Journal: bioRxiv
Article Title: Leveraging the BAF chromatin remodeling complex for targeted transcriptional rewiring in cancer
doi: 10.64898/2026.03.30.715217
Figure Lengend Snippet: a , In vitro TR-FRET ternary complex formation assay. The interaction between biotinylated SMARCA4 bromodomain (100 nM) and FITC-labeled BCL6 BTB domain (500 nM) was measured with increasing concentrations of TRIP1. The biotinylated SMARCA4 bromodomain was captured with streptavidin-terbium cryptate donor (SA-Tb, 2 nM), and TR-FRET signal was monitored upon complex formation. The resulting TR-FRET ratio was normalized to the DMSO vehicle control; data represent mean ± SD, n = 2 independent replicates. b , TR-FRET competition assay. The interaction between biotinylated SMARCA2/4 bromodomains (100 nM) and FITC-labeled BCL6 BTB domain (500 nM) was measured in the presence of 100 nM TRIP1 and increasing concentrations of BCL6 or SMARCA ligand. The resulting TR-FRET ratio was background subtracted and normalized to the DMSO vehicle control; data represent mean ± SD, n = 2 independent replicates. c , SplitHalo assay for BCL6-SMARCA2 interaction. Schematic of the in-cell splitHalo assay to probe induced protein-protein interactions (top). A HaloTag enzyme is split into two complementing parts, cpHalo and Hpep3 peptide, which only assemble into a functional self-labeling HaloTag enzyme when actively brought into proximity and supplied with TAMRA dye. HEK293T cells co-expressing BCL6-cpHalo and SMARCA2(BD)-Hpep3 were treated with a dilution series of TRIP1 or negative controls and incubated with compound and the covalent HaloTag dye TAMRA for 3 hours (bottom). Data is normalized to DMSO vehicle control, which corresponds to the baseline signal upon TAMRA addition; data represent mean ± SD, n = 3 independent replicates. d , SplitHalo competition assay for TRIP1-induced BCL6-SMARCA2 interaction. Schematic of the in-cell splitHalo competition assay to probe the inhibition of induced protein-protein interactions (top). Cells are pre-incubated with excess amounts of protein ligands to saturate binding pockets and prevent or reduce ternary complex formation. HEK293T cells co-expressing BCL6-cpHalo and SMARCA2(BD)-Hpep3 were pre-treated with a dilution series of SMARCA or BCL6 ligand for 30 minutes before adding 1 µM TRIP1 and TAMRA dye for 3 hours (bottom). Data is normalized to TRIP1 with DMSO vehicle control without ligand addition, corresponding to maximum ternary complex formation; data represent mean ± SD, n = 3 independent replicates. e , f , BCL6 transcriptional reporter competition. KARPAS-422 cells expressing a BCL6 transcriptional reporter were pre-treated with DMSO, the BCL6 ligand ( e ), or SMARCA ligand ( f ) for 8 hours, followed by co-treatment with 0.5 µM of TRIP1 for 24 hours. Reporter activity is normalized to DMSO vehicle control without TRIP1 co-treatment; data represent mean ± SD, n = 6 independent replicates. g , CaspaseGlo 3/7 apoptosis pre-degradation. KARPAS-422 cells were pre-treated with DMSO or SMARCA degrader (ACBI1) for 8 hours, followed by co-treatment with 1 µM of TRIP1 for 16 hours. Caspase 3/7 activity is normalized to DMSO vehicle control without TRIP1 co-treatment; data represent mean ± SD, n = 6 independent replicates.
Article Snippet: The following antibodies were used: IgG rabbit isotype control (Cell Signaling Technology, CST3900), BCL6 (Cell Signaling Technology, CST49360), SMARCA4 (Cell Signaling Technology, CST49360), H3K27ac (Cell Signaling Technology, CST8173), RNA Pol II Ser2 phospho (Cell Signaling Technology, CST13499), RNA Pol II Ser5 phospho (Cell Signaling Technology, CST13523).
Techniques: In Vitro, Tube Formation Assay, Labeling, Control, Competitive Binding Assay, Protein-Protein interactions, Functional Assay, Expressing, Incubation, Inhibition, Binding Assay, Activity Assay