Figure 1.

High throughput screen and identification of luteolin as an inhibitor of Msi1. a) Scatterplot displaying the screening results. 25,539 compounds were assayed in a high throughput screen targeting Msi1-RNA interaction. Compounds were tested for inhibition in 7-point dose response study with compounds ranging from 60μM to 8nM. The resulting data were expressed as % activity or the % of bound probe compared to untreated positive control (Msi1 plus Cy3-RNA probe). A 50% activity cutoff was employed to identify potential Msi1 inhibitors. b) Dose-response of luteolin. c) Validation of HTS hits by NMR spectroscopy. ¹⁵N HSQC spectra of free Msi1 (green) and Msi1 in the presence of 0.25mM myricetin or luteolin (blue). Chemical shift perturbations affect a subset of Msi1 residues previously shown to be involved in RNA binding. d) Msi1-luteolin interaction by localized surface plasmon resonance (LSPR). Representative sensograms for a series of luteolin concentrations (cyan, 0.5μM; yellow, 1μM; green, 2μM; blue, 3μM; red, 4μM) show both the association and dissociation phases of Msi1-luteolin interaction. The black lines represent the fitting of data to 1:1 binding model.