Figure 3.

AhR KO compromises IL22-mediated DNA damage response induced by AOM exposure. A: schematic illustration of experimental design. AhR WT or KO mice were injected intraperitoneally with 4 μg IL22 daily for 2 consecutive days. Expression of DNA damage response genes Atm (B), p21 (C), and Puma (D) in sorted colonic stem cells and in sorted colonic progenitor cells (E–G), n = 7 mice per group. H: ɣH2AX formation in distal colonic epithelial cells 12 h after AOM exposure. Insets are representative magnified GFP⁺ crypts. GFP⁺ crypts were quantified. Green, GFP; gray, DAPI; blue, ɣH2AX; red, cleaved caspase 3. Arrowhead indicates cCaspase 3 positive cells. n = 7 mice per group. Scale bar 50 μm. Quantification of ɣH2AX⁺ colon cells (I) and ɣH2AX⁺ colonic stem cells (J) per crypt, n = 107–144 from 7 mice per group. Quantification of cCaspase3⁺ colon cells (K) and Caspase3⁺ colonic stem cells (L) per crypt, n = 107–123 from 7 mice per group. *P < 0.05, **P < 0.01. AhR, aryl hydrocarbon receptor; AOM, azoxymethane; GFP, green fluorescent protein; KO, knockout; WT, wild type.