Figure 8. Treacle-dependent NBS1 recruitment into the nucleoli mediates rRNA silencing in response to DNA damage.
(a) rRNA transcription was measured by EU labeling after transfection of cells with Treacle shRNA and in the presence of 2 Gy of IR. Error bars represent S.E.M. (3 independent experiments; n represents number of cells analyzed: Con: n =110, 100, 90; shTreacle: n =127, 197, 91; 2 Gy: n = 55, 89, 73; 2 Gy + shTreacle: n = 256, 48, 71). (b) rRNA transcription was measured by EU labeling in the presence of Actinomycin D. Error bars represent S.E.M. (4 independent experiments; n represents number of cells analyzed: Mock: n = 4252, 3848, 3310, 4865; ActD: n = 4113, 3936, 4314, 3975). (c) rRNA transcription was measured by EU labeling after transfection of cells with NBS1-GFP-NOLS. Quantification of signal intensities using ImageJ plot profile (2 independent experiments; one representative image shown). Scale bar: 10 µm. (d) Model of Treacle-NBS1-mediated trans-compartmental communication between sites of DNA breaks and the nucleoli.