Figure 5.

MSH2 is required for gap filling opposite genomic CPD lesions. (A) MSH2-depleted U2OS cells were exposed to 5 J/m² UVC and immediately pulse-labeled with EdU. Four hours later, cells were fixed and immunostained for CPDs (red) in ssDNA of nuclei (DAPI, blue) in replicating (EdU-positive, green) and non-replicating cells at the time of UVC exposure. Merge represents combined stainings for CPD lesions in ssDNA and for EdU. ‘Non-denaturated’ means no denaturation of DNA with HCl treatment during CPD immunostaining. (B) MSH2-depleted U2OS cells were exposed to 5 J/m² UVC. Four hours later, cells were fixed and immunostained for CPDs (red) in nuclei (DAPI, blue). Merge represents combined stainings for CPD lesions in DNA and for nuclei. ‘Denaturated’ means denaturation of DNA with HCl treatment during CPD immunostaining. (C) U2OS cells transfected with siMSH2 (3′-UTR) were further complemented with either Flag or Falg-MSH2 and then exposed to 5 J/m² UVC. Four hours later, cells were fixed and immunostained for CPDs (red) in ssDNA of nuclei (DAPI, blue).