Fig. 2. BET proteins promote DNA end resection.

a pDSB was replicated with α³²P[dATP] in reactions containing buffer or JQ1 (BETi). After 45 min, reactions were supplemented with AgeI and samples were withdrawn for 1D gel electrophoresis (n = 4 independent experiments). b, c Quantitation of linear (b) and HMW (c) molecules from (a). d Protein samples from (a) were withdrawn and analyzed by Western blot (n = 2 independent experiments). e, f pDSB was replicated in extract containing buffer or JQ1 (BETi). After 45 min, reactions were supplemented with AgeI. Samples were withdrawn 30 min after enzyme addition and analyzed by amplicon sequencing (n = 2 independent experiments). Results are graphed to show the frequency of insertion products (e), and the frequency of different deletion products (f). g pDSB was replicated in extract supplemented with buffer or JQ1 (BETi). After 45 min, AgeI was added and DNA-bound proteins were isolated by plasmid pull-down. Samples were analyzed by Western blot with the indicated antibodies (n = 2 independent experiments). Non-specific band (*). h pDSB and a control plasmid lacking AgeI sites were replicated in extract. After 45 min, AgeI was added and samples were withdrawn 5 min later for analysis by BRD4 ChIP (n = 3 independent experiments). i Schematic of undigested 2D gel intermediates. The relative position of open circular (OC), supercoiled (SC), and linear plasmids is indicated. An example of resected linear molecules is also shown. j pDSB was replicated with α³²P[dATP] in reactions containing buffer or BETi. After 45 min, AgeI was added and samples were withdrawn 30 min later for 2D gel electrophoresis (n = 2 independent experiments). k Quantitation of linear and resected molecules in (j). Arbitrary units (a.u.). Error bars represent ± one standard deviation from the mean. Student’s two-tailed t test: not significant (ns), p-value < 0.05 (*), p-value < 0.01 (**).