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. 2013 Feb 28;9(2):e1003277. doi: 10.1371/journal.pgen.1003277

Figure 6. ATM-mediated phosphorylation of CtIP promotes the recruitment of BLM and Exo1 to laser-induced DSBs.

Figure 6

A. EGFP-CtIP variants and mRFP-PCNA were co-expressed in U2OS cells with endogenous CtIP or both CtIP and H2AX silenced by shRNAs. Live-cell imaging of EGFP-CtIP in S-phase cells, marked by PCNA S-phase-associated replication foci [68], was performed following laser-induced microirradiation. Representative cells show the recruitment of EGFP-CtIP WT or indicated mutants to laser-microirradiated disk regions, which are indicated by red circles in the 0 min cell images. Absolute intensity of EGFP-CtIP fluorescence signals at damage sites was determined; error bars, s.d. B and C. Recruitment of mRFP-BLM (B) and Exo1-mRFP (C) to DSBs was monitored in U2OS cells expressing HA-CtIP or Nbs1-Myc variants, with endogenous CtIP or Nbs1 silenced. Representative cells show the recruitment of mRFP-BLM or Exo1-mRFP to microirradiated regions (a disk region for mRFP-BLM marked by a red circle and dots on a line for Exo1-mRFP marked by a red line in 0 min cell images). Absolute intensities of mRFP-BLM or Exo1-mRFP fluorescence signals were determined; error bars, s.d. Western blots show expression of indicated proteins, with Ku70 as a loading control.