRG1. NRG1 was added 3 hr prior to CNTF. Six hours after CNTF addition, NPs were lysed and luciferase activity was measured (*p < 0.05). (B) NRG1-mediated inhibition of CNTF-induced GFAP promoter activation depends on ErbB4. NPs were transduced with control or ErbB4 RNAi-ex- pressing lentiviruses. After 3 days, cells were transfected, treated with NRG1 and/or CNTF, and analyzed as in (A). Similar results were obtained with two different RNAi constructs against ErbB4 (*p < 0.05). (C) Only the cleavable isoform HER4 JMa rescues the ErbB4 knockdown phenotype. ErbB4 endogenous to NPs was knocked down by RNAi. After 3 days, the human ErbB4 juxtamembrane isoforms (HER4 JMa or JMb) or the presenilin-resistant HER4 JMa V673I, which are resistant to the RNAi, were transfected along with the reporters. Cells were then treated and processed as in (A) (*p < 0.05). (D) Expression of activated E4ICD is sufficient to inhibit CNTF-induced GFAP promoter activation. NPs were cotransfected with empty vector, WT, or KD LexA-E4ICD plasmids along with the reporters. The next day, cells were treated with CNTF and processed as in (A). Only wild-type E4ICD blocked CNTF induction of the GFAP promoter; this blockade was presenilin independent (*p < 0.05). (E) NRG1-mediated inhibition of CNTF-induced GFAP promoter activation depends on TAB2. NPs were transduced with control or TAB2 RNAi- expressing lentiviruses. After 3 days, cells were transfected, treated, and analyzed as in (A). Similar results were obtained with two different RNAi constructs against TAB2 (*p < 0.05). (F) NRG1-mediated inhibition of CNTF-induced GFAP promoter activation requires the TAB2 C terminus. TAB2 (full-length or DC truncated) was transfected along with the reporters. Cells were then treated and processed as in (A) (*p < 0.05). (G) NRG1 induces E4ICD binding to the GFAP and S100b promoters in a presenilin-dependent manner. NPs were incubated for 30 min with vehicle or DAPT before NRG1 treatment. After 6 hr, ChIP assays were performed with antibodies to ErbB4 or control IgG. PCR primers specific for GFAP or S100b promoters were used. Primers against the first exon of HES1 serve as a negative control.
Article Snippet: For immunoprecipitations, lysates were precleared with agarose-conjugated normal IgG for 30 min and immunoprecipitated with agarose-conjugated ErbB4 antibody (Santa Cruz) or FLAG antibody (M2, Sigma) overnight at 4 C. Samples were washed four times with lysis buffer before the beads were resuspended in SDS sample buffer and boiled for 2 min.
Techniques: Activation Assay, Luciferase, Activity Assay, Inhibition, Transduction, Control, Transfection, Construct, Knockdown, Expressing, Plasmid Preparation, Binding Assay, Incubation, Negative Control