PMC2605190_01
Clinical pictures of XP2GO at different ages. Note the absence of typical XP skin symptoms except some very mild freckling on the lower lips at age 3 years (a), 10 years (b), 12 years (c), and 15 years (d).
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F1
XP2GO is a 16 year old Caucasian male (Fig. 1).
Post-UV cell survival, assignment of XP2GO to complementation group D, and western blotting. (a) Reduced post-UV cell survival of XP2GO fibroblasts compared to normal control fibroblasts (GM00637) and known XP variant fibroblasts (XP3GO) after irradiation with an increasing UVC dose. Error bars: mean +- SD (n=2). (b) Reduced luciferase expression in XP2GO fibroblasts is complemented by XPD cDNA in a host cell reactivation (HCR) assay. The HCR assay measures the ability of the host cells to repair UV-damaged DNA by assessing the recovery of a reporter gene expression, measured indirectly as enzyme activity of the luciferase reporter gene. The amount of luciferase expression represents the cellular repair capacity for UV-induced DNA photoproducts. Relative luciferase activities (percentage of 1000 J/m2 UVC irradiated vs unirradiated pCMVLuc plasmid) are depicted. (c) No detectable XPD protein expression in XP2GO fibroblasts compared to normal AG13145 fibroblasts. The beta-actin expression served as an internal control.
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XP3GO fibroblasts (Fig. 2a). XP3GO is a known XP variant patient with a cellular deficiency in translesional synthesis but normal nucleotide excision repair. XP2GO fibroblasts showed a reduced nucleotide excision DNA repair capability (Fig. 2b) as reflected by reduced host cell reactivation (HCR) of an UV-treated luciferase reporter plasmid. The cotransfection of XPD cDNA exclusively resulted in enhanced reporter gene activities which clearly assigned XP2GO to the XP complementation group D (Fig. 2b). No XPD protein expression was detectable in XP2GO cells (Fig. 2c).