Evaluation of the potency and selectivity of APP blocker-9.
Panel A: Dose responsive measurement of the capacity of JTR-009 to limit APP 5′UTR-luciferase expression relative to posiphen, a known APP translation blocker (JTR-009: IC50 = 0.1 µM; posiphen: IC50 = 5 µM, N = 4). Panel B: Dose-responsive reduction APP levels in SH-SY5Y cells treated 48 hours at 0.1 µM, 0.5 µM and 1 µM JTR-009. Western blot for APP levels using N- terminal 22C11 antibody (standardization with β-actin as loading control). Bottom Panel: Histogram quantitation of the relative expression of APP/β-actin in SH-SY5Y cells. Panel C: Lysates from the experiment in Panel B was analyzed by Western blotting using APP the C-terminal specific (A8717) antibody and β-actin antibody. Bottom Panel: histogram quantitation of the relative expression of APP/β-actin in SH-SY5Y cells from autoradiographic film subjected to densitometry (N = 3). Panel D: Dose-responsive capacity of JTR-009 to limit APP expression in primary E-18 mouse neurons (1 nM). The relative α-synuclein (SNCA) expression was calculated. Shown, the combined data was graphed into a histogram where mean values from separate assays were calculated from densitometry of Western blots (N = 5). Panel E: Real-time qPCR measurement of the dose-responsive measurement of the levels of APP mRNA in SH-SY5Y cells treated with escalating concentrations of JTR-009 for 48 hours. Panel F: Equivalent real-time qRT-PCR analysis to measure APP mRNA and TfR mRNA levels in SH-SY5Y cells after 48 h treatment with 25 µM desferrioxamine (DFO) (Positive control for qRT-PCR analysis shown in Panel E).