piggyBac Transposon Somatic Mutagenesis with an Activated Reporter and Tracker (PB-SMART) for Genetic Screens in Mice
Figure 6
Tissue-specific induction of skin phenotypes by Cre-activated PB mutagenesis.
(A) Luciferase signal marks clones of mutated cells in Luc-PB[mut]7;LSL-PBase;K14-Cre mice. (B) PB-induced alopecia in a PB[mut]7;LSL-PBase;K14-Cre; Ptenlox/+ mouse, (yellow dashed line) shows strong luciferase signal corresponding to hair loss (middle). Fully shaved, luciferase signal demarcates the specific region of alopecia (right). (C) Cytokeratin staining (green) of wild-type dorsal skin shows the normal thickness of the mouse epidermis (white arrowhead). DAPI (blue) marks cell nuclei. (D) Staining as in (c) from the region of alopecia reveals substantial thickening of the epidermis (white arrowhead). (E) A transposon insertion upstream of Myc was mapped to the affected region of skin. (F) Skin-specific mutagenesis in Luc-PB[mut]7;LSL-PBase;K14-Cre mice induces tumor formation and luciferase-labeled tumor cells. The white arrow corresponds to region of luciferase signal that develops into a larger tumor over time. Units, photons·s−1·cm−2·sr−1. (G) Insertion sites (wide arrows) in Gli2 were mapped in multiple skin tumors. (H) By quantitative PCR, Gli2 transcripts were upregulated in each skin tumor (BCC1, BCC2, BCC3, and BCC4) compared to WT skin. (I) The skin tumors bear resemblance to human basal cell carcinoma according to histological analysis, consistent with the activation of the Hedgehog pathway (scale bar, 50 µm).