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. 2023 May 31;9(22):eadf4409. doi: 10.1126/sciadv.adf4409

Fig. 7. FIRRM mediates HR intermediate resolution via MUS81.

Fig. 7.

(A) Immunoblot of BLM-deficient HAP1 cells transduced with nontargeting, FIRRM, or MUS81 targeting sgRNAs. (B) Quantification of SCE frequency in BLM-deficient HAP1 cells treated with the indicated sgRNAs and challenged with 50 nM MMC. n = 2. (C) Immunoblot of HAP1 cells carrying a dTAG at the N terminus of MUS81 either in BLM single knockout (ΔBLM) or BLM and FIRRM double knockout (ΔBLMΔFIRRM) cells. Cells were pretreated with 250 nM dTAG13 for 24 hours, followed by treatment with 50 nM MMC and 250 nM dTAG13. (D) Quantification of SCEs of the conditions depicted in (C). (B and D) Every data point represents a metaphase that was scored blind for SCEs per chromosome per spread. P value was calculated by the Mann-Whitney U test. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001. (E and F) Recruitment of GFP-MUS81 to sites of laser UVA microirradiation after psoralen treatment in HAP1 cells (E). The graph represents the mean of stripe normalized intensity ± SEM for each time point (15 cells). n = 2 (F). (G) Chromatin fractions of wild-type or FIRRM knockout HAP1 cells untreated or treated with MMC at different recovery time points, which were immunoblotted with the indicated antibodies. n = 3.