Supplementary Figure 6: Fate of Blimp1 genetically labelled cells during wound healing.

(a) Blimp1-eGfp reporter mouse shows Blimp1 promoter activity in differentiated epidermal layers in undamaged epidermis and in the wound bed. Section of re-epithelialised wound from Blimp1-eGfp mouse stained for Gfp (green) and Itga6 (red). White arrow indicates newly formed dermal condensate in the magnified insert (Gfp channel only). Representative images of n = 3 mice. (b,c) Sections of back skin showing Blimp1 genetically labelled cells (green) in Blimp1Cre cag-cat-eGfp mice stained for Itga6 (red) in homeostatic (b) and hyperproliferative (c) skin. Hyperproliferation was induced by irradiation with 1,000 J m⁻² UVB. White arrows indicate eGfp labelled Blimp1 expressing cells in the differentiated epidermal layers. Representative images of 3 mice. (d) Section of re-epithelialized wounded back skin stained with antibodies to Blimp1 and Krt14. Blimp1 expression is restricted to terminally differentiated epidermal cells in undamaged epidermis and in the wound bed. Inserts with white lines are higher magnification views. Representative images of 3 mice. (e) Differentiated, Blimp1 positive, epidermal cells dedifferentiate during re-epithelialization. Section of back skin showing Blimp1 lineage cells (red) stained with Itga6. White arrows (left hand insert) indicate tdTomato expressing Blimp1 GL cells in the differentiated epidermal layers far from the wound area. In the middle insert tdTomato labeled Blimp1 cells in the dermal papilla are shown. Right insert shows wound edge. The yellow boxed area is further magnified in the right hand panels. Single fluorescent channel images (left to right: dapi, Itga6, tdTomato) of two Gata6 GL cells indicated by the yellow arrows are shown. Representative images of 2 independent experiments. (f–h) Sections of tail (f,g) or back skin (h) at the indicated time points after wounding showing columns of IFE cells derived from dedifferentiation of Blimp1 GL cells (tdTomato). Sections are stained with Krt14 or Itga6. Nuclear expression of Blimp1 (red) is restricted to the suprabasal layers in the wound bed (g, lower panel). Representative images of n = 2 independent experiments. Inserts with white lines are higher magnification views. Dashed lines indicate dermal-epidermal junction. Scale bars, 50 μm (a–f); 25 μm (g,h).