Article Figures & Data
Figures
- Figure 1.
siB-myb and antisense B-myb constructs downregulate B-myb expression. A, Coexpression with either siB-myb or antisense B-myb downregulates expression in HEK293 cells of human/rat B-myb. pU6 and pcDNA are control, empty plasmids. B, Expression of either siB-myb or antisense B-myb downregulates endogenous B-myb expression in cycling PC12 cells. siLuc and pcDNA are control plasmids. Transfection efficiency was ∼60-80%. C, D, Antisense B-myb represses the upregulation of B-myb in cortical neurons treated with camptothecin (campto). Percentage of stained cells in this and subsequent figures pertains to the population of transfected neurons (as indicated by staining for GFP). E, F, siB-myb represses the upregulation of B-myb in cortical neurons treated with camptothecin. Scale bars, 10 μm.
- Figure 2.
siC-myb and antisense C-myb constructs downregulate C-myb expression. A, Coexpression with either siC-myb or antisense C-myb downregulates expression in HEK293 cells of human/rat C-myb. B, Expression of either siC-myb or antisense C-myb downregulates endogenous C-myb expression in cycling PC12 cells. Transfection efficiency was ∼60-80%. C, D, Antisense C-myb represses the upregulation of C-myb in cortical neurons treated with camptothecin (campto). E, F, siC-myb represses the upregulation of C-myb in cortical neurons treated with camptothecin. Scale bars, 10 μm.
- Figure 3.
Downregulation of B-myb and C-myb protects neuronal cells from apoptotic stimuli. A, Expression of B- and C-myb antisense constructs protects neuronal PC12 cells from death induced by NGF withdrawal. Significance comparisons with vector alone/NGF withdrawal on the same day, *p < 0.03; **p < 0.005. B, Expression of siB-myb and siC-myb constructs protects neuronal PC12 cells from death induced by camptothecin (Campto) treatment. Significance comparisons with siLuc control/campthothecin, *p < 0.005. C, Expression of siB-myb and siC-myb constructs protects cortical neurons from death induced by camptothecin treatment. Significance comparisons with siLuc control/campthothecin, *p < 0.02. D, E, Expression of siB-myb and siC-myb prevents death of sympathetic neurons induced by NGF withdrawal. D indicates percentage of surviving neurons. NGF w/d, NGF withdrawal. E shows percentage of transfected neurons with apoptotic nuclei on day 2 of NGF withdrawal. E, Significance comparisons with siLuc/NGF withdrawal control, *p < 0.05. F, siB-myb represses the upregulation of C-myb in cortical neurons treated with camptothecin. Cultures were transfected with siB-myb or siLuc and EGFP, treated with or without camptothecin for 12 hr, and then stained for expression of C-myb and Cdk4 as indicated. G, siC-myb represses the upregulation of B-myb in cortical neurons treated with camptothecin. Cultures were transfected with siC-myb and EGFP, treated with or without camptothecin for 12 hr, and then stained for expression of B-myb and Cdk4 as indicated.
- Figure 4.
Down regulation of B-myb and C-myb protects neuronal cells from death caused by E2F de-repression. A, B, Coexpression of siB-myb or siC-myb increases survival (A) and decreases apoptotic nuclei (B) in neuronal PC12 cells expressing E2F1(1-374). A, Significance comparisons with E2F(1-374) alone on the same day, *p < 0.02; **p < 0.005. B, Significance comparisons with E2F1(1-374) alone, *p < 0.02; **p < 0.005. C, Coexpression of siB-myb or siC-myb promotes survival of cortical neurons expressing E2F1(1-374). Significance comparisons with siLuc coexpressed with E2F1(1-374) as indicated on the same day, *p < 0.01; **p < 0.002.
